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Seven rules for choosing a gas detector

Supplier: MSA Australia
13 July, 2011

In today’s regulated safety environment the need for reliable, effective gas detection has never been so important.

New players have seen the opportunity to generate cash by jumping on the confined spaces bandwagon and making detectors, leaving consumers with a bewildering array of choice. So how do you choose?


Strangely this is not the first thing that comes to mind when looking at gas detectors yet is critical to reliability. If a detector is not working then everything else is irrelevant.

When choosing a detector you should think of it as a tool of trade. If the product performs like your everyday tools you will face less downtime, lost productivity and cost. The detector must be shockproof, waterproof and robust even out of any carry case. Ask your supplier to allow you to drop the unit on concrete a few times or knock it firmly on a hard surface when trialling. Drop it in water if water is an issue. Make sure this is done with the unit turned on and tested with gas before and after.


Always check the warranty offered and what is covered. Some companies view detectors as "delicate instruments" not tools of trade and generally that is reflected in the warranty.


A gas detector should provide a warning to potentially save your life. It must be accurate every time. Watch for false alarms. We all know about "crying wolf" and the same applies to detectors. It’s really worth knowing how accurate and repeatable the detector is.

Test the detector regularly with known gas and calibrate if needed. This is indicated in all international standards but also is the only way to verify ALL sensors read gas. Zero reading does not tell you the sensor is detecting gas. There is a cost for gas but it is a lot less than a life and probably less per week then most people spend at the pub. Remember when the chips are down if the detector does not respond then the outcome could be dire.

MSA Altair series detectors have a check mark to confirm they have been tested and met MSA standards of functionality. When gas is applied and passes, a confidence tick is issued to the screen. It’s your tick from MSA that the detector response is assured.


Speed does matter: many detectors respond quite slowly in higher ranges and can take up to a minute or more to respond. You can walk a long way in a minute. Recently safety notices were issued by several authorities warning of the risk of slow response. The slow response people experienced resulted in near injury as falling oxygen levels went undetected.

Just because products meet a standard doesn’t mean there are not differences. Make sure your detector meets your standard. It’s your life. The slower the response the less time you have to take action or the further you need to go to reach safety. MSA Altair 4X takes less than 15 seconds to reach 90% of reading. That is up to four times faster than average and eight times faster than the slowest alternatives.


All gas detectors have basic alarms, normally at least visual and audible. You should at least also have a vibration alarm. You will be likely to be using these in noisy environments with other tools. A vibration alarm will greatly improve the chances you won’t miss an alarm.

Exclusively, MSA have a special alarm mode in Altair 4X. This alarm when started detects when the detector remains still for 30+ seconds. Typically these are called ‘Mandown’ alarms and are standard issue for fire fighters. They aim is to detect and activate when the wearer is not moving and potentially unconscious. This may be the most critical alarm, activating when you are in real trouble. Since it relates to movement, it covers many potential situations and is more than just a gas alarm.


A gas detector is a tool that assists you to do your job safely. Like any good tool, it should be simple and easy to use. That includes accessing all standard functions used daily. Having to push multiple buttons or sequences to access everyday functions is not helpful.

Ease of use must be backed with interactive visual detector simulators. If you need to train someone or change something you don’t want to rely on the supplier or expensive training.


Look for innovation in design. That assures you the company is thinking, not just copying. MSA recently introduced a 'glow in the dark' case on Altair 4X. This is a world first and assists you keep track of the instrument in the dark of a confined space. Look for innovation as a sign of leadership.