Start-Up; Required Static Pressure, Pressure Difference; Leak And Pressure Tests; Filling The System - Danfoss PCVD Instructions Manual

Instructions
7

Start-up

10 | © Danfoss | 2016.05
PCVD, PCVSAD
7.1 Required Static Pressure, Pressure
Difference
For a proper functioning, a minimum pressure
difference of p1 − p2 ≥ 0.5 bar is required.
The static pressure p1 in front of the controller
must not fall below 1.5 bar (excess pressure).
Non-observance may lead to cavitation and
damages in the throttling element 1.
p2

7.2 Leak and Pressure Tests

To avoid too high pressures at
the diaphragm actuators, the
following should be observed
prior to any pressure tests:
Actuator of valve unit:
The admissible operating excess pressure in the
actuator 2 is 15 bar . For higher pressures, you
1)
must:
• Remove the impulse tube 3
The admissible operating excess pressure in the
actuator 4 is 25 bar 1) . For higher pressures, you
must:
• Remove the impulse tubes 5 at the actuator
and close the connections with a stopper
• Prior to any leak or pressure test, the
instructions in section 7.3 must be complied
with.
7
2
3
5
1) Pre-condition: Same pressure on both sides of the diaphragm.
If the pressure load is one-sided, the (+)diaphragm chamber
may have an excess pressure of 1 bar in comparison to the (-)
diaphragm chamber.

7.3 Filling the System

Note:
The controller 6 is closed when no pressure is
applied and only opens with a defined flow in the
bypass.
The pilot controllers 7 are closing on rising pressure.
Procedure
1. Open shut-off valves 8 that possibly exist in
the impulse tubes.
2. Slowly open shut-off units first in the return
p1
flow 9 and then in the supply flow 10.
1
7.4 Start-up
During starting-up the filled system, open the
units in the same sequence as described in
section 7.3.

7.5 Putting out of operation

When putting the system out of operation, first
close the shut-off units in the supply flow and
then those of the return flow.
6
4
9
8
10
VI.JA.C3.5B