- #1

- 3

- 0

Example point on the pump curve: 20 psi at 180 gallons per minute.

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter CCM_CAN
- Start date

- #1

- 3

- 0

Example point on the pump curve: 20 psi at 180 gallons per minute.

- #2

berkeman

Mentor

- 59,661

- 9,803

Which force on what where? The force of the stream of fluid on something at some distance away from the nozzle? Or some other force? Sorry, but it's not obvious to me from reading your question. Thanks.

- #3

- 3

- 0

The area I am unsure of is how to use the analysis from the link above with what I know about the pump (pump curve).

- #4

- 283

- 217

You can safely ignore the 2" hose - any contribution from it will disappear in other non-idealities.

You have to determine where on the pump curve that you'll be operating. That is the point where the pump curve intersects with the 'system curve.' This may be done mathematically or graphically - I'd do it graphically. Absent other information, you can approximate the Cv for a 1" (ID) nozzle at 27. The nozzle curve (that you generate from the Cv) is your system curve. Once you determine that point, you'll know the flow and pressure at the nozzle inlet.

You mention 'tuning' the flow rate. If that's by means of pump speed control, you'll need to generate a new pump curve for each speed and determine the new intersection point; if by means of a 'throttle valve' between the pump and nozzle, you'll need to add the flow characteristics of the valve to your nozzle characteristics to get the system curve.

Assuming that you were using a small (or long) hose, the characteristics of that might also need to be included in your system curve.

- #5

russ_watters

Mentor

- 20,571

- 7,222

Do you have a performance curve for the nozzle, or is it just a simple cone?

Example point on the pump curve: 20 psi at 180 gallons per minute.

- #6

- 3

- 0

Simple cone, linear decrease in diameter from 2 inch to `1 inch.

- #7

russ_watters

Mentor

- 20,571

- 7,222

@Dullard gave a good method just before I posted my question. Cv is called a flow coefficient. you can google for the equation, graph it, and see where it intersects the pump curve to get your flow rate.Simple cone, linear decrease in diameter from 2 inch to `1 inch.

Alternately and separately I was plugging values into an orifice flow rate calculator on tlv.com and using a 90% efficiency/discharge coefficient yields the same 27 Cv. You could plug in different values for pressure drop until you hit a point on your curve. It's actually not too far off the point you picked as your sample.

Share: