Instructables

DIY vacuum chamber for sous vide and the kitchen

FeaturedContest Winner
Picture of DIY vacuum chamber for sous vide and the kitchen
This is my first attempt at a DIY home vacuum chamber for sous vide and marinating food in the kitchen.  I spent about $170 including the cost of a new vacuum pump.  Here's a demonstration:

The chamber is a flat piece of high quality plastic (polycarbonate) laid on top of a flat pan or bowl.  Rubber matting is used to create a gasket between the pan and plastic.  A normal automotive pump then sucks out the air.  With this simple setup I can pull a vacuum to 29" of mercury according to the cheap gauge I have, which I understand is better than commercially available vacuum sealers.

One of my goals was to have a setup where I could re-use the bags.  Instead of heat sealing plastic bags I put the food in Ziploc bags with the slide sealer.  I then use magnets on each side of the polycarbonate to close the bag inside the chamber once I pull out the air.

See my inexpensive DIY sous vide controller for the other half of sous vide.
 
Remove these adsRemove these ads by Signing Up

Step 1: Obligatory safety mesage

Before you start out, there are two things you need to keep in mind:
  • If you use a good vacuum pump you are dealing with very high pressure.  Atmospheric pressure is over 14 psi which doesn't sound like much until you realize that  1-foot cube has just over a ton of pressure on each side.  I crushed a thick metal pan (see picture) that I thought could handle the pressure.
  • Keep your fingers away from the air-intake of your vacuum pump.  It will tear or rip off your skin in no time.  You are a complete moron if you check to see that your vacuum is working by using your fingers to feel for air.  Do not ask me how I know this.
I'm amazed you can get 29" of mercury! Most of the vacuum pumps i'm looking at that are 300-400 dollars can only pull about 23-24 inches of vacuum. Can anyone shed light on this? I'm looking at making a degassing chamber for silicone and other liquid materials, and I was wondering if this is enough of a vacuum?
I have a low-end commercial chamber vacuum sealer. The strongest vacuum it can put typically is about -27" of mercury (assuming the gauge is correct). If there is any moisture in the bag, then it should be chilled before sealing. The warmer the liquid, the higher the pressure at which it will start boiling. And you don't want any boiling when you are sealing bags. Boiling liquid will prevent bags from sealing properly and will not evacuate as desired. Some people even complain that if you seal raw chicken in a bag when it is too warm, the water boiling off from its skin will change the texture. Boiling while sealing bags is a bad thing.
Deeg (author)  PandaPropaganda2 years ago
According to the specs on the pump it can pull a vacuum to 750 microns which is way more than necessary (I assume) for a good vacuum chamber.
t.rohner2 years ago
Nice instructable

I have a commercial vacuum sealer and i have some experience, regarding some questions that are in the room.
There are two controls. One is for the vacuum, the other for the time of the sealing heater.
Depending on what you pack, you have to adjust the vacuum.
If you have free liquid, you can't set it too high, otherwise it starts to boil. There are no tricks, to circumvent this, it's physics.
http://en.wikipedia.org/wiki/Vapor_pressure



The pressure on the outside is reciprocal to the vacuum. (1000g per square centimeter at a theoretical total vacuum 0 hPa)
Since you never reach a total vacuum, it will be less than 1000g. But then, at 10 hPa or mBar, you still have 990g.
That is close to a metric ton on a square foot... even if you are far away from a "total" vacuum. (compared to vacuums, used in thin film deposition or semiconductor production, which is around what you have in space)

To reach such vacuums, you need massive diameters in the "pump tubing"(actually stainless steel pipes with a diameter of 2-3 feet), otherwise the molecules don't find the way into the pump. (molecular flow) Funny behaviour..
Because of gassing out, you are very limited in the materials used. Stainless steel, teflon and even gold as gaskets...
And yes, i worked on such equipment.

http://en.wikipedia.org/wiki/Vacuum






The sealer should be a flat heater type, not just a wire.
It should be 2-3mm wide and covered with a teflon tape. (The brown tape in the picture.)
This way, it even securely seals, if there is liquid inside the bag.

One commenter suggested, that it would help to have some sort of mesh in the bag. This isn't needed, for these types of vacuum sealers.

For the cheap "vacuum" sealers, with the bag at atmospheric pressure, during the seal, you definitely need a meshed bag.
But then, most of these sealers are only toys.

Pictures of the sealer and sealed selfmade "Weisswursts".
IMG_20101124_185613.jpgIMG_20101222_214201.jpg
Deeg (author)  t.rohner1 year ago
Thanks for the comments. So if I understand you correctly, you think my vacuum might be too high for wet food? So maybe I should try for ~27 inHG instead of 29 inHG?

The pan I'm using in the video is aluminum. Do you see any problems with out-gassing using aluminum?
t.rohner Deeg1 year ago
Yes, the vacuum may be too high for wet food, if it starts to boil.

I'm not familiar with inHg, but from what i looked up, 29.5 inHg has to be "total vacuum"? Then 27 is less, right?
Although, 29.5 is atmospheric pressure an 0 is vacuum most of the time

On some old vacuum meters, we had Torr as unit, which is mmHg and 760 mm equals atmospheric pressure at sea level, 0mm is "total vacuum".


With my vacuum sealer, i set the vacuum by trial and error. Depending on the goods to seal.
When i put a cup of water inside, the pump won't stop, if i set the vacuum too high. (The water boils)


The out-gassing of aluminum isn't a problem at these pressures.
The top cover of my vacuum sealer is cast aluminum as well.

This is only a problem at high to ultra-high vacuum, where you essentially have to count molecules, to measure the pressure.



Don't you want it to boil it a bit here though?

Isn't the idea to replace the air with water vapour, and then when you re-establish the pressure, the water vapour recondenses, and you have removed the air?

I would think that adding a small amount of hot water in a little cup or something beside the food or even in the bag is actually desirable.
No, it doesn't work that way.

Water vapour has a huge volume, in comparision to liquid water.
This volume needs to to be pumped by the vacuum pump.(your pump won't be big enough, except you whipp up some serious cash...)
If this happens for example on our Weisswursts, their skins rip.


At least not in food packaging. The idea behind vacuum sealing is to remove as much air from the packaging as possible.

If you want to keep the food from oxydising, you need to remove as much air as possible from the package.
On the long run, this only helps, if you use bags with a oxybarrier. (Those bags mostly have a metallic appearance.) Standard PE bags won't do, polyethylene is oxygenpermeable.

Food preserving in combination with vacuum sealing also requires immaculately clean procedures.
Vacuum sealing alone won't do. You will need a preserving technique, like pasteurizing, brining with salt, or adding food grade preservatives like sorbate and so on(not my choice).

For example: the Weisswursts on the picture have been vacuum sealed hot(pastuerizing temp) and cooled in a ice bath in the bags.

The smoked salmon has been brined with salt and smoked. Brining removes free water from the salmon and adds salt.
Together with the smoking and cold storage, the salmon keeps at least for 8 weeks at temperatures above freezing.

By the way, brining fish and meat in a vacuum bag is a really elegant way for small batches.
You're not quite getting what I'm saying. I'm not saying to boil the food, I'm saying boil a few cc of hot water placed in the bag ON TOP OF the food. That way the (small number of litres) of steam will wash away the air as you pump it down, Then when you seal the bag the bag will contain virtually no air.
If you intend to vacuum moist goods, this will happen anyway, if your vacuum gets too high. (with the chance of bursting of the goods)

For dry goods like herbs or teas, you don't want any moisture inside. You can set your vacuum higher here.

I think i get your point, but i really don't see a positive effect.
W1LL72 years ago
where did you find a vacuum gauge for $9 i need one for my freeze dry machine but cant find it for less then $20
Deeg (author)  W1LL72 years ago
It looks like the one I bought is no longer available at Amazon but here's one that's $9: http://www.amazon.com/gp/product/B004KFKYPM/ref=oh_details_o01_s00_i00

They have cheaper ones; look in the "Customers Who viewed this item..." section.
W1LL7 Deeg2 years ago
thanks I must have been searching the wrong phrase there are a lot on there.
walshlg2 years ago
Great work but I'd like to add one word of caution: The reason medical and food grade pumps are twice as expensive is because they are made to keep the cancer causing chemicals from the pump lubricant from running up the vacuum line. This is a very serious issue when you are potentially contaminating your food. May I suggest that you make an adsorbent filter plus a cold trap in the line and also that you only use food grade tubing. Smell your tubing after a dozen uses, does it smell like something you should be eating?
rapier1 walshlg2 years ago
I don't think this is a huge issue in this case. Keep in mind that the vacuum hose doesn't connect directly to the bag - just to the chamber housing. Unless the lubricant vaporizes in the low pressure environment I'd say the chance of contamination is relatively low.
walshlg rapier12 years ago
well that's exactly the problem. When you are talking about parts per billion or trillion contamination, it doesn't take much to be worried. A simple cold trap (loop a coil of the tubing through a bucket of ice water) should help. Also cheap (non-food) grade tubing is contaminated with pthalates. Look it up, this is nasty stuff.
rapier1 walshlg2 years ago
Ah, I wasn't aware that the lubrication would be volatile at these pressures. Yeah, it's a valid point. Either way, you are right in that when dealing with food there is a reason to go with food grade. What about an inline filter of some sort? More complicated but less bulky than a cold trap.
walshlg rapier12 years ago
Personally, I would do both. Rig up an activated charcoal filter. The cold trap is realllllly easy - you just buy 4 more feet of tubing, make a loop-, stick it in icewater, got more tubing, make 2 loops even better.

I've spent a lot of time with vacuum pumps and they have spoiled a many samples. The biggest problem is that every now and then they BUURP and spit out lubricant just when you turn them off or release the vacuum. In light of this, I wouldn't hesitate to get two stopcocks: Close off the one closest the pump first, then the one closest your sample, let air into sample chamber, turn off pump, slowly let air into pump.
Deeg (author)  walshlg2 years ago
Thanks for raising the concern but how dangerous is this? The food is already bagged and the pump is pulling *out* the air. I don't doubt that there is a small amount of carcinogens around the pump but they probably pale compared to the carcinogens that I add when I char the meat with my blow-torch :)
brodie Deeg2 years ago
You only pull air out until the max vacuum level is reached, after that the only flow would be from leaks in the system.
People have been eating charred meat for a long time - meat with exotic lubricants or outgassed chemicals from the tubing? not so long.
A cold trap and filter is also a good idea as most pumps can become contaminated by the fluids evaporated by pulling a vacuum.
sconner12 years ago
As for holding the vacuum.
Try sealing all the threaded connections with epoxy instead of teflon.
sconner12 years ago
Cool.
Do you think you could freeze-dry some food?
If you freeze something say, apple slices. then put them in the vacuum until all the moisture sublimates and is evacuated. Would this be like astronaut food?
rapier12 years ago
I don't want to rain your your parade but I'm not sure why you are insisting on re-using the bags. Bags are a) cheap (a few cents per bag in bulk) and b) very difficult to sanitize properly (they're also slightly air permeable). Since you are using these for sous vide you are dealing with lower temperatures for an extended period of time. In those situations proper sanitation is going to be extra important (including your storage method). Home kitchens are often much less hygienic than well run commercial operations so anything you can do to cut down on contamination issues. I applaud what you are trying to do and the closing mechanism is ingenious but you have to balance your desire to save money and reduce usage against the chance of giving people food poisoning.

If you insist on re-using bags do not just use dish soap and hot water - after washing them very well (disposing of any that feel greasy in anyway) spray the interior with a 10% bleach solution and allow to air dry. Boiling them won't work as they'll deform at 195F. Either way, I wouldn't re-use them for sous vide.

Note: I've been a restaurant cook, I do home canning and preservation, my partner owns a couple restaurants, and I've read the county health department training manual for food handlers and managers for fun. While that's not a huge amount of credibility that's what I'm working from with this comment.
Deeg (author)  rapier12 years ago
What I've been doing is turning the bags inside out, washing them off, and running them through the dishwasher. Then I let them air dry for at least a few days.
brodie Deeg2 years ago
I think most dishwashers do sanitize dishes, but leaving the bags out in the open to air dry can reintroduce bacteria. The safest way would be to sanitize the bags right before use, as any water remaining on the bag at that point is sterile and won't hurt you.
rapier1 brodie2 years ago
Well, the safest way is to just not reuse the bags. Home dishwashers are reasonable good at sanitizing dishes but plastics are a different matter. Different types of plastic has different properties and not all of them are easily decontaminated. You method is probably doing a reasonable job but unless the corners are turned out completely, and you make sure that there is *nothing* in the locking/slide/zip mechanism that's a potential source of bacteria. Remember, bacteria a *really* tiny and you don't need more than a fly speck of food for them to grow on. Also some bacteria can also go in to a spore state where they can't be easily killed by the relatively low temperature of the dishwasher. That's why when I can foods the jars are cleaned in the dishwasher (even if they are new out of the box), sprayed down with a 10% bleach solution, and the rings and lids are boiled for 10 minutes. After that I still need to do high temp processing for safety. Even then I still run a risk of contamination and spoilage. I'm not saying that you *will* get someone sick with this method - only that you are increasing the chances especially given the low temperature method that sous vide uses.

Now, something to keep in mind is that reusing the bags isn't necessarily an ecological win either. You are using a not inconsiderable amount of water, electricity, detergent, and generating waste water in cleaning them. Being that zip lock bags *are* recyclable I'd go that route in order to reduce your waste stream. By reusing them you do save some money - but it's less than 7 to 12 cents per bag (assuming you buy in bulk). So you really have to balance that against the possibility of getting someone sick.

Like I said, the closing mechanism is really ingenious *and* I think the process you are using is pretty cool. The only thing I would caution against is trying to reuse the bags. I really think that's a false economy when you factor in the increased chances of food borne illness. Restaurants run on a really tight budget my feeling is that if they felt they could reuse bags in order to save money they would - but you really don't see them doing that. Obviously, you should do what you think is best in this regard but I hope my comments have given you something to think about.
sheimend2 years ago
First off, great work! This is a really brilliant approach to chamber sealing. I've made several attempts at a DIY chamber sealer, but none had quite the elegance of this idea. Well done.

Second, with regard to the trouble you're experiencing with wet foods, me hunch is that you're just not pulling a strong enough vacuum. I use a VacMaster at home and, although the chamber size is much larger than the bowl you're using, it runs for quite a while before sealing. It pulls ~30" of Hg (should be the very end point on your pressure gauge) and it pulls it for maybe 40 seconds before sealing.

As the pressure in the chamber drops, water will start to boil. As it expands to steam (which is about 1600x the volume of liquid water) it has the effect of increasing the pressure in the chamber. To combat that, just let the pump run for a while more before sealing. You're also on the right track - sealing cold foods and liquids works better.

Anyhow, great job!
Deeg (author)  sheimend2 years ago
Thanks for the kind words and the opinions! I tried as you suggested and let the pump work for a minute before I sealed the bag but the result was the same. Can you give me a quick run-through of what your vacuum chamber sealer does? I'm beginning to suspect that the process is more complicated than I first assumed and I don't know anyone with a vacuum chamber to test it out.

For example, can you determine the length of time between when the bag is sealed and the vacuum is released? Is it (relatively) instantaneous? Is the sealer doing anything in addition to evacuating the chamber and sealing?

I will also explore creating a better vacuum. I was told (apparently erroneously) that commercial chambers only get to 27-28" Hg so I figured that 29" was good enough. I think that the leaks are in the hose connections; if I shut the ball valve and turn off the pump it takes more than 5 minutes for the chamber to lose its vacuum (which I thought to be surprisingly good) but the hose seems to lose the vacuum quickly.

I will try some different tests and posts the results here. Thanks again and keep the comments coming!
brodie Deeg2 years ago
5 minutes is not a good length of time for the chamber to hold vacuum. When you measure using a calendar you have something approaching a vacuum chamber.
With a better seal you may create a better vacuum and will be more likely to remove any fluid from the bag.
Deeg (author)  brodie2 years ago
My thinking (perhaps wrong) was that the leak is slow enough that the pump can compensate and pull a vacuum strong enough for my purposes.
brodie Deeg2 years ago
Probably, I just don't like inefficiency.
And with your setup there looks to be only 4 leak points so it should be easy enough to ascertain where it is leaking and fix it.
Stopping the leak will improve the vacuum, but you may not notice the difference.
brodie Deeg2 years ago
Try adding a piece of plastic mesh to the baggie- this will ensure that any air inside will have a path to exit.
hriosm2 years ago
Nice work.
If you close the valve after getting the vaccum and don´t have leaks, then the needle could stay fixed indefinitely. If see the needle moving fast, then you have leaks.
The vaccum you get also depends on your place´s altitude. At sea level you can get more than at high altitude.
shallnot2 years ago
I suspect the major cost here is the pump. I wonder if something can be done with a $16 hand operated vacuum pump and a different setup.
Deeg (author)  shallnot2 years ago
You could use a hand pump but I think the amount of time it would take to evacuate the chamber would be too much of a hassle. One thing I looked into was using a compressor from a fridge/freezer. I don't think that would pull a good enough vacuum but maybe you could scrounge a compressor for free and use that in conjunction with a hand pump.
DemonNova2 years ago
Absolutely Awesome. Thanks for Sharing!
Mongpoovian2 years ago
This is fantastic! I picked up a medical aspirator pump from a flea market a while back and have been looking for a way to MacGyver a chamber sealer from it. I'll definitely be doing this!
Deeg (author)  Mongpoovian2 years ago
I don't know if an aspirator will create a strong enough vacuum. At least with my experience so far you'll need to get above 29" Hg and aspirators don't come anywhere near that.
Tim Temple2 years ago
Use Goop on the fittings and pull it into the fitting with the vaccuum pump?
vincent75202 years ago
Great …
Now comes the hard part : good cooking !!!…
:-D
Pro

Get More Out of Instructables

Already have an Account?

close

PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!