Gas monitors are used to detect the presence of gases in an area. They can be used for detecting a gas leak and interface with a control system so that a process can be shut down automatically. They are also useful for the detection of flammable, combustible and toxic gases as well as oxygen depletion. Installing a gas monitor requires the use of instrumentation familiarity and skills in order to achieve the best result.
Purchase your gas monitor unit from a reputable vendor and you should disconnect all power before you begin to wire the unit. The red wire should be connected to the positive 24-volt direct current (DC) terminal while the white wire should be connected to the signal input terminal. The third yellow or green wire is the ground wire and the ground should be mounted to the terminal inside the junction box used with the detector.
A two-wire shield cable should be used to make the power and signal connections to the gas detector. You should ensure that the junction box frame is appropriately connected to the cable shield while the cable shield should be connected to the ground at the controller. The distance between the power supply and the gas detector should be kept under the suggested 8,000 feet maximum length so that the unit will perform effectively.
Take a look at the wiring diagram in the manual and confirm that your wiring is correct. The condition of the wiring should be verified in order to ensure that the connectors are firm. The sensor should be monitored and you should allow it to settle down for 24 hours before calibrating it. This will allow hydrogen chloride and ammonia sensors to stabilize because they normally require one hour to stabilize.
The power should be switched on after 24 hours have passed and the unit will be on in the start up mode for a short time. It should then return to the fault mode with flashing indicators as you begin to calibrate it. The “CAL” switch should be flipped and you should use 20.9% O² tank to wash out the system for about 15 minutes. The magnet should be placed over the unit logo on the body of the sensor and should be held there until the “CAL” light appears.
You should watch the unit flash as it zeroes the sensor and as soon as the light is solid, you should apply test gas concentration to 50% of full capacity. This should set off a blinking “CAL” light along with the “MODE” light indicating that the sensor has detected the gas. Both lights should glow for five minutes signifying that calibration has taken place and the unit has stored the new values.