Detcon FP-624C - Manual (Page 6)

3.2.2 Response to Different Gases
An attractive feature of the catalytic detector elements is their almost universal response to lower explosive limits of
hydrocarbons. Most detectable gases produce a similar output, however the signal amplitudes differ. The table in
section 3.7 lists theoretical factors (K factors) for different gases which are a measure of their signal amplitude as
compared to methane which has a K factor of 1.00. Since these factors are theoretical, they will only give a guide to
the response expected in other gases. The Model FP-624C sensor can be conf igured to detect any of the listed gases.
The gas selected for detection is referred to as the target gas. The sensor can also be conf igured to allow the user to
calibrate with a listed gas other than the target gas. This selection is referred to as the calibration gas. Unless other-
wise specif ied, Model FP-624C sensors are conf igured to detect methane and are calibrated with methane to a scale
of 0-100% LEL. Refer to section 3.7 for details.
3.3 S
PECIFICATIONS
Method of Detection
Catalytic detector diffusion/adsorption
Measurment Range
0-100% (lower explosive limit) LEL
Accuracy/Repeatability
± 3% LEL in 0-50% LEL Range; ± 5% LEL in 51-100% LEL Range
Response/Clearing Time
T50 <10 seconds; T90 <30 seconds
Zero Drift
< 5% per year
Operating Temperature Range
-40° to +175° F; -40° to +75°C
Operating Humidity Range
0-99% non-condensing
Output
3 relays (alarm 1, alarm 2, and fault) contact rated 5 amps @ 125 VAC, 5 amps @ 30 VDC;
Linear 4-20 mA DC; RS-485 Modbus™
Input Voltage
22-28 VDC
Power Consumption
Normal operation = 84 mA (2 watts); Full alarm = 128 mA (3.1 watts)
Electrical Classification
Explosion Proof; Class I; Div. 1; Groups B, C, D
Safety Approvals
CSA/NRTL (US OSHA Certified)
Sensor Warranty
2 year conditional
3.4 O
PERATING
S
OFTWARE
Operating software is menu listed with operator interface via the two magnetic program switches located under the
face plate. The two switches are referred to as “PGM 1” and “PGM 2”. The menu list consists of 3 items which
include sub-menus as indicated below. (Note: see the last page of this manual for a complete software f low chart.)
01. Normal Operation
a) Current Status
02. Calibration Mode
a) Zero
b) Span
03. Program Menu
a) Program Status
b) Alarm 1 Level
Model FP-624C Combustible Gas Sensor PG.6