355 N. York Rd., Suite B, Willow Grove, PA 19090

Phone: 215-830-8882 / FAX: 215-830-8922

Operation and Maintenance

of

J.U.M. Hydrocarbon Analyzers

© K2BW Environmental Equipment Services Co. All Rights Reserved.

Introduction:

This manual is intended to provide the instrument technician with information to assist in the operation and maintenance of the J.U.M. model VE-7 total hydrocarbon analyzer. Most troubleshooting and repair work can be carried out by an end-user with good instrumentation skills, using these instructions. This HTML text version is based on our preliminary manual which was never turned into a commercial document. There may be errors or omissions here (we correct them when we find them) for which we are not responsible. We merely present this document as an improvement over the original operator's manual. Also, if you damage your equipment while attempting to follow any directions in this document, you've probably made a mistake. This is the technical document we use to keep a great number of these analyzers (including our own) running and there are no bad procedures in it. Feel free to distribute it for any non-commercial purpose you like but, leave the credits alone. This represents many hours of copyrighted work which is the property of K2BW.

In order to make the most effective use of this information, we recommend that you keep a log of maintenance actions, fuel usage and calibrations (and zero and span potentiometer settings). This will assist you in tracking spare parts usage and may be a helpful reference in troubleshooting as well as setting up minimum back-purge cycles and scheduling periodic maintenance.

Much of the information contained here is applicable to other FID-based analyzers and other analyzers built by J.U.M. in particular the J.U.M. model 3-100, J.U.M. model 5-100, J.U.M. model 3-300 and J.U.M. model 109A. The diagrams for this document will be made available for downloading soon. We may put it all in one zipped Word file. Note that the page breaks were lost in the conversion. It should be easy to put them back. We'll even do it for you, but not right now.


TECHNICAL DATA

Dimensions: Weight: 62 lb. (29 kg)

Width 19.5" (495mm) front panel

Height 8.75" (221mm)

Depth 18.125" (460mm)

Power Requirements: 115 VAC/ 60 Hz/ 1000 Watts

Outputs: 0-10VDC and 4-20mA (standard)

set-point Alarm(s): 1 Amp Potential Free Contact Closure (maximum of two alarms)

Analyzer Ranges: 5 ranges: 0-10ppm(C3H8) to 0-100,000ppm(C3H8) (Standard)

Sample Requirements: Flow: 3 LPM Pressure: Atmospheric (see discussion)

Support Gases:

Fuel Gas: 21psig (see spec. sheet for type); < 0.5ppm THC as CH4

Zero Gas: 15psig Zero Air or N2 < 0.1ppm THC as CH4

Span Gas: 15psig C3H8 in air or N2

(concentration is 80-90% of measuring range)

Purge Air: 75psig (max) Hydrocarbon Free Air or N2

Zero/Span Drift: < 1% full scale per 24Hr.

Linearity: within 1% full scale

Oxygen Effect: < 1% full scale


INSTALLATION: In general, the VE7 works best when run continuously in a clean environment with stable ambient temperatures and clean, stable A/C power. In practice, ideal conditions are rarely achieved and this sometimes causes performance problems in the analyzer. The same applies to the quality of support gases; the analyzer will not perform as well as it should if it must null out a background of hydrocarbon in the support gases.

MECHANICAL: The four mounting holes in the front panel are not to be used to support the full weight of the analyzer. It must also be supported from the rear or underneath. The supplied case handles are rated for 10kg. Handles rated for 30kg are available from K2BW.

POWER: The VE7 should be connected to a separate 15 Amp circuit where possible and never run from an extension cord or a multi-strip if avoidable. Analyzer is intolerant of low line voltage or fluctuating voltage level. It is unlikely that you will be able to power the analyzer and a heated sample line from the same A/C supply circuit.

SUPPORT: All gases supplied to the analyzer in high pressure cylinders should be equipped with pressure regulators capable of providing a maximum of 0-100 psig output to avoid bursting the analyzer's internal tubing in the event of regulator failure or misadjustment. Regulators should also be equipped with a shutoff valve on the low pressure side. Acceptable 1/4" O.D. gas tubing is stainless steel, perfluoroalkoxy alkane (PFA), or fluorinated ethylene propylene (FEP). All regulators and tubing must be scrupulously clean and free of hydrocarbon contamination. Do not skimp on support gas quality. An excessive THC background in Fuel or Zero gases has caused accuracy and sensitivity problems for our customers in the past.

Be especially careful of the quality of compressed air or N2 used to back-purge the sample filter (if applicable). Any oil vapor or water present will be placed inside the sample filter and quickly contaminate the analyzer. While field reality may dictate otherwise, we only recommend bottled Breathing Air or Pre-purified Nitrogen.

Once all support gas connections have been made and leak checked, plumb the sample Bypass fitting to a vent at atmospheric pressure. Care must be exercised if plumbing the FID Exhaust; it must not be restricted and condensed moisture present in the exhaust must not be allowed to flow back into the exhaust port. It should be plumbed to flow downward to an atmospheric vent. The exhaust line may also be heated to prevent the excessive accumulation of condensed moisture.


STARTUP:

IMPORTANT: Visually inspect analyzer for damage and the presence of packing material inside analyzer.

1. Connect analyzer to an A/C power source, set amplifier to range #2 and push Heater button in (green heater LED is on steady)

2. Push TEMP. and AMPLIFIER buttons in to display oven temperature on the analog display. Wait about 10 minutes until the Heater LED (Temp LED in pre-1992 units) begins to flash. Do not attempt to light off analyzer at this time even if fuel supply is already in order. This is due to the temperature sensing arrangement, which may indicate 190 C before the detector and other higher heat capacity components are within operating parameters.

3. Be sure you have connected a cylinder of proper fuel type, inlet pressure to analyzer is 21psig and that any air remaining in the fuel supply line has been purged by loosening the tube fitting at the rear of the analyzer for a sufficient period of time to accomplish this.

4. Leave the analyzer for 30 min, to allow temperature to equilibrate throughout the oven.

5. Be sure the sample inlet is clear and has no tubing connected to it. Push the PUMP and SAMPLE buttons ON. Front panel sample pressure gauge should come up to 200mbar. If pressure does not come to 200mbar in a few seconds, use the regulator adjustment knob directly below gauge to set the correct pressure. Be alert for unusual mechanical noises from pumps if pressure cannot be achieved.

6. Press TEMP button OFF. The analog meter will now read the FID output through the electrometer. Note that when the detector is not lit, the reading is slightly negative.

7. Press the AMPLIFIER button OFF. This is to prevent the destruction of the ignitor which is likely to occur if the AMPLIFIER circuit is on and the ignition is depressed for extended periods as in step #8 below.

8. Depress the IGNITE button for 20-30 seconds. This will open the Fuel Shutoff and Ignition Fuel Flow solenoid valves, allowing the detector to fill with an enriched fuel/air mixture. Proceed now to step #9.

9. Push AMPLIFIER button ON and press IGNITE button for 1 to 2 seconds. Ignition will be indicated by a positive deflection on the analog meter which will drop back down toward zero but will remain more positive than observed in step #6 any time the analyzer is lit. IGNITE LED should turn green at this point.

PROBLEMS LIGHTING:

Problems lighting analyzer can occur for a variety of reasons. They are all easy to troubleshoot and correct if the system is understood. The following is a procedure for determining the cause and making the appropriate adjustment to clear the problem. (Refer to Drawing D-4 and fig. 1)

IMPORTANT: The ONLY proof that the analyzer is lit is the formation of water vapor at the FID exhaust. Using a small mirror or bright piece of metal placed very close to (but not blocking) the exhaust, look for a light distribution of condensation on the object. A heavy or spitting distribution of condensation, coupled with low or no response to span gas indicates burner off peak (rich) or wrong fuel type (i.e. 100% H2 in a mixed fuel analyzer). Correct immediately by supplying proper fuel or re-peaking burner to prevent permanent damage to detector.

1. ANALYZER DOES NOTHING:

(No meter deflection, IGNITE LED stays RED, No condensation at exhaust.)

A). Turn Flame-out set-point potentiometer (R-1) clockwise until IGNITE LED turns GREEN, then back anticlockwise until it just turns RED. Press IGNITE button until IGNITE LED turns GREEN (up to 10 seconds). The ignitor should produce enough heat to turn ignite LED GREEN. This checks the Ignitor and the Flame-out alarm.

If ignite LED doesn't turn GREEN, Ignitor is bad or not getting proper voltage. The Blue and Black wires in the terminal strip adjacent to the FID (but outside the oven) carry this voltage. Voltage of greater than about 4 VAC indicates an open ignitor. No, or very low (<1.0V) voltage indicates a faulty transformer . Verify an open ignitor by disconnecting power to ignitor and measuring for continuity across the ignitor (See IGNITER REPLACEMENT section). Adjust flame-out potentiometer clockwise till IGNITE LED remains green.

B). If ignitor has continuity, voltage is between 1 and 3 VAC, Ignite LED turns GREEN when adjusted as above, check the ignitor's glow. It should be nearly white/orange. If the glow is weak, change to a hotter ignitor. A #4 ignitor should be changed to a #3, etc. If already using a hotter ignitor and glow is weak, the ignitor transformer has become marginal (voltage check above) or there is a loose or corroded electrical connection between transformer and ignitor.

C). If the glow is white/orange, the ignition fuel flow is likely either too high or too low (either case will prevent ignition).

TIP: The ability of the analyzer to sustain a flame once lit may be verified at this point by holding a lighter to the FID exhaust at the rear of the analyzer with the flame-out set-point potentiometer set as above (it should not be necessary to press the IGNITE button). Analyzer should light. If analyzer lights, turn off PUMP switch and allow sample pressure to drop to zero in order to extinguish the flame. Turn the PUMP back on and proceed with the adjustment of the ignition fuel flow.

C). (Continued) While pressing the IGNITE button (limit to 10 seconds), slowly turn the Ignite flow needle valve, first clockwise then anticlockwise until the analyzer lights.

TIP: Turn valve far enough in the clockwise direction so that ignition is achieved while turning in the anticlockwise (opening) direction.

At this point the valve is set a little too far open so back it very slightly in the clockwise direction. Extinguish the flame as above and recheck the analyzer for lighting repeatability.

NOTE: Analyzer, as now adjusted, should relight simply by pressing the IGNITE button. Ignite flow needle valve may be closed further so that the LIGHTING PROCEDURE instructions will still be valid.

2. NO RESPONSE:

(No meter deflection, IGNITE LED turns GREEN, no condensation at FID exhaust.)

A). Start at step C. above.

3. INITIAL RESPONSE, BUT FLAME GOES OUT:

Momentary meter deflection and exhaust condensation, but IGNITE LED stays RED or soon turns RED and meter drops off negative.

A). If IGNITE LED turns RED before meter needle goes negative, turn the flame-out set-point potentiometer clockwise until it stays GREEN when analyzer is lit. When symptom is cleared, reset the flame-out set-point.

B). If meter needle quickly drops below zero even with the flame-out set-point potentiometer set as in 1. A), one of three conditions are likely to exist:

1. Fuel is of wrong type (i.e. 40% H2) or supply pressure is low.

Recheck fuel supply and type, turn supply pressure (at tank) up far enough to rule out a faulty gauge on the regulator. NEVER adjust the two fuel regulators at the rear of the analyzer. Only rarely have they been found to have failed. The correct pressure settings are as follows: Regulator #1; inlet >21psig, outlet 17psig. Regulator #2; inlet 17psig, outlet 10psig.

2. The fuel flow needle valve is misadjusted.

Generally, inspect the fuel and air supply connections inside the analyzer for obvious damaged or disconnected tubing. Euro-nuts should be finger tight only, but not loose. Very carefully adjust the FUEL needle valve clockwise then anticlockwise until flame is sustained. Immediately re-peak flame and re-optimize to avoid heat damage to detector.

3. Coil voltage for the fuel supply shutoff valve is missing.

Check Fuel supply shutoff valve for 28 to 35VDC across the coil when flame-out set-point potentiometer is set to keep the IGNITE LED GREEN. There will be voltage on the coil when either the IGNITE LED is GREEN or the IGNITE button is pushed.

4. LIGHTS, BUT NO RESPONSE:

Little or no meter response, IGNITE LED turns GREEN, condensation at FID exhaust.

A). Check for very light or very heavy (spitting) condensation at the FID exhaust. In either case turn the front panel ZERO potentiometer up until meter reading is slightly positive (this will help quantify a low response). With no input signal, the electrometer should read zero when the ZERO potentiometer is set to 5.00. If meter zeros at 5.00, check the BNC input cable from the FID for proper connection.

1. If condensation is very heavy and you are using 100% H2 fuel, check to be sure the analyzer has not been set up for 40% H2/ 60% He fuel as this is an indication of too much fuel. Otherwise, immediately re-peak flame and re-optimize burner.

2. If condensation is very light, re-peak and re-optimize. It is unlikely that an analyzer set to run on 100% H2 will sustain a flame on a mixed fuel unless it is also far out of adjustment.

You must have a calibration bottle of 700-900 ppm Propane of any accuracy as a minimum to perform any adjustment of analyzer fuel flow. Low concentrations and ambient air are not suitable for peaking the burner for any purpose other than to operation-check the analyzer. You may adjust the ignition fuel flow at will. Do not adjust the burner AIR needle valve if the proper gases for this purpose are not on hand.

Most problems with lighting the analyzer have to do with the flame-out set-point potentiometer being set too low (for too high a temperature). This adjustment is set by the manufacturer based upon a timed temperature drop (flame-out indicated in 60-90 seconds) for a specific set of conditions. The total heat, heater control and flame-out set-point alarm are all affected by variations in line voltage and ambient conditions and it is likely that the flame-out set-point will have to be reset in the field. Set it to indicate a flame-out in 5 minutes or more and this circuit will give no more problems.

An ignitor has an unpredictable service life; it can be adversely affected by high duty cycle use and violent ignition. Keep a spare on hand. Setting the Ignite fuel flow a little rich to avoid loud, "popping" light-offs will help keep the ignitor wire from breaking.

Apply a small drop of thread locker or nail polish between the adjuster threads and the packing nut of needle valves once they have been set. This will keep them from moving if they are loose. J.U.M. solders the locknut in place, effectively disabling it (this is why the heads come off the adjustment shaft sometimes when trying to open the valve). K2BW replacement valves are supplied with functioning shaft locks.

OPERATION:

Upon lighting, the analyzer may output a large (about 80ppm) signal which will gradually diminish. This is normal and should be ignored. Allow the analyzer to run for an hour or two before trying to reset the zero potentiometer to compensate for this offset. Always record the settings of the Zero and Span potentiometer before moving them and lock them down when finished. Span gas may be introduced upon lighting to verify that the analyzer is functioning properly. It should give a reading near what you will expect for the gas bottle concentration (70-120% of target value is not cause for concern; if outside these values, check fuel type and re-peak analyzer immediately).

CALIBRATION CHECK:

Once the analyzer has been running for a minimum of an hour and has "settled down", introduce Zero gas at the sample inlet at atmospheric pressure. The reading should immediately drop. When reading drops to less than 10% of scale, switch to range # 1. When reading stops moving downward, set the indicator to zero with the Zero potentiometer. Switch to a higher range so that the meter movement isn't "pegged" when span gas is introduced. Record the starting and final potentiometer dial values for both the zero and span dials. Introduce Span gas at the sample inlet at atmospheric pressure. Wait a few seconds for full response and adjust the Span potentiometer so that the indicator reflects the tank value. With the completion of the calibration check, analyzer is ready to sample source gases.

BACK-PURGING:

The internal 2.0 micron heated sample filter is cleaned by a pulse of high pressure (<65psig), high purity Air or N2. Connect this supply to the PURGE AIR inlet at the rear of the analyzer. Purging may be accomplished either by the front panel PURGE pushbutton, or remotely, through contacts on the rear panel DB-25 connector (See Drawing D-5). Activation of the purge function closes the sample solenoid valve in the oven to avoid pressurizing the FID. The sample pressure gauge will drop below 150 mbar because of this. Sample pressure in the VE-7P will not be effected.

Purge frequency must be determined by the end user as it is very dependant upon the application. A chart recorder will reveal a cumulative rise in measured THC levels between purges (see fig. 2). This indicates purging should be accomplished more frequently. If purging is not accomplished, the sample filter will clog at some point. Purge the minimum amount necessary. Purge duration should be kept to the minimum necessary. Purging does cool the sample filter. Purging for long periods may cause condensation of sample. If sampling through longer than 50' of tubing or using a probe filter, a heated, atmospheric dump valve may be necessary for effective purge function. This is only likely to be necessary in fixed applications where frequent dismantling of sampling system is impractical.

BURNER PEAK:

Analyzer fuel flow is set to give a maximum response to a given concentration of hydrocarbon bearing span gas. Analyzer response to increased fuel flow forms a bell shaped curve (see fig. 3) as fuel flow is adjusted through response peak. This has to do mainly with the size of the flame and the resulting flame front. Too small a flame presents little surface area while too large a flame crowds into the detector, again producing too little surface area. This adjustment is made at the factory and is verified before shipping to the customer. This valve setting is different for different fuel types and should not vary once set. However, should it become necessary to re-peak the burner, the following instructions are included. The analyzer should be run for at least an hour before re-peaking unless being reset for a different fuel. If setting for a different fuel, peak the burner and optimize once analyzer is lit and again after a couple of hours running (NOTE: change in adjustment, if necessary, will be small).

1. Remove seal wires from the FUEL and AIR needle valves; unscrew and remove valve covers.

2. Introduce a span gas of 800-900 ppm Propane in a background of AIR.

3. With a screwdriver, slowly turn the FUEL needle valve clockwise then anticlockwise for maximum response on the panel meter (NOTE: this is a sensitive adjustment). Proceed directly to flame optimization, if possible.

TIP:

1. Valve adjuster is soft brass so be sure screwdriver fits the slot closely.

2. An analog meter shows this adjustment better than a digital meter.

3. Valve needle seats properly if the final adjustment is made in the clockwise direction.

4. Cap the fuel valve before proceeding.

5. Burner may need to be re-peaked when a new bottle of fuel is supplied due to variation in hydrogen content between bottles.

FLAME OPTIMIZATION:

Analyzer Burner Air flow is set so that varying oxygen content in the sample will have negligible effect on the output. Analyzer response to increasing burner air flow will be increased output (range of adjustment is in the beginning area of a bell shaped curve). This increase in output is unequal for standards of differing oxygen contents however, and this allows the Oxygen Effect to be negated by varying air flow outside the flame. A word about Oxygen Effect: It is the decreased output from an FID due to the presence of O2 in the sample and is likely due to normal combustion taking place before the hydrocarbon molecule reaches the ionization zone of the flame.

Two standards of Propane are required to optimize the flame. They should be nearly the same concentration (800-900 ppm), one in AIR, the other in N2.

1. Immediately after peaking the burner, set the SPAN potentiometer so the indicator reflects the tank concentration.

2. Introduce the N2 backed span gas and adjust the burner AIR so that the indicator reflects the tank concentration.

3. Alternate between the two span gases, adjusting the SPAN potentiometer for the Propane/Air standard and the AIR needle valve for the Propane/N2 standard. The output values will converge.

TIP:

1. Generally, you will be lowering the Span dial and increasing Air flow. Turn each of these adjustments a little past the target value and the adjustment will proceed more quickly.

2. Do not waste the effort to "optimize" beyond the accuracy of the gas standards being used. The analyzer has been set up on a pair of 1.0% accurate gas standards. Gas accuracy errors are additive. For example, if you are using a pair of 2.0% accurate standards, once the analyzer reads within 2.0% of each gas and the gases are reading within 4.0% of each other, it is not possible to achieve greater accuracy with any certainty. You are just as likely to be introducing error into the analyzer.

CHANGING FUEL TYPE

NOTE: A soap bubble type flow meter is required to perform this procedure.

Locate the outlet fittings of the Fuel and Burner Air adjustment needle valves. These are located beneath the panel through which the valves are mounted.

Remove the FKM tubing connection and place the rotameter in series with the plumbing circuit of one, then the other. Adjust the Fuel and Burner Air valves to the following approximate flow settings:

1) 100% Hydrogen: 25 SCCM

Burner Air 350 SCCM

Ignite 60 SCCM

2) 40% H2/ 60% He: 90 SCCM

Burner Air 350 SCCM

Ignite 150 SCCM

3) 40% H2/ 60% N2 100 SCCM

Burner Air 400 SCCM

Ignite 180 SCCM

4) 40% H2/ 60% Ar 150 SCCM

Burner Air 550 SCCM

Ignite 225 SCCM

Re-light analyzer, re-peak and re-optimize using Burner Peak and Flame Optimization procedures.

An expedient method which requires no rotameter may be used. It must be performed quickly and correctly and is presented here for informational purposes only:

1. Gently close the FUEL, IGNITE and AIR needle valves.

2. Open the FUEL needle valve 1/2 turn anticlockwise for 100% H2; 1 turn anticlockwise for mixed fuels.

3. Open the AIR needle valve 2 turns anticlockwise

4. While pressing the IGNITE pushbutton for a maximum of 5 seconds at a time, slowly open the IGNITE needle valve until momentary ignition is achieved (as in PROBLEMS LIGHTING, 1. C) above ).

5. Re-peak burner and re-optimize flame.

OPERATIONAL OVERVIEW: FLOW SYSTEM (Drawing D-6)

The Analyzer flow system is responsible for delivering a precise and repeatable volume of flow into the FID flame per unit of time. A good understanding of the flow components and their interaction will facilitate troubleshooting and maintenance.

Sample is drawn at (or very near) ambient pressure from the rear Sample inlet port directly into the oven. It is filtered through the 2.0u internal sample filter, passes through the Sample solenoid valve and through the Sample pump head. Note that the Purge Air inlet, Calibration gas inlet and Calibration gas overflow ports are all connected on the inlet, before the Sample pump head. The sample gas is positively pressurized after the sample pump and the majority of flow exits the analyzer through the bypass capillary. The bypass capillary restricts flow to set up a positive pressure between itself and the sample pump. The exact value of this pressure is controlled by bringing a supply of air to the point where the sample enters the bypass capillary. The air pressure is controlled by a precision regulator and since, Pneumatically, the sample pump outlet is at the Air regulator outlet, the pressure of all points between the sample pump outlet and the bypass capillary are the same. There are two additional connections in this line. They are the sample pressure gauge and the inlet to the sample capillary. The sample capillary, like the bypass capillary, restricts flow; it will give a repeatable flow at a particular pressure, provided it does not become blocked.

The sample pressure regulator output is also used to supply the FID with a supply of combustion air. The burner air purifier is pressurized at 200 Mbar and the outlet flow from the burner air purifier is metered by the burner air needle valve and the air capillary. The supply of combustion air is delivered to the outside of the flame jet, in what is known as a diffusion flame arrangement.

Fuel enters the analyzer at the rear panel FUEL inlet. The fuel supply pressure must be above 21 psig so that the two fuel pressure regulators can operate properly. The fuel pressure is regulated down and fed to a pair of solenoid valves which are in series. The first valve is the Fuel Supply Shutoff valve which is normally energized by the Flame-out alarm to allow fuel flow when a flame is present. The second valve is a three-way type which allows either the normal or the ignition fuel flow path to receive fuel pressure. Activation of the IGNITE pushbutton energizes both coils, overriding the fuel shutoff and selecting the ignition fuel flow path. Both paths are connected to the inlet of the Fuel capillary. Fuel is mixed with sample immediately prior to entering the FID flame jet.

This arrangement of fixed restrictions and precision fuel and air pressure regulators allows the analyzer to stay on line longer than it would were the sample back-pressure directly regulated. No sample comes in contact with active pressure regulation components. However, this makes it very important that neither the FID exhaust nor the Bypass outlet are restricted in any way. All internal pressure drops are referenced to atmosphere.

OPERATIONAL OVERVIEW: DETECTOR SYSTEM (fig. 4)

The principle of flame ionization is fairly straightforward and a good, basic understanding of detector operation will help troubleshooting a great deal.

When hydrocarbon species are burned in a flame, a fraction of them will ionize into Carbon cations and electrons. This phenomena is exploited in a controlled manner by holding flame shape, temperature, detector geometry and gas flows constant, so that the rate of ion formation varies only with the concentration of hydrocarbon species.

The measurement is made by placing the flame in an electrostatic field, between two plates with a large potential between them. The electrons produced in the ionization are attracted to one plate which is connected to a positive high voltage. The carbon cations are attracted to the other plate which provides a ground through the input of a sensitive current amplifier. When the cations reach the amplifier plate, they pick electrons, become electrically neutral and pass out of the detector. The current produced is measured and amplified as voltage output. From a basic understanding of this principle, the FID may be thought of a carbon counting device in that its response is proportional to the number of carbon atoms present in the sample. For example 100 ppm of C3H8 will give approximately three times the response of 100 ppm of CH4 because propane has three times the number of carbon atoms per unit of volume. For many hydrocarbon species, carbon counting serves as a reasonable model, however it has been shown that a correction factor must be used to correct the response of some species to their expected equivalent response per carbon.

In order for the analyzer output to be meaningful, it must be referenced to some standard molecule which is understood to have a response per carbon atom of 1.0. Generally propane is used for this purpose, though methane is also widely used.

A sample response factor sheet is included in this manual. Response is given in response per carbon atom so the number of carbon atoms in the molecule must be known. All response data is given referenced to response per carbon in propane.

The data given is typical and not suitable for the direct conversion of field data. It is meant only to serve as a guide in developing applications. Do not use other sources of response factor data for direct conversion either. Often, response factor data is given by manufacturers of 2-gas flame ionization detectors. These are fundamentally different from true 3-gas flame ionization detectors in that they do not employ a diffusion type flame (i.e. the sample is predominantly ambient air which provides the oxygen necessary for combustion). They are commonly of the hand held type and the response they give is severely effected by the oxygen content of the sample gas.

A standard FID will not give speciation. If possible, obtain a standard of the target species in 60% to 80% of the expected measuring range. On a properly peaked and optimized FID, the response data generated will be in good agreement with the attached data sheet (within several percent).

FRONT PANEL PUSHBUTTONS: (Drawing D-7)

HEATER: Latching pushbutton which applies A/C power to the oven temperature control card, the oven stirrer fan and the two exhaust fans. The 6.3A fuse for this supply circuit is located in the fuse-holder directly below the switch. The HEATER LED directly above this switch is driven by the output TRIAC on the heater control card. In pre-1992 models, the HEATER LED may be directly driven by the switch and a second LED labeled OVEN TEMP. on the right hand side of the analyzer front panel will be driven by the heater control card.

PUMP: Latching pushbutton which applies A/C power to the Sample and Air pumps and also powers the unregulated 24 VDC supply for operation of all analyzer solenoid valves. The 2.0A fuse for this supply circuit is located in the fuse-holder directly below the switch. The PUMP LED is powered directly by the switch output.

AMPLIFIER: Latching pushbutton which applies A/C power to the +/-15 VDC electrometer power supply, the ignitor/detector bias transformer, and digital panel meter if equipped. The 1.0A fuse for this circuit is located in the fuse-holder directly below the switch. The AMPLIFIER LED is powered directly by the switch output.

IGNITE: Momentary pushbutton which applies 3 VAC to the ignitor (when the Amplifier is on only) and unregulated 24 VDC to the Ignite and Fuel Shutoff solenoid valves (when the Pump circuit is on only). The Amplifier and Pump circuits which supply power to this switch are both fused separately. The IGNITE LED is powered through the double-pole/double-throw relay in the flame out circuit.

SAMPLE: Latching pushbutton which applies unregulated 24 VDC to the Sample solenoid valve through the normally closed contact of the Back-purge pushbutton.

The Pump circuit supplies fused power to this switch. The Sample LED is directly powered from the switch output.

CAL: (ZERO and SPAN switches) Latching pushbutton which applies unregulated 24 VDC to either the Zero or Span solenoid valve. The Zero pushbutton is powered through the normally closed contacts of the Span pushbutton.

PURGE: Latching pushbutton which applies unregulated 24 VDC to the Purge solenoid valve. When applied, it removes operating voltage from the Sample valve.

REMOTE: Latching pushbutton which disables front panel Sample, Zero, Span and Back-purge functions (pre-1994 models) and allows these functions to be performed remotely, via the rear panel DB-25 connector.

TEMP DISPLAY: Latching pushbutton which allows the oven temperature to be read on the front panel meter.

FRONT PANEL DISPLAYS AND ADJUSTMENTS: (Drawing D-8)

ANALOG PANEL METER: Standard analyzer indicator will read in percent of selected full scale. Will read oven temperature if the TEMP DISPLAY pushbutton is actuated. Concentration reading is a straight voltage input from the FID Amplifier output.

DIGITAL PANEL METER: Optional analyzer indicator. Functions identically to analog meter but has an additional gain adjustment on the indicator circuit board to correct display to the output voltage.

SAMPLE PRESSURE GAUGE: Indicates the pressure at the sample capillary. In a properly functioning analyzer, this is 200 mbar while sampling.

SAMPLE REGULATOR: Used to establish and correct the sample pressure to 200 mbar. Also used with the sample pressure gauge to checkout and troubleshoot analyzer flow system.

RANGE SWITCH: This six-position rotary switch is used to assign a full scale value to the analyzer 10 VDC and 4-20 mA outputs. In standard analyzers ranges #5 and #6 are internally hard-wired together, limiting the available number of ranges to five.

ZERO DIAL: 10-turn indicating dial potentiometer which is used to assign a "zero" value to the minimum detector output. In a properly functioning analyzer, the dial setting will be between 4.40 and 4.80, indicating that a small amount of baseline current is being zeroed.

SPAN DIAL: 10-turn indicating dial potentiometer which is used to set the overall gain of the FID amplifier. In a properly functioning analyzer, the dial setting should be below 6.00 indicating that the signal from the detector is strong enough and does not need excessive amplification.

TEMP. ADJUST: 10-turn potentiometer which is used to adjust the oven temperature. set-point is increased in the clockwise direction and should only be adjusted while watching the temperature display as the range of adjustment is large.

REAR PANEL PLUMBING CONNECTIONS: (Drawing D-9)

SAMPLE INLET: 1/4" tube connection to supply analyzer with sample at atmospheric pressure.

BYPASS: 1/4" tube connection to vent excess sample to atmosphere. Bypassed sample is diluted with some of the air used as a pressure reference and is not suitable for further analysis. Do not restrict this port.

FID EXHAUST: Modified 6.0 mm Euro type tubing connector which vents combustion byproducts away from the FID detector. Must be left open or plumbed to an atmospheric vent (see SUPPORT in INSTALLATION section). Do not restrict this port.

PURGE AIR: 1/4" tube connection to supply the analyzer with a 50 to 75 psig source of Hydrocarbon Free Air or N2 for purging contamination from the internal sample filter. See TECHNICAL DATA section for purge air specs.

ZERO GAS: 1/4" tube connection to supply the analyzer with a 15 psig source of Zero gas. See TECHNICAL DATA section for zero gas specs.

CAL GAS OVERFLOW: 1/4" tube connection to vent excess calibration gas to atmosphere.

FUEL GAS: 1/4" tube connection to supply analyzer with a 21 psig source of fuel gas. Check the rear panel Fuel Gas Tag for correct fuel type.

SPAN GAS: 1/4" tube connection to supply the analyzer with a 15 psig source of Span gas.

AMBIENT AIR: 1/4" tube connection to supply the analyzer with a source of ambient air at atmospheric pressure for use in the burner air supply. Hydrocarbon Free Air may also be used if supplied at atmospheric pressure or if the analyzer has been modified to work this way.

REAR PANEL ELECTRICAL CONNECTIONS: (Drawing D-10)

A/C INPUT: Power cord input for 115 VAC/ 60 Hz. A separate 15 A supply for each analyzer is necessary for proper operation.

0-10 VOLT OUT: Phono jack connection to supply a proportional 0-10 VDC signal corresponding to the analyzer's concentration output. Output comes directly from the FID amplifier output. Avoid shorting this output as it will cause both the front panel meter and the current output to read zero concentration.

4-20 mA OUT: Phono jack connection to supply a proportional current signal similar to the 0-10 VOLT OUT. The circuitry to provide this signal and its two adjustment potentiometers are located on the main board. Input signal to this circuit is the 0-10 VDC output from the FID Amplifier.

EXTERNAL RANGES AND EXTERNAL VALVES: 25-pin D-subminiature socket connector used to provide range identification output contact closure outputs and remote range change inputs. Also available on this connector are the connections to remotely control the valve functions (Sample, Zero, Span and Back-purge). See Drawing D-5 for connector pinout.

ALARM OUTPUTS AND OPTIONAL OUTPUT SIGNALS: 25-pin D-subminiature socket connector used to provide flame out, concentration set-point and sample pressure alarms. Also available on this connector are optional voltage outputs proportional to oven and sample filter temperatures. See Drawing D-5 for connector pinout.

SUB ASSEMBLY ACCESS:

GENERAL: Turn off Heater, Pump and Amplifier pushbuttons and remove the A/C power input cord from the rear of the analyzer. Allow the analyzer to cool for at least 30 minutes before attempting to gain access to components internal to the oven. Retain all hardware and replace missing hardware with original metric replacements. All hardware is listed on the spare parts list and may be ordered from stock. Remove the (6) six cover screws from the top of the analyzer using a 2.5 mm hex key. Set the analyzer lid and hardware aside. Be sure the analyzer has enough room above it to allow proper use of the correct tools.

OVEN: (see Drawings D-11 and D12) Remove the (2) two brass thumbscrews which secure the Burner Air Purifier Tube to its supporting cross-member. Cut and remove the (2) two wire ties from the assembly, if present. Lift the Burner Air Purifier Tube up and over the supporting cross-member and rest it horizontally toward the front of the analyzer.

Remove the (2) two M-4 nuts and the single screw from the fan shroud and lift fan shroud from the oven lid. Remove the (2) small nuts from the cover for the (P1) electrical connector on the left-hand side of the oven lid and remove the cover. Cut and remove the wire tie which secures the two halves of the 21-pin connector and separate the cable side of the 21-pin connector. Carefully set it out of the way at the side of the oven. Inspect the connector for cracked or broken pins upon re-assembly. Locate the heater controller circuit board against the inside R.H. analyzer wall above the oven lid. Remove the (2) two threaded keepers which secure the circuit board and lift the board up and away from inside wall. Set circuit board aside.

Remove the (4) screws from the perimeter of the oven lid using a 3.0 mm hex key. Simultaneously pull the oven lid up and forward so that the lid clears the rear cooling fan housing and the heating coil mounted to the underside of the lid clears the lip of the oven front wall. Set the oven lid assembly aside, upside down, on its top.

NOTE: The heating coil may snag on the front wall of the oven. This is because the coil has bent downward over time. Forcing it may bend it further so try to work it front and back to get clearance. If it becomes necessary to bend the heating coil back upward to avoid future removal difficulty, be sure that the stirrer fan blades turn freely to clear both the oven lid and the heating coil. Re-check this clearance immediately prior to re-installing the lid assembly.

If the blades are clear and turning the fan by hand reveals a worn or "dry" bearing, replace the oven stirrer fan. Never attempt to oil this or any other bearing in the analyzer, especially with the assembly still in the analyzer.

SAMPLE PUMP REMOVAL:

Open the oven as above to gain access to the sample pump inlet and outlet fittings. Use two wrenches to stabilize the tube fitting bodies at the pump head and remove the 1/8" tube nuts from the fittings.

NOTE: Both the body and the tube nut take 7/16" wrench.

Locate and remove the (4) four short screws which mount the pump through the bottom plate of the analyzer. Disconnect the two power leads from the terminal strip (TB1); cut and remove wire ties as necessary. Carefully back pump-head out of the side of the oven while lifting pump free of analyzer.

SAMPLE PUMP DISASSEMBLY: (See Drawing D-13) Use a 3.0 mm hex key to remove the (4) four head screws. Use a permanent marker to draw a line down one side of the head/frame assembly while pump is still assembled.

Use a heat gun to warm the head section until the Top plate section separates from the chamber plate with minimal force. Use a razor knife for this purpose rather than a screwdriver to avoid damaging these parts. Use this technique to free the chamber plate from the diaphragm and diaphragm support plate. Use tweezers to remove the two O-rings at the top of the chamber plate. Work on the flexible parts only to avoid damaging the chamber plate. A tooth pick and heat gun are helpful in chasing bits of broken O-ring out of the O-ring groove. Using tweezers only, pinch the two flapper valves and remove them. Remove the diaphragm hold down screw, heat and remove hold down plate and support from diaphragm.

Always replace all of the flexible parts whenever opening the pump head. Pump re-assembles in reverse order and should be turned by hand and inspected for worn or "dry" motor and connecting rod bearings. Replace these items rather than attempting to oil them to avoid contaminating the analyzer. Note that the motor is not available from any source that we are aware of as a spare part. Proper head-space is essential for reasonable component life and is indicated by smooth, nearly equal resistance to rotation through both top-dead-center and bottom-dead-center. There should be some resistance at both top-dead-center and bottom-dead-center but no binding or "knocking". Head-space is adjusted by loosening the (2) two screws on either side of the motor shaft and moving the head support frame up or down along its slotted mounting holes. This adjustment is critical. Be sure to re-tighten and re-check when complete.

PUMP REPAIR KIT: Contains all of the flexible components in the sample pump. All parts should be replaced at one time, whenever degradation of pump performance indicates a rebuild (See pump performance specs.). Repair kit parts replace the originals exactly, but a few points of assembly technique should be noted: New flapper valves are installed rough side out (smooth side against the valve seat). Install flapper valves by folding between thumb and forefinger and inserting the ends of the valve into the slots beneath the split keeper ring. Avoid the use of tools which may nick or puncture the valve.

SAMPLE FILTER HOUSING REMOVAL: (Drawing D-14) Open the oven as above to gain access to the tube fittings which secure the sample filter housing. After completely loosening the (2) two 1/4" tube nuts from the run tee at the front of the housing, completely loosen the (2) two 1/4" tube nuts and the 1/8" tube nut from the modified run tee at the rear of the housing. Secure the housing firmly with free hand while loosening these fittings. It may be necessary to tap the fittings with a light plastic mallet to free the tube from the connector. Do not use a metal object for this purpose.

When all (5) five tube connections are free of their tubes, disconnect the sample inlet bulkhead securing nut and remove the sample bulkhead fitting. This will provide enough room to remove the sample filter housing (on older models this may not be possible; it will be necessary to remove the securing hardware from the front oven wall and move the oven wall forward to get clearance). Pull the sample filter housing free of the oven.

Replacement is in reverse order but all tube nuts should be hand fitted and tightened before final tightening with a wrench and the entire assembly should be pressurized and leak checked as follows: With assembly installed, pressurize the sample inlet port with 15 psig of Air, N2 or He. Use a liquid leak detector at all fittings between the sample inlet and the sample solenoid valve inlet. Also check the sample filter housing O-ring seals.

SAMPLE FILTER HOUSING DISASSEMBLY: (Drawing D-15) Orient the housing assembly so that the two halves are stacked one above the other and gently secure the lower half in a soft jawed vise. Remove the (4) M-3 nuts from the through screws and set the nuts and screws aside.

Warm the housing with a heat gun while exerting slight pressure between the two housing halves with a razor knife. When the entire housing is sufficiently warmed up, it will come apart easily. Housing will be uncomfortable to touch so handle it by the tube connections.

Continue to warm the half still clamped in the vise in order to make the O-rings easy to remove. If filter plate remains in this half, it will come out easily when it is warm enough. Avoid prying the filter plate; it won't seal well with even small dings in it. Repeat this procedure for the other half of housing if the filter plate or any O-rings remain in it.

All of the O-rings must be replaced whenever the housing is apart. Completely remove any bits of the old O-rings which may have stuck in the O-ring grooves. A heat gun and toothpick are useful for clearing the O-ring grooves and will not scratch the sealing surfaces.

Assembly is in reverse order. Tighten the clamping through screws evenly.

FID REMOVAL: Removal of the FID assembly is normally accomplished only for replacement of FID, cleaning of FID base or sample capillary replacement.

NOTE: Actions involving replacement or opening of the FID must be done in a properly equipped, clean workplace. This must include the fuel and calibration gases necessary to evaluate repair effectiveness, re-peak and re-optimize analyzer. These facilities are not normally found at the customer level and the presentation of this material does not imply that incomplete facilities are adequate.

Open oven as above to gain access to the (3) tube fittings which secure the FID assembly. Disconnect the signal BNC connector (J4) at the FID amplifier. Disconnect the (6) six wires from the FID assembly at the terminal strip (TB3) outside the oven. Disconnect the fuel and air tube nut connections inside the front oven wall with an 8 mm or 5/16" wrench. Disconnect the 1/8" sample capillary tube nut at the end opposite the FID with an 11 mm or 7/16" wrench. Remove the (2) two upper and loosen the (2) two lower screws which secure the FID mounting plate to the front oven wall and lift the FID assembly up and out of the oven.

FID assembly installs in reverse order but hand tighten all tube fittings before final wrench tightening.

FID DISASSEMBLY: (Drawing D-16) The FID assembly can be broken down into two sub-assemblies: the base and upper detector. In addition, the upper detector lid may be removed. This will allow the inspection of internal components, limited cleaning of upper detector and the replacement of ignitor and flame-out thermistor. No further disassembly of the upper detector should be attempted.

NOTE: The wiring connections into the detector are permanent and cannot be accessed. The modified Euro-nut connectors should not be disturbed for any reason. The two screws to separate the lid from the upper detector and the base from the upper detector both take a 2.5 mm hex key.

Use window cleaner and cotton swabs to clean the upper detector Teflon insulator, detector body and detector plates. Avoid soaking the inside of the detector which must be completely dry before placing into operation.

REPLACEMENT OF FLAME OUT SENSOR: It will be necessary to replace the flame-out thermistor if it becomes damaged or insufficient adjustment is available for the flame out circuit and the sensor is at fault. Open the oven as above and remove the lid from the FID. Remove the 1/8" tube nut from the FID flame-out sensor connection outside the front oven wall. Pull the thermistor assembly out of the port. Disconnect the two wires from the terminal strip (TB3); cut wire ties as necessary. Install new thermistor assembly and align as follows: Position directly over center of detector or slightly toward the FID exhaust port so that the presence of a flame will produce the greatest heating on the sensor. It may be necessary to slightly adjust this position with analyzer running and lit.

FID BASE DISASSEMBLY: The FID base may be removed for ultrasonic cleaning. In addition, the flame tip may be replaced if blocked, bent, corroded, or if cleaning is unsuccessful. Do not disassemble the flame tip from the flame base unless it is being replaced. The flame tip is held by a length of 3 mm O.D. (approx. 1/8" O.D.) Teflon tubing which is clamped into a modified tube fitting by a modified tube nut. To remove the modified tube nut without damage, clamp the nut in a large drill chuck and use an 11/16" wrench on the flame base. install the new flame tip exactly as the old, using the new Teflon tube and ferrule.

NOTE: Flame tip end should extend approx. 1/2" to 9/16" above the securing nut. Always replace the flame base O-rings whenever base is removed.

IGNITER REPLACEMENT: (Drawing D-17) Open the oven as above and remove the lid from the FID. Leave the FID otherwise installed.

NOTE: The ignitor may be visually checked for glow at this point by carefully reconnecting the A/C power cord, turning the AMPLIFIER on and depressing the IGNITE pushbutton.

Use an 8 mm (5/16") wrench to keep the body of the ignitor from turning while removing the ignitor lead nut with a 7 mm (9/32") wrench, then use the 8 mm (5/16") wrench to unscrew the ignitor from the FID housing. Hand tighten the new ignitor into the FID housing before final wrench tightening. Visually check the new ignitor for proper glow before re-installing the FID lid. Disconnect the A/C power cord before proceeding.

SAMPLE CAPILLARY REPLACEMENT: When low or wandering response indicates a dirty or plugged sample capillary, it must be replaced with a new one. Cleaning sample capillaries in ultrasonic cleaners has not produced long-lasting, effective repair and is not recommended. Remove FID assembly as above and use an 8 mm wrench to remove the sample capillary. Install new sample capillary tightening the tube nut by hand before final wrench tightening.

BYPASS CAPILLARY REPLACEMENT: When a broken or plugged bypass capillary is indicated, it must be replaced with a new one. Repair or cleaning is not recommended as often scale is left or created to which new contamination will adhere. Open oven as above and locate the bypass capillary near, or attached to, the bypass bulkhead fitting. Stabilize the bypass tee with a wrench and remove the bypass capillary 1/8" tube nut from the bypass tee. remove the 1/16" tube nut from the bypass bulkhead fitting and pull the bypass capillary free. Install the new bypass capillary in reverse order, tightening the tube nuts by hand prior to final wrench tightening.

SAMPLE VALVE REMOVAL: The Sample solenoid valve may be removed for replacement or ultrasonic cleaning in deionized water. Open oven as above, stabilize valve body from turning and loosen the two tube nuts attached to the valve. Remove the solenoid operator securing nut and slide the solenoid forward off the operator. Remove the (2) screws through the outside of analyzer case wall which secure the front oven wall. Remove the brass thumbscrew adjacent to the air pump cooling impeller which secures the front oven wall to the L.H. oven wall. Tilt the front oven wall forward enough to free the internal oven tubing from the tube fittings on the sample valve. It may be necessary to tap on the fittings to free the tubing from the fittings. Do not use a metal object for this purpose. Rotate valve body slightly to clear oven tubing and remove back through the oven. Valve installs in reverse order. Hand tighten tube fittings before final wrench tightening.

AIR PUMP REMOVAL: Loosen the small hose clamp on the pump output tube and gently pull both the inlet and outlet tubes free of the pump head. Disconnect the power leads from the terminal strip (TB1). From beneath the analyzer, locate and remove the (4) short screws which secure the pump head to the analyzer floor. Pull the pump free of the analyzer. Pump will install in reverse order.

NOTE: There is play in the mounting hardware. It is possible to install the pump so that the cooling impeller rubs against the Oven, preventing it from turning freely. Also the impeller will rub on the analyzer floor if the mounting screws are loose. Orient the pump to allow proper clearance. If the pump is not free to turn, it will either not operate or it will overheat the motor windings.

AIR PUMP DISASSEMBLY: (See Drawing D-18) Use a 3.0 mm hex key to remove the (4) four head screws. Use a permanent marker to draw a line down one side of the head/frame assembly while pump is still assembled.

The top plate separates from the chamber plate with minimal force. Use fingers or a thin, wide-bladed screwdriver for this purpose. Work on the flexible parts only to avoid damaging the plastic pump head parts. Using tweezers only, pinch the two flapper valves and remove them. Remove the diaphragm hold down screw, hold down plate and support from diaphragm.

Always replace all of the flexible parts whenever opening the pump head. Pump re-assembles in reverse order and should be turned by hand and inspected for worn or "dry" motor and connecting rod bearings. Replace these items rather than attempting to oil them to avoid contaminating the analyzer. Proper head-space is essential for reasonable component life and is indicated by smooth, nearly equal resistance to rotation through both top-dead-center and bottom-dead-center. There should be some resistance at both top-dead-center and bottom-dead-center but no binding or "knocking". Head-space is adjusted by loosening the (2) two screws on either side of the motor shaft and moving the head support frame up or down along its slotted mounting holes. This adjustment is critical. Be sure to re-tighten and re-check when complete

PUMP REPAIR KIT: Contains all of the flexible components in the air pump. All parts should be replaced at one time, whenever degradation of pump performance indicates a rebuild (See pump performance specs.) Repair kit parts replace the originals exactly, but a few points of assembly technique should be noted: New flapper valves are installed rough side out (smooth side against the valve seat). Install flapper valves by folding between thumb and forefinger and inserting the ends of the valve into the slots beneath the circular wire keeper ring. Avoid the use of tools which may nick or puncture the valve.

FID AMPLIFIER REMOVAL: The FID amplifier may be removed for replacement. Repair of the amplifier is not normally feasible due to the extremely high values of the feedback resistors and the requirement that the feedback paths be absolutely clean. Twist and remove the input BNC connector (J4). Unscrew and remove power and output connector (J5). Use a 1.5 mm hex key to loosen the Zero and Span indicating dials and remove dials from the potentiometer shafts. Use a small screwdriver or thumbnail to pry the end cap from the Range selector knob. Use a common screwdriver to unscrew the brass tensioner enough to pull the knob from the shaft. Use a 14 mm (9/16") wrench to remove the jam nuts from the Zero and Span potentiometer bodies, remove dial locators and remove the FID amplifier from the inside of the analyzer. Install new amplifier in reverse order with the following exception: Before re-installing the indicating dials, set them to 0.00 and turn the potentiometer shafts fully anticlockwise After dial set screws are tight, set both dials to near 5.00 and range selector above range #1 (to avoid pegging meter) before applying power.

MOTHER BOARD REMOVAL: (See Drawing D-19) The mother board may be removed for repair or replacement. It is generally not necessary to replace this board unless it severely physically damaged. It is straightforward electrically and no extraordinary skill or electronic knowledge is necessary to troubleshoot symptoms isolated to this board. The (10) ten mounting screws for this board can be removed through the L.H. analyzer case wall with a 2.5 mm hex key. The threaded standoffs are retained on the board. Connectors P9, P2A and P2B and other alarm connectors should be carefully disconnected and placed where they will not snag on the board during removal. Disconnect P1 last while lifting the board up and away from the analyzer case wall to clear the A/C RFI filter. Cut wire ties as necessary.

NOTE: When re-installing mother board, be sure that the analyzer tubing isn't caught under it. Also, be sure of the positioning of the cable mounted connectors before applying power as they are not keyed to prevent reversal. If testing repair before final securing and wire tie installation, be careful in the power supply area; high voltage could be present after removal of input A/C.

PERIODIC MAINTENANCE: There are a few items of maintenance which do not need to be indicated by a degradation in analyzer performance.

GENERAL CLEANING: It is a good idea to keep the analyzer clean. It will be last longer and if there is a failure, repair actions are less likely to contaminate the analyzer. As a minimum, the analyzer should be blown out with a clean source of 25 psig Air. With the power off and the sample and ambient air inlets blocked, gently blow the dust out of analyzer internal surfaces. A soft brush is useful for removing dust from corners, etc. A vacuum cleaner and brush is also effective. The solenoid valve operators and pump motor field windings will benefit the most from being free of an insulating dust layer. Wipe down external surfaces with window cleaner or similar non-organic based cleaner. Inspect tubing for holes, cracks or heat discoloration. Replace as necessary with the proper exact replacement tubing. Inspect internal electrical connections for cracks, frayed conductors and heat discoloration. Replace as necessary to insure connection is clean and tight. During the course of cleaning and inspection, damaged or missing hardware should be replaced with original metric replacements.

BURNER AIR PURIFIER: (Drawing D-20) The glass wool packing and charcoal should be changed yearly in the absence of an indicated failure as follows: Remove the purifier tube from analyzer (See Sub-Assembly Access section). Remove both flat end caps from tube by removing the (6) screws which secure each of them. Wash out the tube with soapy water and a bottle brush and rinse thoroughly so that no soap remains. When tube is completely dry, re-install one end cap and insert enough glass wool inside, against that end, to completely cover the tubing port and prevent charcoal fines from exiting. Fill tube with fresh charcoal (about 100g), leaving enough room to completely cover the other tubing port.

NOTE: Charcoal fines must not be allowed to exit the purifier tube. It could eventually reach the detector and cause erratic readings.

DUST FILTER: The dust filter on the inside of the Ambient Air inlet should be changed about twice a year, though its useful life-span is entirely dependant on ambient air dust loading. The filter should be replaced as a unit, as the housings are designed for one-time assembly. Replacement is straightforward. A spare should be kept with the analyzer.

TROUBLESHOOTING: This section relies on troubleshooting flowcharts.

In order to properly troubleshoot, it must be determined that the analyzer has had an event-related failure. Trouble symptoms which may be induced by the operator (i.e. improper valve, regulator or potentiometer settings) should be cleared before proceeding with these instructions.

SAMPLE PRESSURE:

The most common trouble symptom is the inability to maintain the 200 mbar analyzer sample pressure necessary for proper operation. This can be the result of various conditions, so the most effective approach is to rule out as many potential causes as possible, as quickly as possible.

The sample and air pumps should be the starting point of symptom investigation. In general, sample pressure problems are the result of:

1. Blockages on the inlet side of either pump

2. Pump failure or degradation

3. Leaks and blockages at the outlet of either pump

The Pump Performance Curves chart will help determine if a pump is at fault or if a pump rebuild has been effective.

Before tearing the analyzer apart, a few quick checks can determine where to start:

1. Set analyzer for normal operation as in the STARTUP CHECKLIST.

2. Be sure the Sample inlet is clear and disconnected from any external assembly or tubing.

3. Sample demand should be in the range of 3.5 to 5.0 LPM; this can be measured by attaching a rotameter to the sample inlet.

If the sample demand is low, check for operating voltage on the coil of the sample solenoid valve. There should be an audible "click" when the valve operates. If these conditions are present, it is expedient to first inspect the sample filter as in SUB-ASSEMBLY ACCESS and clean or replace the sample filter if necessary.

Check sample path tubing connections in the oven for a leak or blockage before removing the sample solenoid valve. If it is necessary to remove the sample solenoid valve, consider replacing it. Cleaning or rebuilding is only recommended for cases of minor contamination. The O-Ring seal in the sample solenoid valve should be soft and flexible; if it is hard and brittle, the seal must be replaced.

AIR CIRCUIT:

If the sample demand is in this range and sample pressure is still low after disconnecting the analyzer from the sampling source, the problem is almost certainly in the Air circuit.

Check the air circuit tubing for kinks, pinched sections which can block air flow, loose fittings and broken tubing. Disconnect the dust filter assembly from the air pump inlet and inspect for filter loading.

If sample pressure remains low, rebuild the air pump according to the instructions in the Sub-Assembly Access section. Check the pump before re-installing. Inspect the sample pressure regulator or swap it with a spare to rule it out as a source of failure (the normal failure mode is low pressure; either blocked or over-relieving).

If sample pressure remains low, or if the symptom is only slightly improved, jumper the burner air purifier tube out of the air circuit by connecting the inlet and outlet tubes together. If symptom clears, rebuild the burner air purifier according to the instructions in the Periodic Maintenance section.

Re-install the dust filter assembly; if the sample pressure drops, replace the glass wool and filter element as in the PERIODIC MAINTENANCE section.

Anytime there has been a failure in the air circuit, it is possible that wet or corrosive sample has back-flushed through the air circuit. Always inspect the sample pressure regulator for evidence of sample contamination at the vent hole in the rear of the regulator. If there is evidence of back-flushed sample, rebuild the burner air purifier tube. Sample pressure should adjust smoothly up to about 180-210 mbar when analyzer is cold and 240-260 mbar when analyzer is hot.

WON'T LIGHT OR STAY LIT:

Refer to the STARTUP and PROBLEMS LIGHTING sections.

ZERO/SPAN DRIFT:

Excessive drift is generally the result of:

1. Analyzer contamination with H2O or heavy hydrocarbon bearing particulate.

2. Oven temperature variation

3. Low or varying A/C line voltage

4. High, low or varying sample pressure at the analyzer sample inlet.

5. Loose or leaking tubing connection (usually in oven).

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