Pump Level Float

[Abe5gt]

Hey you guys, just wanted to know your feedback on this current situation that I have. I have two pumps in my plant, each pump must have a LOW LEVEL FLOAT so the pump will stop in low level. The panel that I have has only one input for one float. I had the idea to add a selector switch for LOW LEVEL FLOAT 1 and LOW LEVEL FLOAT 2 and connect it to that input and pick witch LOW LEVEL FLOAT I want to use. The problem comes when I want to use both pumps, is there a kind of switch that I can use for LOW LEVEL FLOAT 1, LOW LEVEL FLOAT 2 and BOTH in case I want to use both pumps and still want the control panel to stop when one of the Level is low? Se attached picture of idea. Thanks!

 

[augie47]

You need to put some thought into the selector switch idea to assure that you don't have a situation allowing a pump to run if the switch is in the wrong position.
The protection should be there without adding a human error possibility
Off the top of my head, it would seem if both pumps are for the same tank that at low level you would want neither to run which could be accomplished by wiring the control circuit for both thru the float (common control) or having a relay on the float to interrupt both control circuits.

 

[GoldDigger]

Clearly (?) if the two controls do not apply the same voltage to the float contacts a relay will be needed.
The (none)/1/2/both selector function is often found in battery selector switches.

 

[Jraef]

You need to put some thought into the selector switch idea to assure that you don't have a situation allowing a pump to run if the switch is in the wrong position.
The protection should be there without adding a human error possibility
Off the top of my head, it would seem if both pumps are for the same tank that at low level you would want neither to run which could be accomplished by wiring the control circuit for both thru the float (common control) or having a relay on the float to interrupt both control circuits.

Exactly right. If each pump has a separate float already, or you want redundant floats for some reason, just wire them in series to a common point in the control circuit. If each pump has a separate control circuit, have the float circuit go to a relay as Augie47 said. This way if either float drops and opens, it shuts down whatever is running, no user decision required.

 

[GoldDigger]

Exactly right. If each pump has a separate float already, or you want redundant floats for some reason, just wire them in series to a common point in the control circuit. If each pump has a separate control circuit, have the float circuit go to a relay as Augie47 said. This way if either float drops and opens, it shuts down whatever is running, no user decision required.

I think that one if the OP's goals is to include the pump selector function in the switch. Your idea to shut down whichever pump is running is fine, but still leaves the pump selection to be done some other way.

 

[Jraef]

I think that one if the OP's goals is to include the pump selector function in the switch. Your idea to shut down whichever pump is running is fine, but still leaves the pump selection to be done some other way.

I didn't see that stated in his post. Everything just says "float". He says he has a control panel, it just has only one input for low level cutoff and he apparently has two low level float switches. So I suppose I am ASSuming the rest of the control panel functionality is to his liking, he just wanted to figure out how to deal with that extra float switch issue.

 

[GoldDigger]

Well, he did say that he could just select the single float to whichever pump he wanted to use, but needed a way to allow him to also choose to use both pumps. I inferred the rest from that.

 

[USMC1302]

Not to confuse things further, but if you're trying to control both pumps with one low-level cut-off, and possibly select one or both pumps, why not consider an alternating relay. You can select either/both pumps or auto and have the low-level/enable float alternate pump operation.