chw/hw pressurization pump

[Kalikot]

I am involved once on the design and selection of chw/hw pressurization pump, I just used to calculate the flowrate by assuming that 1 AHU is under flushing condition. Is there any standard procedure to calculate the flowrate of pressurization pump?

 

[ChasBean1]

RegieCayas, I think people might be slow to respond due to possible language issues - not sure what a pressurization pump is nor what 1 AHU under flushing condition is. Pump flow rates can be obtained from the manufacturers' curves knowing two parameters, best usually being pump speed and differential pressure.

If you could clarify, it would be easier to be more helpful.

CB

 

[Kalikot]

Sorry If I dont make it clear, so pressurisation pump is one which makes filling and pressuring up the system. The AHU means Air Handling Unit - 1 no.

 

[quark]

Now there is another question. Why should you pressurise a chilled water/ hot water system? Do you mean hydro testing? Why should you flush when you are hydro testing?

 

[Joesteam]

If I understand the question, it sounds like the initial fill of the system, where the city water pressure may be too low to top it off due to the static head. I have seen some contractors use a little pump they temporarily hook up, first letting the city water fill until the max pressure is reached and then use the temp pump. Also some use the Glycol make-up pump also for this service, if there is one.

Basically, just use your total volume and pick a pump that will not take two years to fill the system.

Joe Lambert

http://www.control-associates.com/

 

[Kalikot]

Joesteam pick up my question, normally city water pressure are common use but nowadays designer are installing permanent pressurisation pump because of non stable pressure of city water and to avoid possible mixing of chemical treated water to city water.

 

[khan644]

Kalikot, there is no hard and fast rules regarding the flow rate of those small pumps inside the Press'n units.

At one project I have seen a Dedicated booster pump doin the job and at other a .25 hp pump in consoled tiny unit.

There is more to cost saving also involved into it.

An approximate guidelines have seen is one AHU at a time.

But still "assumptions are the mother of all F*%# ups"
I would love to see any concrete source on this...

 

[Joesteam]

There are commercially available systems just for this need. They are sized pretty small, not for the initial fill but to keep the pressure in the system in case of small outflows and pressure drops. Look at attachment of one we have used.

Joe Lambert

http://www.control-associates.com/