Air compressor from fire extinguisher - video

**Jon** · Mar 3, 2022, 02:43 PM

Air compressor from fire extinguisher. 10:05 video:

**nova_robotics** · Mar 3, 2022, 06:02 PM

Is that a Kinder Surprise Egg air filter?

I'm a bit worried about that fire extinguisher as an air tank. Doubt there's much corrosion allowance on that stamped carbon steel tank that's meant to hold a dry chemical. There's no easy way to drain it because all the fittings are on top. Don't know how long it'll hold up to condensation when in use. I just don't want to die due to ruptured air tank.

**paul1950** · Mar 3, 2022, 10:46 PM

Originally Posted by Jon

Air compressor from fire extinguisher. 10:05 video:

There is a few very good reason why pressure vessels are certified and have regular inspections.
One of them is because they can explode and cause serious injury.
I would not even think about using a rusty fire extinguisher

**Saaglem** · Mar 3, 2022, 10:59 PM

I am a bit more worried by the fact that he used a possible oil base lubricant on the connection between the regulators and the tank. You shouldn't use ANY oil substance on it. Oil base substances can cause an explosion under pressure!

**nova_robotics** · Mar 4, 2022, 01:55 AM

Originally Posted by Saaglem

I am a bit more worried by the fact that he used a possible oil base lubricant on the connection between the regulators and the tank. You shouldn't use ANY oil substance on it. Oil base substances can cause an explosion under pressure!

Really? Because I have definitely done this. I've poured oil into air tanks as a corrosion inhibitor, and I've filled compressor sumps with 10w30. Vacuum pumps too. It's not exactly good practice because you're supposed to use non-detergent oil, but otherwise I've never heard of this being a problem. How does it cause an issue?

**Saaglem** · Mar 4, 2022, 02:17 AM

You should NEVER use grease or oil on a regulator. Not only will it gunk up the inside and contaminate your reaction system, but these organic materials can react with the air being dispensed. When air is being pumped into a cylinder the water in the air cause erosion that can dislodge when the air is released. This can travel on the inside and on its route to the outside and cause a spark, now because it is compressed it is under normal conditions not possible, but, when mixed with oil or grease it creates an chain reaction of the friction that is caused by bonding of the air and oil. Then it can explode!

The reason why refrigerant doesn't cause an issue with oil is because it is not explosive gas, plus, the system is being vacuumed before hand.

A couple of years ago my Dad showed me how normal butane gas can be used as a refrigerant an it boils at a higher temperature, free, and everywhere and it's discharge effect is less corrosive to the environment than refrigerant, only bad thing about it it is explosive.

Look it up, there is a lot of scriptures regarding oil versus regulators.

Cheers

**nova_robotics** · Mar 4, 2022, 03:23 AM

Originally Posted by Saaglem

You should NEVER use grease or oil on a regulator. Not only will it gunk up the inside and contaminate your reaction system, but these organic materials can react with the air being dispensed. When air is being pumped into a cylinder the water in the air cause erosion that can dislodge when the air is released. This can travel on the inside and on its route to the outside and cause a spark, now because it is compressed it is under normal conditions not possible, but, when mixed with oil or grease it creates an chain reaction of the friction that is caused by bonding of the air and oil. Then it can explode!

That sounds very questionable. I agree that applying grease upstream of a regulator is probably not a great idea (for the sake of good regulation), but the part about the water causing a sparks and a chain reaction...... I'm not sold on that part. The only failures I have ever heard of with air compressors are the tanks rupturing, which is purely a physical failure of the tank and not caused by ignition. If downstream sparks and ignition were an issue, air compressors would be fitted with spark arrestors similar to oxy-acetylene torches, and oil mist lubrication systems would be outlawed completely.

**BuffaloJohn** · Mar 4, 2022, 11:49 AM

I don't think the worst problem is the potential grease or oil explosion.

I go back to the heavily rusted fire extinguisher and the stick welded top fitting.

It's a good thing he painted the tank RED as it is a bomb. Not "the bomb", just a bomb...

**NortonDommi** · Mar 6, 2022, 10:29 PM

Oil used on Oxygen bottles in particular is actually prohibited by law in most countries and yes it can be a problem with compressed air as well at high pressure.
I think that was a sealer not grease that he applied to the threads.
Most fire extinguishers have a standard charge pressure of 195 P.S.I. with a max charge of 390 P.S.I. If the fire extinguisher is in good condition low pressure use should be O.K. as long as not corroded. Be a great airbrush unit.
Should have mounted the bottle upside down or made some provision to drain back to the tank to return the oil. In refrigerators some oil gets carried with the refrigerant but ends up back in the compressor, part of the reason the first leg goes to the highest point.
Feel free to set me straight refrigerator guys.