Applying Gas to the Sensors (Part 3)
While we have just looked at the beginning of the processes required to calibrate and auto zero the detector, we should also address occasions when passcode protection is enabled. If this is the case, you will be required to enter in the proper code after the auto zero process completes. (For a list of common default codes, see the Product Pass Codes page) You will need to scroll using the up and down arrows on the front of the detector to encounter the correct code. If the code is not correct or it is not confirmed within five seconds, the LCD screen will inform you that the previous values will be saved. You will not be able to continue with the procedure. If the correct code is entered, the unit will beep twice before proceeding to the auto span function (refer to this section in the owner's manual).
First, the LCD screen will inform you of three choices. You will either be able to apply the associated gas, use your arrows to select the correct sensor or bypass this step by pressing the down arrow. The GasAlertMicro 5 IR will only give you the choice to apply the span gas. Please note that the sensors will be spanned in a very specific order. This order can be found on page 50 of the owner's manual. As mentioned previously, a generator will need to be used when dealing with ozone and chlorine dioxide.
For chlorine dioxide, you are required to use a piece of equipment known as a Tedlar bag between the generator and the detector. This bag should be filled with the gas for several minutes before the calibration begins. If you are unfamiliar with this process, ask a supervisor or consult BW Technologies by Honeywell.
For ozone span, you will not need to use a Tedlar bag. Instead, you will use the single gas calibration cap as described in the previous section. You will need to set the flow of gas at .5 parts per million and .5 liters a minute.
Applying Span Gas
Recall that a single gas calibration cap will be required when spanning O3 (SR-G04) and ClO2 (SR-V04) sensors. Otherwise, you will refer to figure three in the owner's manual to attach the cap correctly. There are certain flow rates that need to be adhered to. For NH3 and Cl2, you will span the gas at 1,000 milliliters per minute. For carbon dioxide (recall that nitrogen will be used), you will apply the gas at a rate of 500 milliliters a minute. All other gases will enter at a rate of between 250 and 500 milliliters a minute.
You will note a flashing icon upon the LCD display while the unit detects the relevant gas. This will occur for approximately thirty seconds. You will know that it has been completed when the unit beeps. The icon “AUTO SPAN” will flash while the spanning process takes place. Different gases will require different times to complete this process. You can refer to table 13 on page 51 to see the different time periods.