Pump Automation

[EEENGRX]

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

 

[waross]

Cowboy engineering.
Install an open top tank above the pump.
From the tank drop to the primer case.
Operation.
A timer will open the check valve and allow the water to fill the primer case.
When adequate time has elapsed to fill the case, close the valve and start the pump.
Tap off of a pressure line and feed back to the tank via a restricting orifice.
A small flow will refill the tank and then overflow back into the sump.
Philosophy:
Deliberately prime each start or worry about possible loss of prime?
I choose prime each time.
I like KISS.

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?

My first choice would be a flow switch in the discharge line. That depends on cost and the customer's budget.
But, then current monitor relays are not cheap. either.

 

[Compositepro]

A pressure switch is almost always preferable to a flow switch (far more robust). The pressure switch is often wired into the start circuit so that the motor will start when the start switch is pressed but it will not stay latched-on until there is pressure developed by the pump.

 

[waross]

A pressure switch is almost always preferable to a flow switch (far more robust).

At one point I did a lot of Fire Alarm design and installation.
Flow switches were always used to indicate flow.
There was a reason why pressure switches were not suitable, but the flow switches proved their dependability.
It does often take more tooling and expertise to install a flow switch on larger lines as opposed to a pressure switch.
Pressure switches were only used for alarm on loss of supply pressure.

 

[EEENGRX]

A pressure switch is almost always preferable to a flow switch (far more robust). The pressure switch is often wired into the start circuit so that the motor will start when the start switch is pressed but it will not stay latched-on until there is pressure developed by the pump.

Thanks but due to the concern of the pump prime, what would be the best way to effectively prime pump or hold prime before automating the pump. even if the pump is automated and there is no prime . This will lead to pump damage.what do you think?

 

[EEENGRX]

A pressure switch is almost always preferable to a flow switch (far more robust). The pressure switch is often wired into the start circuit so that the motor will start when the start switch is pressed but it will not stay latched-on until there is pressure developed by the pump.

yes good idea but what would be the best way to handle the pump prime. i am looking for a way to handle the prime remotely as well as automate the pump start stop based on sump level

 

[EEENGRX]

At one point I did a lot of Fire Alarm design and installation.
Flow switches were always used to indicate flow.
There was a reason why pressure switches were not suitable, but the flow switches proved their dependability.
It does often take more tooling and expertise to install a flow switch on larger lines as opposed to a pressure switch.
Pressure switches were only used for alarm on loss of supply pressure.

yes i really like those vertical mount float switches for level control but dealing with pump prime and shut down protection is another thing.lookimng for something not too complicated but very effective

 

[waross]

A FLOW SWITCH IS NOT THE SAME AS A FLOAT SWITCH.

 

[waross]

but what would be the best way to handle the pump prime

See post #2.

 

[3DDave]

You have two separate problems. One is that the motor may overheat if it is running but no water is passing through. Use a temperature switch on the motor case for that. The other is if the motor does not run when expected. Use a water level switch in the sump to detect that too much water is in the sump, separate from the water level switch that operates the pump.

 

[TugboatEng]

A typical self-priming centrifugal pump will lose prime and stop pumping before it pumps all the water out of its casing. It will continue to self-prime until water is available to pump again. It will self-prime as long as there are no checked valves on the discharge side of the pump. You may want to monitor the temperature of the water in the pump, if the source is dry, the pump will overheat.

 

[LittleInch]

Hang on here. You have a self priming pump and yet you're trying to prime the pump?

Those self priming pumps (it would help t know which one" commonly retain sufficient water even if the inlet line is drained or empty to self prime. That's what they are designed for.

First fill yes, you need to add water, but after that it should just look after itself.

A foot valve / NRV on the inlet is always a good idea, but not 100% reliable.

In terms of alarms etc, a flow switch or meter somewhere downstream the pump is probably your best bet. Pressure can be used, but is sometimes difficult to get right.

But let us know which pump you've got and why you want to keep filling it.

 

[waross]

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.

 

[LittleInch]

OK. There are good pumps and less good pumps.

If you want or be certain, then just main a supply and as part,of the start sequence open the valve for 30 seconds or so before pump start. Keep it simple.

 

[EEENGRX]

Hang on here. You have a self priming pump and yet you're trying to prime the pump?

Those self priming pumps (it would help t know which one" commonly retain sufficient water even if the inlet line is drained or empty to self prime. That's what they are designed for.

First fill yes, you need to add water, but after that it should just look after itself.

A foot valve / NRV on the inlet is always a good idea, but not 100% reliable.

In terms of alarms etc, a flow switch or meter somewhere downstream the pump is probably your best bet. Pressure can be used, but is sometimes difficult to get right.

But let us know which pump you've got and why you want to keep filling it.

Yes it is self-primer pump that requires manually filling the pump case with prime water so that it will pick up prime and start pumping and not damage the mechanical seal. What would be the best way to solve this issue of priming since I want to automate pump based on the Level of sump. Adding a foot valve will help but it will It won’t provide shutdown protection or alert the control room to a problem if for some reason the pump doesn’t pick up a prime. Trying to find the best possible options and compare with my plan with the view of having a very robust automation

 

[3DDave]

What is it that a separate water level switch and a thermal switch won't do as far as monitoring is concerned?

You won't know why it failed to "pick up a prime." It could be that someone left a cleaning rag in the sump, it could be that the wires to the motor burned or were eaten by a rat. It could be that the pump vanes have been eroded. Are you wanting to detect all those individual problems as well?

It seems unreasonable to have to manually prime a sump pump. What will you do if the prime pump for the self-priming pump fails?

 

[LittleInch]

Well if you have a self priming pump that you need to print each time then you might as well just buy a normal pump and fill the suction line each time. Self priming pumps tend to be less efficient.

Or interlink an actuated valve in the suction line below liquid level.

Or buy a submersible pump or a shaft driven submerged pump.

You seem to be trying to fix a problem by controls systems when to me you've got the wrong pump. IMHO.