Carbon Dioxide tank overpressure

Recently, a HAZMATNATION reader submitted an interesting CO2 call with us that we would like to share. Thank you Mr. Lopez.

Aright everyone I made a CO2 alarm last night and would like some insight. This was the first call I’ve ever made on a co2.

We were dispatched for a CO2 alarm at a gas station/ fast food Restaurant. When we arrived on scene there was audible alarms and visual alarms. Most of the building was evacuated and we began moving out the rest. There was a noticeable sound of a leak coming from the outside fill station(for the CO2) a driver for the CO2 company was on scene and advised he thought it was over pressured that’s why it was coming out the pressure release at the full. We suited up and made entry into the building with a 4 gas and kept a 20.9 o2 reading the entire time. We made entry isn’t the room with the CO2 cylinder and immediately noticed it was completely frozen over. I wish had pictures to show. The pressure was reading over 350 psi when it should be reading (from what the driver said) 100-150psi.

The CO2 alarm monitor was reading 35000ppm. We exited the building and asked the driver to empty the tank from the exterior. He did. We set up a fan and the CO2 % dropped but Ppm were still above 10900. We waited for about an hour and a half before the PPM dropped to 10817. Still not low enough to reset the alarm system. I did a quick google search to learn the system the best I could in 30min. We unplugged power to the system restored power and after a 2 minute restart the system was back in normal operations.

Any idea on what caused the system to over pressure? The reason it was leaking back into the store was because there was no insulation in between the exterior fill station and interior wall. So while it was self venting it was sending tons of product back into the store.

Here is 2 photos In the comments of the top of the cylinder about 1 1/2hrs after it was emptied.

So what do you think?