Carbon Monoxide Sensor AirTest Model TR-1000

TR-1000 - 4-20 mA Sensor / Transmitter

The TR-1000, when equipped with the appropriate solid-state, metal oxide (MOS) sensing element, can be used to detect Carbon Monoxide (CO), Combustibles, and Refrigerant gases. This sensor is generally used for monitoring areas not continuously occupied, such as parking structures and refrigerant compressor rooms.

Specifications  |  Installation  |  Calibration  |  Indicators, Test Points & Potentiometers  |  Dimensions  |  Wire Diagrams

Installation

1. Locate a flat surface to mount the enclosure so that the sensor can face downward. If the rear power entry is to be used, remove the plug before mounting the enclosure. The second power entry is at the end opposite the sensor.
2. Remove the cover of the enclosure by removing the 4 screws in the corners. Be careful here since the circuit board is connected to the cover. The circuit board is also connected to the sensor, so the cover will hang from these wires when removed. Remove the plug from the end power entry if it is to be used.
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. NOTE: To prevent shorting problems do not leave ground wire to box bare (if one is used) - cover with electrical tape.
4. Connect the wires to the removable connector block as shown on the wiring drawing.
   (See Fig.1)

Calibration

SOLID STATE SENSORS:

The TR-1000 has been factory calibrated and is ready for use. If however there is a level of background gases, it should be calibrated on site. If the range is to be changed, the TR-1000 must be re-calibrated.

1. Connect power and signal return wires to a suitable controller that will provide sensor excitation and signal processing. (See Fig.1)
   
   For all the following readings TP1 (RED) is the COMMON POSITIVE jack. 
2. Power up the unit, the ready light will come on in 10 seconds. Check TP2 (Black) for correct voltage of 5.0V ±0.1V. If it is satisfactory let the sensor burn-in for 24 hours. If voltage is unsatisfactory the board is faulty and must be serviced.
3. TO SET ZERO Adjust the ZERO potentiometer, RV1, until the ACTIVE LED (YELLOW) just goes off.
4. TO SET ZERO OFFSET Before proceeding, it is critical that the sensor is exposed to clean air. If clean air cannot be assured, a sample of clean air, or "Zero" gas should be applied to the sensor. Monitor the OUTPUT test point - TP3 (Yellow) - and adjust the ZERO OFFSET potentiometer - RV3 - so the meter reads 0.4 volts (this is equivalent to 4 mA). NOTE: The 4 to 20 mA loop must be complete.
5. TO SET SPAN While still monitoring the OUTPUT test point - TP3 (Yellow), apply a sample of gas consisting of the target gas mixed with air. The concentration of the gas should be the same as the desired full scale of the TR-1000.The flow rate of the gas must be 0.2 liters/minute. Adjust the "GAIN" trimpot - RV2 - so the meter reads 2.0 volts. (This is equivalent to 20 mA). Note: apply the gas through a humidifier (see Calibration Kit drawing). The mixture must be AIR based not Nitrogen based.

It is recommended that sensor calibration be carried out on an annual basis.

Figure 1

Figure 2

Indicators, Test Points & Potentiometers

1. The ready, green LED, indicates that power has been correctly applied. 
2. The active, yellow LED When "ON" indicates the sensor output is in the active area. When "OFF" indicates the sensor output is below zero or overrange.
3. Test Points are:
   • RV1 -ZERO potentiometer
   • TP1 (Red) -COMMON reference point for TP2,TP3 & TP4, voltmeter POSITIVE connection. 
   • TP2 (Black) 5V ±0.1v, circuit power. 
   • TP3 (Yellow) -OUTPUT VOLTAGE, 0.4 to 2.0 volts (equates to 4-20 mA). 
   • TP4 (White) -SIGNAL test point, typically 0.0 to 1.6 volts. 
4. Potentiometers: 
   • RV1 -ZERO potentiometer 
   • RV2 -GAIN potentiometer 
   • RV3 -ZERO OFFSET potentiometer

Figure 3

Recommended humidifier arrangement to be used when calibrating solid-state sensors

Dimensions

1. TR-1000 Layouts Standard & Duct Mount

Wire Diagrams

1. TR-1000 Wiring