Detcon 971-071170-LRY - Manual (Page 5)

If the air flow falls below a user definable predetermined set point the following will occur: the flow
fault/liquid level alarm relays will energize; an LED indicator mounted on the flow fault/liquid level PCB
will illuminate; and the door mounted fault indicator lamp will illuminate.
If liquid accumulates within the internally mounted liquid level module to the point where there is a
danger of the liquid being sucked up into the pump, all of the circuit functions that occur during a flow
fault condition will take place because power to the pump is wired through the flow fault/liquid level
relay contacts. To remedy this situation, drain the liquid from internally mounted liquid level module by
unplugging the connector attached to the liquid level assembly and then remove the cable assembly from
the liquid level assembly by unscrewing it. Allow all the moisture to drain then re-connect the cable assem-
bly. The external moisture filter container should also be inspected and emptied of excess moisture.
Flow Fault/Liquid Level Setup
Because the pressure inside the sample and vent flow tubing differs according to the tubing length , the
flow fault circuit will require calibration after installation. Follow the instructions below to calibrate the
flow fault circuit. The liquid level circuitry does not require any set-up or maintenance.
To calibrate the flow fault circuit, first determine at what point it is desired that the flow fault circuit is
to be activated. Typically, air flow should range between 500 and 1000 ml/min. (milliliters per minute) as
seen on the flow meter located on the left of the enclosure. It is recommended that the flow fault circuit be
set to activate at a flow of approximately 300 ml/m.
To adjust the flow fault, first set the air flow to the point where you want the fault condition to activate.
Next turn the flow fault adjust potentiometer (see illustration on previous page) clockwise until the flow
fault LED illuminates and its relay fires. Make adjustments as necessary by increasing and decreasing air-
flow until the flow fault function occurs at the desired set point. Once the flow fault circuit has been set,
return the air flow to between 500 and 1000 ml/m.
NOTE: Because sample and vent tubing can become congested over a period of time, the flow fault func-
tion should be checked periodically and adjusted if necessary.
1.4 CALIBRATION
Model 971-071170-LRY sensor assembly is calibrated prior to shipment and should therefore require mini-
mal adjustment at time of commissioning. However, it is recommended that a complete calibration be per-
formed on a periodic basis to assure optimum system performance. Refer to the sensor instruction manual
for gas type, range and sensor specific calibration instructions.
Note that the sensor instruction manual requires the removal of rain/splash guards for the application
of gas. This requirement will be superceded by the instructions below. The calibration adapter attached to
the sensor head should not be removed during calibration.
Required material:
1. Span gas cylinder containing gas as per instructions in the sensor instruction manual.
2. 1/4" Tee tubing fitting as shown in the illustration below.
To Calibrate: (refer to illustration on the following page)
1. Turn the 3-way valve so that the arrow is pointing down. Sample is now being drawn from the CAL port.
2. Using the 1/4" Tee assembly, connect the span gas cylinder to the calibration port. Note that the cylinder
flow rate should be 1000 ml/m while the sample draw flow rate should be adjusted to 500 ml/m. This will
assure that the sample is not diluted. Be sure to ad the 6” vent tubing as shown to prevent dilution.
3. Follow the calibration instructions given in the sensor instruction manual.
4. Close cylinder valve to allow clearing/zero stability. Note that zero and span functions may interact
slightly with one another. Zero and span tests may be repeated 2 or 3 times as necessary.
5. When calibration is complete turn the 3-way valve so that the arrow is pointing up.
Detcon Model 971-071170-LRY Gas Detection System PG.5