Manual
3.2 APPLICATION
Model FP-524C MicroSafe™ sensors are designed to detect and monitor combustible gas in ambient air in the range of
0-100% LEL. Minimum sensitivity and scale resolution is 1%. Operating temperature range is -40° F. to +175° F. While
the sensor is capable of operating outside these temperatures, performance specifications are verified within the limit.
3.2.1 Sensor Placement/Mounting
Sensor location should be reviewed by facility engineering and safety personnel. Area leak sources and perimeter mounting
are typically used to determine number and location of sensors. The sensors are generally located 4-6 feet above grade.
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
virtually any combustible gas. 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 from other gases. The Model FP-524C sensor can be configured to detect any
of the listed gases. The gas selected for detection is referred to as the target gas. The sensor can also be configured
to allow the user to calibrate with a listed gas other than the target gas. This selection is referred to as the calibra-
tion gas. Unless otherwise specified, Model FP-524C sensors are configured to detect methane and are calibrated
with methane to a scale of 0-100% LEL. Refer to section 3.7 for details.
3.3 SPECIFICATIONS
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
Linear 4-20 mA DC
Input Voltage
12-28 VDC
Power Consumption
1.9 watts @ 24V
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 OPERATING SOFTWARE
Operating software is menu listed with operator interface via the two magnetic program switches located under the
face plate (reference figure 6). 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
flow chart.)
01. Normal Operation
Model FP-524C Combustible Gas Sensor PG.6