Parallel To Series To Parallel

[Knoell]

If you are operating a 2-stage pump in Series and decide to switch to parallel in order to supply more water to additional hoselines, can you do it while still operating or do you have to shutdown. If you can do it while still operating does the pressure on the hoselines drop and would an automatic govenor compensate to maintain the pressure? Conversely, does the pressure on the lines increase if you drop from Parallel to series (should cut volume by half and increase pressure unless govenor compensates).


Never had to do it but wonder what would happen

Roger

[GreggGeske]

No, you do not have to shut down to switch from Pressure to Volume. The pressure will drop slightly and the governer would bring up the RPM to the set pressure. You are also correct that the pressure would rise when switching from Volume to Pressure.

[ADSNWFLD]

It depends on the age of the pump and who makes it. Some of our rigs can be switched while at pressure and others can't, or shouldn't.
It doesn't take long to drop the rpms and throttle back up. So it shouldn't be that much of an issue.
Far more important is to teach the MPO how to anticipate what is going to be requested during the fire. With todays engines you really don't need a two stage anyway.
If you have an automatic gov. it will change when switching modes to maintain pressure.

[lmrchief2]

Make sure your pressure relief is set (on older pumps on) When you go from volume to pressure.