Plumbing/Physics cooling line question...

[Aglifter]

One of our new, spiffy machines has become a bit tempermental, and, while it had some other issues, since sorted, we also have a problem w. the lines coming off the cooling system.

Our cooling tower runs a 1 1/2" pipe loop at 15 PSI (about 24 gal/min). The freezer in question, is supplied by 20' of 3/4" lines, and requires 15.87 gal/min*.

The freezer does not seem to be getting an adequate supply, unless we throttle down the loop in front of it, at which point the cooling tower lacks sufficient water to operate properly.

*Which we then throttle down, to get a delta of 9 degrees F, between inlet and outlet.

So, it has been suggested we add a booster pump, and that may be correct, because our outlet side of the loop is only 8" below the inlet side of the coolant loop, and I think that's an insufficient fall to push the water through the freezer at a sufficient rate, and since the pressure is the same on the inlet and outlet, the pressure cannot push the water.

A) Am I being crazy?

B) Is there a purely plumbing solution to this, other than dropping the outlet line lower?

C) How far down should it drop?

D) Would running 1 1/2" lines, necking down to 1" at the freezer, work?

The cooling line also supplies a small pasteurizer, but that has been cut off while we are trying to sort out our freezer.

[blackeagle603]

That 20' of 3/4" is a long series resistor. Can you swap out for a larger line or add a couple in parallel to the existing line to increase flow (at least up to the final 3/4" input restriction assuming there's only port and it can't be modified)?

[Aglifter]

We bumped up to 1" lines tonight. We're added a 1hp booster pump as well (unfortunately, only 12 gpm) - would have rather had a 1.5hp one, but we couldn't get one rapidly enough.

Now, I don't know if its really the problem - we didn't have this problem until it got hot out - and we've had problems hooked in directly to the main from the city - but it could have been marginal, and the 3/4" lines were always there.

There is still one 3/4" valve between the 1.5" loop and the 1" line to the freezer, but that's a bit involved to replace right now - we might replace it this weekend, but we're working on things while keeping the plant has to stay running.