WIKA PCA_HP - Manual (Page 5)

INSTRUCTION MANUAL
NI-281E
Rev. 5 11/02
10 - TROUBLESHOOTING
IMPORTANT NOTE: operations involving replacement of essential components must be carried out at our workshop, especially
for instruments with explosionproof certificate; this is to guarantee the user the total and correct restoration of the product
original characteristics.
MALFUNCTION PROBABLE CAUSE REMEDY
Set point shift
„ Permanent deformation of the sensitive element
due to fatigue or excess over-ranges.
„ Variation of the elastic features of the sensitive
element due to its chemical corrosion.
„ O-ring wear (only PCS2P, PCS3P, PCA2P and
PCA3P).
„ Recalibrate or replace the sensitive element.
„ Recalibrate or replace the sensitive element with
another made of a suitable material. If necessary
apply fluid separator.
„ Replace the piston subgroup and recalibrate.
Poor repeatability
„ O-ring wear (only PCS2P, PCS3P, PCA2P and
PCA3P).
„ Air bubbles or condensation (only for types with
pressure < 1 bar).
„ Replace the piston subgroup and recalibrate.
„ Drain the process connection lines and if necessary
modify them.
Slow response
„ Clogged or obstructed connection line.
„ Root valve partially closed.
„ Too viscous fluid. „ Check and clean line.
„ Open
valve.
„ Provide instrument with suitable fluid separator.
No actuation or
undue actuation
„ Root valve closed.
„ Microswitch contacts damaged.
„ Loosened electrical joints.
„ Interrupted or short-circuited. „ Open the valve.
„ Replace the microswitch.
„ Check all electrical joints.
„ Check the conditions of the electric line.
Undue actuation „ Accidental shocks. „ Modify the mounting.
11 - STOPPING AND DISMOUNTING
Before proceeding with these operations ensure that the plant or
machines have been put into the conditions foreseen to allow
these operations.
With reference to figures 6 or 7
Remove the power supply (signal) from the electrical line.
Close the root valve (6) and open the drain.
Remove the plug (2), open the valve (3) and wait until the process
fluid has drained from the tubing through the drain.
Do not dispose of the process fluid into the environment, if this
can cause pollution or damage to people.
Unscrew the three piece joint (8).
CAUTION: do not open the cover of explosionproof pressure
switches (Series PCA) when energized, in explosive
atmospheres.
Unscrew the three piece joint (10) (electrical cable tubing).
Remove the instrument cover and disconnect the electrical cables
from the terminal block and earth screws.
Remove the screw fixing the case to the panel (or pipe) and
remove the instrument, taking care to slide the electrical
conductors out from the case.
Mount instrument cover. Insulate and protect cables around, if
any. Temporarily plug pipes not connected to the instrument. In
case of explosionproof instruments (Series DE) it is
recommended to follow - at least – the standard EN-60079-17 for
the withdrawal from service of electrical apparatus.
12 - DEMOLITION
The instruments are mainly made of stainless steel and
aluminium and therefore, once the electrical parts have been
dismounted and the parts coming into contact with fluids which
could be harmful to people or the environment have been properly
dealt with, they can be scrapped.