View Full Version : Pressure Drop in a 26" line due to installing a 24" valve

25-11-2010, 04:49 PM
I have an application on a 4500 ton chiller using R22 that involves installing a valve on the suction side on the compressor.

My question is, what is the added pressure due to installing a 24" butterfly valve instead of a 26" butterfly in this line. The temperature of the R22 is 37 Deg F and 66 PSI.

This is a 2 stage Carrier Centrifugal Compressor, is there any way to determine the added HP due to this additional pressure drop?

25-11-2010, 04:50 PM
BTW, this is a 26" pipeline between the cooler and the compressor.

25-11-2010, 05:27 PM
hi sampson ,
is this 24inch valve on the evaporator chilled water?
or on the condencer < cooling water< between cooling tower and w-chiller ? eitherway would you sign that the jobs been done to spec,?

25-11-2010, 07:58 PM
Check with the manufacturers of the valves, they will have pressure drop tables for their products, no guess work then. :)

edit: Is the valve going to be simply slipped between the 26" flanges or is it going to have reducers fitted?

26-11-2010, 02:19 PM
The 24" Valve is on the R22 suction line to the compressor.

A 26" Valve was specified but a 24" valve was installed and I am calculating the performance degradation due to the 24" Valve and method of installation.

26-11-2010, 02:26 PM
If you're interested I can post a drawing of the installation that has been rejected. You wouldn't believe how it was installed, 24" Weld Neck Flanges were inserted into the 26" pipe. The outside of the 24" Weld Neck throat was welded to the end of the 26" pipe leaving the exposed end of the 24" WN on the interior of the pipe. There is approximately a 3/4" gap where the end of the flange will protrude into the flow stream creating additional resistance and turbulence. This is being replaced but now we are debating the effect of the valve size reduction.

26-11-2010, 07:37 PM
They do reckon that butterfly valves offer negligible resistance, liquids, but I have to say that your installation does lack a certain finesse.

A discussion paper may help..