Sciencemadness Discussion Board

Water pump problem

Db33 - 7-1-2017 at 17:42

i tried my first vcuum distillation today and EVERYTHING went great except one part. the simplest part! The condenser wasnt working. Not the condenser but i couldnt get water to pump from the bucket threw the conenser.


IMG_0281.jpg - 103kB

This is the pump i was using next to the condenser, the tubing didnt fit like i thought so i used a different tubing and still for some reason it would only push water 10 inches up the tubing and then stopped? Is this pump just too weak? Can someone please give me a link to a good strong condenser pump and the correct diameter to fit the 3/8 arm of the condenser?

Edit: descriptive title

[Edited on 1-9-2017 by zts16]

DDTea - 7-1-2017 at 18:39

Yeah, it sounds as if the pump isn't strong enough. Maybe try siphoning from the condenser's water outlet to get the flow going.

Sulaiman - 7-1-2017 at 18:49

I have a similar small water pump ... check that there are not closed flow control shutters at the water intake,
you could raise up your water reservoir,
but will you feel comfortable trusting that pump when you are not watching ?

SelfInflicted - 7-1-2017 at 20:07

The pump has a maximum head pressure of 10 inches it appears. Tubing size will not change that. No matter how much volume of water the pump can move it can only push water uphill 10 inches.

The recommendations of raising the basin you are pumping from or creating an siphon are valid. If the water in the basin, that the pump is immersed in, is within 10 inches of the highest point of tubing water will flow.

If you fill the tubing and condenser jacket up with water and create a siphon the water will flow. The return line outlet must be below 10 inches above your water source.

The pump will move more water at 1 inch head than 9 inches of head. Probably not much water will pump at 9 inches and no water will flow at 10 inches, since you have determined that it can only pump to 10 inches. Immersing the return line in your water source would equate 0 inches of head pressure.

Small tubing can restrict the flow, restricting the volume of water that can be delivered over time.

Magpie - 7-1-2017 at 20:48

That doesn't sound like much of a pump. I bought a Little Giant pond pump at Ace Hardware over 10 yrs ago and it is still going strong. It will raise water at least 3' and only cost about $25. Literature came with it providing height vs flow rate.

As the previous poster said once you get a siphon going it doesn't take much of a pump, however.

Edit: price: $46; model P-AAA; shut-off head: 4.2': fountain pump

[Edited on 8-1-2017 by Magpie]

JJay - 7-1-2017 at 23:25

Those Little Giant pumps are great and will run forever if maintained. They have an internal membrane/rotor that is supposed to be greased with a petroleum lubricant.

Hydroponics stores usually sell small pumps that work well with condensers despite less throughput than the Little Giant.

unionised - 8-1-2017 at 02:07

If you fill all the tubing and the condenser with water (from the tap) before you connect the pump it won't have to overcome any head- it just needs to push the water round the system.

It takes a lot more work to fill the tubing than to keep it full because a lot of the work out into raising the water on one side is recovered when the water falls down the other.

Herr Haber - 9-1-2017 at 04:01

I got the smallest and cheapest pump possible from the hydro store and it works just fine.

As Sulaiman said: check the pump
Maybe it's just "stuck" because it is brand new or intakes are blocked.

JJay - 9-1-2017 at 04:07

I have a couple of hydroponics store pumps that look similar, but I suspect that's actually an aquarium pump. They aren't designed to lift water like hydroponics pumps.

Bert - 9-1-2017 at 08:43

Look at replacement pumps designed for water cooled tile saws, if you do not mind using AC mains power... They are a bit more industrial, probably have a bit more head than 12V DC fountain pumps and do not choke on a bit of debris.

https://www.amazon.com/s/?ie=UTF8&keywords=mk+tile+saw+p...

biomechem - 9-1-2017 at 10:54

Rise the bucket a little bit so the pump will be less loaded.

[Edited on 9-1-2017 by biomechem]