Throtelling Pump systems
Throtelling Pump systems
(OP)
Hi all,
I will be using a 10-15kpsi (20 US gpm) pump to perform water blasting operations. Due to the existence of different type of paintings and substrate materials to be stripped, I will need the capability of working at different water pressures.
For an electrically driven pump I was wondering if somebody could advise me on energy efficient methods for controlling the ouput pressure of a pump.
Is the use of a VFD a reasonable option? or would a bypass system connected in the output be enought?
The pump is to be used for periods upto 20 minutes, and the total operation per day would probably not exceed 5 hours.
Thanks
F.
I will be using a 10-15kpsi (20 US gpm) pump to perform water blasting operations. Due to the existence of different type of paintings and substrate materials to be stripped, I will need the capability of working at different water pressures.
For an electrically driven pump I was wondering if somebody could advise me on energy efficient methods for controlling the ouput pressure of a pump.
Is the use of a VFD a reasonable option? or would a bypass system connected in the output be enought?
The pump is to be used for periods upto 20 minutes, and the total operation per day would probably not exceed 5 hours.
Thanks
F.





RE: Throtelling Pump systems
VFD is very commonly used for a PD pump. Although a VFD is normally used to control the flowrate, it can also control your discharge pressure. When the speed of the pump is reduced, the flowrate is reduced. Since the nozzle size is the same, pressure drop through the nozzle will be reduced due to reduced velocity.
A bypass system is possible in theory. The problem is how to adjust the huge differential pressure without creating cavitation problem. I would not try this if I have other choice.
RE: Throtelling Pump systems
RE: Throtelling Pump systems
I have no idea how one of these units is plumbed up- but seeing them operate- the flow is not constant- it turns on and off as the water jetter starts/stops flow. As such a VFD probably won't help a great deal (if the flow stops- the pump would also have to stop). I can only presume (guess) that the units are using some sort of internal recycle to control the system pressure.
RE: Throtelling Pump systems
I'm trying to figure out how to control the output pressure electronically (via a PLC), so far I have come across two options offered by the manufacturers of this pumps:
1)a VFD that would control the rpm of the driver, changing the flow rate; and by keeping the nozzle diameter constant thus varying the output pressure.
2)a pneumatic regulator which will bypass the water at the exit.
Unfortunatelly varying the nozzle diameter is not possible. I'm not too sure about the second option, as it would call for the need of a control loop system say a PID with a pressure transducer, and I am a bit hesitant if it would end up reducing the pump's life by not effectively controlling the output pressure and putting the pump under an oscilating load.
Also this would mean dumping a portion of the liquid that has been risen to a high pressure to meet the output pressure requirements, not the most energy efficient method.
RE: Throtelling Pump systems