April 6, 2022

Air Monitors

These are somewhat expensive, but as the saying goes, "what is your life worth?".

Anyone who is serious about exploring old mines should have a gas monitor. I get by with just an oxygen monitor, but it would be far better to have a 4 gas unit. The four gases are Oxygen, Hydrogen Sulfide, Carbon Monoxide, and "LEL". "LEL is for flammable hydrocarbons, which are a big deal in a coal mine, but not likely in metal mines.

BW Clip oxygen monitor

I use the BWC2R-X unit. It will run for 2 years then need to be discarded and replaced.

You can also buy a less expensive BWC2-X, but it does not provide a display of the current oxygen level, and I appreciate being able to see the current level, even if the monitor is not making noise due to levels being below its alarm threshold.

I purchased my first unit for $105 in December of 2018. When it came time (April of 2022) to purchase another, the price for the "R" unit was up to about $200 (the less expensive unit without the real time display was about $110). I purchase from PK Safety.

The particular unit I chose displays the percent of oxygen, so you get more than just an "idiot light" type device that triggers an audible alert if the oxygen goes below 19.5, which I think is very important. The unit will run for 2 years once turned on, then you throw it away and get another one. The unit has a 6 month shelf life before activation, and has an "activate by" date marked on it.

PK Safety is in Alameda, California. My partners say they have excellent service, but I have yet to need it. They offer free shipping on orders over $99

Sensors

The annoying thing about these devices is the sensors. They are effectively "consumables" and use themselves up and/or go out of calibration in a short time (a few years). They are not usually replaceable by the end user and/or are as expensive as an entire unit. This is unfortunate, but there seems to be no way around it.

Other gases and gas monitors

If you want to do this right, you get a four gas monitor. This gives you O2, H2S, CO, and LEL. The downside of this is the cost, nearly $500. All of these are important. For metal mines, LEL (lower explosive level) of combustible gases is perhaps the least important (until you blow yourself up). If you are coal mines or other mines in sedimentary strata (perhaps even uranium mines), both H2S and LEL issues are real possibilities. For the sorts of mines I visit, also having CO (Carbon monoxide) would be a nice addition to O2.
Feedback? Questions? Drop me a line!

Uncle Tom's Old Mine Info / tom@mmto.org