Build a Chamber Vacuum Sealer.

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About: general bloke type of tinkering

Most of you are familiar with the food saver vacuum sealers, technically a channel vac sealer as shown in the second photo.

There are expensive versions like the VacMaster PRO350, but by and large they are restricted to the embossed pattern type plastic bags.

Some folk have found work arounds using smooth plastic bags on a channel vac, like straws or strips of shower sponges (bunched up nylon net), but the finished product looks like a dogs breakfast and leaves much to be desired.

Enter the chamber type vacuum sealer, it has none of the drawbacks of the channel vacs and can use any smooth plastic bag that the heat element is capable of sealing. I have even vac'd and resealed a foil type coffee beans bag, mylar plastic I believe.

Bonus feature of using a chamber vac is that the plastic bags are much cheaper than the embossed ones.

Final cost was 2500 ZAR (South African rands). To put it into perspective one needs to compare it to the price of a commercial unit, the Vala DZ300 costs 15000, I dont know if a DZ 200 version is made, but Im guessing it might retail in the 9999 area, so my home made unit is roughly 4 x cheaper.

While shopping at the Cape Town agents for the Vala machines, I had a look in their repair section and saw a DZ620 with a fractured 20mm thick domed lid, probably an expensive replace, which brings me to another point.

My unit is easily repaired by me, spares for the pump and sealer are available and having built the unit, I have the skills to repair it too.

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Step 1: Let Me Show You Its Features. Lol

No fancy electronics here, everything is manual, start the pump till the desired vac level and press the seal button.

I initially used a 0.7mm thick roasting pan for the chamber, don't know what I was thinking, some calcs show a force of 460kg on the bottom of the pan, that's approx 1030lbs which caused the pan to warp like wet spaghetti.

I pop riveted a section of angle iron underneath to reduce warping and the sharp edge of the angle almost tore through at the upper vac levels the small KNF pump achieves.

I'm busy with plan B which is 8mm thick steel bottom plate, 3mm x 50mm side walls with a top cap strip of 3mm x 20mm for the silicone seal to seat against. It took the better part of a 10 ton press to straighten out the curve caused by welding, so it should be more than adequate for the task.

I used some brake tubing epoxied into the pan so that I could access the vac pump without having to open the box every time.

Step 2: Vacuum Pump

The vac pump is a laboratory diaphragm pump, KNF Neuberger N022AN18 which had a broken reed valve and plenty of corrosion. I pulled it apart and glass beaded the head with a sand blaster.

A quick fix was to cut a new valve out of a feeler gauge with the dremel, while I waited for the agents to send a new set of valves.

It worked well enough but didn't get down to the 100 mbar abs spec, there was some flutter on the gauge needle showing the the valves were fairly worn out. When the new set arrived, vacuum was restored back to spec levels.

This is the perfect pump for this application, requiring no maintenance or oil top ups at all.

Step 3: Lid and Seal

I used 15mm thick perspex for the lid with a custom seal that was poured in a 6mm x 5mm groove routed in a piece of mdf. I used epoxy release agent, needed about 3 coats but the silicone released with no problems.

I first used the red auto gasket high temp silicone but it was too soft and deformed too much under vacuum. I tried a 2 pass method because I didn't know how much it would take and was worried I would need another tube halfway.

Next, some simple maths yielded a volume of 32ml and I used black auto silicone sealer which was firmer, it released fine and I was pleased with the end result.

Initially the silicone seal bar for the element pressed too hard and sealed the bag as soon as it was put in the chamber, under vac it would inflate like a balloon, the solution was to clamp the element after vacuum was completed, how the commercial version does that is unknown to me.

My idea was to have the presser mounted on a sliding bar, 3mm chromed rod from a cd rom, press it down manually at whatever level of vac I wanted and then engage the seal button. It works fine with a small O ring to stop vac leaks.

Step 4: Sealing Element.

Here I used aluminum channel on standoffs I milled out of solid bar and then covered the channel with 2 layers of kapton tape to prevent the element shorting out. One end of the element is screwed to the pan via the standoffs and the other end is isolated with a bulkhead fitting that came with the KS200 impulse sealer.

The element expands in length and a tension spring is needed to prevent the element kinking up, it then gets hot enough to burn the teflon fiber top wrapping that touches the plastic bag.

My solution was to use a section of a tape measure's coil return spring.

Step 5: Internals.

Basically, a Vala KS200 impulse sealer was gutted and all its internals mounted inside the box, along with a vac pump.

I tee'd the sealer supply into the switch panel of the pump so that both devices have power when the unit is plugged into a socket, exactly how they originally functioned.

The vac gauge was bought new, it fits a Vala DZ300, but seems similar to the gauges from all the DZ range of machines.

Step 6: Multi Use Tool.

I'm well pleased with the chamber vac's functionality, its very useful, at the very least it can be used on my Harvey oil filter, but with the vac port it can do much more.

Removing bubbles from stirring epoxies, urethanes and silicones is a handy feature, but it can also be used in experimental work.

I was expecting the slice of bread to get flatter, still it will be interesting to see if it develops mold before or after its companion crust left in the bread packet.

In parting, Tigger caught nothing, not for want of trying though, but his space suit inflated like a balloon in the vacuum on the moon's surface and he rolled around like Michelin Man.

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    16 Discussions

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    manicmonday

    Question 5 days ago

    I don't understand the reason for putting a vacuum in the chamber. Looks like increased pressure there would work better.

    3 answers
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    petercdmanicmonday

    Answer 5 days ago

    There's only 2 ways to do it, evacuate the air out of a bag outside the device, in which case you have atmospheric pressure pushing the bag contents into the vacuum machine hence the need for a spillage tray and the pulse function in a channel vac.

    The other way is to make a chamber, put the bag and contents inside the chamber and evacuate the air. That way there's no atmospheric pressure pushing the pasta and sauce out. Once you've sealed the bag, no spillage can occur and when you reintroduce atmospheric pressure, stuff is flat and airless.

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    manicmondaypetercd

    Reply 5 days ago

    That is a great explanation. I think I understand it now!!!

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    petercdmanicmonday

    Answer 5 days ago

    Thats because of the way you have internalized the process, you see the bag deform and conclude the atmospheric pressure is pushing out the air in the bag.
    Its not correct, the fundamental action is that the pump is sucking out all the air particles leaving a vacuum behind.
    When you get the core function that we're sucking out the air, the benefits of the chamber style become more obvious.

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    manicmondaydrlexluthor

    Reply 9 days ago

    I've used the other kind but this one seems completely different. I would love to see it work. Maybe you could get some help making a video. Once you knew how to do that I think you would enjoy it.

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    RomasP

    11 days ago

    Commercial ones have some chamber beneath sealing element and valve to open outside air to this chamber when vacuum is reached or inside vacuum in other time. This chamber is made from soft tube like fire hose. There are return springs also.
    BTW great work!

    2 replies
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    petercdRomasP

    Reply 10 days ago

    Thanks, nice to have the inside info. I spose a silicon tube underneath the top presser bar would have worked, but would have needed rails for locating it and I'd be worried it could crack the lid or unseat the seal.

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    RomasPpetercd

    Reply 10 days ago

    This tube is not elastic like simple silicon, it is from rubber with thread or cloth! So it has specific size when full of air and can not swell like bubble. Ends closet very simply with steel plates and bolts.There is no rails, just two simple shoulders holding sealing element part. For heating element insulation is used Teflon tape with glass fiber like "PTFE Heat Seal Tape"
    BTW in bigger devices there always is 2 heating elements, one flat for sealing, one narrower or special with thin edge for cutting They had separate timers

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    ScaRR_ZA

    11 days ago

    Thanks for sharing. Great to see a fellow South African posting :)

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    JonS4

    12 days ago

    Nice work! A few years ago I spent some time building a similar machine but could not come up with a better way of activating the sealer than putting a hole through the top as you did. I was concerned it would leak, good to know it actually works well. Maybe I will finish mine now.

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    85rocco

    12 days ago on Step 6

    Well done! This is the first time I've seen anyone make a diy vacuum sealer, a little surprising given the cost of the commercially available units.

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    Alex in NZ

    12 days ago

    Well done, and thank you for sharing your work. You totally nail the reason for making things with your "if it breaks _I_ can fix it" comment. Too right!