Air Horn Compressor

[OldDan1943]

CO2 shouldn't contain any moisture (water vapor) as opposed to compressed air, so the valve freezing shouldn't be an issue.

Ted

The Thresher's main ballast tank blow valves iced over, preventing air to flow into the main ballast tanks contributing significantly to its Thresher's loss with all hands and a number of ship yard workers.
My question is, would CO2 freeze faster? When discharging CO2 we can see ice crystals form.

 

[O C Diver]

The Thresher's main ballast tank blow valves iced over, preventing air to flow into the main ballast tanks contributing significantly to its Thresher's loss with all hands and a number of ship yard workers.
My question is, would CO2 freeze faster? When discharging CO2 we can see ice crystals form.

They're not ice crystals. When you discharge liquid CO2 into a container, you get dry ice. When it melts, you get CO2 gas, not water. When you discharge a CO2 fire extinguisher, the valve cools and moisture / ice forms on the outside of the valve from humidity in the air. The valve may cool which may impair its function, but you won't find ice in the valve.

The pressure inside a liquid CO2 tank varies hugely with surrounding air temperature. Most all applications using CO2 as a pressure gas have a regulator on the tank which reduces the output to a desired fixed pressure. The cooling from converting the high pressure liquid to a relatively low pressure gas is at the tank and regulator. If the tank and regulator were 10 to 20' away from the valve controlling the horn, there would be probably little to no noticeable cooling.

To your question of whether CO2 would freeze faster than air. Given the same volume and pressure parameters as a gas after discharge, CO2 will generate more cooling going from a liquid to a gas than air being released from a high pressure to a lower pressure.

Ted

 

[stubones99]

If you do a long blow with CO2, I'll bet the horn has snow on the diaphragm when you're done If I recall correctly, at operating pressure *3200psi, a CO2 tank has something like 400 times expansion, so you'll have quite a few blows on a tank. But using a scuba tank with compressed air would provide the same thing with cheap refills too.

 

[angus99]

Hi Angus, my suggestion is to remove one of the yellow wires (in your picture) that connects to the pressure switch. This should stop the compressor. Then wait 5 or so minutes and try the horn as I see it is operated by a seperate solenoid valve. If the horn sounds your tank is probably holding pressure and it is most likely the pressure switch at fault. If you stay with your compressor set up adding a small pressure gauge to the tank would be useful in tracking future faults and setting the pressure switch setting.

You nailed it, BeeJay. The tank remained pressurized 30 minutes after I cut the compressor off. (Sucker is impressive! It’s about 25” long and sounds like the hammer of the gods.) So, no leaks and the connections look clean. I’ll call Grover tomorrow and see what they spec for a pressure switch.

Thanks again.

Edit: it’s been 3 hours and still lots of pressure

 

[psneeld]

A friend sent this link on CO2 and freeze ups....

http://www.harrisproductsgroup.com/en/Expert-Advice/Articles/CO2-Freeze-Up.aspx

 

[OldDan1943]

A friend sent this link on CO2 and freeze ups....

CO2 Freeze Up | The Harris Products Group

They recommend a heater regulator to prevent freeze up.

 

[BeeJay]

That's good, it should be an easy fix. You can buy simple adjustable pressure switches similar to what you are currently using. As Ski says I don't think you will need an un loader for DC use. It looks like you may have a non return valve (or it could just be an adaptor) where the compressor line feeds into the tee. What typically happens with this style of compressor is that when the pressure switch comes into play and the compressor cuts out , the pressure leaks down past the valves in the compressor head. Hence on restart it probably starts unloaded any way. It could also be why you have a small coil of additional tube before what looks to me to be the non return valve.

 

[angus99]

I may try fiddling with the adjustment screw to see if anything comes unstuck. I appreciate the on-point advice, BeeJay and all.

 

[stubones99]

That's good, it should be an easy fix. You can buy simple adjustable pressure switches similar to what you are currently using. As Ski says I don't think you will need an un loader for DC use. It looks like you may have a non return valve (or it could just be an adaptor) where the compressor line feeds into the tee. What typically happens with this style of compressor is that when the pressure switch comes into play and the compressor cuts out , the pressure leaks down past the valves in the compressor head. Hence on restart it probably starts unloaded any way. It could also be why you have a small coil of additional tube before what looks to me to be the non return valve.

The coil of tubing is a cheap aftercooler to get rid of some of the compression heat before feeding it to the tank. A check valve is a good idea since compressor valves often leak while still, but work well enough to compress air while running.

Just make sure you find all the leaks and put in a pressure regulator for output, and a pressure cut-off switch to shut off the compressor once it gets up to pressure. Check to see if the tank is aluminum, since steel tanks corrode and can be a time bomb if not drained of moisture regularly.