Re: [Amel Yacht Owners] Diaphragm Bilge Pump failure.

James Alton

  Have a great time in the Bahamas.  We have spent quite a bit of time over there on various boats over the years.
  What a great resource you are.  It will be intersting to compare the actual test data to the predictions.  If I decide to add this pump, I think that I can get by with only 6-7' of piping which would be 2" smooth bore fiberglass piping with a length of hose to connect the pump to the piping.  No elbows but some gentle bends. Can you tell me the losses to expect in a vented loop?   This would also be fiberglass pipe so I can make the radius the optinum curve.  I assume that some energy is returned as the fluid is falling from the vent to the discharge but have no idea of how to calculate that part.  The 4 foot actual lift might be 3 1/2' but the vented loop may add another foot?
  The Seland pump can be an ongoing offer and maybe if you want I will also send down the 4000 pump for you to test as well if it is of interest.

SV Sueno, Maramu #220

Sent from Samsung Mobile

-------- Original message --------
From: "greatketch@... [amelyachtowners]" <amelyachtowners@...>
Date: 12-03-2017 12:02 PM (GMT-04:00)
To: amelyachtowners@...
Subject: Re: Re: [Amel Yacht Owners] Diaphragm Bilge Pump failure.



Your offer of testing a Sealand pump in an Amel bilge is fun and fascinating. Unfortunetly we'll be headed to the Bahamas before such fun could be had!

Yes, the Rule can pump 27 feet up, but at zero flow rate.  Also, the head required to actually move water is more than just the lift height.  The piping resistance is the larger and usually more significant contributor.  

(Note, I am a chemical engineer, and for a time pumps and pump selection was an important part of my world.  So I'll likely subject the good members of this forum to way more detail than they need...)

I did a quick and dirty calculation of flow rate for the following system:

10 feet of smooth bore 1.5" hose, two elbows, a total of 4 feet of vertical lift. I calculate such a system would require a pump discharge head of about 6.7 feet at 10 00GPH.  Pretty close to a Rule 4000 pump curve.  (Details available on request for you masochists out there...)  2 inch hose would be better, but you get the idea...

Bill Kinney
SM160,  Harmonie
Fort Lauderdale, FL

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