building vaccum chamber, need help

[Chasper]

I have this vaccum pump and I want to build a vaccum chamber. I see that I will need to get a hose to run from the pump to the chamber, I'll need the appropriate fittings on the hose, and I'll need a vaccum gauge. The instructions with the pump tell me how to pump refrigerant out of an cooling device which is not at all useful. I understand that I will be able to use a glass jar, if I can find one with a 10" opening so I can put my molds inside. Some questions:
1. Can I use a flexible rubber hose or do I need to use copper tubing?
2. What do I use for a lid on the glass jar? Will a standard thin matal lid be strong enough?
3. I'll put a fitting through the lid to attach the hose, that will require some gaskets to get it good and tight so it does not leak, right?
4. If I were to use a straight side chamber like the attached picture, could I make a wood lid with a big piece of rubber/gasket material? Would that hold vaccum?
5. Where does the vaccum gauge go? I know that poly resin should not be vaccumed to greater than 26 pounds or it will boil. Can I just pump it down to that level, turn off the pump,and turn off a valve on the lid?
6. There is a capped opening on the pump (where the arrow is) that says "air," what is that for?

What else do I need to know?

 

[jskeen]

I used 1/4 in tubing from a refrigerator icemaker install kit. Had most of the parts I needed and the tubing stands up to vacuum just fine. If I was doing it again I would consider making it upside down with all the fittings and tubings under a base plate with a sheet of rubber gasket material glued down to it (really well). that way you could just set your molds down inside the circle and put the jar down over them, and turn on the pump.

 

[KenV]

I am pretty sure you will never get to 26 pounds vacuum as perfect vacuum at sea level is 14.7 plus or minus --

Could be a measure called "inches of mercury" and most of these can pull about 20-24 inches -

Note that the pressure pots will work as a "vacuum pot" if you really need a large opening. Or an old pressure cooker works great with vacuum.

 

[Larry in Harrow]

Be very careful around glass containers under vacuum. Implosion is the word but it sure doesn't describe what actually happens.

 

[desertrat]

You will need a second chamber to catch the overflow when vacume is first introduced to keep the solution out of your pump. The solution will boil and foam violently for the first few minutes. I use two 1 gallon pickle jars. The first has an inlet and an outlet while the solution jar has only an outlet.

desertrat

 

[Chasper]

I like the idea of a dome over the vaccum intake instead of lid on a jar. I have a slab of marble I'm thinking of using for the base, some good gasket material well glued to the base to make a seal with the dome.
29 inches of mercury is the max, not 29 pounds, thanks for that correction.
Heavy glass containers so they don't implode, got it.
Second jar to catch the overflow, OK. What keeps the overflow from getting out of the second jar and into the pump?

Does is end up looking something like this illustration?

 

[jskeen]

The second jar is insurance, really. If you want you can extend the outlet tube up through the base to above the level of the top mould to make it that much harder for anything to get drawn into the tubing. Any resin that gets into the tube will be a major pain to clean up anyway, so an ounce of prevention... ect. ect. if the surface of the marble is polished, and the lip of the peanut jar is fairly wide, you may be able to dispense with the gasket altogether and just use a thin layer of thick grease as a sealant. That's what most scientific type vacuum pumps use to seal their bell jars to the platform. You will need some sort of relief valve at some point if you want to be able to open it though.

 

[desertrat]

The overflow jar will not fill up. Mine normally gets around 1/4th inch or less of liquid. Not much but enough to really mess up your pump if it gets into it. Looks like you have a good plan in place now the fun really begins.

desertrat