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ISC #12: The truth about the shelf life of calibration gases

Calibration gases are an important component in ensuring your gas detector is functioning properly. Regular calibration increases the ability to accurately measure gas concentration values. During calibration, the sensor’s installation values must be set in accordance with the concentration of the calibration gases. Based on the sensor’s response, the device adjusts itself to compensate for the sensitivity of the sensors that have changed or consumed during use. Improper or expired calibration gas will result in incorrect calibration, insecurity, and incorrect display equipment.

The gas expiration date for correction is in written on all gas bottles. The expiration date is based on the standardized shelf life of each bottle. The concentration of gas in the tank may decrease or even disappear over time due to the gas reacting with moisture, oxygen, or other chemicals. When the gas bottle expires, it should not be used again.

Calgaz USA standard gas bottles are most commonly used
Calgaz USA standard gas bottles are most commonly used

This often causes some questions such as: “How can we use up all the calibration gas?” Or “Why can’t I adjust to expired gas?” The answer is quite simple:

Let’s say you’re about to perform a monthly calibration for one of the Gas Detection Machines. You prepare your standard instruments, flow adjuster, air duct, and gas bottle. While connecting the adjuster to the gas bottle, you take a moment to reread the gas bottle label and notice that the gas bottle expired last month. Will you still edit the device with that bottle? Having only expired a month, how bad could it be?

Now say you are cleaning your kitchen. You find a barrel of still un unlocked milk placed in the corner of the refrigerator. You check the label on the carton and see that it expired last month. Will you still drink it? Having only expired a month, how bad could it be? Although this is probably normal, the fact is that milk can be reduced in quality over time, even when stored in a closed container in a good storage environment. With a calibration gas bottle does not differ much.

As mentioned earlier, the reaction of the gases can weaken over time, and some do faster than others. Over a period of time, chemical reactions that occur inside the gas bottle (like a milk carton) can alter the composition of the gas bottle. There are not any manufacturers or users that can extend the life of the gas can, since we cannot control the nature of gas reactions of this type.

For the above reasons, it is best to always use an un expired gas can. For safety, never correct the gas detector with an expired gas bottle. If you don’t drink expired milk, why would you calibration lifes saving equipment with expired gas?

The following chart shows the expected standard life of gases:

Standard air life chart
Standard air life chart

Note: Group I and H2S, NO2 and SO2 gases from group II can be used in combination in a gas bottle.If a combined gas bottle is used, the default expiration date will be according to the first expiration date of the gas.

trans by TES Industry

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