Vacuum Relief Valve

General Discussion
1

just bought a Busch SV 1008 Dry vane vac pump by mistake ( didn’t realise I had bid on Ebay) but looks like a happy accident to get into the compsands and for £10 too. Spec is 8m3/h and should pull 20Hg. Doesn’t come with Filter but been offered that seperately and also a relief valve. From what I can google it is a safety valve to protect the pump in that it lets in air when a certain vacumm is reached looks to be factory set to be just lower than max vacuum. Did a search and found only one reference

http://www.swaylocks.com/forum/gforum.cgi?do=post_view_flat;post=185442;page=2;sb=post_latest_reply;so=ASC;mh=25;

I am assuming there is no need as I will be maintaining a much less than max vacuum by way of a vac switch or bleed system. Can anyone confirm .

thanks

mark

2

I’ve never needed more than 11 - 12" Hg when pressing on skins, even thick ones that don’t take the curves easily.

Any more pressure and you’re crushing EPS, borderline with 12!

Switch the pump on and fiddle with the switch, if it allows it, see what it does.

Sounds like the pump will be perfectly happy to be constant-run, so no need for a proper vacuum switch, just use a bleed valve.

When I get a pump that can run continuously, i’ll probably change to a bleed valve, good vac switches are pricey (more than a second-hand pump!)

3

good catch a Busch for 10 quid…

when shopping for a pump I found the wikipage : http://en.wikipedia.org/wiki/Vacuum_pump to be useful in that it has details of all the various types of pumps. It doesn’t look like a dry vane pump needs a relief valve if you will be bleeding air anyway. I am further assuming that the relief will be necesary to avoid overheating the pump, again something you can control with a bleeder hole/valve in your bag, or something you could probably put together yourself with parts from a DIY shop. I ended up with a old GE oil vane pump which can pull (after an oil change!!) up to 30 inches HG!! so bleeding is necessary, it has a built in so that’s handy but as I recently discovered when making test panels, a vac bag is often quite happy to “help” with a few bleeder/relief holes…

4

I have to order the relief valve to come with the pump and haven’t had a reply back about what it does so will give it a miss unless it is variable. The pump is supposed to be unused. Seems sensible to have a filter ( extra cost) otherwise I expect bits can be sucked into the vanes and ruin them.

I would really like to have seen and ridden more boards from regarded shapers before making my own. Not sure wether to plough on and rely on compsands needing different design for maximum benefit or have another go at getting/riding some of the exciting boards already out there. Should really travel as well.

Thanks

Mark

5

Where are you working? I’m based in Milford Haven and do loads of vac bag and infusion stuff, you might like a look around the College, maybe we can help or vice versa!

Rik

6

Thanks Rik I am in St. Davids. Quite amusing all the worldwide places that other Swaylockians reside in and I am just down the road from you. Yeah I have been meaning to look in at what goes on in the Marine Technology Centre. Surf mainly Whitesands for convenience .

Mark

7

I’ve pm’d you to discuss further…