Venturi pump from Matco

General Composites Discussions Equipment Talk
#1

After failed attempts to repair my electric pump last week, I decided to just purchase a Matco venturi pump. The red one with the handle.

IMO its a great pump. I bagged a few things over the weekend and just did my first infusion with it. I enjoy the quietness of it. It has 4.2 cfm and and pulls 29.5 in/hg at sea level. I don’t know what our level is here, but the most I got @90PSI was 27.5 - 28ish. I usually get 25. I think my gauge might be leaking…

I figured I’d just let everybody know that this works equally as well as my 5.2 cfm electric pump so if anybody really needs a pump for a good price I’d say go to Matco. Harbor freight has a similar model with the same specs for $15 but I wouldn’t trust that. It might stat leaking at the wrong time.

I do have one question though. I already know that I can lower the flow to 15 in/hg after pulling a complete vacuum when vacuum bagging, but can I do that after I infuse a part? Say I infuse a part, and I juts want to lower the pressure to save on the air compressor running. Is that ok? Or should I avoid this? I don’t want to try it on any lives parts, and I don’t want to waste materials doing a test.

Anybody else has any experience with venturi pumps? Anything I might be missing or overlooking when comparing it to an electric one? I really like this, and I’m thinking of switching completely over to all venturi instead of electric. It woudl be nice to just have a big air compressor stuffed in a corner of the shop and run some lines around the shop with pumps / gauges at the end of each one.

#2

You want full vacuum until the resin cures, always.
Ventrui pumps are ok, but they take a long time to pump all the way down, you are using compressed air, so you have a compressor running, and I don’t know many that get as low as a good vacuum pump should pump down too. However, they are cheap, and if you have a large compressor and don’t mind the usage and noise, and don’t NEED a full vacuum.
However, I’m a “do it right” person. I say invest in a good pump that will last you a long time, like a Gast rocking piston. 500$, but will pull all the way down, and very maintenance free.

#3

Also calculate the cost of compressed air per cfm. This might want you chage to electric again. Install a decent pump and a pressure switch, so the pump only starts when needed.

#4

I’m going to switch back to electric once I can afford a good one. I infused a large piece yesterday and after the first hour I put a laser thermometer to the air compressor. The body alone was over 200F and the motor was over 350F. The walls around it were over 100F. I was worried of a fire so Id rather use an electric. The venturi pump works great other then that, I just think I need a bigger more powerful compressor to be comfortable. IMO the venturi pump is a perfect temporary fix for those who don’t want to spend 300 on a wimpy electric pump and would rather save some more.

I was going to try a harbor freight venturi pump for $15, but I didn’t want to risk it breaking at the wrong time.

#5

Our Thomas vacuum pump ( electric ) was rebuilt bought off ebay for $70. It works great for vacuum bagging. I have yet to infuse with it.

I want to get a central vacuum pump so i can run 4 stations off it. I’m just not sure what type of cfm i would need to be able to suck down 4 bags and maintain 26+ hg?

#6

Totally depends on bag size. However, it is a good idea to run the pump on a high vacuum level, and have pressure regulators at your 4 stations, or at least limiters. This prevents vacuum loss on 3 stations when a bag is sucked down on the 4th station.

Also have filters on all stations, this will protect the vacuum regulators and your piping.