Spectra Watermaker Clark Pump Troubleshooting

[redpointist]

I have a used spectra ventura 150 that I'm installing, but so far the feed pump pressure is only going to 50psi (recommended range is 60-90) and the product flow rate is almost 5gph on one side and almost 3gph on the other (both should be over 6gph).

Here's a video of the watermaker running: https://youtu.be/3Re9LDxZlyc

Basically on the 3gph flow side the pressure starts at 50 psi and drops to 40psi. When the clark pump switches to the other side the flow rate jumps to 5gph and the psi rises from 40 to 50. If I put my ear up to it, I can hear a slight hissing from the clark pump when its on the 3gph stroke.

I tested the feed pump by clamping off the brine discharge and it reached the cutoff level of 125psi and shut off just as it should, so feed pump probably isnt the problem. It also puts out about 1.25 gpm brine discharge with the pressure relief valve closed and 50 psi. I opened the 'test port' and saw about 4 drips per minute coming out. The manual (https://www.sv-zanshin.com/r/manuals...pairmanual.pdf) says that 1 or 2 drops per minute is ok...I wonder if my 4 drops per minute is really enough to cause this problem (and the slight hissing sound) or if theres something else going on as well.

I have not replaced the old membrane yet. at 50 psi feed pump pressure its making 850-900ppm water. I wonder if the ppm will drop when the feed pressure issue gets resolved? I have a new membrane available but think it might be best to get everything otherwise running correctly and see how the old membrane does before I install it.

Does anyone have any tips before I crack this thing open and start looking for wear points? Im a bit nervous, but the manual has a pretty good troubleshooting quide starting on page 12 I plan to use as guide. Is there anyone that sells individual parts for clark pumps? So far I have found a "full rebuild kit" for $675 and have found a pack which contains only the various o-rings for $110. Theres also an "offshore kit" for $469. I guess my best bet at this point is to hope that the problem is just an o-ring! I'll have to measure some of the o-rings too and see if they seem to be generic sizes available locally (anyone had luck with this?).

[Tellie]

Originally Posted by redpointist

I have a used spectra ventura 150 that I'm installing, but so far the feed pump pressure is only going to 50psi (recommended range is 60-90) and the product flow rate is almost 5gph on one side and almost 3gph on the other (both should be over 6gph).

Here's a video of the watermaker running: https://youtu.be/3Re9LDxZlyc

Basically on the 3gph flow side the pressure starts at 50 psi and drops to 40psi. When the clark pump switches to the other side the flow rate jumps to 5gph and the psi rises from 40 to 50. If I put my ear up to it, I can hear a slight hissing from the clark pump when its on the 3gph stroke.

I tested the feed pump by clamping off the brine discharge and it reached the cutoff level of 125psi and shut off just as it should, so feed pump probably isnt the problem. It also puts out about 1.25 gpm brine discharge with the pressure relief valve closed and 50 psi. I opened the 'test port' and saw about 4 drips per minute coming out. The manual (https://www.sv-zanshin.com/r/manuals...pairmanual.pdf) says that 1 or 2 drops per minute is ok...I wonder if my 4 drops per minute is really enough to cause this problem (and the slight hissing sound) or if theres something else going on as well.

I have not replaced the old membrane yet. at 50 psi feed pump pressure its making 850-900ppm water. I wonder if the ppm will drop when the feed pressure issue gets resolved? I have a new membrane available but think it might be best to get everything otherwise running correctly and see how the old membrane does before I install it.

Does anyone have any tips before I crack this thing open and start looking for wear points? Im a bit nervous, but the manual has a pretty good troubleshooting quide starting on page 12 I plan to use as guide. Is there anyone that sells individual parts for clark pumps? So far I have found a "full rebuild kit" for $675 and have found a pack which contains only the various o-rings for $110. Theres also an "offshore kit" for $469. I guess my best bet at this point is to hope that the problem is just an o-ring! I'll have to measure some of the o-rings too and see if they seem to be generic sizes available locally (anyone had luck with this?).

You have an asymmetrical Clark pump. The hissing noise usually will emanate form the top block where the annular rings are located. Your lower production is from uneven pressures being created and I would expect the higher TDS readings as normal levels in this instance, so yes, fix the Clark pump first before condemning the membrane. My best advice to you is to call me and I'll walk you through a few things first before you attempt a re-build. It may be a simple fix that you can do yourself or it may get a bit more complicated.


HaldenMarineService@yahoo.com

[redpointist]

I decided to go ahead and take it apart yesterday evening. The center block check valves looked pretty gunky, so I cleaned all 4 of them (1 seemed worse than the others though). I sanded the annular rings and cylinder walls a bit since they had a bit of grooving. Might have helped a bit. I also noticed one of the valve port o-rings is missing! That seems it would cause an external leak though, which I cant really see any leak from the valve block. I didn't have any silicone grease handy (only super lube synthetic grease, which Im not sure would be membrane safe), so put it back together dry and the center block/cylinder junction does seems to have a tiny leak though. I'll have to find some silicone grease.

Put it back together and now both strokes are symmetrical. Getting 5-5.3 gph on each stroke, and psi starts at about 53 at beginning of stroke and ends at about 58. The test port is dripping 6 drops per minute now, maybe because of the higher pressure. The hissing on the low pressure stroke is gone now. Tds dropped from 850-900 originally to 750 now.

I'll call you on Monday Tellie and see where you think I should go from here with it.

[SV Bacchus]

Went to one of Tellie's "classes" at his shop in Lauderdale. He is a really neat guy that appears to be a straight shooter and really knows his stuff.

We on CF are lucky to have resources available such as Tellie and Rich to help us with these little problems!