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09-30-2010, 02:11 PM
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#1
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Join Date: Dec 2007
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Ball valve for march pump, Necessary?
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My setup recirculates the mash. As it is now the flow is only controlled by the valve on the mt, is this ok? I don't see the need to choke it twice, since you have to carefully control the flow out of the mt. Or is it better for the pump if you choke it(on the output side) more than the output flow of the mt?
Am I making sense, or do I need more sleep?
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09-30-2010, 02:19 PM
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#2
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Location: Southern Maine
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This is my impression (disclaimer: I don't own a pump):
March pump cannot be run dry, so restricting the in-flow (i.e. at the MT) is BAD....its possible that you can restrict too much and cause the pump to seize.
You want to restrict the pump on the out-flow, because that way its harder for the pump to be run dry.
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09-30-2010, 02:21 PM
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#3
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The flow control valve should always be on the output side of the pump. Restricting the flow on the suction side would not harm the pump, but it could cause cavitation problems and possibly collapse the suction hose. The cavitation could also cause the pump to lose it's prime. You can still carefully control the flow out of the MT with the valve on the output side of the pump. That's exactly how I do it. Also, IMO, a gate valve works much better than a ball valve for this application as it allows more precise adjustment. You can expect that those who have big bucks invested in SS ball valves will most likely strongly disagree with this opinion.
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09-30-2010, 02:22 PM
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#4
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Vendor and Brewer
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You'll be OK if the connection between the MLT and pump is rigid but if it's soft tubing, it will likely get crushed due to the pressure drop when you really tighten down on the flow.
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09-30-2010, 03:29 PM
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#5
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Quote:
Originally Posted by Catt22
The flow control valve should always be on the output side of the pump. Restricting the flow on the suction side would not harm the pump, but it could cause cavitation problems and possibly collapse the suction hose.
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But you still can't run the mt wide open, or stuck sparge city. In hot water testing, I had no problem with collapsed hoses, that was with silicone, and some braided poly.
I ran a slow recirc for an hour with no problem, just wondered if it would harm the pump?
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09-30-2010, 03:56 PM
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#6
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Quote:
Originally Posted by wildwest450
But you still can't run the mt wide open, or stuck sparge city. In hot water testing, I had no problem with collapsed hoses, that was with silicone, and some braided poly.
I ran a slow recirc for an hour with no problem, just wondered if it would harm the pump?
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If you restrict the outflow of the pump you are still restricting the outflow of the MLT, just from ~2-3 feet further away.
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09-30-2010, 04:35 PM
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#7
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Quote:
Originally Posted by camiller
If you restrict the outflow of the pump you are still restricting the outflow of the MLT, just from ~2-3 feet further away.
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Yes, but my question, and I know i'm doing a piss poor job explaining it it. Is it better to have a set flow from your mt, then choke that flow down a bit from the out side, thus insuring the pump cavity is always full. Is that necessary?
Like everything I do, am I over thinking this? I don't want to trash a pump if I can help it.
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09-30-2010, 04:42 PM
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#8
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A valve on the output of the pump is the only way to control the flow downstream. There will be times when you want to turn the pump flow off momentarily or reduce the flow. And for optimum peformance, the pump head should always be full, or as nearly full as practicable. I pump out of a grant vessel, but I use the outlet valve a lot during recirculation.
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09-30-2010, 04:45 PM
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#9
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Quote:
Originally Posted by wildwest450
Yes, but my question, and I know i'm doing a piss poor job explaining it it. Is it better to have a set flow from your mt, then choke that flow down a bit from the out side, thus insuring the pump cavity is always full. Is that necessary?
Like everything I do, am I over thinking this? I don't want to trash a pump if I can help it.
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Personally, I like keep the BV on the MLT WFO and meter the flow after the pump via ball valve. My thinking, and I could be wrong, is I want the maximum amount of liquid going to supply the pump to guard against losing prime.
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09-30-2010, 04:51 PM
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#10
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Quote:
Originally Posted by Hugh_Jass
Personally, I like keep the BV on the MLT WFO and meter the flow after the pump via ball valve. My thinking, and I could be wrong, is I want the maximum amount of liquid going to supply the pump to guard against losing prime.
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Good point. I guess if you choke it down on the outflow, you wouldn't get a stuck sparge with the mt valve wide open. I can't believe how stupid I am. I guess I shouldn't post with 3 hours sleep. 
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