Degassing Chamber

General Composites Discussions Equipment Talk
#1

I have seen this degassing setup in ebay. I like the concept. Looking for Plexiglass tube I have found this one. It is cut to your length and the price becomes reasonable for a large degassing chamber. I was thinking about 300mmm diameter and 300 mmm height.
http://www.plexiglas-shop.com/ES/es/cutter.htm?comeFrom=detail&$product=kuhx5cvw62~p
The problem i dont know if 6mm wall thickness is enough? Whats your opinion?
The top could be a 300mm x 300mm x 25mm plate glued on top.
http://www.plexiglas-shop.com/ES/es/cutter.htm?comeFrom=detail&$product=qhvele5tpum~p

meanwhile i found pmma providers with a wall thickness of 12mm. That should be enough i bleieve

The price would be nice
Any opinion or alternatives?

#2

I made mine with a pressure cooker pot, 1/2inch thick lexan lid and a rubber gasket.
http://www.compositescentral.com/showthread.php?t=6432

#3

Maybe a SN4 or SN8 sewer pipe is an anternative ?
I’m making a degassing chamber of it. The pipe cost me around €25 with a cap.
The wall thickness is around 8 mm and the pipe is 315 mm dia. There are a lot of different types and sizes.

#4

Here some pictures of it.

I will use some SBR rubber to seal the top and I will use 2 8mm plexiglas plates bolded together. This is not the best solution, but it was free. I lasercutted the rubber and plates at school :cool:.

#5

Hi,

I build my degassing chamber of a 200 mm long Plexiglas tube with 133 mm outer diameter and 5 mm wall thickness. A 1/2 liter pot fits in which is big enough for the parts I do.

Top and button plates are made of 15 mm Plexiglas as well.
Button plate and 4 pillars with 15 x 15 mm are clued to the tube with Plexiglas glue.

The pillars hold glued in threads to bolt the top plate on which is sealed to the tube with an O-ring. Two brass fittings with plugs are integrated in top plate.

Maybe a bit over-designed, but wanted to have a clear look from all sites. In addition it was a nice project to learn to work with that material.

#6

Nice job. Looks great. Do you apply 29,5hg vacuum without significant deformation of the degassing chamber?

#7

My degassing chamber is in the works. It’s a 6 inch pvc coupling and 2x polycarbonate sheets top and bottom that are 1/2 inch thick.

#8

no message

#9

Can pull full vacuum better than 1 mbar abs./29,8 inHG rel. without any signs of deformation.

But keep in mind my chamber only have an inner diameter of 133 mm / 5,2 inch were the Plexiglas only needs to bridge short distances.

A chamber with 300 mm/11.8 inch diameter and height have much larger surface and load to carry. Not sure if I would go with 6 mm / .25 inch walls.
Button/top plate with 25 mm/1 inch thickness should be fine.

PS: where do you found PMMA tubes with 12 mm walls thickness?

#10

http://www.lumetalplastic.com/pmma_tub_red.htm
Still havent talked to them. Maybe they sell only 2m pieces

#11

Great looking chamber Halto.

Some thoughts:

  • You’re removing the epoxy after degassing, right? Is there any reasonto try to design a way to feed epoxy while still in the chamber? Or a diminishing returns type of thing for non aerospace stuff?

  • Has everyone found their container to undersized in retrospect? (ie having to degass multiple cups of epoxy versus doing in one shot)

#12

I like the bottom to be metallic, as sometimes it really helps to give the barrel a good toss to help the resin-foam which rises upwards to implode.

Thoughts of Fritz:

-1. You remove the resin from the barrel after degassing. The other option is to use a lid with a connector which allows a resin feed hose to be pushed through, into the resin. Of the ones I showed you can do that with the 30x30cm barrel (using an optional connector in the lid) or with the 45x45 barrel (which has the connectors in the lid as standard)

Of course you need the pressure brought back to athmospheric in the chamber, otherwise the resin will not travel.

-2. Too small: At some point everything is too small, too slow, etc. Check the attached picture: 3 degassing barrels, each capable of holding an oil drum (209 liter) which for convenience was only filled with 130 kgs of mixed resin. Total amount of resin needed was 2300 kgs, which meant some 16 of these barrels were degassed. At the start of the infusion the 3 barrels were full, and a mixed batch was waiting in the mixing barrel (not on picture). After opening the resin ports, 1 barrel was transferred into the boat within minutes, after which that barrel could be isolated, and the next degassed batch could take over. The empty degassing barrel was refilled with mixed resin, and a new batch was mixed. All by just operating the valves.

#13

Hello, I’m trying to make a degassing chamber with an old pressure cooker, the problem is that the rubber seal of the old pressure cooker maybe too hard and I need to buy a new softer rubber to provide a better seal. But. What kind of gum I have to purchase? Could make myself with silicone or with other thing?

A greeting and thank you very much

#14

I used some butyl rubber sheet, i think silicone rubber sheet will work too?

#15

Did you buy a 12x12 sheet and just trace the ring and cut it out?

Right now I’m using a 6inch pvc coupling with bagging taped 1/2 inch polycarbonate sheet on bottom and the same on the top. I ended up taping the top and cutting a plastic bag ring seal to go around it to make due but there’s still leaks, I then sealed it with bagging tape but it’s a real pita to remove every time you degas your resin.

I have it hooked up directly to my pump and a release valve going out the other side.

#16

Use a foam rubber on one side.

#17

Is that stuff still going to give me an airtight seal after I cut it the circumference of my pvc coupling so I can see through my polycarbonate top?

#18

I buy it (foam rubber) in narrow rolls, self adhesive. Section is some 1/2" wide and less than 1/4" thick. But a soft solid rubber should work as well.

#19

Can you post a link so I know exactly what product you’re talking about?

#20

cellrubber could be the word to search for.