# Pump Power Consumption

1. Sep 3, 2013

### jderulo

1. The problem statement, all variables and given/known data
Determine the power consumed by a pump when it is pumping a fluid of density 1,200kg/m^-3 60m3/h at 500kPa with an 80% overall efficiency.

2. Relevant equations
I believe it to be: $$P = q_m ρ g h_p$$

3. The attempt at a solution
Stuck at the above part, I don't have enough info?

2. Sep 3, 2013

### Staff: Mentor

The formula looks useful. What is qm?

Instead of g and a height, you are given the pressure. How are those concepts related?

3. Sep 3, 2013

### jderulo

qm is mass flow-rate. g is gravity, h isn't height but energy head..

4. Sep 3, 2013

### Staff: Mentor

Similar enough.

The main idea is that you can write down a similar formula where you replace ρ, g and hp to include pressure instead of those two parameters.

I am surprised that it is the mass flow rate and not the volume flow rate.

Anyway, you need the delivered power output of the pump (that's what your formula can do).
Once you have that, you can see how you can include the 80% efficiency.

5. Sep 3, 2013

### jderulo

My mistake it's volumetric flow. - but unsure how to do the first point.

Last edited: Sep 3, 2013
6. Sep 3, 2013

### jderulo

$$h_p = p / ρ g$$

?

Am I right in thinking the final formula would be

$$P = q_v ρ g (p / ρ g)$$

Last edited: Sep 3, 2013
7. Sep 4, 2013

### Staff: Mentor

Right. You can simplify that formula, ρ and g will drop out and you are left with a simple product.