Need Low Volume Water Pump

[zevon8]

One thing I have discovered about washer fluid pumps... many of them must be submersed/wet at all times. This maintains the prime, provides lubrication/cooling for the pumping mechanism. They can have very short lives when run dry. They can burn out the pump/diaphram in short order due to friction.

 

[philba]

One thing I have discovered about washer fluid pumps... many of them must be submersed/wet at all times. This maintains the prime, provides lubrication/cooling for the pumping mechanism. They can have very short lives when run dry. They can burn out the pump/diaphram in short order due to friction.

yes, that is true for most of the small pumps I looked at. Run dry and die... I couldn't find a really small self priming pump. The WW pumps are low duty cycle devices as well. You need to build in a time out so that it doesn't run for an extended period of time, dry or not. It's one of the reasons I used a microcontroller but a 555 could be used to time limit the pumping action.

 

[Hero999]

I recommend you use latching relays, the main advantage is that you don't need any semiconductors or even a low voltage power supply as you can get relays with mains coils.

 

[tunedwolf]

hey noggin, umm...I have the feeling I already know ya from somehwere :>)

Keep it simple as 123, no point in re-inventing the wheel. I would suggest that you get a hold of an old tank sender unit outta the scrap yard, the kind used to indicate your fuel level in the tank of a car. Use the rod mechanism and float etc with a small paddle of some sort on the end and 4 cheap optical sensors, you can always cut/bend the rod etc to achieve the correct angle and arc. The sensors would be arranged with some discreet logic to detect failure and either shut the pump off, of empty the tank, either way, it gives you an opportunity to indicate failure of the control mechanism. You will need to be fairly inventive in order to strip it down to something useful to your application though.

Use a bistable or something equally simplistic, or a small micro if you must, to control your pump. You don't really need to pump it out as such, just prevent it overfilling, so maybe a 20-30 sec burst of the pump will be sufficient if the pump isn't rated for the duty. If the pump is capable of safely running long enough to completely empty the tank then use something state driven, much less chance of a failure or screw up.

You could always use a small micro and just read the resistance from the rheostat on the tank sender, if you can find a way to keep it as part of the mechanical setup, and just perform a table read/compare to control the pump.

Also, make sure your tray is sloped slightly and draw the water off from the deepest point.
in the case of a submersible/ flooded suction pump, you'll want this point to always have enough water in it so as not to lose the prime.

In any case, the more complex it is, the harder it will be to build, the more expensive it will end up, and the less reliable it will become.

Just my thoughts...

 

[panter]

self priming pumps

i've been using these for some years now and not one died yet.

**broken link removed**

I believe the company Gorman-rupp also makes this type of pumps though these tend to be more expensive.
These pumps are self priming up to more than a meter, In my instruments they draw water from 1.25m without a problem. These also can lift that water considerably and here those cost from 15EUR.

However there is a drawback to them, running dry for a short time, a few minutes or so will not damage them although you'll emediatelly notice that it's dry, it gets really noisy.
Those work on 220V and there's a version for 110VAC. The flow is also not on a bright side, maybe 1-2l/min for this smallest one but then again do you need more?

Good luck.

 

[Bob Scott]

How about a small boat type bilge pump? Or at least the factory made float/switch assembly?

 

[things]

you said it was a humidifier... right? if it was an ultrasonic humidifier, the fogger automaticly turns off if the water is low, so maybe you couls use that as a switch. or you could have a sensor to see if the fogger is activated. if i remember, i think they operate at about 1.6mhz?, if you can find a sensor that will be able to detect that frequency, it could tell you when it is off.

 

[mneary]

DEhumidifier.

 

[mwaniki]

I would like a water level controller circuit to control pumping from a reservour to a storage tank to the demands of the user.

 

[KMoffett]

Velleman Components n.v. The onboard relay can switch a larger external realy the run your pump. Use three stainless steel rods for detectors.

Ken

 

[Ubergeek63]

if worse comes to worse you could get a gear motor and build your own peristaltic:
Peristaltic pump - Wikipedia, the free encyclopedia

 

[ditch182]

I've been looking for something similar, and found a couple of good suggestions. Thanks everyone.