WIKA TXA - Manual (Page 5)

INSTRUCTION MANUAL
NI-492E
Rev. 0 01/05
9 - PUTTING INTO OPERATION
As the signal transmitted by the instrument is used in a complex
system, it is necessary that the means of putting it into operation
are established by those in charge of the plant.
The instrument starts operating as soon as it is powered.
In case of explosionproof instruments (Series TXA and TXN),
initial inspections are to be carried out according to customer
procedures and at least in accordance with Standards EN-60079-
17 and EN-50281-1-2.
10 - FUNCTIONAL VERIFICATION
It will be carried out according to customer control procedures.
Explosionproof instruments (Series TXA, TXN) installed in
hazardous areas due to the presence of inflammable dusts
should be periodically cleaned externally to avoid dust
accumulation.
Instruments Series TXS may be checked on site if installation has
been made according to Fig. 9 to 12.
Instruments Series TXA, TXN may be checked on site but if
testing equipments are suitable for the environment and electric
supply is off.
Otherwise it is necessary to stop them working, remove them and
carry out checks in a test room.
The verification consists in checking the calibration value and
adjusting it if required (see §5).
In case of explosionproof instruments (Series TXA and TXN)
inspections of the electrical installation are to be carried out also
according to customer procedures and at least in accordance
with Standards EN-60079-17, EN-50281-1-1.
11 - TROUBLE SHOOTING
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
„ Deposits on thermowell or bulb
„ Filling fluid leakage „ Check and clean surfaces
„ Replace the instrument
Slow response „ Deposits on thermowell or bulb „ Check and clean surfaces
No actuation
„ Loosened electrical joints
„ Interrupted or short-circuited electrical line
„ Microswitch contacts damaged
„ Filling fluid leakage „ Check all electrical joints
„ Check the conditions of the electrical line
„ Replace the instrument
„ Replace the instrument
Undue actuation
„ Accidental shocks
„ Interrupted or short-circuited electrical line „ Modify the mounting
„ Check the conditions of the electrical line
12 - STOPPING AND DISMOUNTING
Before starting the following operations, ensure that plant and
equipments have been put in conditions allowing to carry out
them safely.
Remove the power supply (signal) from the electric line.
With reference to Fig. 5.
Loosen stuffing gland (2) taking care not to twist capillary and its
armor.
Loosen and slide out union (3), then exctract bulb from
thermowell holding the capillary, without twisting it.
With reference to Fig. 9.
Unscrew the electrical three-piece joint. Remove junction box
cover and disconnect electric wires from terminals and ground
screws.
Unscrew fixing screws of junction box and remove instrument
sliding out the electric wires.
Replace the junction box cover, insulate and protect loose
leadwires. Temporarily plug the thermowell. In case of
explosionproof instruments (Series TXA, TXN) it is recommended
to follow - at least – the Standards EN-60079-17 and EN-50281-
1-2 for the withdrawal from service of electrical apparatus.
13 - DEMOLITION
The instruments are mainly made of stainless steel and
aluminium; therefore, once the electrical parts have been
dismounted and the parts coming into contact with fluids which
could be harmful to people or to environment have been properly
dealt with, they can be scrapped.
14 - NOTES FOR INSTALLATION
14.1 TEMPERATURE SWITCHES CLASS SAMA II A
A difference in height between bulb and case exceeding two
meters causes a systematic error in the set point calibrated value
(“bulb elevation error”).
This error can be corrected during calibration by either increasing
or decreasing the set point value by a constant depending on the
difference in height foreseen for the installation. The “bulb
elevation error” can be corrected using the table attached to our
technical instruction IS-TC.401E, available on request.
14.2 TEMPERATURE SWITCHES CLASS SAMA II C
The temperature switch must be installed with a difference in
height between bulb and case not exceeding two meters.
With a difference of approximately two meters the set point value
fixed during calibration may be affected by an error depending on
the normal reference temperature, the working temperature and
the set point temperature. In the worst operating conditions the
set point temperature value fixed during calibration may be
affected by a maximum error of 1,5°C. For further clarification
request IS-TC.401E.