Manifold with 1" pipe off pump with 3/4" output

[inktomi]

Hi folks!

I know all the drawbacks of manifolds - you have to tune all the outputs whenever anything changes, etc - but none of the equipment I want to run off mine is all that sensitive so I really don't think it'll be an issue. What I am wondering about though is this:

I have a pump with 3/4" output that I'd like to use to power my manifold. I have a bunch of leftover true union 1" gate valves as well. I know going from 3/4" to 1" will slow down the flow of the water - is that going to be an issue? I plan on having a valve for every output, and also a valve at the end of the line before it dumps back into the sump, so by closing down that final valve I feel like I could still pressurize the line a bit, right?

If this is just a bad idea, I'm more than happy to buy a new set of 3/4" valves - but thought I'd ask! I've seen lots of threads about this issue for tank drains into the sump, but none for manifolds where the manifold itself is a larger pipe size than the pump's output.

I'm curious what you all think. Can I save myself a couple hundred in fittings?

 

[fishguy242]

hi,which pump ? GPH ?

 

[inktomi]

I've got a Red Dragon Speedy 3 Mini, about 1300 GPH, that I am planning on using.

I need ~300-700gph through my PaxBellum, ~150-350 through my chiller, and the only other thing is a John Guest GFO reactor with it's own valve that can be tuned to get it to slightly tumble.

 

[fishguy242]

i'd say good to go ,imo.

 

[WVNed]

My manifold isn't built that way. It is 1.5 inch and has valves near each device it supplies of the same size as the feed.
So 1/4 inch tubing gets a PTC valve and 3/4 gets a ball valve.
The manifold itself has PVC threaded size adapters at each position so I can change them if I want to connect to something different later.

 

[inktomi]

Threaded reducers on the T's of the manifold make a lot of sense, though maybe I'll put those after the valve so that I can replace one while the system is running. My gate valves are all 1" valves.

 

[Lost in the Sauce]

Given the service load you're planning to run on it, I don't see any issues.

 

[TheBear78]

The flow through whatever equipment you are adding will be governed by the pump output and the restriction through the valves and equipment only.
The diameter of the connecting pipework is irrelevant (unless it's really small) and, will only affect flow in the actual pipe.

If all of the equipment was 3/4" but the pipe is 1" then the flow will slow down as it enters the pipe but then speed up again as it reduces back to 3/4".
There are probably some losses due to the shape of the internal step change in diameter but these will be negligible.

 

[inktomi]

Thanks for the information! It seems like I can save some money and use the 1" valves, so I'll do this:

- Bulkhead out of sump near filter socks
- Red Dragon Speedy 3 mini
- 3/4" union for cleaning
- 3/4 to 1" adapter
- 1" PVC and T's x 4
- 1" union gate valve with adaptable ends
- Threaded fitting somewhere in here for swaps and cleaning
- Equipment connected
- 1" Union Valve for pressurizing the manifold and cleaning
- Bulkhead back into return area of sump for any leftover water