Do any of you know what pressure this little pump can give?
600L/H and 3.8m pump head.
The 'head' is a measure of pressure.
See here for some details: http://www.pumpfundamentals.com/what%20is%20head.htm (http://www.pumpfundamentals.com/what%20is%20head.htm)
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
http://www.engineeringtoolbox.com/pump-head-pressure-d_663.html
This website has a converter for all measures of pressure.
Tx seems I'm on the right track(more or less) ::)
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.
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.
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)
Tx for all the info. Got a danfoss heat pump from a friend that he used for his homebrewing.
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
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...
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 ;)
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.
Fit a valve after the out and partially close to keep the pump from running dry?
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.
Do you not get cavitation or aeration from all the pushing into a smaller restricted space?
Oversize ing the inlet pipe, kinda making a new reservoir connected directly to the pump?
You don't get cavitation from a restriction downstream of the pump, you get it when suction is created on the inlet to the pump (which can happen if you have too many restrictions like valves or a long length of narrow feed line and the pump has to 'suck' the liquid in rather than it flowing in freely) in combination with high liquid temperatures the liquid will start to boil and form bubbles. These bubbles then get pressurised by the pump and collapse with nasty consequences - from my experience it sounds like you're pumping gravel and the inside of the pump looks like it has too! You might get some aeration with a valve if you have too sudden a restriction - but again if you use the right valve this isn't an issue.
You don't need to oversize the pump inlet so much that you have a reservoir, you just need to balance the flows. If I was starting out to design a pump being fed by gravity, I'd assume a flow velocity in of 0.5m/s and I would design for a velocity out of 2m/s. With the same size pipe in and out that means that with this setup the flow out is four time the flow in, which obviously will result in the pump running dry. But suppose you have a 1/2" line coming from the pump and a 1" feed in - a 1" line has four times the area of a 1/2" line so now you have enough flow into the pump for it to pump out without any issues - hope this is all someway clear!
Sorry if I'm getting into too much detail but those pumps with the same size inlet and outlet annoy my head -they work fine in certain situations but you need to be careful about their setup.
What's a decent pump without breaking the bank for a single vessel recirculating system?(self priming!)
Not sure such a thing exists :(
Quote from: CH on January 08, 2014, 10:36:14 PM
Not sure such a thing exists :(
Can one be bought for <100 ?
Nope :(
Start with buying a couple of solars
Quote from: iTube on January 09, 2014, 10:49:55 AM
The solar projects pumps are direct drive, as in the impeller is driven directly by the output shaft of the motor. Two things about this: if it gets clogged the motor burns out, and maybe more importantly the liquid being pumped comes into contact with the motor's bearings which is not considered food safe.
Very true - and as you start to look for better seals and food grade material the prices start rocketing. If I was building a brewery I'd be looking at preferably peristaltic or double diaphragm pumps (both self prime and the peristaltic doesn't even contact the liquid), but any costs I've seen for peristaltic are too high to consider using them at home and the double diaphragms need compressed air to run.
I was in a farm shop recently and saw some interesting pumps - I reckon the farm/dairy industry is the most likely to have cheaper equipment that would be food grade, must look into that a bit more, see if there's anything that could be used for brewing.
Only problem i might see with Dairy/Farm pumps is they wont be rated to 110C as most f/d apps would be low temp.
Nope! That's an extreme situation though, normally cavitation sounds like there's something rattling around in the pipes. I worked on a job once where a pump was cavitating badly and it really was like rocks in the line, the pump had to be taken out every few days. Moved the pump to directly below the feed vessel, increased the inlet line size and problem disappeared. Same principle applies to the little solars, get the set up right and they'll run away no problem, but if it's wrong they'll let you know fairly quickly.
I have you now.
Thanks!
I've decided to buy the solar projects SP20/20 . Should I buy the fittings, olives and hose with it or is that stuff easily sourced locally
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The fittings are handy and at the price you can't go wrong, you can always replace later with brass or SS .
I would also highly recommend the transformer that can be purchased (15 poundish). It allows you to set the speed electrically so that its not going full pelt against your discharge valve that is nearly closed. I normally set it low see what the flow is like then tweek with the Discharge valve to suit, really good for Mash Tun recirc clarification.
Thx DaMun, does the 20/20 indicate 20mm fittings or are they standard imperial sizes that I'll get locally?
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They're imperial! So standard plumbing fittings work.
There are 3 different HP/Watt ratings and for the 3 extra quid get all the horses with the 14 watt one.
http://shop.solarproject.co.uk/Solar-Project-Pumps-c-2.html