pump pressure

[Rats]

Do any of you know what pressure this little pump can give?
600L/H and 3.8m pump head.

[JD]

The 'head' is a measure of pressure.

See here for some details: http://www.pumpfundamentals.com/what%20is%20head.htm

[Rats]

Tx will have a look at it. I want to pump through 2 solenoids and want to get the right valve. The one I'm looking at operate at 0.005-0.6Mpa

[ColMack]

http://www.engineeringtoolbox.com/pump-head-pressure-d_663.html

This website has a converter for all measures of pressure.

[Rats]

Tx seems I'm on the right track(more or less) :

[donnchadhc]

This is not so simple, you need to know what pressure is being supplied to the valves not what is outputted from the pumps. For this you need to take the discharge head and subtract the head losses from friction due to the hose, the losses due to gravity and losses from joints. This sounds a hell of a lot more complicated than it actually is. Try to keep the distance and the number of joints between the pump and the valve to a minimum and you should be fine though.

Putting in a T joint and splitting the flows could cause an issue though, as might trying to run two valves off the same pump. Play around with it.

[Ciderhead]

A word of warning those solar pumps are very fickle and if you are going to the trouble of solenoids, invest in a better pump to start with.

[Rats]

Was also thinking on a bigger pump, but don't want to buy new one if I can get away with mine.
In short this is what I want to do.
Only 2 valves will run at the same time(1 in and 1 out)

[Rats]

Tx for all the info. Got a danfoss heat pump from a friend that he used for his homebrewing.

[JD]

I would think you'll be fine as long as you use hoses with a decent inner diameter and as long as the difference in height between input liquid level and output liquid level is not too high. There are many variables though.

My experience with Solar pumps has been mixed. My most recent system--I'm currently rebuilding--was a three-keg single-tier system. I used one Solar pump to move liquid through all three vessels. I fixed my pump about six inches below the lowest point of the three vessels to ensure that the pump would always be able to prime itself. Three times out of four it would fail to prime though. It would only reliably prime if the outlet hose was also positioned below the level of the pump. Looks like my priming 'head' was insufficient.

If you're getting manual with it, this is not a problem, but if you are trying to automate things, this type of priming problem would be difficult.

My conclusion: these pumps are great as long as they're not let run dry and have to be re-primed. 

If I do use them again, and in fairness I probably will, I'll use hoses with a larger inner diameter to reduce hose friction and look into a better priming option: maybe place the pump even lower than I've previously done.

/JD

[Hop Bomb]

They're grand for the money but defo a case of buy cheap buy twice. Mine failed, CH failed, Rossa has been through a few...

[Ciderhead]

I have a brand new chugger winking at me in the shed, but my last little solar won't give up and convince me to get me to get my arse in gear and buy the push fits, so I leant it to pob, I'm sure he will sort it

[Dr Horrible]

A word of advice for anyone looking to install a centrifugal pump like the one above - you should ALWAYS try to make the inlet feed pipe at least a size bigger than the outlet pipework.  For instance if your outlet line is 1/2", you should try to make the inlet line at least 3/4", ideally 1".  You should also try to make this inlet line length as short as possible a run from the feed vessel   - and minimise bends and number of valves.  This applies doubly in the case of pumping hot liquids where there is a danger of cavitation which will destroy a pump very quickly.
I realise this is a little awkward as you will probably have to fit a reducer right before the pump, but believe me, it's worth it.

[Ciderhead]

Fit a valve after the out and partially close to keep the pump from running dry?

[Dr Horrible]

Yep, that will work - if your pump is big enough to be able to handle the extra head you've added by throttling the valve and still be able to meet the flowrate that you want - this is common enough when you're sizing a pump, make it 50% too big and then throttle it back.  If you are going to throttle, try to use a needle valve or diaphragm valve, ball valves are very difficult to get good flow control from.
It's still worth your while to select a large size inlet feed line to the pump though, because the pump can only push out what flows into it, so if you can maximise the flow in, operation of the pump becomes a lot simpler.