WIKA 910.27 - Manual (Page 5)

9045830 10/2006
GB
5 WIKA Operating Instructions Diaphragm Seals
Diaphragm Seal Measuring Systems
4. Commissioning
In order to avoid pressure peaks, a shut-off valve, if available, is to be opened slowly.
5. Admissible ambient and working temperatures
When installing the pressure gauge it has to be ensured that, taking the influence of convection
and heat radiation into consideration, no upper or lower deviation from the permissible ambient
and medium temperatures can occur. The influence of temperature on the class accuracy is to
be observed. When selecting the diaphragm seals, the pressure and temperature stability of
the fittings and flange components has to be observed by choosing suitable materials and
pressure ratings. The pressure rating marked on the diaphragm seal is valid for ambient
temperatures. For higher temperatures the max. working pressure should be taken from the
industrial standard marked on the diaphragm seal.
Use of diaphragm seals with pressure measuring instruments in hazardous areas:
■ When using diaphragm seals with pressure transmitters in hazardous areas, the permissible
ambient temperature limits for the pressure measuring instrument must not be exceeded.
Hot surfaces at the part cooling element (capillary or cooling tower) might also be a
possible ignition source. Appropriate measures have to be taken.
■ When mounting diaphragm seals with flame proof throttle, the permissible ambient
temperature is determined by the mounted pressure measuring instrument. In an explosive
atmosphere the temperature around the flame proof throttle must not exceed +60 °C.
See also supplement to operating instructions for diaphragm seals with built-in flame proof
throttle.
6. Installation instructions for diaphragm seal measuring systems with
capillary extension
■ Do not carry the measuring system at the capillary
■ To protect the capillary extension from mechanical stress, do not lift or carry the diaphragm
seal measuring system by the capillary extensions
■ Do not kink capillary extensions; this will increase the risk of a leak or the setting time of the
measuring system
■ Make sure that the system is not overstressed because of the risk of kinking and fracture
especially where the capillary extension and diaphragm seal and capillary extension and
measuring instrument ar joined
■ When laying the capillary extensions, do not bend under a radius of 150 mm
■ Fit capillary extension so that it is not subject to vibration
■ Permissible differences in height
When installing the pressure gauge above the measuring point, the maximum difference in
height must not exceed 7 m in the case of diaphragm seal measuring systems with silicon,
-glycerine or paraffine oil filling (measurement H1).
If halocarbon oil is used as filling liquid, the maximum difference in height (H1) is 4 m
(see examples 1 and 2).
If a negative pressure can occur while measuring, the permissible difference in height must be
reduced correspondingly.