Detcon FP-624C Manuel d'utilisateur télécharger pdf (Page 3)

3.0 DESCRIPTION

Detcon MicroSafe™ Model FP-624C, 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 features of the sen-

sor is its method of automatic calibration which guides the user through each step

via instructions displayed on the backlit LCD. The sensor features field adjustable,

fully programmable alarms and provides relays for two alarms plus fault as standard.

The sensor comes with two different outputs: analog 4-20 mA, and serial RS-485.

These outputs allow for greater flexibility in system integration and installation. The

microprocessor supervised electronics are packaged as a plug-in module that mates

to a standard connector board. Both are housed in an explosion proof condulet that

includes a glass lens window which allows for the display of sensor readings as well

as access to 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. The technique is referred to as

non-selective and may be used for the detection and monitoring of target com-

bustible gases. Model FP-624C sensors are specifically designed to be resistive to poi-

sons such as sulfides, chlorides and silicone. The sensors are characteristically stable

and capable of providing reliable performance for periods exceeding 5 years in most

industrial environments.

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 bead of alumina. A catalytic mixture is applied to the detecting element while the

compensating 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 flame arrestor. The plug-in sensor module uses gold plat-

ed pins and mounts inside the stainless steel sensor head via mating gold plated sockets.

3.0.2 Microprocessor Control Circuit

The control circuit is microprocessor based and is packaged as a plug-in field replaceable module, facilitating easy

replacement and minimum down time. Circuit functions include a basic sensor pre-amplifier, sensor temperature

control, on-board power supplies, microprocessor, back lit alpha numeric display, alarm status LED indicators, mag-

netic programming switches, an RS-485 communication port, and a linear 4-20 mA DC output.

Model FP-624C Combustible Gas Sensor PG.3

Alumina Bead

Platinum Wire

Catalyst

Construction of

Detector Bead

Sintered Stainless Steel Can

Header

Gold Plated Pins

Beads

1 2 3 4 5 6 7 8 ... 25 26

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Detcon FP-624C Manuel d'utilisateur Page 3