Help me find a pressure/vacuum tank!

Factual Questions
1

I am looking into getting some sort of tank/canister that I can create a vacuum in, then later pressurize to assist in dyeing woods.

I am looking in the 1-10 gallon size range.

If it helps, what will basically happen is that I will put the wood in the container, shut it, and create a vacuum. From there, I would like to insert dye into the container through a valve losing as little vacuum as possible (the option to turn the vacuum back on at this point would be nice in case I mess up on the valve). Then after a while I would like to release the vacuum slowly and pressurize the container for a little before releasing the pressure and opening it up.

I have been googling like crazy but I keep getting industrial size tanks or vacuum cleaners for carpets.

Maybe I am not calling this tank the right name? Any help would be greatly appreciated.

2

Is this anything like you’re looking for?

3

Ah yes, it is! Apparently “pressure pot” is the term I was looking for. You either already knew exactly what I was looking for, or your googling abilities are legendary. Either way, thanks!

4

How about a used pressure cooker? Cheap, strong, and available at second hand stores.

5

That’s an interesting idea. I’ve never used a pressure cooker before (for anything). I forgot to mention that I’m looking in the range of 50-80 psi. What type of pressure do they use when cooking?

6

Not even close. Pressure cookers typically operate at about 15 PSIG max.

7

Are you sure you need that much pressure or is that just an estimate for your process?

8

Hah, I wish it was the latter but I had a good feeling that was what you had in mind.

I see you’re planning to dye the wood so you will need the 50 - 80 psi range. Somehow I missed that part of the OP.

9

Man, if only I knew a real life Tim Allen…

10

An outdated 30 lbs fire extinguisher?
Don’t know how much of a vacuum it would handle but they are capable of that kind of pressure.

11

Did you get what you needed? If not, I can ask around; plenty of enclosed explosives testing chambers are designed for much higher PSI ratings than you’re looking for. Snap-On makes some chambers I’ve seen used, for example.

12

Okay, I’m an idiot. Turns out, some joker epoxied Snap-On buttons onto a few of our tanks. I’ve been getting shit for asking who made the other ones all day. Turns out, they’re all made in house. Sorry I couldn’t have been more help, but hopefully you got as much of a laugh out of it as those guys did.

13

You didn’t mention the dimensions of the wood you intend to treat, but a trip to your local plumbing supply will probably turn up everything you need.

Some pipe with screw on caps. And caps of course. Valves and fittings for vacuum and dye entry.

If you need large diameters you might be able to use PVC to save costs.

14

Yes, looking at mine the gage goes into the red zone above 20 psi. Sorry.
You could also try paint pots that use a seperate spraygun. The one I have shows it will take 60 psi air.

15

It’s probably not a very good idea to monkey around with haywire solutions when you are looking at 80psi. Even on a little three inch pipe you have 565lbf, or 2.5kN (on the threads), lets assume a 300g end cap, that force can produce a 8.3km/s/s of (F/m=a) acceleration. Assuming, 0.01s rupture, and final velocity is (v=at) 83m/s, with a kinetic energy of (KE=1/2mvv) 1.0kJ, which Wiki says is edging into rifle territory. So please don’t cobble together a solution.

Everybody in construction knows a friend of a friend who swears that they saw a split rim tire go through a cinder-block wall because it was put together incorrectly. And then there is the guy who lost a finger/hand/etc when he though he found a pressure leak and put his hand in front of it.

Even small pressure vessels are very expensive, say $20,000* for a little one (0.5m diameter, 1.4m height), and you can double that if you want stainless steel. *Based on an equipment costing text.

16

I only gave that page a cursory glance (so perhaps this is a non-issue), but if you buy some sort of pressure pot, make sure it’s rated for vacuum pressure if you’re also using it for same. Pressure vessels with externally applied pressure (vaccum tanks, in this instance) are susceptable to buckling, which is not an issue for internal pressure pressure vessels. The vessels on the linked page look pretty stout, but internal pressure rating is not necessarily a good guide for vacuum rating. As a cite, I offer a 2-liter pop bottle.

17

Of course Mythbusters got a regular hot water heater to over 330psi. But I am not sure you want to do that in your garage.

Then there is this fun video of a tank car implosion.

One of my profs likes to tell a story about how he destroyed a $20k piece of lab equipment checking for leaks. He decided to put it under a vacuum, and wait and see if the pressure increased, but instead it broke because it couldn’t tolerate low pressure.

18

That looks exactly like a Mr. Science experiment where he heats water to steam in a 55 gallon drum, seals it and then sprays cold water on it.

With the crowd around the rail tank it looks like a deliberate event.

19

I wouldn’t have suggested it if I didn’t remember having used PVC pipe with a rating of 200psi stamped on it.

So I’d recommend checking the rating stamped on the pipe itself.

20

The problem is that pressurizing the pipe with compressed gas isn’t the same as pressurizing with water which the PVC pipe was made for. It’s not my area of expertise but AFAIK PVC shatters when it fails under pressure whereas ABS would split. That’s not to say it would fail when pressurized to 80 psi just a reminder to the OP to be aware of the potential failure points which could also become projectiles as Zany Zeolite Zipper mentioned. Anything you thread into the pipe (end caps, gauges) needs to have threads rated for your working pressure and introduces a weakness in your system. No matter what method you use consider installing a pressure relief valve.