Dessalator D60 DC only producing 20L or less, and bubbles in capacity flow meter

[sgtPluck]

I just got my boat with a D60 watermaker.

For anyone who has this unit, is it normal for the occasional air-bubble to pass through the production meter?

I'm only seeing 20L of water production, and it drops off below that on occasion. I know I should expect 60L but in earlier tests i thought I was seeing at least 40.

I did just change the 5 micron filter (with a generic one) and as I said I believe was getting better production rate before that. I thought I had a good seal but was wondering if other owners have experienced similar and have any trouble shooting tips on low production.

[fxykty]

We have the same water maker, now 17 years old. Our previous owner disconnected the control panel and we only use it for on/off switch and pressure adjustment. The flow meter is also disconnected.

You may have an air leak in the measurement hose - check your hp hose connections and all hoses.

How clean are your membranes? We recently pulled both membranes and gave them a good rinse and soft scrub.

Measure your output via the waste hose: time filling a container for one minute and work out your output. Or, as we do, monitor your tank gauge for how quickly it fills. With original membranes, 20 degree C water, clean pre-filter and good battery voltage we’re getting 55-60 litres per hour.

[BillKny]

Originally Posted by fxykty

How clean are your membranes? We recently pulled both membranes and gave them a good rinse and soft scrub.

FYI: This is a worthless exercise. The membranes are actually spiral wound, and all the active surface is internal and can not be seen or cleaned by “rinsing and wiping”. All you are doing is cleaning the external shell of the membrane housing!

[fxykty]

Originally Posted by BillKny

FYI: This is a worthless exercise. The membranes are actually spiral wound, and all the active surface is internal and can not be seen or cleaned by “rinsing and wiping”. All you are doing is cleaning the external shell of the membrane housing!

We flushed them through both ends, so got their insides too. But the outside of the membranes (not the housing, doh) should be clean too - if they sit for a while they can get gunked up.

[Bean Counter]

Sea water inlet may be clogged/ restricted, barnacles/plastic bag etc, (we found a small dead eel in our generator inlet once). The air bubble may be an indication of a tiny leak in the high pressure hose connector at the back of the display panel, usually accompanied by salt or corrosion build up. The 5 micron filter may not be suitable type or has swallowed a pile of mud/sand eg if running the WM when pulling up the anchor, or small seaweed, check your engine water filters too if this has happened.

[cajucito]

the first problem I had with my dessalator was when it was over 10 years old. The service center called me back about 15 minutes after I called them and spent almost an hour on the phone at their cost until issues were resolved. They provided the best service I have ever got from any boat equipment supplier... ever ... so call them you will be pleasantly surprised by how helpful they are.

[CdS2 Roland]

It's normal to have some bubbles passing trough flow meter wenn you start the watermaker. Wenn not working, some gas is produced by the dead micro-organisme decomposition.
If you still have bubble, for sure you have an air leak. In my case it was the big O-Ring on top of the raw water filter, it looks fine but didn't do it's job no more. At the same time check all connections and check free flow to the filter. If clogged or reduced system will begin to suck air through a weak point.
Good luck.

[kcj]

Have a now modified d60...

What is the ppm of the output? If not lt300 membranes may be suspect...

Is pump getting up to full pressure? Eg 800psi...or green zone on gauge... if not pump seals and or valves may need a rebuild...

More importantly what is the water flow into pump and out of membranes ? This can be measured with no back pressure on membranes...with less than ideal voltage and amps the dc motor won't spin fast enough to provide necessary rpm to pump
...pump spins slower, provides lower gpm, therefore lower output

Ymmv
Good luck
Cheers