Surflo pump innards.. (1 Viewer)

[andy63]

Had a pump to take to bits and have a look at..
Fairly common in a lot of motorhomes ..its the 20 psi model so ill post a few pictures in case its of interest to anyone..
They are posotive displacement pumps and can self prime against a small lift i believe..
The pump body is located on the motor with 3 machine screws..
The motor drives an excentrically mounted bearing which drives 3 plastic pads on a flexible diaphram.. in an elliptical fashion in the pump casing...

Removing another 3 self tapper type screws opens up the actual pump casing..
Seen in the picture above..
the moving plastic diaphram on the left which provides the pumping action by moving round the casing such that the volume changes over the inlet and discharge ports...which are seen on the right hand of the above picture .. or rather the discharge ports are visible ...the inlet ports are under the rubber valves ..
A picture of the reverse side showing the central discharge port under the rubber non return valve ...and one of the inlet valves removed...showing some build up of deposits..

Again in the above picture on the right you can see the discharge chamber with another small spring loaded non retirn valve... once the water flows through there it is fed to the pump outler... and there is a small leak off to another chamber which operates the pump cut off switch...
Im guessing the pump pressure is governed by the spring that is fitted.. there is an adjusting screw on the switch which has a minimal effect on the pump cycling time
Which under test was only noticable if the pump was pumping into a system that had a bit of volume..( my garden hose which would be about 15 m long..)
Some pictures of the switching arrangement fitted to the pumps..
Cover removed...

And individual bits of the switching arrangement.

Surflo recommend the pump is mounted with short lengths of flexible hose to the system as by9 the nature of its operation it tends to vibrate a bit..
Ive noticed on my chausson the connections are to semi rigid pipes which might account for it been a bit loud... something ill get round to altering soon i hope...
And finally my set up for testing it.. reassembled after cleaning it up it held pressure overnight so it may still be useful as a spare..

Andy...

 

[funflair]

Nice one Andy, I guess it cleaned up a bit from your pictures, good as new now

A "swash plate" or "wobble plate" pump.

Martin

 

[andy63]

Nice one Andy, I guess it cleaned up a bit from your pictures, good as new now

A "swash plate" or "wobble plate" pump.

Martin

Ahh is that what they are called martin... ?
The box says diaphram pump but i didnt think that was an accurate description...
Btw thanks for letting me have it, and dont tell the owner its a working pump

Andy

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[tonyidle]

Ahh is that what they are called martin... ?
The box says diaphram pump but i didnt think that was an accurate description...
Btw thanks for letting me have it, and dont tell the owner its a working pump

Andy

It is a diaphragm pump with 3 diaphragms operated by a swash plate . The 'diaphragm' bit simply means that it pumps using flexible diaphragms to alter the volume of the chambers in turn rather than, for example, pistons. If you wish to see an extreme example of a multi-piston swash-plate pump I can recommend dismantling a car air-con pump.

 

[funflair]

Ahh is that what they are called martin... ?
The box says diaphram pump but i didnt think that was an accurate description...
Btw thanks for letting me have it, and dont tell the owner its a working pump

Andy

I think the swash plate describes the wobbly bit and in this case it drives a diaphragm pump with the advantage that there is a minimum of moving parts, in other designs it can drive pistons in cylinders via followers, you can even get them with an adjustable throw.

I won't tell @Debs

Martin

 

[andy63]

I won't tell @Debs

Squelar
Cheers for the explination martin.. and yours tony @tonyidle .

Andy

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[GAVLAD]

Thanks @andy63 - this is very useful

 

[The Wino]

Found this thread its an old one but was looking as our pump is leaking between the motor and the pump assembly on the bottom but only when on high flow. Will get it off today and look at it anyone else had a similar problem is it best to swap it or can you just get new seals

 

[funflair]

Just take it apart and clean it up, I have done a couple and just a bit of Vaseline on the sealing face and as good as new.

@The Wino my guess is your leak is at the joint in the black plastic bits?

Martin

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[The Wino]

Just take it apart and clean it up, I have done a couple and just a bit of Vaseline on the sealing face and as good as new.

@The Wino my guess is your leak is at the joint in the black plastic bits?

Martin

Yes it is going to get it off today and have a look. Had 3 unrelated fresh water issues last week. Kitchen tap leaking from underneath (had the same with bathroom tap last year ) water inlet needed replacing as flap catches snapped (took 3 trips to get correct hose) off and pump leaking took !!!!!!! Just about fed up with it!

 

[The Wino]

Just take it apart and clean it up, I have done a couple and just a bit of Vaseline on the sealing face and as good as new.

@The Wino my guess is your leak is at the joint in the black plastic bits?

Martin

Do you just unscrew the pump fitting with wing nuts on looks like it? ( a bit like minature domestic heating pump valves)

 

[funflair]

Do you just unscrew the pump fitting with wing nuts on looks like it? ( a bit like minature domestic heating pump valves)

Yes that looks right, they say things come in threes.

Martin

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[The Wino]

Yes that looks right, they say things come in threes.

Martin

Dismantled the pump and reassembled with a smear of vaseline as you suggested no leak so far!!!! Tap off got one looks exactly the same from screwfix for £27!!!! just about to fit it