Add also my home made pressure pot http://compositeforum.werksberg.com/showthread.php?t=1152&highlight=pressure
Baz
Has anyone ever used one of these types of vacuum pumps?
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=3952
I’m waiting on my refridge pump, but I was also thinking of using one of these.
Venturi type pumps work very well, but obviously you also need a pretty good compressor as well as the pump itself.
Plus you gotta listen to the compressor running till the part is done.
If your just doing once in awhile stuff get a Robinair, J/B, or Ritchie type pump.
If your doing a lotta stuff everyday get a Busch R5 or Rietschle type pump hooked into a good reservoir sysetm, with the CFM to match your output.
Unless the compressor you have doesnt have a cut off switch (which seems unlikely!), it will only run when pressure in the tank goes below a certain amount.
Unless sealing of vac is very poor indeed, a good multi stage venturi pump isnt going to have a lot of work to do, pressure drop on a reasonbly sized compressor tank isnt going to be that great, and compressor wont be running for very long at all.
I may buy one just to have it right now, as the friend I am getting the refrig pump from is quite the alcoholic, and prolly forgot by now.
Remember you will need a reasonable compressor to make a single stage vac pump work properly, and ideally some sort of tank to contain vacuum.
I thought I would tag this onto an existing thread rather than create a new one because…
I’m looking at buying a pump and have been offered a Rietschle V-vte 6, the spec is here:
http://www.gd-elmorietschle.com/uploadedFiles/Elmo-Rietschle/Downloads/Content_V/VTE_DTE/D187.pdf
But to save you the trouble the juicy bits are:
4cfm (6 - 7.2 m3/h) of airflow and 150mb of pressure.
Is 150mb enough? I’m having problems converting to the units you guys are familiar with, but I get that to be 112509 microns or 4.4" Hg using this convertor here:
http://www.unitsconverter.net/
Given that your Robinairs are 20 microns I was expecting this to pull my face off, but it doesn’t - I put my finger over the intake and it just held it on there nicely, a bit like a household vacuum cleaner.
What do you think to these specs?
4 cfm is decent, but 4" is crap. Low micron is better. My pumps pull over 28.5".
Lower microns is better???
Track down a refrigerator repair vehicle or business (HVAC).
I can pull 23-25 inches with my harbour freight venturi style. But I can only use that one at work.
I get a bit better results with my robinair but I have to deal with the exhaust. I’ve been using it in the house and venting outside but it’s not ideal by any stretch of the imagination.
Fridge compressors sell on ebay for $40-$150 but I don’t know that any of them are good enough and I hesitate to spend the money.
But with the venturi style one you must have the air compressor running nearly all the time. That would be loud, annoying, and waste a lot of energy.
The Robinair should produce much exhaust. Exhaust smoke is due to a bad job on bagging. If no air comes in, nothing comes out.
A very apt name you have there sir. 
I do the vacuum bagging (actually pulling the vacuum while it cures) in my apartment. Accordingly any exhaust is too much. you’re correct, it’s not much, but it’s enough that I don’t want it floating around in my apt.