Non return valve for shower and bilge pump

[B2019]

Hi boaters, 

 

I've had a look at my shower and bilge pump and seen I've got no non return valve on the pipes. My bilge pump outlet is quite close to the water ( 8 inches) and just want to be on the safe side. Any recommendations of return valves to use and where to place them on the outlet pipes?

[Alan de Enfield]

8 minutes ago, B2019 said:

Hi boaters, 

 

I've had a look at my shower and bilge pump and seen I've got no non return valve on the pipes. My bilge pump outlet is quite close to the water ( 8 inches) and just want to be on the safe side. Any recommendations of return valves to use and where to place them on the outlet pipes?

Lengthen the bilge pump hose and form a 'Swan-Neck' with the loop as high as possible (several inches above the outlet) and it will be fine.

Don't use a non-return valve as it will reduce the flow, and, if you ever need it 'in anger' you want to be pumping out the maximum you can.

 

"The quickest way to move water, is a man in a sinking boat with a bucket"

 

 

From the BSS :

 

To reduce the risk of your boat sinking if it keels over or is excessively weighed down, it's a good idea for privately owned boats to only have openings which are at a height of at least 250mm (10ins) above the waterline. Where openings are necessary below this level this risk can be reduced by ensuring that these openings are permanently and securely connected to ducts or pipes, which are watertight up to that level.

[BEngo]

Any non return valve on the shower will rapidly clog up with hair, soap and stuff.  Fit a swan neck as suggested above for the bilge pump.

 

N

[Boater Sam]

Golden boat rule,  keep it as simple as possible.

Non return valves will always eventually be a problem.

[Jen-in-Wellies]

You really don't want to be clearing hair/soap/scum clogs from the valve on a regular basis to keep it working. As others have said, take a loop of hose, securely jubilee clipped to the skin fitting in the hull up at least 10" above local water level, then back to the pump (Whale Gulper!).

[blackrose]

1 hour ago, Alan de Enfield said:

Lengthen the bilge pump hose and form a 'Swan-Neck' with the loop as high as possible (several inches above the outlet) and it will be fine.

Don't use a non-return valve as it will reduce the flow, and, if you ever need it 'in anger' you want to be pumping out the maximum you can.

 

 

Yes, this is the best thing to do. Do you really have a bilge pump in the shower tray? Nothing wrong with that I suppose.

 

[Alan de Enfield]

1 minute ago, blackrose said:

 

Yes, this is the best thing to do. Do you really have a bilge pump in the shower tray? Nothing wrong with that I suppose.

 

I think he is confusing the situation - I read it as 'he has noticed a valve in his shower pump hose, should he have one in his bilge pump hose'.

[blackrose]

5 minutes ago, Jen-in-Wellies said:

You really don't want to be clearing hair/soap/scum clogs from the valve on a regular basis to keep it working. As others have said, take a loop of hose, securely jubilee clipped to the skin fitting in the hull up at least 10" above local water level, then back to the pump (Whale Gulper!).

 

Doesn't the Whale Gulper 220 actually have it's own NRV fitted?

 

 

1 minute ago, Alan de Enfield said:

I think he is confusing the situation - I read it as 'he has noticed a valve in his shower pump hose, should he have one in his bilge pump hose'.

 

Ah, I see. Perhaps you're right.

[Jen-in-Wellies]

Just now, blackrose said:

 

Doesn't the Whale Gulper 220 actually have it's own NRV fitted?

 

 

No idea! Fitted eleven years ago on mine and never had to do anything to it.

Jen

[blackrose]

7 minutes ago, Jen-in-Wellies said:

No idea! Fitted eleven years ago on mine and never had to do anything to it.

Jen

 

I think it does and this raises an interesting question: How come Whale can fit a NRV on their shower drain pump and it never clogs, but if I fit a NRV to a waste pipe or bilge pump outlet pipe it will clog? 

 

https://www.ebay.co.uk/itm/Whale-gulper-Pump-Replacement-Rubber-Tricuspid-non-return-Outlet-/323596099452

 

Edited July 28, 2019 by blackrose

[Batavia]

21 hours ago, blackrose said:

 

I think it do

es and this raises an interesting question: How come Whale can fit a NRV on their shower drain pump and it never clogs, but if I fit a NRV to a waste pipe or bilge pump outlet pipe it will clog? 

 

https://www.ebay.co.uk/itm/Whale-gulper-Pump-Replacement-Rubber-Tricuspid-non-return-Outlet-/323596099452

 

Possibly because the Gulper NRV is of the type known as a duckbill valve.  As these are basically full-bore valves, they are very difficult to block.

However, most people probably wouldn't think of fitting one in a boat, as they would be more familiar with a swing check or spring check type valve.

 

Despite being excellent for certain applications (typically in drainage systems) duckbill valves do have a couple of disadvantages, though.  First, they don't completely prevent reverse flow and second, they normally have to be fitted (somehow) between flanges if they are to be installed in a pipe (as opposed to the end of an outlet).

 

Chris G

[PeterF]

My shower pump is of the diaphragm type, which is a positive displacement pump which has to pump liquid forward and will creste a high pressure if restricted. Therefore, if the NRV does gum up, the pressure increases until it blows open and flow starts. On my bilge pump I have a centrifugal type (spinning disc with vanes) and these have a maximum pressure that they can develop. I had an NRV of the duck bill type in it and it gummed closed and the pump could not develop enough pressure to force it open. The same is true for a waste pipe on a sink, there is not enough pressure to force a gummed up valve to open.