A Look at Diagnostics Testing and Applying Gas to the Sensors


As we have just seen, calibration setpoints are an extremely important function of the detector that need to be properly understood. However, there are other diagnostic tests that are also very critical to the safe operation of the device. Normally, these tests will be carried out automatically immediately when starting up the device. Let us take a look at how these work before we move on and examine how gas should be applied to the sensors of the GasAlertMicro 5.


Normal Diagnostics Testing


One function that needs to be understood is known as the “auto zero” function. This is when the unit will test both the ambient air (remember that this should be done in a safe environment) as well as a gas that is entering inside (the auto span function). In essence, auto zero will allow the detector to return to baseline gas levels. However, if this is done with a toxic ambient gas present, the auto zero option will be incorrect. The way that this will be determined is by the LCD screen displaying that the test has failed. It will also list the affected sensor (and therefore the ambient gas that is present). You can see an illustration of this instance on page 45 of your owner's manual.


There may also be times when the target gas is not detected. Should this be the case, you will note a message that informs you that the detector is exiting calibration mode. All previous values will be retained. You should make certain that the correct gas is being applied and that a sensor (or sensors) is not at fault. Should this failure continue, you should refer to the troubleshooting section of the owner's manual.


Applying Gas to the Sensors (Part 1)


You will need to use the calibration cap (M5-TC-1), the single gas calibration cap and the hose that come shipped with the sensor to perform this task. If you need help with installing these devices, you can refer to figure 3 and table 11 of the owner's manual. Recall that both the calibration cap and the single gas calibration cap are only to be used during the span process.


The Single Gas Calibration Cap


It is important to note that if either an O3 (SR-G04) or a ClO2 (SR-V04) sensor is in what is known as the Toxic 2 position (figure 3 and table 11), ONLY a single gas calibration cap is to be used. You will need to look at figure 4 and table 12 to help you with this procedure. First, insert the cap into the Toxic 2 sensor. You will know that it is firmly in place when the tabs on either side click. Then, connect the hose to the cylinder and thereafter, to the cap itself. You are then ready to begin the calibration procedure. Please note that you will see an arrow on the cap. This is designed to help illustrate the direction of gas flow. In the next section, we will continue to look at this procedure. It is always helpful to refer to the diagrams in the manual to fully understand this process.