Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 26-08-2009, 15:32   #1
Vendor
 
witzgall's Avatar

Join Date: Oct 2006
Location: Eastern Shore, MD
Boat: Camper Nicholson 44 Ketch
Posts: 1,777
Understanding the Watermaker Equation

Hi all;

I have ben futzing around on the internet researching watermaker parts and design. The Filmtec membranes of the 2.5x14 inch size variety take 800psi, and the output is 150 gpd. How much gpm will the high pressure pump need to deliver to push that much water through the membrane? Or put another day, what is the typical rejection rate for a Seawater watermaker?

Chris
__________________

__________________
witzgall is offline   Reply With Quote
Old 26-08-2009, 16:04   #2
Registered User

Join Date: May 2008
Location: Pender Harbour, BC
Boat: Stevens 47
Posts: 95
Dow has a software package you can download to design/rate watermakers:

ROSA

Doug
__________________

__________________
s/v Thea is offline   Reply With Quote
Old 26-08-2009, 16:37   #3
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,596
Images: 240
The supply product ratio is ROUGHLY 10:1, so the 150 GPD (6 1/4 GPH) watermaker pump will require ABOUT 62 GPH.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 26-08-2009, 17:49   #4
Sponsoring Vendor
 
Tellie's Avatar

Community Sponsor

Join Date: Oct 2007
Location: Hollywood, Fl.
Boat: FP Athena 38' Poerava
Posts: 3,046
Gord is right a rough estimate is a 10:1 ratio.
I'm assuming you're intent is to design and build your own watermaker. So my question to you is why are you considering a 2.5"x14" membrane?
Tellie is offline   Reply With Quote
Old 26-08-2009, 18:01   #5
Vendor
 
witzgall's Avatar

Join Date: Oct 2006
Location: Eastern Shore, MD
Boat: Camper Nicholson 44 Ketch
Posts: 1,777
I am trying to see what I can come up with on the lower DC draw side of things. Most likely, it is only an academic exercise, as it looks like even matching the gal/AH of the Katadyn's is hard to do.

Chris


Quote:
Originally Posted by Tellie View Post
Gord is right a rough estimate is a 10:1 ratio.
I'm assuming you're intent is to design and build your own watermaker. So my question to you is why are you considering a 2.5"x14" membrane?
__________________
witzgall is offline   Reply With Quote
Old 27-08-2009, 07:06   #6
Sponsoring Vendor
 
Tellie's Avatar

Community Sponsor

Join Date: Oct 2007
Location: Hollywood, Fl.
Boat: FP Athena 38' Poerava
Posts: 3,046
Quote:
Originally Posted by witzgall View Post
I am trying to see what I can come up with on the lower DC draw side of things. Most likely, it is only an academic exercise, as it looks like even matching the gal/AH of the Katadyn's is hard to do.

Chris

Yeah it would be very hard to do on a 12V home built unit.
Is an engine driven pump out of the question?
Tellie is offline   Reply With Quote
Old 27-08-2009, 09:04   #7
Vendor
 
witzgall's Avatar

Join Date: Oct 2006
Location: Eastern Shore, MD
Boat: Camper Nicholson 44 Ketch
Posts: 1,777
No, engine driven is not out of the question - and the boat was cruised by the original owner with one. There is a PTO on the front, and he had a shaft over the engine to drive both a WM and refrigeration. Both are gone now, and I removed the shaft, but I could easily mount a pump on top of the engine driving it from the double pulley PTO.

Running the engine every few days for water would not be so bad, but I am trying to exhaust other possibilities before going that route. We have 240w of solar and soon a wind genny, so right now I think we are energy independent. Once we have it all up, and can spend some more days on the hook, I will have a better idea.

Chris

Quote:
Originally Posted by Tellie View Post
Yeah it would be very hard to do on a 12V home built unit.
Is an engine driven pump out of the question?
__________________
witzgall is offline   Reply With Quote
Old 27-08-2009, 12:08   #8
Sponsoring Vendor
 
Tellie's Avatar

Community Sponsor

Join Date: Oct 2007
Location: Hollywood, Fl.
Boat: FP Athena 38' Poerava
Posts: 3,046
Quote:
Originally Posted by witzgall View Post
No, engine driven is not out of the question - and the boat was cruised by the original owner with one. There is a PTO on the front, and he had a shaft over the engine to drive both a WM and refrigeration. Both are gone now, and I removed the shaft, but I could easily mount a pump on top of the engine driving it from the double pulley PTO.

Running the engine every few days for water would not be so bad, but I am trying to exhaust other possibilities before going that route. We have 240w of solar and soon a wind genny, so right now I think we are energy independent. Once we have it all up, and can spend some more days on the hook, I will have a better idea.

Chris
The nice advatage to an engine driven unit is you can make it big enough to make a lot of water faster with less operating intervals. Staying energy independant on 12V watermaker gets real hard without energy recovery. If you decide to build an engine take off let me know. I usally have a bunch of used spare parts that might help you keep the cost down, membrane vessels, valves etc.
Tellie is offline   Reply With Quote
Reply

Tags
watermaker

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Understanding a model for battery charge acceptance Rick Electrical: Batteries, Generators & Solar 8 03-06-2017 22:46
watermaker feelsgood Plumbing Systems and Fixtures 13 08-03-2009 11:03
Watermaker Hankthelank Monohull Sailboats 17 28-01-2009 11:46
watermaker ? redbreast Multihull Sailboats 19 11-09-2008 14:57
Looking for a watermaker geoffgroves Plumbing Systems and Fixtures 20 30-09-2007 03:27



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 13:31.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.