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Dave builds his own Pela pump.


dave21478

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So, Pela vacuum pumps are getting a good write-up on here and a couple of other forums I read. I quite fancy one, but dislike the 50+ quid price tag, plus postage.

 

Since I am tighter than a nuns chuff, but have plenty of free time I decided to make one.

 

Step one - rummage an old garden sprayer out of the back of the garage. I had this lying spare but they only cost a fiver or so for a cheapo one.

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This is the pump mechanism which hangs down inside the container. This pumps as standard, to pressurise the bottle and spray out weedkiller or whatever. I need to make this work as a vacuum pump instead of a pressure pump.

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On the bottom is a rubber flapper valve which lets air outbut not back into the tube.

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I need this to let air INTO the tube and not back out. I tried just fitting it on the inside, but it wouldnt seal properly, so I cut the end off the tube and glued it back on the other way round with a jubilee clip to strengthen it.

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The handle that slides up and down this tube is a plunger with another one way valve on the end which normally allows air into the tube on the upstroke and seals on the downstroke, forcing air past the flapper and into the bottle.

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I need this to work the other way.....pulling air out of the bottle via the modified flapper valve on the upstroke and letting air past and into the tube to allow the handle to return to the bottom for the next stroke. I considered trying to plugup those half-round holes and redrill them in the top part but it was easier to just pull it off the handle, cut the mountings off and re fit it upside down with a long screw right through it into the handle.

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And that should work.

Buuuut....there is a problem....

 

 

 

 

....cont.

 

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The problem is that the pump hangs down inside the bottle so will be under the level of any liquid inside it. This isnt a problem in its original configuration as when you pressurise it, it just blows bubbles through your weedkiller, increasing the pressure anyway, but as a vacuum pump, once the end is submerged, things will get messy.

I never thought of this while building and in hindsight, this is why the real deal has the pump in a tall section above the tank.

 

All is not lost though, just need a way for this to suck air from the top of the bottle, not the bottom.

 

Tickle a couple of washers together....

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Centre* bore an M6 bolt....

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Weld it to the washers to make a push-on hose tail.

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Add a bit of tubing and it can sook from the top of the bottle now....

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Just need to bin the original dip tube that connects to the lance so it could draw weedkiller from the bottom....

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And thats it. I cut off the spray nozzle from the lance and added a length of tubing, keeping the trigger control in place.

 

Works nicely.

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I forsee a sudden flurry of oil changes coming soon!

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Couldn't you just make an attachment to go over the oil filler cap? Then you can pressurise the engine so the oil comes out of all the gaskets instead?

 

I'd like a Pulverisateur du Jardin....

I have done this with a compressor and some fishtank hose down the dipstick tube, I was only trying to get a syphon going but instead I found out how fucked all my breather hoses were. 

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Here's a better, cheaper solution.

 

Go under the car and undo the plug at the bottom of the engine and let all the oil and shit come out that way.

 

Costs no £££'s.

Providing your car has a sump plug. Also if that sump plug is actually accessible from all the undertrays and crap on the bottom.

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