Description
Electronic unit for the generation of periodic pulses to
initiate a blowdown cycle via the GESTRA rapid-action
intermittent blowdown valve type MPA 46 or 47, i.e.
automation of intermittent boiler blowdown. Equipment for
steam boilers to TRD 401, section 6.4.
The programme-controlled blowdown system consists of
an electronic cycling timer, a three-way solenoid valve and
a strainer.
The equipment meets the German regulations for use in
steam-boiler plants operating without constant supervision
or with limited supervision (TRD 602 and TRD 604, sheet 1).Function
The cycling timer type PRS 8 generates a control pulse which,
after the preset blowdown interval, operates the three-way
solenoid valve. This in turn actuates the rapid-action blowdown valve by means of compressed air or pressurized
water and closes it again at the end of the pulse (blowdown)
duration.
The blowdown interval and the pulse duration can be coarsely
preset with a code switch. Final adjustment is carried out with
the aid of two potentiometers.
For test purposes and in the event of power failure the
three-way solenoid valve can be operated by hand.
A push-button manual override is provided on the solenoid valve which allows a test of the blowdown valve as
required by certain regulations in force.