View Full Version : Varem Pressure Tanks

31-07-2012, 03:24 PM

Does anyone have experience on Varem Pressure Tanks?

The tank is there to maintain constant pressure in the closed loop system. The tank will be installed after the pump, i.e. on the discharge line of the pump.

They ask for the pressures, min & max pressures, in the catelogue. I am running a -4C propylene glycol 25% at a flow of 5l/s. How do I know what my min & max pressures are?

The Viking
31-07-2012, 08:36 PM
It depends on where on the system the pumps and the plant is located...

Our old physics tells us that for every 10 meters, the pressure will change 1Bar.
Say that your plantroom is on the roof of a 20m tall building, then the minimum standing pressure will be 0Bar. However, if the plantroom is at ground level then the minimum standing pressure for the same system would be 2Bar.
Same system just readings from different points...

Now, to the minimum standing pressure above you will have to add a safety margin to ensure all sections of the system at all times are above atmospheric pressure, normally this would be 0.5-1Bar.
Add to this the fact that you will need a pressure differential across the pump in order for it to move the water around, normally somewhere around 1Bar but it can be as little as 0.2Bar or as much as 6Bar.

As you can see it all comes down to the design of your system, in my example above with a 20m building the answer to your question could be 0.5 to 0.7Bar or 2.5 to 3.5Bar both answers equally within "normal" values.



install monkey
31-07-2012, 11:55 PM
may help

01-08-2012, 06:56 AM
Thank you all.

The layout is as follow: all the equiopment is on the rooftop and drops through the slab and runs hard agains the slap, lets say 0.5m

The return line comes to the pump, on the discharge line the pressure vessel(with blader) and then the chiller. From the chiller it goes to the valve station witch is 2.5m below the slab.

The valve station consists of the following: on the supply line is a ball valve, then goes trough a jacked vessel, on the return line is 2 ball valves and 3 way valve with by pass. Then the return goes back to the pump.


01-08-2012, 11:28 PM
Try this sizing document, it may help....


You pipeline sketch seems to show the 'expansion vessel' as a buffer tank with the flow passing through the vessel.

Normally an expansion vessel is simply 'connected' to the system pipework via a 25 or 32mm pipe.

02-08-2012, 08:02 AM
Yes I noticed I drew it wrong. It was something quick but I have changed it. Thank you