Detcon FP-624C - Manual (Page 14)

h) Exit back to normal operations by holding the programming magnet over “PGM 2” for 3 seconds, or automati-
cally return to normal operation in 30 seconds.
i) Replace the junction box cover on the remote sensor enclosure.
Bridge voltage set is complete. This procedure need only be done once after initial power up.
3.6.3 Initial Operational Tests
After a warm up period has been allowed for, the sensor should be checked to verify sensitivity to combustible gas.
Material Requirements
* Detcon PN 6132 Threaded Calibration Adapter
* Span Gas 50% LEL methane in air at a controlled f low rate of 200 ml/min.
NOTE: If the sensor has been conf igured for calibration with a gas other than methane you will need to use
that gas. See section 3.7 for further information on calibration gas.
a) Attach the calibration adapter to the threaded sensor housing. Apply the test gas at a controlled f low rate of
200 ml/m. Observe that the LCD display increases to a level of 20% or higher.
b) Remove the test gas and observe that the LCD display decreases to “0 % LEL”.
c) If alarms are activated during the test, and have been programmed for latching operation, reset them according to
the instructions in section 3.10.2.
Initial operational tests are complete. Detcon combustible gas sensors are pre-calibrated prior to shipment and will,
in most cases, not require signif icant adjustment on start up. However, it is recommended that a complete calibra-
tion test and adjustment be performed within 24 hours of installation. Refer to calibration instructions in later text.
3.7 T ARGET G AS AND C ALIBRATION G AS S ELECTION
Because of the catalytic detector elements almost universal response to lower explosive limits of combustible gas,
the FP-624C sensor can be conf igured to specif ically detect any of the combustible gases listed in table 1. This spe-
cif ic gas is referred to as the “target gas”. In addition, the sensor can be conf igured so that it can be calibrated with
any of the listed gases, regardless of which target gas is selected. This gas is referred to as the “calibration gas”. These
two features allow a signif icant degree of f lexibility in the detection and calibration process.
Unless otherwise specif ied at time of order, Model FP-624C combustible gas sensors are conf igured to detect
methane gas in the range 0-100% LEL and are calibrated with 50% LEL methane in air. In this conf iguration,
methane is chosen as both the target gas and the calibration gas.
CAUTION:
Verif ication of specif ic target gas and calibration gas settings is required before commissioning.
To verify target gas and calibration gas settings, or to reconf igure the target gas or calibration gas, follow the
instructions below.
3.7.1 The “K” Factor
Most detectable gases, as listed in table 1, produce a similar output, however the signal amplitudes will differ. This
difference in amplitude is ref lected by a numeric f igure known as a “K factor”. The K factors are referenced to
methane which has a K factor of 1.00. It should be noted that these factors are theoretical and should only be used
as a guide to the response expected in other gases.
3.7.2 Verification of Target Gas and Calibration Gas Configuration
Verif ication of target gas and calibration gas conf iguration is obtained via interaction with the menu driven display
which requires the use of a programming magnet.
Material Requirements:
Detcon PN 3270 MicroSafe™ Programming Magnet
Model FP-624C Combustible Gas Sensor PG.14