Bilge Pump Pressure

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hi all,

I have one of these...

http://www.ebay.co.uk/itm/Adjustabl...K_BOI_FarmingEquipment_RL&hash=item3f044174d8

And I wish to use a bilge pump to push the water through it...

http://www.sipuk.co.uk/tools/info_SIP06819.html

I am concerned about the level of pressure pushing against the float valve when the float has risen and blocked off the water flow

I have phoned the manufacturers of the bilge pump and all the info they can give me is it pumps 233 litres a minute

In a normal situation if the float valve was connected to a main pressure pipe then the pressure would allways be pushing against it when the float was closed.

When using a bilge pump as I understand it due to the way the motor works if the outlet pipe blocks the water then it circulates back on itself or it dosent push anymore water against the blocked output pipe?

I know running a bilge pump dry is a definiate no no but they are ok if the output is blocked...according from a tech guy I spoke to a while ago anyway

Anyone any ideas?

Thanks
 
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What is the float valve/ pump arangment for?
if it is for instance, filling a tank then you may be better off using float switches

Matt
 
Acording to what the guy who sold me the valve has just told me on the phone the float valve is rated

Pressure - 0.05 - 1.0 Mpa (as of the Ebay description)

From what hes told me this is the equivalent of 0.5 bar - 10 bar

A normal UK tap is 1 - 4 bar acording to a plumber I have just phoned
 
What is the float valve/ pump arangment for?
if it is for instance, filling a tank then you may be better off using float switches

Matt

The system already has float switches for turning the pump on and off.

The float valve is being used as a water inlet and for mechanical protection as the float is above the float switch that controls the pump.

So in effect the float valve would only close when there is a problem i.e the electronics go wrong and it decides to keep pumping the blige pump via a relay i.e sticking relay or simliar
 
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Gotcha ;)
In that case, only other thing I could suggest is to interlink the pump with a flow switch installed in the pipewoirk if you are that worried but you would also need a delay timer (for starting purposes)

Matt
 
Thanks for the reply..

I am not looking to put more switches/sensors etc on the system as it is already built. I am wondering what happens if you block the output pipe on a bilge pump i.e does the pressure kind of back feed into the tank rather than continuously push and build up against the blockage?

The float switch is rated at 0.5 - 10 bar so I trying to guage if it will hold shut when the pump is pushing against it when its closed
 
The pump is likely a centrifugal design.

Google wrote....
If you dead head a centrifugal pump by closing a discharge valve the impellar will churn the same volume of water as it rotates in the casing.
This will likely lead to a temperature rise to the point where it will flash to vapour.
If the pump is run for a significant amount of time in this condition it will become damaged.

We've burnt a few out when they've run out of water! Float switches don't always work. We only use ones now with no float switch.
 
The pump is likely a centrifugal design.

Google wrote....
If you dead head a centrifugal pump by closing a discharge valve the impellar will churn the same volume of water as it rotates in the casing.
This will likely lead to a temperature rise to the point where it will flash to vapour.
If the pump is run for a significant amount of time in this condition it will become damaged.

We've burnt a few out when they've run out of water! Float switches don't always work. We only use ones now with no float switch.

Thanks for that...If you run them dry i.e they run out of water then they will die pretty quickly...where it says it will churn the same amount of water in the casing does this mean it will continuously push against the valve with an imense build of pressure? Or does the pressure divert back into the water source at the bottom of the pump?
 
No Pump should ever be run for a period of time against a closed valve, the pump will serioulsy overheat, and damage the seals and impellor, or even the motor if you must do this, fit a pressure relief valve that will open at the closed valve prssure and dump water back to the source ;)
 
No Pump should ever be run for a period of time against a closed valve, the pump will serioulsy overheat, and damage the seals and impellor, or even the motor if you must do this, fit a pressure relief valve that will open at the closed valve prssure and dump water back to the source ;)

The reason the valve is there is for mechancial protection in the unlikely event of the electronics going haywire (custom built 24 input, 24 output, 3 analogue input GSM controller) if this happens then there is a chance the pump will keep on pushing water, reach the float valve level right at the top of the tank then stop anymore water from entering...so as I see it its either the pump possibly burning out or a large flood..im asuming the pump will have a built in thermal cutout also?

What I am trying to establish is will the 0.5 - 10bar float valve withstand this sort of pressure being pushed against it when closed
 
You could have several complex back up systems and all could fail.
Fit an overflow off the tank and forget about shutting off the discharge flow. Job done.
 
bowlingo, you're drip-feeding the forum with a load of questions, each related to the other. How about you outline the whole design (and be willing to redesign the thing if necessary) so that we've half a chance of seeing the whole picture, and giving appropriate advice to you.
 
Oh NO!!! PLEASE DON'T :cry:
Just click on Bowlingo's profile there are endless posts about this!!
 
bowlingo, you're drip-feeding the forum with a load of questions, each related to the other. How about you outline the whole design (and be willing to redesign the thing if necessary) so that we've half a chance of seeing the whole picture, and giving appropriate advice to you.

He has asked numerous questions about this system. It seems he is building an automated hydroponic system. One of the main applications of hydroponic systems is for growing exotic smoking herbs. I'm sure the OP has no intention of cultivating such a crop and this system is intended for his tomatoes.

If the OP thinks his posts and purchases haven't registered on Mr. Plod's radar, I'd suspect he may be in for a rude awakening.
 

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