Does anyone order supplies from ACP? I’m looking for a decent vacuum bagging setup that isn’t going to cost a grand to get into. I came across this:
http://www.acpsales.com/Auto-Vac-System.html
Curious if this system would be worth my time or if you can recommend another vacuum setup.
Thanks.
Auto-Vac electric pump, set to 18" and rated up to 20" Hg
Vacuum switch adjustable from 3" - 20" Hg
If i’m wright 20 Hg is very low, you want 29 Hg or so (I work with bar so don’t know for sure).
Thanks, that’s not a bad price.
CFM is just how rapidly the air is evacuated, and Hg or bar is a measurement of negative pressure inside the theoretically air-tight environment right?
is 6 CFM necessary? I need to do more research, it would be nice to have an automated system that only runs when it needs to - i guess that’s what vacuum switches are for, I guess you’d run one to a relay that brakes the 110V (or 220 for the rest of the world) power to the pump? Are vacuum switches adjustable for upper and lower limits?
You are right: CFM is the amount of air pumped. (cubic foot per minute). Keep in mind that this number drops as vacuum develops.
The Hg or bar is the amount of vacuum it can develop.
For composites, there are 2 nice settings:
-29" Hg or more for infusion (20 mbar abs as a maximum for the metric people)
-14" Hg for wet bagging (500 mbar abs, or -0,5 bar relative to ambient)
With infusion you want to be able to influence the setting. After infusion it is common to raise the pressure, to fight remaining voids.
As a means of influencing pressure there are 3 options:
-spring loaded leak valve. Simple, relatively cheap, an example is Airtech VAC-REG, but your pump will hate you. (pumps are not designed to work halfway their vacuum range)
-lossless pressure controller. Also simple, a tad more expensive, but at least your pump is happy. Great to have if you have a system with high vacuum, and you need something more towards ambient. Pump keeps running Always.
-pressure switch. A bit more complicated. The mechanical ones just need wiring up, but if the switch is not able to cope with the currents, you also need a relais switch, making things just a bit more complicated. These units are available from very cheap (as low as 20 USD) to expensive (200 USD). You get what you pay for, in general. The cheap ones are unreliable, sometimes do not kill the pump, and hysterese (amount of pressure between switch on and switch off) is varying, way too large (in the 150-200 mbar range, or 20% of the complete vacuum range) and cannot be adjusted.
The 200 USD one can be adjusted very finely, and has adjustable hysterese (10 mbar is the minimum, or 1% of the range). And there are some inbetweens.
A digital switch does the same, has adjustable hysterese (up to 1 mbar), and as a bonus you get a digital vacuum gauge with 1 mbar resolution. Drawback is the added complexity, wiring the thing up. (a one time set it and forget it operation).
I am in the process of writing a how-to on the digital vacuum pressure switch setup, so everyone can copy.
that would be great. I’m probably a month out from making the purchase so I have some time to get educated before I buy.