Groco Duplex Strainer

[SuzieWong]

Dear Community,
My boat is equipped with a Groco Duplex Strainer.
Unfortunately not too much information about that solid piece around. Except: it should be possible to clean one side while the other side is in operation.
Well, somehow that does not work on my unit. Whichever side I select to be in operation, cooling liquid will leak heavily and drain the engine oil f coolant when I try to open for cleaning. I tried the ‘dead’ side as well as the ‘operating’ side,
What I discovered is that the valve rotates only 90 degrees while the handle swings over by 180 degrees. Might there have been a mistake when installing the unit / handle?
I’ll attach pictures for clarification.
Any advice on proper installation and operation of the Groco Dublex Strainer highly appreciated.

 

[cafesport]

I think someone may have installed it in the wrong orientation ie confused the inlet port with the outlet port. These are designed to only allow flow into one strainer at a time never both.

 

[SteveK]

Looks like raw water strainer, where does the engine oil come into play?

 

[Nick F]

I had similar Groco duplex strainers on my current boat.

The handle turns a cone which switches both the inlet and the outlet. Since both inlet and outlet are switched I cannot attribute your problem to wrong hose hookup.

I suspect that the cone is not turning to the correct orientation. I suggest trying all 4 positions. You could remove the cone and, looking at the porting, you can see how it works and what orientation is correct for each side of the strainer.

As for me, I am replacing mine with current Groco ARG single strainers. These duplex strainers are monstrously heavy and bulky.

If anyone want a pair of 1-1/4" duplex units, please make any offer!

 

[HopCar]

It is a Groco 932 series strainer. There are two o-ring gaskets on the tapered cone, #14 & 15. I think if these are damaged they may cause your problem. Another possibility is the cone isn’t tightened enough. Is the handle easy to turn? Try tightening the nut (#16) on the back to pull the cone into the strainer more. There should be a little resistance to turning the handle.
Call Groco customer service at 410-604-3800.

 

[Nick F]

It is a Groco 932 series strainer. There are two o-ring gaskets on the tapered cone, #14 & 15. I think if these are damaged they may cause your problem. Another possibility is the cone isn’t tightened enough. Is the handle easy to turn? Try tightening the nut (#16) on the back to pull the cone into the strainer more. There should be a little resistance to turning the handle.
Call Groco customer service at 410-604-3800.

The O-rings at the ends of the cone only stop leakage out to the atmosphere past the ends of the cone - they do not affect the directing of the seawater to the strainers.

 

[HopCar]

The O-rings at the ends of the cone only stop leakage out to the atmosphere past the ends of the cone - they do not affect the directing of the seawater to the strainers.

You’re right. The only thing I can think of is water is getting past that center ridge on the cone. Tightening the back nut might pull it into place.

This is mounted on the suction side of the pump isn’t it?
Is it mounted below the water line?

 

[twistedtree]

Dear Community,
My boat is equipped with a Groco Duplex Strainer.
Unfortunately not too much information about that solid piece around. Except: it should be possible to clean one side while the other side is in operation.
Well, somehow that does not work on my unit. Whichever side I select to be in operation, cooling liquid will leak heavily and drain the engine oil f coolant when I try to open for cleaning. I tried the ‘dead’ side as well as the ‘operating’ side,
What I discovered is that the valve rotates only 90 degrees while the handle swings over by 180 degrees. Might there have been a mistake when installing the unit / handle?
I’ll attach pictures for clarification.
Any advice on proper installation and operation of the Groco Dublex Strainer highly appreciated.

Yup, pretty brain dead, right? Mine "works" the same way and it's incredibly annoying. Cleaning a strainer, whether the engine is running ot not, dumps salt water all over the engine room. I have discussed it extensively with Groco and it's inherent in the design of the valve. The cone valve obstructs water flow, but it does not provide a positive shutoff the way a ball valve or gate valve does. It will ALWAYS leak, it's just a question of how much. It does NOT work the way a duplex fuel filter does, where whichever side it not in operation is completely shut off and can be cleaned without dumping fuel.


On my worklist is to replace this $5000 piece of bronze sculpture with separate strainers and ball valves. As built, it's completely unsuitable for any space that you are trying to keep dry, which is basically everything if you have dripless shaft seals. If you are on a work boat or any boat where a steady, but controlled flow of salt water into the boat is OK, then it's a great strainer, I suppose.

 

[twistedtree]

You’re right. The only thing I can think of is water is getting past that center ridge on the cone. Tightening the back nut might pull it into place.

This is mounted on the suction side of the pump isn’t it?
Is it mounted below the water line?

The center o-ring blocks bypass flow between the intake and outlet sides. When you operate the valve, the center cone "dams" the out-of-service side and opens the service side. But the "dam" is only as good as the machining of the cone and valve body contact area, and inherently not a positive seal. So it will limit, but not stop flow.


I too found all this out the hard way, have confirmed other installations operate the same way as mine, and confirmed with the owner of Groco that this is expected given the design.

 

[Nick F]

Is there actually a centre O-ring?

As regards replacing with multiple individual strainers, I simply went to one strainer and the seacock for shutoff.

 

[SuzieWong]

Looks like raw water strainer, where does the engine oil come into play?

Thank you for all the answers.
Apologies: I had made a mistake: I didn’t meant oil leaks, it is cooling liquid which leaks.
To explain: the boat has keel cooling and this particular shipyard is known to have rust in their system. Thus I asked for a duplex strainer installation to protect the engine from rust debris

 

[SuzieWong]

It is a Groco 932 series strainer. There are two o-ring gaskets on the tapered cone, #14 & 15. I think if these are damaged they may cause your problem. Another possibility is the cone isn’t tightened enough. Is the handle easy to turn? Try tightening the nut (#16) on the back to pull the cone into the strainer more. There should be a little resistance to turning the handle.
Call Groco customer service at 410-604-3800.

There is resistance when turning the handle. But: the first time when I wanted to rotate the handle I t was very stiff. I suspect this was as the shipyard had delayed the whole boat by five years and thus the rubber seals were sticky

 

[SuzieWong]

Yup, pretty brain dead, right? Mine "works" the same way and it's incredibly annoying. Cleaning a strainer, whether the engine is running ot not, dumps salt water all over the engine room. I have discussed it extensively with Groco and it's inherent in the design of the valve. The cone valve obstructs water flow, but it does not provide a positive shutoff the way a ball valve or gate valve does. It will ALWAYS leak, it's just a question of how much. It does NOT work the way a duplex fuel filter does, where whichever side it not in operation is completely shut off and can be cleaned without dumping fuel.


On my worklist is to replace this $5000 piece of bronze sculpture with separate strainers and ball valves. As built, it's completely unsuitable for any space that you are trying to keep dry, which is basically everything if you have dripless shaft seals. If you are on a work boat or any boat where a steady, but controlled flow of salt water into the boat is OK, then it's a great strainer, I suppose.

Thank you. I already feared I’m the only one with that problem. Yes, a duplex strainer which does not seal the non working side is useless.
Expensive bronze sculpture in the engine room ��

 

[Nick F]

If you apply "seacock" grease to the cone it may seal enough for you to be able to "live with it".

Blakes Seacock Grease, or equivalent - its a very sticky heavy grease.

 

[twistedtree]

Is there actually a centre O-ring?

As regards replacing with multiple individual strainers, I simply went to one strainer and the seacock for shutoff.

I might do that too. I like the idea of two separate intake and strainer systems so if one gets blocked I can just switch over to the other. But dual strainers and all the valving will take up a lot of space and be expensive, so maybe not....

 

[twistedtree]

Thank you for all the answers.
Apologies: I had made a mistake: I didn’t meant oil leaks, it is cooling liquid which leaks.
To explain: the boat has keel cooling and this particular shipyard is known to have rust in their system. Thus I asked for a duplex strainer installation to protect the engine from rust debris

OK, I'm really confused about where the duplex valve is being used, and what's flowing through it. It sounds like engine coolant is flowing through it, and it's being used to filter rust out of the coolant? If so, I don't think it will be very effective at doing that.

 

[Steve DAntonio]

Adding to Twister Tree, the closed cooling side is under pressure, 12-18 lbs., I don't believe this strainer is designed to work under this pressure, or at 200F. I'm pretty sure Groco would not approve, and it sounds like overkill, I think all you need is an inline bronze plumbing strainer with an isolation valve. https://www.mcmaster.com/products/y-strainers/low-pressure-bronze-y-strainers-8/

The Groco strainers are a bit odd in that the handle moves 90 deg. with 0 resistance, without doing anything, then it reaches what feels like a hard stop, you push beyond that with a lot of effort another 90 deg, and that turns the valve.

 

[amalnak]

Go to the source

I think the factory is located on the eastern shore of maryland, at least it was when I bought my strainers from them.

 

[Bmarler]

Adding to Twister Tree, the closed cooling side is under pressure, 12-18 lbs., I don't believe this strainer is designed to work under this pressure, or at 200F. I'm pretty sure Groco would not approve, and it sounds like overkill, I think all you need is an inline bronze plumbing strainer with an isolation valve. https://www.mcmaster.com/products/y-strainers/low-pressure-bronze-y-strainers-8/

The Groco strainers are a bit odd in that the handle moves 90 deg. with 0 resistance, without doing anything, then it reaches what feels like a hard stop, you push beyond that with a lot of effort another 90 deg, and that turns the valve.

I think the logic was so that the handle pointed to the strainer in operation, as well as having it laying down and not protruding above the housing so it doesn’t get caught on anything.
Sure seems like they could have ported it differently, but who knows.
I like double strainers a lot, but that one, not so much.

 

[Steve DAntonio]

Yes it is still there.

 

[SuzieWong]

Thanks for all the replies and pointing me into the correct direction.
Until now I was unaware that duplex strainers won’t work well in a pressurised system.
Probably best will be to install a new Y strainer instead of the installed duplex strainer.
Added to my never ending ‘to do list’