Valves & flow control
rOtary VaLVes –
air LeakaGe and PerfOrMance
All rotary valves leak air (or gas) even
where there is no pressure differential
as even the product entering the valve
displaces air into the inlet area.
This is significantly increased when
operating under a pressure differential
due to losses past the operational
clearances and carry-over of pockets of
high pressure decompressing into the
inlet. The total of such losses are normally
referred to as ‘leakage’ and given a single
quantity value.
There are many factors that affect the rate
of leakage and the ratio of the elements
that make up the total. All are affected by
the system conditions prevailing at any
given time.
In practical terms most manufacturers
only offer leakage charts based on tests
measuring leakage past valves in a static,
product-free condition. Because the
presence o