WIKA DE - Manual (Page 6)

INSTRUCTION MANUAL
NI-223E
Rev. 2 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
„ Air bubbles in the connection lines (condensa-tion in the
case of use of gas).
„ Solid particles deposited inside the measure-ment cham-
bers of the instrument.
„ Permanent deformation of the sensitive element due to
fatigue or non-tolerated over-ranges.
„ Variation of the elastic features of the sensitive element
due to its chemical corrosion.
„ Leakage of filling fluid.
„ Drain using the appropriate plugs.
„ Dismount the measurement chambers and
clean them (during the mounting phase the
screw locking couple is 80 N•m).
„ Recalibrate or replace the sensitive element.
„ Recalibrate or replace the sensitive element
with another made of a suitable material. If
necessary apply a fluid separator.
„ Send to the manufacturer for checking.
Slow response
„ Clogged or obstructed connection line.
„ Root or service valve partially closed
„ Too viscous fluid. „ Check and clean line.
„ Open valve.
„ Provide instrument with suitable fluid separator
(Return to the manufacturer).
No actuation or
undue actuation
„ Root or service valve closed.
„ By-pass valve open.
„ Microswitch contacts damaged.
„ Loosened electrical joints.
„ Interrupted or short-circuited electrical line. „ Open the valve.
„ Close the valve.
„ Replace the microswitch.
„ Check all electrical joints.
„ Check the conditions of the electrical line.
Undue actuation „ Accidental shocks or excessive mechanical vibrations. „ 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 and 7
Remove the power supply (signal) from the electrical line.
Close the service valve (2) and open the by-pass valve.
Carefully open the drains.
Do not dispose of the process fluid into the environment, if this
can cause pollution or damage to people.
Unscrew the three piece joint (1).
CAUTION: do not open the cover of explosionproof pressure
switches (Series DE) when energized, in explosive atmospheres.
Unscrew the three piece joint (11) (electrical cable tubing).
Remove the instrument cover and disconnect the electrical ca-
bles from the terminal block and earth screws. Remove the
screws fixing the case to the panel (or pipe) and remove the in-
strument, 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 recom-
mended 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 alumin-
ium and therefore, once the electrical parts have been dis-
mounted 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.