A (dumb) question about pump with a ball/gate valve

[Miami Reef]

I have a silly question.

Let’s say I have an ac pump connected to a pvc/soft tubing pipe. If I were to put a ball valve/gate valve/kink on the tubing, will that make the pump explode with pressure?

Because pumps don’t have brains…it can’t detect if there’s a kink, so won’t the pressure build up? It’s not like the pump would say, “oh, we should slow down to match the output rate”…

I hope I’m making sense here.

 

[Logical_Plan]

A good question. This is called dead heading a pump and it is bad for centrifugal pumps.

The pump will continue to circulate water in the pipe and the friction of the water in the pipe will continue to heat till it vaporizes. Most likely causing heat damage to the motor and bearings.

What happens when you dead-head a pump?

Find out what happens to your pump when you deadhead it? A useful guide put together by our team of experts at Global Pumps...

www.globalpumps.com.au

 

[Subsea]

If your pump was a positive displacement pump, that would be true.

Centrifugal pumps only put out the pressure they are rated for. When you restrict the discharge on a centrifugal pump, both flow and watts decrease And what logical said, thou unlikely, can happen.

 

[Logical_Plan]

If your pump was a positive displacement pump, that would be true.

Centrifugal pumps only put out the pressure they are rated for. When you restrict the discharge on a centrifugal pump, both flow and watts decrease And what logical said, thou unlikely, can happen.

If watts are decreasing due to a dead head you are still having major heat damage to the pump. There is no inherent safety feature on most simple AC pumps to save it from dead heading.

In aquaria, the major exception is RODI booster pumps that have a built in bypass.

Some of the smart DC pumps would catch it as a flow / power discrepancy or internal overheating as well.

 

[Pntbll687]

I have a silly question.

Let’s say I have an ac pump connected to a pvc/soft tubing pipe. If I were to put a ball valve/gate valve/kink on the tubing, will that make the pump explode with pressure?

Because pumps don’t have brains…it can’t detect if there’s a kink, so won’t the pressure build up? It’s not like the pump would say, “oh, we should slow down to match the output rate”…

I hope I’m making sense here.

It depends on a couple things, especially how big the pump is and how much pressure it's rated for.

If the pump is big enough, the pressure could blow the tubing off of whatever connector it's attached to. If it's a gate valve, it could blow out the connections if there is a union, or burst a pipe.

In reality, it would probably just heat up and seize at some point. I highly doubt the pump would blow up or rupture through it's housing, simply because some pressure is going to escape back out the water inlet.

 

[Subsea]

I don’t disagree with the physics. If you run a pump dry, it will also heat up as flowing water removes the heat. I doubt major damage or pumps melting.

 

[KStatefan]

I have a silly question.

Let’s say I have an ac pump connected to a pvc/soft tubing pipe. If I were to put a ball valve/gate valve/kink on the tubing, will that make the pump explode with pressure?

Because pumps don’t have brains…it can’t detect if there’s a kink, so won’t the pressure build up? It’s not like the pump would say, “oh, we should slow down to match the output rate”…

I hope I’m making sense here.

The pump will only create the max head pressure when it is deadheaded.

 

[Water Dog]

Throttle it back, you’ll be fine. I’ve always used AC pumps since I started on theis hoback in the mid 90s, well before the advent of DC controllable pumps. From my externnal Little Giant to the venerable Eheim and now to my Sicce ADV, they’ve all used a ball valve to throttle back and tune the flow. My experience tells me if your pump is sized properly, you have nothing to worry about.