Detcon FP-624D-HT - Manual (Page 5)

Model FP-624D-HT
FP-624D-HT Instruction Manual Rev. 1.1 Page 1 of 44
1. Introduction
1.1 Description
Detcon Model FP-624D-HT High Temperature combustible gas sensors are non-intrusive “Smart” sensors
designed to detect and monitor combustible gases in air. Range of detection is 0-100% LEL (Lower Explosive
Limit). The sensor features an LED display of current reading, fault, and calibration status. The sensor is
equipped with standard analog 4-20mA, Modbus
TM
RTU output, and 3 relay contact outputs. A primary
feature of the sensor is its method of automatic calibration, which guides the user through each step via fully
scripted instructions displayed on the LED display.
The microprocessor-supervised electronics are packaged as a plug-in replaceable Transmitter Module that is
housed in an explosion proof junction box. The Transmitter Module includes a four character alpha/numeric
LED used to display sensor readings, and the sensor’s menu driven features when the hand-held programming
magnet is used.
Figure 1 Sensor Assembly Front View
Catalytic Bead (Pellistor) Sensor Technology
The sensor technology is a poison-resistant catalytic bead type. Catalytic bead sensors show a strong response
to a long list of combustible gases. The sensor is supplied as a matched-pair of detector elements mounted in a
plug-in replaceable module. One bead is a catalytically active detector and the other is a non-active reference
detector. Each detector consists of a fine platinum wire coil embedded in aluminum oxide. A catalytic
mixture is applied to the active detector while the reference detector is treated so that oxidation of the gas does
not occur. The technique is referred to as non-selective and may be used to monitor most any combustible gas.
Detcon catalytic bead sensors are specifically designed to be resistant to poisons such as sulfides, chlorides,
and silicones. The sensors are characteristically stable and capable of providing reliable performance for
periods exceeding 5 years in most industrial environments.
PGM 1
PGM 2
MODEL FP-624 HOUSTON, TEXAS
FLT 1 2 CAL
MicroSafe LEL Gas Sensor
ALM ALM
TM