Watermaker woes

[berwick]

I have been helping a friend with a watermaker issue and we are stumped. His flow rate went way down and his PPM went way up. The watermaker manufacturer told him his membrane was shot, sounds reasonable, had another one shipped to Georgetown, Exumas. The new membrane had the same issue, we can get the pressure up to 800 PSI (with the valve is fully closed) where my WM seems to have lots in reserve, but the output is down to about 6 gph vice the 20 gph it should be and PPM stil way too high. The manufacture is saying it must still be the membrane, shipped another in, the same issue!!! Thought maybe it is a pump issue, took apart the valves and they seem to be working as one way valves when blowing through them. Didn't go any further with the pump and don't have another to swap with.
Any ideas? Could the pump not be working right even though we can get the pressure up to 800 PSI (barely though). It had too much oil in it, could that have gotten into the system and mess a membrane up very quickly, yet cause the output to be low?
Any other ideas?

thanks
Richard

[Tellie]

What watermaker brand is it?

[Badsanta]

Oil will mess up your membranes alot. Have you checked the intake and pre filters for obstructions. How is the flow when you flush the system. Should have cleared the oil before replacing membrane.

[TacomaSailor]

How much bypass water is pumped out per minute?
What is the manufacturer's specified bypass flow rate?
Is every feed pump running all the time?
What is the voltage AT the FEED PUMP at 6 GPM output?
What is the necessary voltage at the feed pump?

What should the pressure be on the high side?
What is the pressure on the high side with the 6 GPM output?

What is the PPM of the output?
What is the normal PPM output?

Note - all measures and specs have to be compared to the correct manufacturer's specs for a given seawater temperatur?

The manual will probably provide a very specific test process.

[Catamoron]

What is the name of the boat? We are down here in Georgetown also and maybe we can help...we don't have a bunch of experience with water makers although we did rebuild ours from the ground up, maybe just somebody else to talk things through might be helpful.

Kevin with s/v Catchin' Rays

[1affiah]

I am involved with this as well. It is a SK brand, less than 3 yrs old. A nice, clean professional install with top quality hoses & parts. We checked for kinks. The inlet pre-filters are new. We don't have the equipt to check pressures & flows except that which is installed on the panel. We have removed hoses and visually checked feed water flows, which seem similar to my own unit with similar sized membrane and HP pump.
It seems really strange to me that the panel mounted needle valve
turns all the way down (clockwise) to the stop to barely read 800 psi at the gauge, where mine will easily overpressure the system with a slight rotation.
Owner claims it has been this way since new. The last membrane removed appeared like new as installed 1 wk previous. If it were an oil problem from the pump, would that instantly foul the membrane? Or gradually reduce flow?
Does a new membrane flow product water at a high rate out of the box (while flushing the preservative?).

[1affiah]

PS
We don't know if there is oil from the pump, in the system. The pump crankcase appeared slightly overfilled, but no obvious signs of oil in the system.
Larry

[GordMay]

Greetings and welcome aboard the CF, Richard.

[svlamorocha]

Originally Posted by 1affiah

We don't have the equipt to check pressures & flows except that which is installed on the panel. We have removed hoses and visually checked feed water flows, which seem similar to my own unit with similar sized membrane and HP pump.

I am sure you can check flows with the equipment you have.

You can measure reject flow by disconnecting the brine hose that goes to the "out" seacock and counting how many seconds to fill a bucket.

You can measure product flow with a similar process.

Feed flow should be (in equilibrium) sum of the two flows above.

All this will give you the three flows and the ration between product and reject brine.

You can get feed water temperature from any boat around echosounder with temp sensor that has been calibrated.

If you do not test kit to measure ppm salinity Google it up. look it up for the part of the ocean where you are.

With all this data and configuration of the system (size of membrane, specs of feed pump etc) it is typically easy to figure out what is the problem.

The only other thing I can think is a possible error in the high pressure gauge, but that is not very likely.

If you post the three flows and the detailed model number of the equipment I am sure you will get help from the forum.

[SV THIRD DAY]

Forget about the possibility of crank case oil getting to sea water flow stream and membrane, over filled or not. The SK piston pump is like the one we use....and they just don't fail that way.

SK isn't giving you around the clock 7 day a week tech help with this? That surprises me because this isn't a difficult problem to trouble shot at all to be honest. So here are the data points we need to figure out the problem and if I can do this from the booth of the Miami Boat show thumb tapping on my smart phone...well I'm not sure what the SK excuse is quite frankly.

1. Take your system to 800psi and then measure two things: the product water flow rate and the brine flow rate. Now when you add these two flow rates together if it equals the rated flow rate stamped on the pump then your pump is ok. If the total flow rate is less than the rated, then you most likely have a pump problem (valves or inlet flow to the pump isn't enough)

2. There is a comment that you don't have a way to measure the flow rate....but you do. Just fill a container of known volume and record the time. Then we can calculate the GPM flow rate.

3. What is the GPM flow rate of the HP pump? A 20gph water maker with a 40" membrane will have a 1.6gpm pump, so verify that.

The SK system is similar to ours, so when you get the No1 data point above, fontact me directly at rich@cruiserowater.com and I will get right back to you. The email will come straight to my phone and we can get this figured out.

[svlamorocha]

Originally Posted by 1affiah

I am involved with this as well. It is a SK brand, less than 3 yrs old..

Is it a HC 440 model with two 2 1/2″ X 21″ membranes and one AC-driven 1.5HP pump?

[svlamorocha]

Originally Posted by SV THIRD DAY

. The email will come straight to my phone and we can get this figured out.

Now that you are on the job Rich, please let me learn from you, before we get data back from OP:

Aren´t the symptoms consistent with a situation where there is air in the feed water (leak in hose between raw water inlet and HP pump, probably compounded by obstruction in inlet )?

After all, if a piston pump does not get water to pump but keeps running at rated rpm then it has to fill its intake with something, be it air (which will most likely show up downstream) or just vacuum "bubbles" (which will dissapear and only evidence themselves as low total product+reject flow rate?

With a bit of luck this boat has see-through prefilter housings like those form Echo-Tec and they can see air...

[1affiah]

As Richard and I are not the owners, and he is in communication with SK support, I do not want to get in the middle of that and foul those waters.

Rich B, the pump is the General WM series, same as yours, with 1hp motor. We are now looking at the pump being overfilled and generating too much heat, as the fresh output is quite warm. We will adjust the oil fill level, and measure output flows with bucket. Input temp is approx. 80F.,

Thanks for the help.

Larry

[1affiah]

PS
This is a single 40" membrane unit. All salt water inlet units pieces are checked for debris, and clean. Inlet hose is clear, and no bubbles present.
Salt water flow from boost pump alone is verified and will be measured. HP pump flow added to boost is verified and will be measured.

It still puzzles me about the needle valve, it closes firm and the pressure maxes out at 800. Do they have a built in stop? No other pressure regulating devices on the pump or inline.

Thanks,
Larry

[berwick]

Wow some good stuff to check out this morning thanks! Our latest thought is that the water temperature coming out of the HP is very warm (and this is feeling thru the HP hose), would this high temperature be enough to increase the PPM and reduce the output down a third? We are going to drain the pump oil and check for particles and put new oil at the correct level. The output water is quite warm (almost bath) and this is starting at the HP pump so I think this might be the issue. Any parts inside the pump that would cause this?

thanks
Richard