What liquid expands the most with a temperature change?

[4570Man]

I can't go into the details of the project but basically I intend to fill the bottom side only of a "hydraulic" cylinder with a yet to be determined fluid. What is going to provide the most movement of the cylinder with a temperature change? Just looking at a couple of charts that I have no idea what they actually mean maybe Ammonia.

 

[Tractor Seabee]

There are more complications to this than appears on the surface. Ammonia is nasty to work with and needs to be under a high pressure to remain liquid. Any gas off the liquid will be compressible so will not move the push rod. The seals on a hydro cylinder will probably not be compatible with a lot of fluids, especially like ammonia. Think Teflon seals. A lot of research on temp/press relationships and hydro calcs are in your toolbox for this. You will be dealing with more than one liquid/gas physics laws. My arm chair engineering at work.

Ron

 

[4570Man]

I've already thought about at least the corrosive part. The possible solution was to use an expansion tank. Put the expanding liquid in the rubber bladder and put put oil in the other side. Then it expands and forces oil out of the cylinder into the tank.

 

[texasranger556]

I suppose a pertinent question is what are you trying to accomplish? Detect a temperature change? Move something heavy (or light) based on temperature? Something else?

Have you ruled out electronic sensors and actuators?

 

[4570Man]

I'm trying to move something light based upon a temperature change. Electric isn't an option.

 

[MossRoad]

Remember that many liquids don't expand at a regular rate. That is, they don't expand proportionally to temperature changes. Mercury in a thermometer expands very regularly through a broad temperature change. So keep that in mind for your project X.

Also, you can't compress a liquid, so if its under pressure, it won't move much. Release the pressure and woosh!

 

[MossRoad]

I'm trying to move something light based upon a temperature change. Electric isn't an option.

Have you thought about using metal like a thermostat?

 

[4570Man]

Have you thought about using metal like a thermostat?

I probably need 10 pounds of push and 3 inches of travel. I don't think the metal could accomplish it.

 

[MossRoad]

I hope you share the project once its done.... sounds interesting. :thumbsup:

 

[bcp]

Greenhouse vent cylinders.

From:
Automatic Greenhouse Vent Openers & Circulation Fans

How automatic vent openers work: Vent openers do not require electricity. The opener has a metal cylinder containing a mineral which expands when heated. This pushes a piston that opens the vent. As the temperature cools, the mineral shrinks and a spring closes the vent and resets the piston. The opening and closing of the vent is gradual allowing just the right amount of air flow for cooling.

and

From:
Greenhouse Accessories : Univent Automatic Vent Opener Replacement Cylinder

Use the Standard Vent Opener to lift up to 15 lbs, and the much stronger Gigavent, with powder-coated green, all metal construction, to lift up to 65 lbs.


Bruce

 

[4570Man]

That's pretty much what I'm trying to accomplish but I need it to close at a lower temperature. Since other similar devices exist I might as well spill the beans since I'm not going to get rich. I'm trying to activate a water shutoff valve when it gets below freezing. I'm hoping to use no electric before most of the other versions do use electric and I'm hoping that with spring assistance it will turn the water back on when it warms up.

 

[davedj1]

Use water then. It expands when frozen and will contract at room temp from frozen size. Make your own cylinder out of some plastic pipe. Test random sizes, I would start small diameter so it would freeze before valve. Like tow sizes of pex ? Or maybe even a rubber diaphragm with some sort of gas in it? You could pull the valve instead of push it?

 

[countrybumpkin]

May do some searching in this area, you might get some more ideas.

Pages - Typical Self-acting Temperature Control Valves and Systems

 

[4570Man]

Use water then. It expands when frozen and will contract at room temp from frozen size. Make your own cylinder out of some plastic pipe. Test random sizes, I would start small diameter so it would freeze before valve. Like tow sizes of pex ? Or maybe even a rubber diaphragm with some sort of gas in it? You could pull the valve instead of push it?

By that point my water lines are already frozen.

 

[Renze]

Salt expands quite extreme, but it turns liquid only after 450 degrees Celsius or so.

What do you need it for, a Stirling engine ?

 

[Tractor Seabee]

Greenhouse vent cylinders.

From:
Automatic Greenhouse Vent Openers & Circulation Fans

How automatic vent openers work: Vent openers do not require electricity. The opener has a metal cylinder containing a mineral which expands when heated. This pushes a piston that opens the vent. As the temperature cools, the mineral shrinks and a spring closes the vent and resets the piston. The opening and closing of the vent is gradual allowing just the right amount of air flow for cooling.

and

From:
Greenhouse Accessories : Univent Automatic Vent Opener Replacement Cylinder

Use the Standard Vent Opener to lift up to 15 lbs, and the much stronger Gigavent, with powder-coated green, all metal construction, to lift up to 65 lbs.


Bruce

They also use a linkage that multiplies a small movement into a longer stroke. There is an engineering principle there.

Ron

 

[Tractor Seabee]

That's pretty much what I'm trying to accomplish but I need it to close at a lower temperature. Since other similar devices exist I might as well spill the beans since I'm not going to get rich. I'm trying to activate a water shutoff valve when it gets below freezing. I'm hoping to use no electric before most of the other versions do use electric and I'm hoping that with spring assistance it will turn the water back on when it warms up.

Quarter turn water valves take more pressure than you may realize so size your cylinder commensurate with that issue.

Ron

 

[4570Man]

Quarter turn water valves take more pressure than you may realize so size your cylinder commensurate with that issue.

Ron

I actually need to turn off a frost free hydrant because it's the only water source I have and it'll freeze if it's open.

 

[Tractor Seabee]

I actually need to turn off a frost free hydrant because it's the only water source I have and it'll freeze if it's open.

They take more power to open and close. This project may turn into something more trouble than it's worth.

Ron

 

[4570Man]

They take more power to open and close. This project may turn into something more trouble than it's worth.

Ron

Likely so but I enjoy a challenge. After I posted this thread I've found a valve that Ts into the water line and opens once the water reaches 35 degrees. That solves 2 possible 3 of the 4 hurdles in this project. The next issue is if I use that approach how do I turn the water back on?