False positives for training help

[CheedarBob]

I am in the process of putting together a HazMat Tech class and to aid in the "fun" of HazMat I want the guys to get actual readings. Anyone have any tips on what to use to get false positives so I don't have to use the real thing? Geiger, multi-gas meter, PID, Etc.

[Jolt826]

It's not the best, but carbon dioxide is easy to come by, relatively safe, and easy to make. In a past vehicle accident scenario I've used a cracked SCBA cylinder (just loud enough to be audible during size-up) in conjunction with a small container of dry ice. Once the "leak" was noticed participants could attach the gas meter to a pump and the indications would change to show an oxygen deficient atmosphere. Baking soda and vinegar will also make carbon dioxide, but also in pretty small quantities.

The problem is that a lot of the cross-sensitivities are for gases that are also hazardous. If you're willing to take the risk and it makes sense for your training, you can crack open a propane or butane cylinder while participants are monitoring and then promptly close it. I've used an unlit grill before to show the operation of combustible gas detectors.

VOCs may not be difficult to find. You can probably find a hairspray or perfume that will display on your PID.