Flowserve PA46 - Manual (Page 17)

7
Operation
Duration and frequency of intermittent boiler blowdown
When the GESTRA intermittent valve opens, a localized lowpressure area forms around the blowoff
opening and the boiler sludge rushes out at high velocity, giving the steam boiler a short blow. The
discharge of sludge and precipitated solids (valve fully open) takes approx.  seconds. In order to
ascertain the blowdown frequency, the operating data of the installation have to be taken into account:
. Use formula of fig.  to calculate the amount of boiler water in [kg/h] that must be discharged so that
the admissible conductivity value of the boiler water will not be exceeded. Example: 10 kg/h
. Use the capacity chart to determine the discharge capacity in [kg/h] of the existing intermittent
valve or of the intermittent valve that has been selected according to the size of the boiler standpipe.
Example: 2.5 kg/s
3. The results of item ) and ) give a blowdown duration of 4 seconds.
For an effective blowdown the valve must only be open for  seconds, which means that according to the
above calculation  cycles per hour are required.
The time period between blowdowns (valve closed) is therefore 30 minutes.
The GESTRA automatic intermittent blowdown control TA.... features the following settings: Blowdown
duration (valve open) usually  seconds. Blowdown frequency (time between blowdowns  valve closed)
adjustable, e. g. 30 minutes. It is possible to reduce the intermittent blowdown frequency if continuous
(top) boiler blowdown is performed instead (see installation instructions BA.../ BAE...).
Emergency operation MPA 46, MPA 47
Risk of severe injuries to the whole body. Make sure that the line for the control fluid of
the diaphragm actuator is depressurized (zero bar) and isolated during the emergency
operation of the MPA 46, MPA 47.
Insert the hand lever for emergency operation only to operate the valve and remove it
immediately after operation.
Danger
Fit hand lever for emergency operation
. Fit hand lever for emergency operation 2, operate intermittent valve for removing boiler sludge.
. Remove hand lever for emergency operation 2 immediately after operation.
GESTRA intermittent valves for removing boiler sludge PA 46, PA 47, MPA 46 and MPA 47 are usually
free of maintenance.
After starting up the steam boiler or pressure vessel, the intermittent valve for removing boiler sludge
should be completely opened and closed once. The valve must close automatically, ensuring tight
shutoff.
The stuffing box must be leakproof! Inspect the check hole
C in order to detect any fluid leakage.
Maintenance