Self-priming pump and air-trap

[cervantes]

Hello,

I was wondering if self-priming pump can work properly in position shown in attached drawing. There could be a
possibility of air-trap which can affect on work of a pump. Using non-return valve at the begining of suck hose should help, however I'm not sure if it will work correctly.

Regards

 

[BigInch]

It could work as shown on your pic. Pump must develop enough "suction" to raise water up and over the "goose neck". As long as the goose neck elevation is reasonable, it should work just fine.

Adding a "foot valve", a check valve at the entrance to the goose neck, will improve the time it takes to restart flow, as without the check valve, the liquid in the riser will have a tendency to fall back into the tank when pumping is stopped. With the check installed, the liquid will tend to stay in the riser.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[25362]

Cervantes (is it Don Miguel?), you mention a self-priming pump but don't show or explain how is the priming done, in particular, if it is a centrifugal.

Apart from their frictional loss, foot valves sometimes malfunction due to the presence of small particles that may induce leakage.

 

[cervantes]

25362:
I will propably use EBARA JESX8 or ESPA Aspri 35/4 (Aspri's manual doesn't allow this configuration, I haven't seen Jes manual yet).

Miguel de Cervantes Saavedra

 

[insult2injury]

I would think that it wouldn't be too hard to put a connection near the bottom of that basin and then you wouldn't have to worry.

 

[25362]

These small pumps generally contain sufficient volume at the suction and at the discharge side acting as priming chambers. Once primed for the first time, the withdrawal of water from the suction chamber creates a partial vacuum on the suction side sufficient to allow the atmospheric pressure on the gutter basin to force water up the gooseneck and into the pump.
Anyway, why not ask the pump supplier if the arrangement (including dimensions) as described in your sketch is acceptable ?

Good luck.

 

[Artisi]

It will work - no problem, the only thing I would add is;
Fit a stop valve / tap or similar on the hose otherwise you are likely to empty the tank by syphon effect after you "stop" the pump.

Naresuan University
Phitsanulok
Thailand

 

[katmar]

Cervantes, I have used systems just like you describe and they work well, but there are a few practical things that can help.

Depending on the balance of the piping (on the delivery side of the pump) you may or may not require the foot valve in the sump, but it is best to have it. These sumps tend to accumulate bits of plastic, rags and assorted debris which can block the foot valve. You can buy foot valves with integral strainers, but they can be very heavy and require the piping to be lifted out of the sump to be able to clean them.

I have found it is more practical to install a reducer at the bottom of the pipe, with the larger end down, so that an over-size foot valve can be used. This allows most debris to be sucked up into the piping and you just install an in-line strainer at the suction of the pump where it is more accessible for cleaning. Each time you clean the strainer you will lose the prime, so install a valve at the top of the gooseneck so that you can easily refill the piping and prime the pump.



Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[cervantes]

thanks for the help

 

[DiaphragmPumps]

If the picture shows the correct heights, then there won't be any syphoning back into the container. Looking at the inlet port It shows an above centre line inlet, therefore it is most likely a self priming unit. As the Inlet pipe will be full to the level of water in the tank, there will not be any priming issues after the first operation unless evaporation empties the bottom of the volute chamber

 

[Artisi]

if the level of water in the suction tank is higher that discharge point it will syphon thru the discharge once the pump is shut down - that's until the inlet tank level is equal to the discharge point - therefore you need a method of overcoming the syphon effect.

Naresuan University
Phitsanulok
Thailand