HELP WITH POWER FORMULAE MATHCAD 9

[JM_3218201]

Hello

I have the next formulae of power but I think  there is an mistake, Please somebody help me

Pot=(PxQ/360)/1.358

P pressure in bar=225 bar

Q flow in l/min=78 l/min

Pot=( (78*225)/360)/1.358=35,8kW

Thanks

[terryhendicott]

Hi,

The equation is an empirical one in that it is not unit consistent.

So you need to strip the units from each term of the equation.

Do this by dividing.

Then you need to apply the units of the equation.

[Fred_Kohlhepp]

Terry,

The equation is unit consistent:

We need to look harder at his sheet.

[MartinHanak]

Hi

where did you get the following information?

Pot=(PxQ/360)/1.358

P pressure in bar=225 bar

Q flow in l/min=78 l/min

[JM_3218201]

Hi

This Iis in a hydraulic manual.

It's usually in hydraulic power calculations

JM

[MartinHanak]

---

@JM_3218201 wrote:

Hi

This Iis in a hydraulic manual.

It's usually in hydraulic power calculations

JM

---

Hi,

how do you know that the result of Pot=( (78*225)/360)/1.358 should be 35.8 kW ?

 (Fred_Kohlhepp)

[MartinHanak]

I am just uploading my exercise ... verification of the formula

[Fred_Kohlhepp]

This is a very nice demonstration that Mathcad's unit conversion works:

  Well done, 

The question is why does the formula originally posted result in a different answer?

[JM_3218201]

Hi 

I have revised some hydraulic books an I think you have proposed are OK

I think the problem are  the units

Pot=(PXQ)/(612xµ)

P=bar or kg/cm2

Q=l/min

Pot=kW

Thanks

[Fred_Kohlhepp]

The formula has values for unit conversion and also efficiency (I believe).

See attached