Features

Microprocessor based modular design

Electrochemical Sensor Technology

Industry standard 4-20mA output

Field adjustable Alarm level

Single point Non-Intrusive calibration

Bright 3 digit LED display

Displays oxygen concentration, calibration prompts and sensor fault codes

Class I, Div 1, Suitable for use in Hazardous Location

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.

Specifications

Sensor Type

Continuous diffusion Catalytic Bead

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

10% 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

sensor fault status.

Approvals

ABS Type approved

ATEX / CSA approved for use in

hazardous locations.

CSA Performance test:  ISA-S12.13-

Part I-1995

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 20 Ohms

Cable Entry Hub