Partial stroke testing is common
practice in many process plants
enabling valves to be tested without
causing major interruption or downtime
to the production process.

Shut-off valves, usually activated by a
solenoid valve, in a safety loop allow
operators to shut down process lines
in the event of an emergency.

As part of its range of control
valves, positioners and accessories,
Samson Controls offers a range of
electro pneumatic positioners
which allow stroke tests to be
carried out without disrupting the
process line. One example is the
type 3730-3 positioner that has an
ESD (Emergency Shutdown)
function. It can be mounted on the
valve in addition to the solenoid
valve, or to replace it, and enables
the valve to be moved precisely to
follow the set point within the
valve’s working ratio.

The partial stroke test is
integrated into the positioner to
detect a sticking valve, caused for
example, by corrosion. Test
schedules can be flexible and
prolonged if necessary.