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12V Pressure switch


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With the current load-shedding and water becoming the next concern, we are considering a water backup solution.  Due to the inverter not being big enough to handle a pressure pump as well, we would like to do an off-grid 12/24V setup.  12/24V pumps are readily available, however, the pressure switches are nowhere to be found.  Does anyone know of a low-voltage pressure switch?

The only alternative is something like this:

https://www.waterpumps.co.za/product/12-volt-dc-003-diaphragm-pump/

This however feels a bit light to give water to a small home......

Any help is appreciated.

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5 hours ago, wimmelman said:

With the current load-shedding and water becoming the next concern, we are considering a water backup solution.  Due to the inverter not being big enough to handle a pressure pump as well, we would like to do an off-grid 12/24V setup.  12/24V pumps are readily available, however, the pressure switches are nowhere to be found.  Does anyone know of a low-voltage pressure switch?

The only alternative is something like this:

https://www.waterpumps.co.za/product/12-volt-dc-003-diaphragm-pump/

This however feels a bit light to give water to a small home......

Any help is appreciated.

This pump is quoted at 17 litres per minute. Enough for showering, dishes but my experience is that they don't give the quoted output. 

No need for a pressure switch as the pump has one internally. 

https://www.waterpumps.co.za/product/pump-pressure-switch-ps-02c/

Edited by Scorp007
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In addition, I see it is restricted in operating time. Keep that in mind

"This pump is also not a continuous use pump. It should not run longer than 30 minutes at a time with a 15 min cool down period to ambient temperature, allowed between runs."

 

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  • 2 weeks later...
On 2023/05/18 at 5:55 PM, wimmelman said:

With the current load-shedding and water becoming the next concern, we are considering a water backup solution.  Due to the inverter not being big enough to handle a pressure pump as well, we would like to do an off-grid 12/24V setup.  12/24V pumps are readily available, however, the pressure switches are nowhere to be found.  Does anyone know of a low-voltage pressure switch?

The only alternative is something like this:

https://www.waterpumps.co.za/product/12-volt-dc-003-diaphragm-pump/

This however feels a bit light to give water to a small home......

Any help is appreciated.

The pressure switches we use are just a switch, the switch supplies voltage to the contactor's coil. Always remember that if you switch a DC coil there is quite a bit of back-emf when the power gets removed from the coil. 12v Dc coil contactors are quite bigger than 230v AC coil contactors. 

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29 minutes ago, Vaal said:

The pressure switches we use are just a switch, the switch supplies voltage to the contactor's coil. Always remember that if you switch a DC coil there is quite a bit of back-emf when the power gets removed from the coil. 12v Dc coil contactors are quite bigger than 230v AC coil contactors. 

Easy to kill the back EMF that's why you normally find a free wheel diode reverse biased over the coil. DC coils are large but that is normally to get a high resistance as there is no inductance to limit current flow as we have with AC coils.

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10 minutes ago, Scorp007 said:

Easy to kill the back EMF that's why you normally find a free wheel diode reverse biased over the coil. DC coils are large but that is normally to get a high resistance as there is no inductance to limit current flow as we have with AC coils.

I know it as a snubber diode.

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