Air Lines, Food for thought!

[Rrumbler]

Good point on rusting in iron and steel pipe, Digger Dave.. Here in the wonderful dry southwest, though, it is not near the problem it must be in the more humid areas of the continent. I've dismantled systems that have run for years in the desert environment with little or no rust accumulation; in coastal areas, though, rust was a problem, if the system was not drained regularly, and cleaned out from time to time. If the cost difference was much smaller, I'd probably be more amenable to using copper; it is cleaner, in terms of both appearance, and the "smooth factor". But, here in "Vegas, baby", it's so dry most of the time, you could almost light a match just by waving it in the air.

Good idea about protecting the drops in a copper system.

 

[TorqueWrench]

Interesting thread here guys...anyone ever used PEX for there air lines? It is cheaper than copper right now.

So, I am curious, what is the difference between gas pressure and liquid pressure? 100psi is 100psi, regardless if it is liquid or gas.

I personally think all this is more of a preference thing anyway.

 

[PAToyota]

100psi is not 100psi when you compare liquids and gases. Liquid doesn't compress while gas does - think about getting air in your brake lines, the volume changes insignificantly. So liquid doesn't have the embodied energy that gas does.

PEX will work if it is rated for the proper pressures - normal domestic water PEX isn't. The advantage of PEX over PVC is that it is not brittle and will just split if ruptured instead of throwing shrapnel.

 

[TorqueWrench]

100psi is not 100psi when you compare liquids and gases. Liquid doesn't compress while gas does - think about getting air in your brake lines, the volume changes insignificantly. So liquid doesn't have the embodied energy that gas does.

PEX will work if it is rated for the proper pressures - normal domestic water PEX isn't. The advantage of PEX over PVC is that it is not brittle and will just split if ruptured instead of throwing shrapnel.

I realize that you can compress gases and not water, however, when taking a static pressure reading 100psi is 100psi, pressue gauges are not calibrated for specific liquid or gas.

 

[Charles (in GA)]

I realize that you can compress gases and not water, however, when taking a static pressure reading 100psi is 100psi, pressue gauges are not calibrated for specific liquid or gas.

True, but PAToyota is referring to STORED ENERGY, which compressed gasses have, that pressurized liquids do not have. That is why large aircraft hydraulic systems sometimes have accumulators, to make use of springs or compressed gas (nitrogen) to store energy to make parking brakes and other compontents work when the pump is not running.

Its the stored energy that is so dangerous.

Charles

 

[edl]

I am not sure how most auto drains work on some compressors but here is what I did.
I removed the petcock valve from the bottom of my compressor and installed a brass elbow. Added a 4-5" length of tube to that and then put an electric solenoid valve on the end of that. My thinking there is that the brass elbow and tube create bit of a resevoir for any water that is going to accumulate there and that keeps the bottom of the tank from rusting. The brass does not rust anyway. The electric solenoid valve was bought surplus and is connected to a lamp timer that turns it on for one minute once a day. The output of the valve is dumped out on the ground.
Best Regards,
James

James, can you describe in a more step by step fashion how your gizmo works - pictures would be great - thanks!!!

 

[ZRX61]

You could just add a ballvalve to the end of the brass elbow deal...

Living in the Mojave Desert I've probably drained at most a total of 1pt of water from my 60Gal Devilbiss compressor... over a period of almost 10 years.....
It runs 4-5 days a week

 

[trainer]

I realize that you can compress gases and not water, however, when taking a static pressure reading 100psi is 100psi, pressue gauges are not calibrated for specific liquid or gas.

Think of it this way... 1 cubic foot of liquid at 100 psi occupies 1 cubic foot. If you change the pressure to atmospheric, it still occupies 1 cubic foot.

1 cubic foot of gas (ie air) at 100 psi is still 1 cubic foot. But if you take the same amount of air from 100psi to atmospheric pressure, it suddenly occupies a huge number of cubic feet.....taking any shattered pieces of pipe, bodyparts, etc with it.

 

[DIGGER_DAVE]

Good point on rusting in iron and steel pipe, Digger Dave.. Here in the wonderful dry southwest, though, it is not near the problem it must be in the more humid areas of the continent.

Good idea about protecting the drops in a copper system.

If I only lived in a "dryer" part of the country!!
This morning the humidex is up to 92%!! (I drained almost a GALLON of water from the AIR DRYER alone this morning!!)

The steel pipe, protective "sheaths" (over the copper drops) did their job; a truck backed into one of the "drops" yesterday - left a dint in the STEEL pipe!!

 

[EdNJ]

How about using DOT airline used for air suspensions? It's around $50 for a 100ft roll of 1/2" OD tubing,easy to work with,and fittings are available in PTC (push to connect) or compression style.

 

[PAToyota]

Outside of possible shrapnel, the biggest problem with anything other than metal is that it won't condense water vapor out of the compressed air in the lines.