Coiled Pipe

DYI · Wed Aug 08, 2007 12:06 pm

McMaster sells coiled steel (or SS, or brass) pipe that is used to protect gauges from steam.

I think that these work by putting water in the coil. As the steam pushes up the incompressible water, the water compresses the air above it, giving a fairly accurate reading on the gauge.

I was thinking of making a homemade version to protect a gauge in a steam gun that I am making, and was wondering if this is actually how they work, or if there is something more complicated involved. IF I am correct, they could be easily replicated with standard pipe and fittings. Ordering from McMaster is not an option for me.

potatoflinger · Wed Aug 08, 2007 12:15 pm

I don't know how they work, but your explanation sounds like it could work pretty well.

jasonsmithmyer · Thu Aug 09, 2007 2:37 pm

If i'm thinking of the thing that you are talking about, we commonly call them a 'pig tail.' what they do is form a water trap that protects the 'pressure-trol' against positive and negative pressure surges. A pressure-trol is just the name we call the little device that measures the internal pressure of a steam system. you could easily replicate this with stanadard pipe to get the same effect though, i think the ones you would buy would be engineered to have the correct trap weir<sp>.

hope that helps

DYI · Thu Aug 09, 2007 9:50 pm

I built one yesterday and tried it today. Despite the fact that it takes an ungodly amount of time to get to 100 psi (I need more fire

), the gauge is fine. Only time will tell whether the gauge is actually being protected by the water in the coil.

trap weir

I have no clue what that means.

CannonCreator · Sun Aug 12, 2007 3:57 pm

Make a prototype with pvc, but use the gauge, and the coil, put in the water, and steam, if that works, it will definatly work on a steam gun.

Pete Zaria · Sun Aug 12, 2007 4:01 pm

CannonCreator wrote:Make a prototype with pvc, but use the gauge, and the coil, put in the water, and steam, if that works, it will definatly work on a steam gun.

Somehow putting steam (which is very hot, and under significant pressure) in plastic pipe seems to me like it's been done before.... oh yeah! we call that a pipe bomb.

PVC (and ABS) get weaker with higher temperatures. Putting hot, high-pressure gas in plastic pipe is just asking for trouble.

@ DYI, I think that'll work just fine.

Peace,
Pete Zaria.