How does a pump trade flow rate for head, i.e., pressure? 6

[Robert Clark]

A pump’s power is a product of its pressure rise times volume flow rate. Commonly, a pump is specified by giving the pressure rise, or head, it can provide and the flow rate, such as in gallons per minute(GPM).

But some pumps provide the user with a chart that shows how the pressure rise can be varied with a corresponding change in flow rate, inversely related.

This is what I need for my application. I need a higher head than what the specs say for the pump, allowing for the reduced flow rate. The specs don’t say whether or not these values can be varied. So is there some common method by which this is done for pumps with this capability?

I thought they just reduce the inlet size to change the flow rate, with an associated change in the size of the pressure rise. But then I thought this would just mean the pump would just suck harder on the water input source, making the flow rate stay the same.

So how do pumps with this variable capability do it, and can other pumps be adapted to also do it?

Robert Clark

 

[Robert Clark]

Rputvin, thanks for responding. Yes, for a hose held aloft thousands of feet in the air extending horizontally for a distance of several miles, you would have to get FAA approval. However, since this is for region that extends from a lake, pond, creek, etc. in the direction towards a forrest fire I would imagine there would be minimal air traffic in that direction anyway.

About the feasibility, that’s why I wanted to test it for low cost pressure washers first, with their low flow rates of ca. 1 - 4 GPM. This low flow rate would also mean relatively low weight of water would have to be supported by the drones or self-supported by the pressurized jet water exhaust.

By the way you could also have the full distance be traversed in stages, a sort of leap-frogging arrangement. This would reduce the weight of water that had to be supported by reducing the length of hose that was held aloft before it came back down. At each stage when the hose came back down to the ground, the water would be made to flow into a holding tank, and then the next stage would take the water from this holding tank, etc.

 

[Artisi]

Question, have you every been any closer to an active forest fire than a TV screen?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[1503-44]

Orbited a 100m long garden hose full of water.