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Pump Automation 1

EEENGRX

EEENGRX

Electrical
Sep 11, 2021
88
I have a self primer pump that requires to manually fill up the primer case with prime water to enable it pick up prime and start pumping and avoid damaging the mechanical seal.The pump is used for a sump that i need to automate based on the sump level.i plan to add a foot valve. do you think this will be sufficient to hold prime or it will just reduce the time it takes to prime the pump?what are the various options for shutdown protection or elert to the control room if the pump does not pick up prime for any reason whatsoever? will aan amp monitor at the bucket work? or a solenoid valve on a timer for the priming water which will be activated by the motor starting, per start and close after a set period of time.allauggestions are highly welcome as i want to go with the best possible option as well as less complicated
 
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waross said:
I suggested an automatic prime each start, whether it is needed or not.
Based on experience with a self priming pump that frequently lost its prime when there was no water available at the suction.
I had a 5 gallon bucket, a hose to the priming port, and a shutoff valve.
I would prime manually and when the pump started, leave the valve open until the backflow refilled the bucket.
Note. #1. This was a domestic supply from a supply system that often was out of water.
Note #2. If the Original Poster says that he is losing prime, I won't argue that point. I have had the same issue with at least one model of self priming pump. Over a lot of years I have seen two instances of a supposed self priming pump losing prime when there was no water available on the suction side.
Click to expand...
So the pump motor is already wired to DCS and there is a Radar Level transmitter to monitor Sump Level. I think I can just program the start and stop of Motor directly in the DCS instead of going through a longer route. Once I can have the pump primed automatically whenever the motor stops based on low level. I simply have to go one more step to handle the amp protection. What do you think?
 
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EEENGRX said:
I simply have to go one more step to handle the amp protection. What do you think?
Click to expand...
Are you meaning current monitoring to detect loss of prime?
If you can do that in software with the existing hardware, go ahead.
 
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The details so far -

there is a distributed control system (dcs) factory system made by someone to monitor at least one sensor
there is a radar level sensor to measure sump level
there is no indication of what sensor/system causes the pump to operate
the pump is new and barely used
the pump either does or doesn't maintain prime
either way, the pump is going to be force-primed to avoid some amount of seal wear
nothing can be done to replace the pump

note that the amperage will be low if the pump fails to prime or if the inlet to the pump becomes blocked but the motor will tend to overheat

How far along is this problem statement and what important details remain missing?

Is there a functional flow-chart diagramming the dependencies and state transitions that are required?
 
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This is how the flow goes. How do you implement your deliberate priming of pump based on your suggestion?
 
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Not the plumbing diagram, the one that shows which logic is required. What do you want the system to do and what should it react to?

Perhaps I am reading this wrong - where is the pump?

Let me clean that up for you:
pump.jpeg
 
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The pump is there. The waste water goes into the sump and when it gets to a certain level. Pump is turned on and when level gets to a certain low level . Pump shuts down. There is also a feed line for prime water into pump casing
 
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One would normally circle the pump, not the letter "P", but with more work and turning the diagram again, sure, I see where it is.

Change the plumbing so that the entry pipe goes above the inlet and comes back down as a trap and then the prime source only has to fill it when the pump shuts down. Depending on the cycle of the sump pump, one could run the prime from a timer a few minutes an hour to minimize the odds of either over-filling or underfilling.

I did like the tutorial about how a sump pump works. It did not include anything about your control room reporting requirements, how the information gets from the radar level sensor to anyplace or how it is used, or even why this appears to be so complicated for you to solve.

I presume that the budget is $0 and the ability to alter anything is also zero and that you have been told to solve several problems by creatively being unable to change any part of this and that is why you are reaching out to get new no-cost, no-change ideas.
 
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Ok, the priming water comes from a pipe.

So the pump is the thing that looks like a tank?

And the other thing that looks like a tank is the motor?

And there aren't actually any tanks at all?

How, exactly, is the motor that overheats when it's not doing any work (no prime, no flow, no work) ok at rated load? Is there a secret water cooling circuit for the motor?

What was the problem again?
 
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I think you need to state your issues a bit better and what your constraints are.
Also how this pump starts/ stops or is is to be automated.

It is also important to know what the stop level is compared to submergence of the inlet pipe below low water level.

If the low stop signal is sufficiently above the bottom of the inlet pipe by say 300 to 500mm then I really don't see what your issue is. The flow is held by the discharge non return valve and unless you have air creeping in somewhere then the inlet pipe should remain full.

As drawn (the piping isometric would be good to see) when you prime the pump, once you get to a certain level, all you're doing is filling the tank. Insert a simple relatively low reverse U bend in front of the pump and yuo will keep enough liquid in the pump to allow it to start.

As it stands I don't know what the YL is measuring on the motor, but you seem to have very little to actually look at to detect low / no flow / no prime.

In terms of no prime, then you could probably automate something that when the pump starts, but there is no change in level within say 60 seconds, then it provides an alarm to say no flow.

If you want to spend zero money, then that's something you could do.

But please fill us in on the whole picture.
 
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Start/stop is local. There is a low level cut off for motor. And it has to be manually primed for each start when it gets to a certain level. There is no remote start/stop at the moment
 
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I appreciate you've come into this from an electrical / control background / viewpoint, but there are some mechanical / piping / process control issues here which need to be tackled first.

If I was you I would report back that the issues with this pump are not control or electrically based, but much more mechanical / piping and how exactly does process want this pump to operate.

When they are fixed, then you can do your modifications to meet the process control requirements.

At the moment you seem to be blundering around trying to sort out problems for which you have no real understanding or means to change anything. That isn't your fault and this operation should be a straightforward, simple operation to empty a sump tank when it reaches a certain level, then stop pumping once it gets below a certain level.

Or do it manually when someone needs to fill the pump, turn it on, watch the operation, turn it off once it reaches a certain level marked on the side of the sump. This works if this sump only needs clearing out once every two weeks or more weeks.
 
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Thanks I have just cracked the puzzle as to why it wasn’t priming. Pump is self priming as we speak and I have programmed it to start/stop based on Level.
 
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