Just another reason to bump test your gas detector….

For the first post of 2012, I thought that it would be appropriate once again to talk about bump testing.  But this time, I am going to venture away from looking at bump testing from the point of view that the only way you know that a gas sensor will respond to gas is to test it with gas.  I’ve recently learned of another reason why you should bump test your gas monitor regularly. 

Portable gas monitoring instruments typically are powered by some type of lithium battery.   Single gas instruments that are meant for long life typically utilize primary (non-rechargeable) lithium batteries and under normal operating conditions draw very small amounts of current from them.  During a normal chemical reaction that takes place in the battery during storage or under very small load conditions, a thin film of lithium chloride forms what is known as a passivation layer on the lithium anode of the battery.   This passivation layer serves to prevent the battery from self dishcharging and helps to maintain its overall life capacity during storage.

The down side of the passivation layer is that as it forms, the working voltage of the battery is reduced and its ability to deliver power to a high current load, such as your gas monitor going into alarm, is diminished.  As the passivation layer “burns” off, the battery’s ability to deliver the higher currents is restored.

So, one way to ensure that the battery in your gas monitor is properly conditioned and has the passivation layer depleted is to periodically force the instrument into the high current mode by bump testing it and activating the alarms.  In this case the bump test will tell you that the alarms are functioning properly and help condition the battery so that it can operate the alarms properly as it needs to if you encounter a dangerous concentration of gas in the field.

As I said, just another reason that bump testing your gas monitor should be part of your daily routine.

Here’s to a healthy and gas safe 2012!

Dave