Detcon 971-071170-0DL - Manual (Page 8)

Model 971-071170-0DL
3. Start Up
Upon completion of all tubing connections and field wiring turn on the power switch located on the enclosure
door. Note that the power lamp illuminates. If applicable, note that the sensor LCD indicator activates.
Varying readings may occur during sensor warm-up. Allow approximately 1 hour to stabilize (24 hours is
best).
Set sample flow through the flow meter. Adjust the sample flow meter as necessary to achieve the desired
dilution. Adjust the air flow meter as necessary to achieve the desired dilution. Assure that all field tubing
connections are secure by obstructing the end of the sample line and observing that the flow meter decreases to
“0” flow.
3.1 Flow Fault Detection
Flow fault detection consists of a flow fault circuit assembly located inside the enclosure and a door mounted
fault indicator lamp. If the diluted air/sample mixture flow falls below a predetermined set point the following
will occur: the flow fault alarm relays will energize; an LED indicator mounted on the flow fault PCB will
illuminate; the door mounted flow fault lamp will illuminate; the 4-20mA signal will be opened via relay #1 on
the flow fault circuit board (this will allow for flow fault programming at the remote recording device or
computer.
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.
To calibrate the flow fault circuit, first determine at what point it is desired that the flow fault circuit is
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:
1. Set the air flow at the point where you want the fault condition to activate.
2. Turn the flow fault adjust potentiometer (PT1 as seen in the illustration on the previous page)
clockwise until the flow fault LED illuminates and its relays fire. Make adjustments as necessary by
increasing and decreasing airflow 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 function should be checked periodically and adjusted if necessary.
4. Calibration
Model 971-071170-0DL Sample draw with sensor assembly is calibrated prior to shipment and should
therefore require minimal adjustment at time of commissioning. However, it is recommended that a complete
calibration be performed 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 superseded by the instructions below. The calibration adapter attached to the sensor head should not be
removed during calibration.
971-071170-0DL Instruction Manual Rev. 0.0 Page 4 of 8