Pressure relief valve to ease quick couplings

[MossRoad]

The world of digital thermometers is sapping knowledge from our yungins

Ken

See my comments on "board swappers".

 

[SPYDERLK]

I have mentioned this many times before. You only need one QD fitting. a short hose, and a plug in the end of the hose.

When you remove the attachment from the PT, plug the adapter in to the matching QD. This will let any fluid that may expanded, seep into the adapter hose. This may cause only a few psi of air in the adapter. If the hot attachment ever cools down, it will suck in a little air. No biggie.

Could also use a needle valve on a tee before the QD to release pressure.

:thumbsup: Anybody listening?
... larry

 

[oldnslo]

Larry,
I agree JJ's idea is great. Only concern would be if you have multiple implements at different locations or worse yet multiple operators that go care about your equipment or the next guy. Then the possibility of using "connect under pressure" QD's would make more sense.

Roy

 

[PTWannaHave]

:thumbsup: Anybody listening?
... larry

My apologies to JJ, I somehow missed that simple solution when reading various forum threads. It would work great for the homeowner (where only 1-3 people use the machinery), provided that the adapter can indeed be connected with little force, to relieve the pressure. (I like this idea more than a 'pressure relief screw fitting'.)

I.e. my wife could use this home-made adapter that is kept on the tractor, relieve the pressure in the implement and/or tractor, and then make the QD connection between tractor and implement.

Heck, I would even ask Power-Trac to make me one and throw it in when taking delivery of a new machine...

Thanks for the feedback,

 

[jeffinsgf]

Well here's one less thing to worry about: sitting in the sun won't increase the pressure in your hydraulic system. Unlike gases, fluids don't expand or contract with temperature.

Oh, boy, do you need to go back to class. Everything expands and contracts with changes in temperature...liquids, solids and gasses. Why do bridges have expansion joints? Why does concrete crack? Why do ice cube trays overflow?

You're confusing expansion and contraction with compression. Gasses can be compressed. Liquids cannot. That's what makes a hydraulic cylinder work differently from an air compressor.

 

[MossRoad]

Oh, boy, do you need to go back to class. Everything expands and contracts with changes in temperature...liquids, solids and gasses. Why do bridges have expansion joints? Why does concrete crack? Why do ice cube trays overflow?

You're confusing expansion and contraction with compression. Gasses can be compressed. Liquids cannot. That's what makes a hydraulic cylinder work differently from an air compressor.

Liquids can be compressed.

 

[jeffinsgf]

Liquids can be compressed.

Liquids and solids can be compressed, but the pressure needed to affect a significant change is enormous. This is a quick quote from a wiki page:

The effect of pressure and temperature on the densities of liquids and solids is small. The compressibility for a typical liquid or solid is 10−6 bar−1 (1 bar=0.1 MPa) and a typical thermal expansivity is 10−5 K−1. This roughly translates into needing around ten thousand times atmospheric pressure to reduce the volume of a substance by one percent. (Although the pressures needed may be around a thousand times smaller for sandy soil and some clays.)

 

[oldnslo]

My apologies to JJ, I somehow missed that simple solution when reading various forum threads. It would work great for the homeowner (where only 1-3 people use the machinery), provided that the adapter can indeed be connected with little force, to relieve the pressure. (I like this idea more than a 'pressure relief screw fitting'.)

I.e. my wife could use this home-made adapter that is kept on the tractor, relieve the pressure in the implement and/or tractor, and then make the QD connection between tractor and implement.

Heck, I would even ask Power-Trac to make me one and throw it in when taking delivery of a new machine...

Thanks for the feedback,

PT,
for this to work you have to connect the length of hose when there is no pressure on the system. I.e. when you are removing an implement. If you don't the pressure will build do to heat and you will not be able to connect the hose the same as it won't connect to your tractor.

Does this make sense?

Roy

 

[MossRoad]

Liquids and solids can be compressed, but the pressure needed to affect a significant change is enormous.

I believe we discussed this much earlier in the thread.

 

[PTWannaHave]

PT,
for this to work you have to connect the length of hose when there is no pressure on the system. I.e. when you are removing an implement. If you don't the pressure will build do to heat and you will not be able to connect the hose the same as it won't connect to your tractor.

Does this make sense?

Roy

Ah, yes, thanks Roy! One 'dongle' per implement then, and perhaps an additional one on/for the tractor.

Cheers,