Trouble Shooting; Fault, Possible Cause, Remedy; Diaphragm Break Of The Controller Savd - Danfoss PCVD Instructions Manual

Instructions
8

Trouble Shooting

12 | © Danfoss | 2016.05
PCVD, PCVSAD

8.1 Fault, Possible Cause, Remedy

Fault Possible cause
Air in the actuators
Controller does
not hold the
pressure on a
constant level
Impulse tubes or impulse tube
connections are dirty or damaged.
Pilot valve AVD (SAVD) does not close:
Pressure is
Valve seat or plug is dirty or damaged.
too high
Valve VFG2 does not close:
Valve seat or plug is dirty or damaged.
Rolling diaphragm in the actuator AVD
(pilot controller) is defective,
i.e. valve AVD does not close.
Rolling diaphragm in the actuator SAVD
Pressure is too
(pilot controller) is defective, i.e. valve AVD
low, no or low flow
is not closed by the safety diaphragm. In
this case, some water penetrates at the
threaded fitting of the actuator.
Rolling diaphragm in the actuator of the
valve unit is defective, i.e. valve VFG2 does
not open.
1) The trim can be replaced by qualified personnel up to DN 125.
From DN 150 replacement should be carried out by the Danfoss service personnel.

8.2 Diaphragm Break of the Controller SAVD

If the control diaphragm 1 breaks, pressure is
developped in the two intermediate chambers 2.
This pressure acts upon the safety diaphragm 3
and causes the following:
• The valve is closed.
• The control function does not operate.
• A slight water leakage at the threaded
joint 4 indicates a break of the diaphragm.
The controller must be replaced
Remedy
1. Loosen impulse tube connections
at the actuators by approx. 1 rotation.
2. Deaerate, Caution: hot water !
(move impulse tube until medium
penetrates).
3. Tighten impulse tube connections.
1. Remove impulse tube.
2. Clean impulse tubes and impulse
tube connections and check for free
passage.
1. Remove impulse tube.
2. Dismount actutor and trim.
Procedure see section 9.4.
3. Clean seat and plug.
4. If damaged, replace trim or valve.
1. Remove impulse tube.
2. Dismount actutor and trim
Procedure, see section 9.2.
3. Clean seat and plug.
4. If damaged, replace trim or valve.
1. Remove impulse tube.
2. Replace actuator, see section 9.3.
1. Remove impulse tube.
2. Replace actuator, see section 9.3.
1. Remove impulse tube.
2. Loosen union nut SW 46 and remove
actuator, see also section 9.1.
3. Replace actuator.
Pilotregler SAVD
1) .
VI.JA.C3.5B