s/v Jedi: watermaker pre-filter unit

[s/v Jedi]

Working on one of the projects on the list: the perfect watermaker. This is the pre-filter unit. Much thought has gone into specific parts used: for example, the filter housings have no metal parts that can corrode. Also, the service- and purge valves make maintenance a breeze and the pressure/vacuum gauge shows filter performance.
Also, part of this design will be a small sink with kitchen faucet in the lazarette for cleaning the filters; the filter housings will be mounted above that to contain the messy part of making water.

[Chotu]

The sink is a great idea. It’s so messy dealing with the prefilters.

[Tupaia]

I like the permanent purge valve, much better than using the plug on top of the filter housing.

Like many others I installed my WM in an engine room. BIG mistake, salt water, in fact any water should be kept away from areas around engines. When I re-powered I moved it to the heads compartment, the WM is installed behind the shower and the pre-filters next to it so spillage is directly into the shower. No more mess, easily cleaned and no gymnastics required. Initial product flow is also directed into the shower and the outlet is sited so that I can also fill tubs, stood in the shower, that I use to wash dive gear.

I now only use one 5 micron filter and it has not significantly increased the change / cleaning frequency.

[s/v Jedi]

Originally Posted by Tupaia

I like the permanent purge valve, much better than using the plug on top of the filter housing.

Like many others I installed my WM in an engine room. BIG mistake, salt water, in fact any water should be kept away from areas around engines. When I re-powered I moved it to the heads compartment, the WM is installed behind the shower and the pre-filters next to it so spillage is directly into the shower. No more mess, easily cleaned and no gymnastics required. Initial product flow is also directed into the shower and the outlet is sited so that I can also fill tubs, stood in the shower, that I use to wash dive gear.

I now only use one 5 micron filter and it has not significantly increased the change / cleaning frequency.

The nice thing with the purge valve is that it is at the very top of the line that goes all the way down to the input of the high pressure pump. Also, with the 1/4” pex drain line attached, there are no spills and you can leave it open after a filter change to fill the housings and input line to the high pressure pump, closing it when a steady stream comes out.

The sink will have 4 spouts (cut ends of pex tubing) discharging in it: the purge valve drain, the brine discharge and for each membrane the product sample line. If one membrane has failed, you can just let it’s product output discharge in the sink while feeding the product from the other membrane to the tank. Diagrams for all that will follow.

Your single pre filter works great for some areas, not so much for others. I can just leave the housing for the 20 micron filter empty when it’s not needed. In the Bahamas, water is clean but some grass manages to pass the sea strainer and is caught in the 20 micron filter. It’s the only one I need to clean now. In Panama, with rivers flowing out, I needed both to control sediment and cleaning was every other day when running daily

[tkeithlu]

Nice work I think you do.

[mvmojo]

The only problem I have with the plastic filter housings is that they tend to be very hard to unscrew the filter bowl. I had to make sure they were very securely mounted so that I could put a filter wrench on them and use a fair amount of torque on it. For some reason, the plastic filter bowls don't seem to be as difficult to remove if the top of the housing is metal (bronze or stainless steel). Maybe I'm just screwing them on too tight...

[Pitchondesign]

Originally Posted by mvmojo

The only problem I have with the plastic filter housings is that they tend to be very hard to unscrew the filter bowl. I had to make sure they were very securely mounted so that I could put a filter wrench on them and use a fair amount of torque on it. For some reason, the plastic filter bowls don't seem to be as difficult to remove if the top of the housing is metal (bronze or stainless steel). Maybe I'm just screwing them on too tight...

You might try silicon grease on the threads of the housing. I find plastic is sometimes subject to gauling and the silicon helps. Don't use regular grease as it might attack the plastic.

[sailcrazy]

Following. We have a CruiseRO watermaker, and the pre-filter module is very, very similar to what you have drawn. But instead of mounting it with the watermaker (ie, hidden and hard to get to), I like your thought of moving it to someplace easily accessible and close to a sink. We used a simple 90* valve for the relief port, but adding a discharge tube(vs holding a bucket under it to catch the outflow as you get the trapped air out of the system) is a good idea.

[hzcruiser]

Excellent idea to have a small sink nearby!

[s/v Jedi]

Originally Posted by mvmojo

The only problem I have with the plastic filter housings is that they tend to be very hard to unscrew the filter bowl. I had to make sure they were very securely mounted so that I could put a filter wrench on them and use a fair amount of torque on it. For some reason, the plastic filter bowls don't seem to be as difficult to remove if the top of the housing is metal (bronze or stainless steel). Maybe I'm just screwing them on too tight...

The housings that mount to a metal bracket still have plastic upper housings... at least the ones I have. These Pentek housings are very nice because they use a big O-ring instead of the flat seal. They also have a special wrench available plus, and that's the big one, a vacuum break pushbutton valve on top to make removing the bowl a breeze.

[s/v Jedi]

Originally Posted by sailcrazy

Following. We have a CruiseRO watermaker, and the pre-filter module is very, very similar to what you have drawn. But instead of mounting it with the watermaker (ie, hidden and hard to get to), I like your thought of moving it to someplace easily accessible and close to a sink. We used a simple 90* valve for the relief port, but adding a discharge tube(vs holding a bucket under it to catch the outflow as you get the trapped air out of the system) is a good idea.

Richard Boren is very good at this and my watermaker is originally a Village Marine from 2003 but is slowly turning into a CruiseRO unit as I have replaced membranes and pressure housings, as well as the high pressure hose with their offerings. They managed to find an obscure fitting to go on my non-standard (titanium) Parker/AquaPro pressure pump so that I could use a standard high pressure hose

[s/v Jedi]

As usual for me, a quick update/revision to v1.1

The change is at the input of the filters and done to reduce the number of threaded connections and use the same service valve as for the output. For my install the boost pump is down in the bilge so I need an elbow to make the turn downwards. This is a push-in stem elbow so easy connections.

[s/v Jedi]

I posted the intake unit here: https://www.cruisersforum.com/forums...ml#post3509904

[s/v Jedi]

and the membrane unit: https://www.cruisersforum.com/forums...ml#post3510505