Dead Head pump dry running

I got my water system as follows
1HP self priming pump connected to the municipality water mains 1" pipe
Pressure tank 24 Liter
Pressure switch set to 50/70 psi
It happend few times that the water main has very little water to the extend that the pump can not fill the tank and reach to 70psi to shut itself off and keeps running untill i discover that by chance
In a trial to protect the pump , I bought a Flow Switch (Watts) model FLU25/ST it is a (paddel type)and I intended to fix it before the pump to see the low flow and connect it in serious to the pressure switch to cut the electricity feed to the pump when the flow is low.
I read the data sheet of the Flow switch but I found it meant to be fixed after the pump obviously to feel the high pressure of the pump which should feed a boiler then switch off the boiler when the pump dischanre is under certain limit ( the setting of the switch )...this is what is written in the Flow Switch data sheet.
The question now , can that flow switch work in my case too ? with that water mains relatively low pressure which can be as low as 10psi?
I want to know that before I fix the switch in the system and incur costs and effort then if it did not do the job I would not be able to return it to the shop.
Thanks very much in advance!

I'm not real sure how you intend to use this flow switch. But if you make it so when there is no flow and the flow switch kills the pump. The tank won't be able to fill and turn off with the pressure switch.

You might do better with a device similar to the Pumptec that senses low amps produced by the lack of water to pump. This shuts off the motor for a specified amount of time.

bob...

The flow switch doesnt seem correct for this application.

Replace the pump pressure switch with a low pressure cut-off type switch for about 20 dollars.... square D

When the pumped side drops to about 30psi the pump will be disconnected. You can restart by raising the lever and holding it until the pressure exceeds 20 or 30 psi

Raucina said:

The flow switch doesnt seem correct for this application.

Replace the pump pressure switch with a low pressure cut-off type switch for about 20 dollars.... square D

When the pumped side drops to about 30psi the pump will be disconnected. You can restart by raising the lever and holding it until the pressure exceeds 20 or 30 psi

Click to expand...

I dont understand that ! , the pumped side = the mains side?
The mains side pressure varies, it sometimes go down to 10psi
I need an automated protection system which cuts off the pump when the mains pressure is very low and reconnectes the pump automatically when the mains water pressure is suitable for pumping

speedbump said:

I'm not real sure how you intend to use this flow switch. But if you make it so when there is no flow and the flow switch kills the pump. The tank won't be able to fill and turn off with the pressure switch.

You might do better with a device similar to the Pumptec that senses low amps produced by the lack of water to pump. This shuts off the motor for a specified amount of time.

bob...

Click to expand...

I am inteding to fix the flow switch on a T to the mains pipe line which feeds the pump then I will connect it electrically in series between the pressure switch and the electricity source in order to allow feeding electricity to the pressure switch ( which feeds the pump ) only idf there is enough water pressure in the water mains , does that help you understand it? hope to have an answer soon
Thank you

The pressure switch with a low pressure cut out feature should protect the pump when it does not have enough feed water. But you will have to manually reset it. The pump-tec might work better and also restart automatically. Cant say much about a flow switch unless its exact operational specifications are provided.

A flow switch tied in series with the pressure switch will allow either the flow switch to shut the pump off during low flow, or the pressure switch to shut it off at high pressure. The problem is that the flow switch will not let the pump come back on when the pressure switch calls for it. The pump is off, and there is no flow, so the flow switch does not make and let the pump run. Flow switches are usually used in combination with a relay timer. The timer actually starts the pump, then if the flow switch makes, it overrides and keeps the pump running when the one minute timer shuts down. Low pressure cut off switch, Pump Tec, or Cycle Sensor are better ways to handle the no flow condition.

That's what I was trying to say.

I have both if your interested.

bob...