Detcon FP-524C - Manual (Page 3)

3.0 D ESCRIPTION
Detcon MicroSafe™ Model FP-524C, combustible gas sensors are non-intrusive “Smart” sensors designed to detect
and monitor combustible gas in air over the range of 0-100% lower explosive limit (LEL). One of the primary fea-
tures of the sensor is its method of automatic calibration which guides the user through each step via instructions
displayed on the backlit LCD. The sensor output is a standard 4-20 mA signal. The microprocessor supervised elec-
tronics are packaged as a plug-in module that mates to a standard connector board. Both are housed in an explo-
sion proof condulet that includes a glass lens. A 16 character alpha/numeric indicator is used to display sensor read-
ings as well as the sensor’s menu driven features via a hand-held programming magnet.
The sensor technology is of the catalytic pellistor type. Catalytic pellistors show a good response to a long list
of combustible gases. Refer to section 3.7.1 for a partial list of detectable gases. The technique is referred to as non-
selective and may be used for the detection and monitoring of target combustible gases. Model FP-524C sensors are
specif ically designed to be resistive to poisons such as sulf ides, chlorides and silicone. The sensors are characteristi-
cally stable and capable of providing reliable performance for periods exceeding 5 years in most industrial environ-
ments.
3.0.1 Catalytic Detector
The catalytic detector is supplied as a matched pair of elements mounted in a plug-in replaceable housing. One ele-
ment is an active catalytic detector and the other is a non-active compensating element. Each element consists of a
fine platinum wire embedded in a porous bead. A catalytic mixture is applied to the detecting element while the com-
pensating element is treated so that catalytic oxidation of gas does not occur. The beads are mounted in a plug-in
module that is enclosed by a sintered porous stainless steel f lame arrestor. The plug-in sensor features gold plated
pins and mounts inside a stainless steel sensor housing via a mating gold plated socket.
Model FP-524C Combustible Gas Sensor PG.3
Alumina Bead
Platinum Wire
Catalyst
Construction of
Detector Bead
Sintered Stainless Steel Can
Header
Gold Plated Pins
Beads