Pressure variance on diameter 5

[Asisraja D]

Hi
It is room temperature fluid
Centrifugal pump
Pump head is 25 meter (2.5 bar)
Cooling tower pump
Header size is 3"
Branch size is 1.5"


We are getting 3.5 bar pressure at reactor manifold?

Is it possible to get 3.5 bar pressure at 2.5 bar head centrifugal pump ?

Fluid temp is room temperature (25 to 32 deg.c)
Constant density (998 kg/cm2 to 1000 kg/cm2)
Flow rate is 45 m3/hr

Is it possible?

 

[LittleInch]

Yes if the inlet pressure into the pump is 1 bar or more.

Or the nanifold is 10 m lower

Or the flow is zero or a lot lower than the pumps duty point

Or if the pump is going faster

Or if your guage is measuring bara? Ir is not reading properly

Is that enough to check?

A decent diagram with levels would help...

 

[Asisraja D]

Littleinch
The inlet pressure is - 0.264 barg
The flow is not zero.
Pump rpm is 2900 rpm
Our gauge is gauge pressure not absolute

DIagram is bit tough to time taken

 

[LittleInch]

What is your pump curve and actual flow?

What is pump suction pressure?

What are elevations of this mysterious reactor manifold compared to the pump discharge flange?

 

[Asisraja D]

Pump rated flow rate is 45 m3/hr

Suction pressure is 0.29 barg

Manifold is 4 meter frome the pump eye

 

[LittleInch]

But what is your actual flow rate? If you don't know find out.

And what does your pump curve look like?⁵

4 m up or down?

 

[Asisraja D]

4 m down From pump eye.

Unfortunately the pump cure is not available but

Vendor told me the shut off head is 32 meters

 

[LittleInch]

Well with 3m inlet head, at least 25m differential head ( that's what the 25 m means), plus 4m extra head is a total of 33m, is pretty close to 3.5 barg.

If you're flowing a bit less than 45 m3 then that's your extra 2m.

Pump heads are always given in differential head.

 

[Asisraja D]

Could u please explain me a little bit

 

[LittleInch]

I thought I just did. Which bit didn't you understand?

I'm not being sarcastic.

 

[EdStainless]

As long as the inlet head doesn't blow the pump casing to pieces all that the pump does is add energy.
So you take inlet head, what the pump adds, and then any elevation related addition or loss on the outlet.
In the end you get actual pressure.
You need the pump curve and actual flow so that you know what head it should be making.
Or otherwise you use the pump curve and know pressure differential across the pump and then see if the curve flow matches the actual.
I don't want this to sound like a scold but you should insist on having pump curves for every pump.
For small pumps you can rely on the 'general' catalog curves.
For larger pumps the curve should be from and actual test of your pump.

 

[Asisraja D]

Little inch
I need basics of pumps and factors influencing pump discharge pressure

 

[LittleInch]

Try sites like this https://www.introtopumps.com/pumps-101/

Lots of things influence discharge pressure including

Inlet pressure
Pump speed
Impeller diameter
Fluid Specific gravity - centrifugal pumps generate the same head regardless of contents density. Pressure is head x density so varies with SG
Elevation difference from pump centreline to point of measurement.

 

[pierreick]

Hi,
Engineering is about hard work.
Use these documents to support your study.
Pierre

 

[pierreick]

Another great resource.
Pierre

 

[GD2]

Littleinch
The inlet pressure is - 0.264 barg
The flow is not zero.
Pump rpm is 2900 rpm
Our gauge is gauge pressure not absolute

DIagram is bit tough to time taken

What's your pump make and model?