Spirax Sarco DP27, Installation And Maintenance Instructions Manual

Page: 11 / 40

IM-P470-03
CH Issue 7 11
DP27E
The DP27E (Figure 2) is supplied as for the DP27 with
a control spring but the maximum pressure is limited
to 10 bar g due to the addition of the solenoid valve. A
solenoid operated valve is fitted in the pipe between
the pilot valve and the main diaphragm chamber and is
thus in series with the normal pilot valve.
The purpose of the solenoid valve is to override the pilot
valve thus causing the main valve to shut-off. It can be
controlled by any device capable of interrupting the supply
of current to the solenoid coil.
The solenoid is arranged to open the valve when the coil
is energised so that whatever switching device is used it
must be arranged to break the current to close the main
valve. In this way the unit will always 'fail-safe' i.e. will close
the main valve in the event of a failure in electrical supply.
Note: A special pilot valve assembly is used in the 'E'
version to prevent leakage past the pilot valve plunger
when the solenoid is used to close the valve.
Electrical supply
It is important that the solenoid is connected to the correct
voltage. Therefore always check on the supply details
which are stamped on the solenoid valve name-plate
before attempting to connect up.
Electrical connection is by cable plug to DIN 43650. All
wiring, connectors, etc. in close proximity to the valve
should be of heat resisting type and comply with local and
national electrical codes.
Earth
The solenoid valve should be adequately earthed.
DP27R
The DP27R (Figure 3) is supplied ready for fitting.
Downstream pressure can be adjusted remotely by a
controlled air supply to the pilot diaphragm chamber. The
actuating air supply must be at a pressure approximately
0.7 bar g above the required downstream pressure and
controlled through a metal bodied self-relieving regulator.
A check valve should be fitted to prevent steam entering
the air system, in the unlikely event of a failure of the pilot
diaphragm. Any filter should be fitted with a metal bowl
and should preferably be on the upstream side of the
check valve.
The actuating air supply controlled by the regulator
should be connected to the union fitting attached to
the air control block as shown in Figure 4. The air inlet
connection is suitable for 6 mm O/D copper tube. The
maximum reduced pressure available through the DP27R
is 15 bar g. Typical installation is shown in Figure 9,
page 17.
Solenoid
valve
Fig. 2 DP27E
Fig. 3 DP27R