Dual Input Gas Detection Monitor AirTest Model CT-2100

CT-2100 - Dual Input Monitor

The CT-2100 is a dual input monitor for stand-alone applications. It is normally supplied with one onboard Carbon Monoxide (CO) solid-state sensor and one remote Combustible gas (Propane, Natural gas) solid-state sensor. If desired both sensors may be mounted remote, up to 50' wire length, from the monitor. The CT-2100 has 2 alarm relays with user adjustable time delays for each channel and a common fault relay. A main power light is provided as well as low, high, and fault lights for each channel. An audible alarm can be set to activate on low alarm, high alarm or both . To eliminate drilling on-site, power entrances are provided on the top and back of the enclosure. A main power kill switch is also standard. For use as a dual channel controller the CT-2100 can be supplied without onboard sensors and factory configured to accept 2 or 3-wire 4-20 mA input signals.

Specifications  |  Installation  |  Calibration  |  Dimensions  |  Wire Diagrams

Installation

1. Locate a flat surface to mount the enclosure so that the sensor(s) 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. Attach the CT-2100 to the wall, panel, column, etc. using the four mounting holes provided.
2. Open the cover of the enclosure by loosening the 2 screws in the corners. The circuit boards are connected to a swing panel for easy access to the relay output and power input connectors. 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

SETTING THE ALARM POINTS - MOS SENSORS:

The sensor should be allowed to warm up and stabilize for 24 hours before setting alarm points.

Method using DVM and Calibration gas.

1. Connect voltmeter negative probe to the REF (Black) test point. Connect the positive probe to the YELLOW test point corresponding to the sensor being calibrated. 
2. Apply low alarm calibration gas, at the appropriate rate, to the sensor and note the maximum voltage reading. (Takes 1 ½ to 2 minutes). 
3. Connect voltmeter positive probe to the RED low alarm test point of the sensor being calibrated and set the voltage to the value noted in Step 2. Low alarm is now set for that sensor. 
4. Repeat steps 1 to 3 using high alarm calibration gas and high alarm test point. 
5. Repeat steps 1 to 4 for second sensor.

Method using calibration gas only.

The alarm points can be adjusted and set at any time while the CT-2100 is powered and ON. If the unit is in alarm, turn the alarm trimpot you wish to adjust (counterclockwise) until it comes out of alarm. Alarm settings should always be made from an out-of-alarm state to an alarm state.

1. Through a humidifier (see Calibration Kit drawing), apply a calibration gas mixture to the sensor equal to the level required for the LOW alarm point. Allow 1 ½ to 2 minutes for sensor to stabilize.
2. Adjust alarm 1 (LOW) so that the relay 1(LOW) LED comes on. (Red LED on front cover).
3. Repeat for alarm 2 (LOW).
4. Through a humidifier (see Calibration Kit drawing), apply a calibration gas mixture to the sensor equal to the level required for the HIGH alarm point.
5. Adjust alarm 1 (HIGH) so that the relay 1 (HIGH) LED comes on. (Red LED on front cover).
6. Repeat for alarm 2 (HIGH)

Calibration Gas Flow Rates:

1. MOS Sensor 0.4 SCFH (0.2 LPM)
2. NO2 Electrochemical Sensor 2.0 SCFH (1 LPM)

SETTING THE ALARM POINTS - 2-WIRE, 4-20mA OUTPUT SENSORS:

Sensor + 12 VDC and Signal Return are connected to the 2 pin sensor input connector as shown below. On AirTest 4 - 20 mA transmitters there is no need to observe the polarity.

When equipped with a 4 - 20 mA input capability, the CT-2100 is factory set so that 0.4V equates to 4 mA and 2.0V equates to 20 mA. ( Measured at REF (Black) negative Test Point and ZERO/SPAN (Yellow) positive Test Point.

To set the alarm points, connect negative probe of voltmeter to REF (Black) Test Point and positive to LOW or HIGH (Red) Test Point. Set the voltage with corresponding alarm trimpot to read the value obtained from the graph below.

The graph displays voltage on the vertical axis (0.4V to 2.0V corresponding to 4mA to 20mA) and transmitter range on the horizontal axis ( 0 to 100%).

e.g. An NO2 sensor with a range of 0 - 10 ppm is connected at the transmitter. An alarm point of 5 ppm is desired, this is 5/10 = 50% of range. 50% of range = 1.2V Set alarm voltage at 1.2V

Or, using the formula:

Figure 1

SETTING THE ALARM POINTS - 3-WIRE, 4-20mA OUTPUT SENSORS:

Sensor + (pos) and SIGNAL are connected to the 3 pin sensor input connector. The sensor - (neg) is connected to the 2 pin sensor input connector. Connections are shown below.

When equipped with a 4 - 20 mA 3-wire input capability, the CT-2100 is set up so that 0.8V equates to 4 mA and 4.0V equates to 20 mA. ( Measured at REF (Black) negative Test Point and ZERO/SPAN (Yellow) positive Test Point.

To set the alarm points, connect negative probe of voltmeter to REF (Black) Test Point and positive to LOW or HIGH (Red) Test Point. Set the voltage with the corresponding trimpot to read the value obtained from the graph below.

The graph displays voltage on the vertical axis (0.8V to 4.0V corresponding to 4mA to 20mA) and transmitter range on the horizontal axis ( 0 to 100%).

e.g. An LEL sensor with a range of 0 - 100 % LEL is connected at the transmitter. An alarm point of 20 % LEL is desired, this is 20/100 = 20% of range. 20% of range = 1.44V Set alarm voltage at 1.44V

Or, using the formula:

Figure 2

Figure 3 - MOS SENSOR CALIBRATION KIT

Figure 4 - RELAY TIME DELAY SETTINGS

Dimensions

1. CT-2100 Layouts

Wire Diagrams

1. CT-2100 Wiring