So went to check out a pump house job the other day that feeds roughly 150 residences. There is a storage pit/tank that holds water from 4 separate well pumps with a 4-float system. There is also a pair of series pumps with 7.5 HP. They mount vertically on the pumps (but I have not gotten information off of the pumps themselves yet). These pumps are running via a control loop with a VFD and pressure sensor on the pump outlet line. I'm wanting to know two things:
In particular, what is the relationship between the motor/pump RPM and the line pressure? I'm wanting to look more at the components of this control loop before I decide if we should take the job, and I have never done an RPM/Line pressure control loop before.
On a non-technical note, how do you guys handle it when a customer is demanding something be done in a specific manner, even though you know it will lead to issues? An example would be that on the 4-float system in the tank, the bottom float (low-low), in my opinion, should be an emergency float that shuts down the system if the tank level gets too low and throws an alarm to prevent the system from running dry, however the customer is wanting the pump to just run at a very slow RPM if the water level drops below the last float.
I've dealt with well-storage-pump systems before, but I've never had a couple of the curveballs that this one was thrown.
In particular, what is the relationship between the motor/pump RPM and the line pressure? I'm wanting to look more at the components of this control loop before I decide if we should take the job, and I have never done an RPM/Line pressure control loop before.
On a non-technical note, how do you guys handle it when a customer is demanding something be done in a specific manner, even though you know it will lead to issues? An example would be that on the 4-float system in the tank, the bottom float (low-low), in my opinion, should be an emergency float that shuts down the system if the tank level gets too low and throws an alarm to prevent the system from running dry, however the customer is wanting the pump to just run at a very slow RPM if the water level drops below the last float.
I've dealt with well-storage-pump systems before, but I've never had a couple of the curveballs that this one was thrown.