Need Help with High-Pressure Line for Watermaker

[rigormortis]

Hi folks:
Need advice on what type of hose to use from the high pressure (engine-driven) pump to the membrane housing. That is, carrying the sea water, under about 800psi, to the membrane.
I have burst two hoses already in the past 2 years, due to vibration/chafing on metal bulkhead caused by the pulsing set up with the high pressure pump. I think I've corrected the chafe issue.
When I arrived here in the Philippines I had some new hoses and fittings made up but they are for hydraulic fluid. I've read elsewhere in this forum that hydraulic hoses are not well-suited for this purpose (taste?) but I have this to add: I replaced a short section of hose (1 foot) running from the sea water strainer intake to the first-in-line filter housing with a chunk of hydraulic hose that I picked up in Chile. After about 6 months first filter (20 mic?) was filthy black and the 2nd ( 5mic) filter looked ok. The only reason I can think of for this black crap is that the short section of hydraulic hose is shedding particles (a sea water problem?). This worries me and I will change that 1 foot section and it further worries me that my new hydraulic hose (not yet installed) from high pressure pump to membrane would be worse disaster, fouling the membranes in short order.
So, back to original question: what is accepted standard for hose from high pressure pump to membrane (and from membrane to control panel)?
I looked at the Parker hose site but the choices are almost limitless and I am not an engineer.
Thanks for any help.
Pete

[Tellie]

Parker is a good source for hoses that are potable quality and should easily handle the pressures generated by a (ugh) engine driven high pressure pump. That's an easy fix. But Are you saying you did not change out your pre-filters for six months?

[rigormortis]

Hi Tellie:
Thanks for the reply. I did go to the Parker site but it is confusing in that there are so many types of hose available.
Yes, I did not change my paper filters between Chile and A. Samoa (7 months) but they looked ok when I did. When I changed again in Philippines (6 months) the first filter was black. Second one looked normal to the eye. The only thing I can attribute the black stuff to is the chunk of hydraulic hose (1') I had placed upstream of the filters.
I am singlehanding and make water once per week, at best. The boat is new to me (3 years) and the watermaker came with the boat (no instructions, however). I am expecting grief from you for not changing my prefilters more often. Be gentle.
Pete

[Nauticatarcher]

Aircraft grade hydraulic hose is what I used, but also Know of people who have used normal hydraulic hose with no problems, certainly a lot cheaper and you can always carry some extra and use field fittings on ends and you can change yourself if you need to. Black filter was probably just because you didnt change it, use washable pleated filters and you will get a lot longer out of them

[Tellie]

Originally Posted by rigormortis

Hi Tellie:
Thanks for the reply. I did go to the Parker site but it is confusing in that there are so many types of hose available.
Yes, I did not change my paper filters between Chile and A. Samoa (7 months) but they looked ok when I did. When I changed again in Philippines (6 months) the first filter was black. Second one looked normal to the eye. The only thing I can attribute the black stuff to is the chunk of hydraulic hose (1') I had placed upstream of the filters.
I am singlehanding and make water once per week, at best. The boat is new to me (3 years) and the watermaker came with the boat (no instructions, however). I am expecting grief from you for not changing my prefilters more often. Be gentle.
Pete

Grief? Why I'm the nicest old bastard here!
Yeah, you definatly left the pre-filters in too long. But I understand not having the manual for your unit and learning the system by trial and error. You're not the first. A black pre-filter is almost always biological growth. The first one in line will usually turn black first. By the time it is totally black it is shot. So throw it away and start with new filters. In warmer climates biological growth happens quickly. If you are only using your watermaker once a week I'd suggest you check your pre-filters at least every two weeks and give them a gentle cleaning. That fact that you have an engine mounted high pressure pump could mean several things. The first is that the chances are good that when you fresh water flush your unit the pre-filters do not get flushed with fresh water, which means they will get fouled a lot faster, especially if salt water sits still in the housings for a week. Also I'm concerned that if you haven't changed out your pre-filters in six months have you changed out your charcoal filter?
The hose is another matter. Just give Parker a call and tell them you need high pressure hose that is suitable for drinking water around the 2000psi range. You'll of course need the measurements of the fittings attached to the pump and membrane vessel. If you are experiancing chafe and vibration problems it sounds like your 12' hose is too short. I'd suggest a longer hose coiled one wrap. This should give you the clearance from the bulk head and not stress the hose or fittings.

[rigormortis]

Tellie:
Thanks for the info. Maybe the black in filter #1 was only biological and not hydraulic hose problem. That is encouraging.
You also mention charcoal filter. I don't have one, pretty sure. You talking about a filter in the system just ahead of the taps, to help with drinking water?
Am hauled out now in the Philippines so I may install one.
Thanks,
Pete

[delmarrey]

An Aussie having the same problem in this threads> http://www.cruisersforum.com/forums/...tml#post749076

Check it out!