The steel pipes of an HVAC system
Posted in: Gas Detection

HVAC Gas Detection: A Special Circumstance

We’ve all seen the movies, the gas moves through the ventilation system. The evil doer releases it in an elaborate plan to flood the generic laboratory. The HVAC system is ideal for this plot with its system of vents reaching every corner of the facility. Yet the truth is that HVAC Gas Detection is an important part of the system.

This scenario is very unlikely, and probably something that could only happen in Hollywood.

Were someone to try to release toxic gases into an HVAC system in real life a sensor placed near the intake would detect it, an alarm would sound, and the HVAC system would shut down.

The inconvenient loss of air conditioning would be the worst most employees at the lab would experience.

Even without the evil mastermind most buildings deal with hazardous, or potentially dangerous substances in some way. This could include freezing agents for refrigerator units, natural gas for heating, or chemicals for fire suppression systems, among others.

A leak in any of these systems could lead to toxic gases making their way into the HVAC system. Leaking from there through the facility.

The Unique Problems of HVAC Gas Detection

Because of this very real threat to HVAC systems Gas detection is needed not only for the well being of the workers but also to avoid total disaster.

Because of the unique environment created by HVAC systems there are three major issues gas sensors must deal with.

The first problem is the air speed. With air moving between 23 and 68 miles per hour the sensors must withstand these forces to function.

The second issue is dilution. Because of the large amounts of air moving through the system the gas will be diluted very quickly. For this reason to detect dangerous levels of gas the sensors must be able to pick out particles at a few parts per million. As well combustibility detection should be set to 10% LEL or less before triggering an alarm.

The last issue is stratification. Because of the way conduits wind and turn there is the possibility for these twists to trap the gas in certain areas, leading to a higher, and dangerous, concentration at these choke points. For this reason it is important to identify those locations and place sensors nearby.

With gas detectors set in the proper places the HVAC system is an asset. It will make workers comfortable in their work environment. It will do this while creating almost no risk.

October 29, 2020
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