Toxic Gas Sensor AirTest Model TR-3200

TR-3200 - 4-20 mA Sensor / Transmitter

The TR-3200 is a Toxic Gas Sensor that uses electrochemical cell technology as the sensing element. It is available in a variety of toxic gases such as Nitrogen Dioxide (NO2), a product of diesel exhaust; Ammonia (NH3), used as a refrigerant; Carbon Monoxide (CO), a product of combustion; ppm Hydrogen (H), battery off-gas; and others.

Specifications  |  Installation  |  Calibration  |  Dimensions  |  Wire Diagrams

Installation

1. Locate a flat surface to mount the enclosure using the mounting feet provided.
   The power entry is at the bottom of the enclosure.

2. Remove the cover of the enclosure by removing the 4 screws in the corners. Be careful here since the circuit board, including sensor, is connected to the cover. The complete assembly can be set aside while wiring is installed.

3. Connect the electrical fittings to the enclosure and bring in the electrical wires. NOTE: BE SURE WIRING IS DONE ACCORDING TO THE LOCAL ELECTRICAL CODE REQUIREMENTS.

4. Connect the wires to the terminal block as shown on the wiring drawing.
   (See Fig.1)

Calibration

Figure 1

1. Connect the TR-3200 unit to a controller, one wire to + and the other to the 4-20 mA Loop Return (-). Power-up the unit. TP4 (Black) is the COMMON REFERENCE for all voltage measurements. A high impedance DVM must be used.

2. Sensor Bias Voltage. APPLIES TO NH3, HCL AND NO SENSORS ONLY. The bias voltage has been factory set but can be checked. (Bias voltage test point is tab at 10:00 o'clock position on sensor - see Fig. 1 above). The reading is: 0.250V for NH3; 0.300V for HCL; 0.200V for NO

3. Monitor Signal Test Point TP2 (Yellow) and adjust the ZERO POT (RV1) so the meter reads Zero (0 +/- .001V) (Calibration area free of gas or Zero Gas applied).

4. Monitor the Output Test Point TP3 (Red) and adjust the OFFSET POT (RV3) so the meter reads -0.04V. (A current meter in the power line loop will read 4 mA.)

5. While still monitoring the Output Test Point TP3 (Red), apply test gas to the sensor. (Flow rate1.0 LPM for NO2/HCL/CL2 otherwise 0.5 LPM). Wait until the reading stabilizes.

6. Adjust the GAIN POT (RV4) so the "Test Gas to Range" Ratio is in proportion to the Maximum Output Current. See formula below. There is some interactivity and it will be necessary to repeat steps 3 - 5 until no change is noted in the offset reading
   (-0.04V)

Figure 2

Dimensions

1. TR-3200 Layouts

Wire Diagrams

1. TR-3200 Wiring