Description

Model PT295-LEL is a microprocessor-based sensor designed to combustible hydrocarbons in % volume level. The unit features easy one-man calibration initiated by simply activating a magnetic switch and applying the gas.

The complete sensor consists of a stainless steel sensor head assembly, a user connection board and a transmitter board assembly. All of the sensor electronics are enclosed in an explosion proof instrument box. The unit's modular design allows easy maintenance, troubleshooting and high reliability.

The unit provides a 4-20mA signal proportional to 0 to 100% of the detection range of the sensor and a fully programmable alarm relay.

The sensor transmitter board includes a three (3) digit LED display for continuous indication of the gas concentration. The calibration mode, alarm and fault status of the sensor are also indicated on the digital display. In the normal operating mode the digital display and 4-20mA reading is proportional to the gas concentration detected by the sensor. In the calibration mode the digital display indicates the calibration status, alarm relay output is inhibited and analog signal output is set to 2 mA to avoid any false alarm by the control monitor. In the sensor fault mode the transmitter drops the output signal to < 1 mA

Model PT295 Stand Alone Combustibles Gas Sensor
Specifications

Measuring Range
0 to 100 % LEL

Repeatability
± 2 % Full scale

Zero Drift
< 5% per year

Response Time
T50 < 10 seconds
T90 < 30 seconds
with 100% LEL methane gas applied

Classification
Class I, division 1, Groups B,C &D

Operating Temperature
-40°F to +158°F (-40°C to +70°C)

Operating Humidity
1 0% to 90% RH, non-condensing

Mechanical Specifications
Length: 7 inches (178 mm)
Width: 5 inches (127 mm)
Height: 4.5 inches (114 mm)

Display
Bright 3 digit LED display

Status Indicators
Three-digit display for gas concentration,
Alarm relay status, calibration mode and
ensor fault status.

Input Power
14-28 VDC. 24 VDC nominal

Power Consumption
150mA @ 24 VDC typical

Alarm Relays
Fully programmable. 0 to Full scale range
of the sensor. Latching or Non-Latching.

Relay Ratings
SPDT Form "C" type Relay contacts
5 Amps @ 250 VAC or 30 VDC

Analog Output
Linear 4-20mA (300 Ohms max. load)
2.0 mA - Calibration mode
< 1.0 mA - Sensor malfunction

Calibration
Non-Intrusive activated by internal magnetic switch

Cable Requirement
3 wire shielded cable. Max loop resistance of
20 Ohms @ 24 VDC nominal

Cable Entry Hub
¾" NPT Female