The appropriate national safety regulations (i.e. VDE 0100 /
EN 60 079-14 / EN 837-2) must be observed when installing,
commissioning and operating these instruments.
Do not work on the gauge while it is powered
Serious injuries and/or damage can occur should the appropriate regulations
not be observed
Only appropriately qualified personnel should work on these instruments
2. Operating principle
The differential pressure transmitter consists mainly of a mechanical measuring system (1) with an elastic pressure element (2), a Hall-effect sensor (3) with
signal processing board (4) and a case with the connections for the electronics.
A magnet (5), rigidly coupled to the
pressure element, influences the
electromagnetic field of the HALLeffect sensor. The resulting signal is
amplified to a standard output signal
via the signal processing board.
2155079.01
For recalibration, zero and span
can be adjusted by means of easily
accessible potentiometers (6).
Pressure entries are identified by the
symbols; j high pressure and i low
pressure
The pressure transmitter should be installed and operated without exposure
to vibration. It is common practise to install the pressure transmitter fitted to
an isolating device to enable replacement while the system is pressurised
and to isolate the transmitter when reading is not required.
Test connector
Local safety codes such as those for pressure or steam vessels may specify
isolating devices to enable on-site testing of the pressure transmitter.
Mounting provisions
If the pressure system or tailpipe is not rigid enough to accept the weight of
the transmitter, or capable of withstanding any vibrations present, the transmitter should be wall-mounted using a suitable bracket.
Effects of temperature
The operating temperature of the pressure transmitter, resulting from the
effects of the pressure medium, ambient temperatures and possible radiated
heat, must not exceed the temperature range the pressure transmitter is
intended for. Suitably shaped tailpipes or syphons with water filling may be
used to separate the pressure transmitter and its isolating device from hot
pressure media.
Overload protection for pressure elements
Should the measuring media be subject to rapid pressure fluctuations or
there is a possibility of pressure surges, these must not be allowed to act
directly on the pressure element. The effect of any pressure surges must
be restricted, for example, by fitting integral restrictor screws (to reduce the
bore in the pressure connection) or by using adjustable snubber devices.
GB
Pressure test connection
The pressure test connection, with a sufficiently large bore (≥ 6 mm diameter), should be arranged, as far as possible, over a shut-off device, in a
position where the accuracy of reading will not be affected by the flow of the
media being measured. The piping between the pressure test connection
and the pressure transmitter should have an inner diameter large enough to
avoid blockages or delays in pressure transmission. It should also not have
any sharp bends. It is recommended that it is laid with a continuous incline
of approx. 1:15.
Installation instructions / 4. Installation and commissioning
Piping
The piping should be arranged and fitted so that it can withstand the
GB
stresses caused by expansion, vibration and the influence of heat. When
the media is gaseous, a water drain point should be provided at the lowest
point. For liquid pressure media, an air bleed should be provided at the
highest point.
4. Installation and commissioning
Correct sealing of pressure connections should be achieved by means of
suitable sealing rings, sealing washers or WIKA profile seals.
If the pressure transmitter is positioned lower than the pressure test connection, the tailpipe should be thoroughly cleaned prior to fitting the transmitter.
Once the pressure and electrical connections have been made, the transmitters
are ready for immediate use.
No attempt should be made to remove a pressurised transmitter. If the transmitter cannot be otherwise isolated, the pressure system must be fully vented.
Any residual pressure medium contained in the pressure element may be
hazardous or toxic. This should be taken into account when handling and
storing pressure gauges which have been removed.
Proven measuring arrangements for various types of media.
The recommended arrangements for particular applications are shown below.
Liquid mediaGaseous media
Contents of
tailpipe
Typically
Pressure
instrument
higher than
tapping point
Pressure
instrument
lower than
tapping point
LiquidLiquid with
vapour
CondensateBoiling liquid Liquefied gas Dry airMoist air,
Vapour
only
Gas onlyWet gasLiquid gas
Flue gas
condensate
Steam
6. Wiring details
Electrical connection of this pressure transmitter is made by cable and connector. Precise wiring diagrams can be seen in the following drawings.
In addition to the wiring details, output signal and required power supply are
given on the rating plate.
GB
Description of terminal designations used:
UB+ Plus terminal for supply voltage
0 V Minus terminal for supply voltage
S+ Plus terminal for output signal
S- Minus terminal for output signal
Test Test terminal
The instruments must be included within the plant’s equipotential bonding
6. Wiring details / 7. Version with LCD-display (optional extra)
Terminal assignment
Terminals 1 and 5 are bridged internally within the connector, so that two terminals are available for the 0 V / S - connection.
GB
4 ... 20 mA 2-wire system 0 ... 20 mA 3-wire system
0 V / S-
UB+ / S+
Test -
Test +
mA
Evaluation
(display/recorder)
Power supply
Connector
housing
0 V / S-
UB+
Test +
S+ / Test-
mA
Evaluation
(display/recorder)
Power suppy
Connector
housing
The transmitter can operate using a non-stabilised supply voltage within the
given limits, so long as the voltage available to the transmitter does not fall
below 10 V, or below 14 V for the LCD-display version.
7. Version with LCD-display (optional)
On integrated LCD-displays, for local pressure read-out, the output signal is 2wire 4 ... 20 mA. For the required power supply for the integrated LCD display,
please refer to Chapter 8, Technical Data.
Limitation on zero point and span adjustment:
If an LCD display is integrated, it must be noted that the zero point and span
adjustment is only to be used for resetting the measuring range. Changes to
the measuring range, made using the zero and span adjustment will not be
shown on the display.
Average TK on span≤ 0.4 % of span/10 K
LCD-display (optional)
Voltage loadDC V3.5
Display3 ½-digit, height 12.7
Ambient temperature°C0 … 50
Storage temperature °C-10 … +80
WiringTerminal box (screw terminals up tu 2.5 mm²)
Wiring protectionProtected against reverse polarity and overvoltage
EMC (electro-magnetic
compatibility)
Ingress protectionIP 54 (optional IP 65) according EN 60 529 / IEC 529
Weightkgapprox. 1.3
B
A
bar25
to medium
exposed to medium
DC V
2 x G ¼ female, bottom, in-line, centre distance 26 mm (optional: other
pressure connections male or female or compression fitting with ferrule for
pipe Ø 6, 8 or 10 mm respectively)
GD-AlSi 12 (Cu) 3.2982, black painted (optional GD-AlSi 12 (Cu) HARD-COAT
surface protection or stainless steel)
stainless steel and FPM/FKM
Cu-alloy or stainless steel, 1x Press. equalising valve, 2 x gauge valve,
1 x valve for purging or air bleeding
10 < UB ≤ 30 (optional LCD-display 14 < UB ≤ 30)
4 … 20 mA, 2-wire system RA ≤ (UB - 10 V) / 0.02 A with RA in Ohm and UB in Volt
0 … 20 mA, 3-wire system RA ≤ (UB - 10 V) / 0.02 A with RA in Ohm and UB in Volt
Interference emission per EN 50 081 - 1 (March 93) and EN 50 081 - 2 (March 94),
Interference immunity per EN 50 082 - 2 (March 95)
Always open isolating devices gently, as abrupt opening may generate sudden
pressure surges that may damage the transmitter.
The pressure transmitters require no maintenance or servicing and will give very
long service when handled and operated correctly. It may well be necessary
to check and readjust the zero point periodically. This depends on the working
conditions.
To check zero point
In general, the zero point should be checked and adjusted with the instrument in the unpressurised state.
With differential pressure transmitters the zero point should be checked and
adjusted by opening the pressure equalising valve while under a static load.
The plug screw (NP), found on the top of the case, must be unscrewed to
correct the zero point of the pressure transmitter. The zero point potentiometer
can then be readjusted using a small screwdriver:
turning anticlockwise ⇒ reduces the output signal
turning clockwise ⇒ increases the output signal
To check measuring span
Checking and adjusting the measuring span is a little more complex and has
to be carried out when the pressure transmitter is under pressure, up to the
upper limit of the effective range.
A sufficiently-accurate pressure standard is necessary as a reference.
Only when it is necessary to correct the measuring span should the plug
screw (SP) in the top of the case be unscrewed, and the measuring span
potentiometer can then be readjusted using a small screwdriver:
GB
turning anticlockwise ⇒ reduces the output signal
turning clockwise ⇒ increases the output signal
Once this has been done, the zero point must be checked again and, if necessary, the zero point must be readjusted. This procedure should be repeated
until the zero point and span are calibrated.
9. Service and maintenance / 10. Special instructions ...
Position of potentiometers in the electronics case
GB
SP potentiometer for span
NP potentiometer for zero point
2158991.01
10. Special instructions for integrated pressure equalising valve or
4-way valve manifold
10.1 Integrated pressure equalising valve
For zero point control on working
processes. Offset errors can be adjusted
using the zero point potentiometer (see
Chapter 9. Service and Maintenance)
Principle of operation
When the button is pressed, the
separation between the measuring chambers is released. The pressure
is thus equalised in both chambers, and the differential pressure is zero.
Releasing the button separates the chambers again and the current differential pressure is measured.