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Old 13-11-2015, 02:43   #1
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Single strainer - 3 takeoffs??

I am thinking of using an existing 1.5" through hull for my aircon, genset, and watermaker. This is simpler than a bunch of adapter fittings at the seacock for the genset/watermaker, + a new small seacock and strainer for the aircon(s)

Total if all are running at once is 35 USG/Min. That is unlikely but you never know......

The plan is to run a 1.5 hose from the seacock to a Groco 1.5 strainer. Output side of the strainer will have a custom manifold with the 3 outlets.
Can this hose support that flow rate?

The only flow chart I can find for the Graco is unreadable. Can the Graco support that flow rate

Dumb idea or not?
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Old 13-11-2015, 10:36   #2
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Re: Single strainer - 3 takeoffs??

I assume you mean Groco (GROCO MARINE PRODUCTS)
Try Gross Mechanical Laboratories, Inc. at (410)604-3800.
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Old 14-11-2015, 08:20   #3
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Re: Single strainer - 3 takeoffs??

Take a look at the Groco RWM manifold. It will give you an idea of what size hoses Groco thinks you can hook to an 1-1/2" supply.
GROCO MARINE PRODUCTS
What size are the hoses you're going to connect to your manifold?
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Old 14-11-2015, 08:31   #4
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Re: Single strainer - 3 takeoffs??

Look up Vetus bronze manifolds. These screw onto your bottom valve then distribute the water.

Whatever solution you use, if no duckbills in the system then all attached hoses must be up to the pressure of the highest pressurised system.

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Old 14-11-2015, 08:39   #5
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Re: Single strainer - 3 takeoffs??

Quote:
Originally Posted by HopCar View Post
Take a look at the Groco RWM manifold. It will give you an idea of what size hoses Groco thinks you can hook to an 1-1/2" supply.
GROCO MARINE PRODUCTS
What size are the hoses you're going to connect to your manifold?
I see that - (1 x 1/4) + (2 x 1/2) + (1 x 1/4). That seems like a lot if everything was on at the same time.

That is a very nice fitting and I will keep it in mind if I need to do this again
I need these inputs strained as well so it is easier to use an 1.5" strainer and tee off that.

I plan to have 1 ea. 1", 1/2" and 3/4" off the 1.5" strainer
Flow 35 USG/Min if everything is on. That scenario is unlikely and more commonly the flow would be 29 USG/Min
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Old 14-11-2015, 08:49   #6
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Re: Single strainer - 3 takeoffs??

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Originally Posted by barnakiel View Post
Look up Vetus bronze manifolds. These screw onto your bottom valve then distribute the water.

Whatever solution you use, if no duckbills in the system then all attached hoses must be up to the pressure of the highest pressurised system.

b.
It is not clear to me if the single seacock can support the combined flows in either the Vetus or Groco manifolds.

In my case that flow rate is 35 USG/Min worst case

Porting at the seacock poses a strainer question and it is easier to manifold at the strainer
I do not know if the 1.5 bronze Groco strainer will support that flow either
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Old 14-11-2015, 10:28   #7
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Re: Single strainer - 3 takeoffs??

I would just call Groco, they are very knowledgable and easy to get on the phone in my experience.
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Old 14-11-2015, 14:55   #8
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Re: Single strainer - 3 takeoffs??

1-1/2" hose can support 35 gpm, at least in theory. But the 1-1/2" is on the suction side of the pumps and some pumps may have reduced flow with all three running, depending on the configuration and suction line length.

You would want to keep the strainer clean and ideally have the manifold below the water line level. In a perfect world the pumps would be close to the manifold too. This as centrifugal pumps like a march AC pump push much better then it pulls. Suction head is generally limited.

The genny and water maker will be positive displacement pumps and should be fine. Putting a check valve after the AC pump will help reduce cross flow or air entrainment issues.
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Old 14-11-2015, 19:55   #9
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Re: Single strainer - 3 takeoffs??

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Originally Posted by sailorchic34 View Post
1-1/2" hose can support 35 gpm, at least in theory. But the 1-1/2" is on the suction side of the pumps and some pumps may have reduced flow with all three running, depending on the configuration and suction line length.

You would want to keep the strainer clean and ideally have the manifold below the water line level. In a perfect world the pumps would be close to the manifold too. This as centrifugal pumps like a march AC pump push much better then it pulls. Suction head is generally limited.

The genny and water maker will be positive displacement pumps and should be fine. Putting a check valve after the AC pump will help reduce cross flow or air entrainment issues.

That is what I am looking for - thanks

There are 3 pumps involved:
Ikiwa mag drive centrifugal aircon = 26 USG/Min
Ikiwa mag drive centrifugal feed to the HP watermaker pump = 4.2 USG/Min dicated by the feed pump output rate
Genset cooling pump = 3 USG/Min

The most likely high flow operating scenario is genset + aircon = 29 USG/Min
Or more commonly genset + watermaker = 7.2 and a non-issue
It is possible if the house batteries are fully charged and no load on the genset to run all three at 33.2 USG/Min

Will try and locate the strainer low and the 2 Ikiwa centrifugal pumps with a positive head on the feed

I also see that Groco has "high flow" fittings for 1.5 NPT that use a 1.75 hose and I am going to try this. Groco through hulls are high flow.
How much flow could a 1.75" ID hose support?
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Old 14-11-2015, 20:35   #10
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Re: Single strainer - 3 takeoffs??

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Originally Posted by Stumble View Post
I would just call Groco, they are very knowledgable and easy to get on the phone in my experience.

Looks like the 1.5 strainer can support that flow no problem so I could tolerate a bit of constipation on the screen. Arg-1500 is 1.5"

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Old 14-11-2015, 20:53   #11
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Re: Single strainer - 3 takeoffs??

Quote:
Originally Posted by Hoghead View Post
That is what I am looking for - thanks

There are 3 pumps involved:
Ikiwa mag drive centrifugal aircon = 26 USG/Min
Ikiwa mag drive centrifugal feed to the HP watermaker pump = 4.2 USG/Min dicated by the feed pump output rate
Genset cooling pump = 3 USG/Min

The most likely high flow operating scenario is genset + aircon = 29 USG/Min
Or more commonly genset + watermaker = 7.2 and a non-issue
It is possible if the house batteries are fully charged and no load on the genset to run all three at 33.2 USG/Min

Will try and locate the strainer low and the 2 Ikiwa centrifugal pumps with a positive head on the feed

I also see that Groco has "high flow" fittings for 1.5 NPT that use a 1.75 hose and I am going to try this. Groco through hulls are high flow.
How much flow could a 1.75" ID hose support?
The 1.75" hose may help, But it's tough to say without seeing the layout. The issue is pressure drop on the suction side of the pumps. As in there is not lots.

Assuming you have a foot or two of positive head at the through hole. That at 35 gpm will be taken up with entrance loss and pressure drop across the strainer before we even get into pipe, hose and valve pressure drop.. Then your into NPSH (net positive suction head) which is the part between 0 psig "gauge" and 0 psia (absolute) which is 14.7 psi or 33.9 ish feet absolute head at sea level.

I tried to google the ikiwa pump but got no where. So I looked at a march pump, series 6 for 26 gpm. It needs 15 feet npsh to function at 26 gpm. That leave all of 19 feet to use as suction pressure drop, which factoring valves and fittings should be enough. Worst case the pump cavitates, which will reduce flow, make noise and generally cause an early death to the pump. Placing the pump as close as possible to the manifold will help prevent that.

Also placing a check valve on the outlet of the AC pump would be recommended. If the genny was running and AC was off, it might be possible for the genny raw water pump to pull air back through the AC pump. More so as the strainer filled with "stuff". That would cause the generator to run hot. A check valve in the discharge after the AC pump would prevent that. Please note that check valves in seawater tend to fail at some time. So it's something that would need checking and R&Ring every so often.

Both the genny and the HP pump on the water maker will be positive displacement so air would not be drawn backwards through them. Only the AC pump is the issue. My guess is the 1-1/2" hose should be enough. As long as you don't have a long run of hose before the AC pump.
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Old 14-11-2015, 21:00   #12
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Re: Single strainer - 3 takeoffs??

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Originally Posted by Hoghead View Post
Looks like the 1.5 strainer can support that flow no problem so I could tolerate a bit of constipation on the screen. Arg-1500 is 1.5"

Cool the 1500 would be fine, as long as it's clear and does not have a layers of mud and stuff in it. Looks like only 1 psig drop or 2.3 feet of head loss for 35 ish gpm. Not bad.
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