Siemens SITRANS P Bedienungsanleitung PDF herunterladen (Seite 152)

SITRANS P measuring instruments for pressure

Remote seals for transmitters and pressure gages

Technical description

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Siemens FI 01 · 2009

Response time

The response time is dependent on the following factors:

• Internal diameter of the capillary: The bigger the internal diam-

eter, the shorter the response time

• Viscosity of the filling liquid The greater the viscosity, the

longer the response time

• Length of the capillary: The longer the capillary, the longer the

response time

• Pressure in the pressure measuring system: The higher the

pressure, the shorter the response time

Recommendations

The following should be observed to obtain an optimum combi-

nation of transmitter and r

emote seal:

• C

hoose the biggest possible diameter for the remote seal. The

effective diameter of the seal diaphragm is then bigger and

the temperature error smaller.

• Choose the shortest possible capillary. The response time is

then shorter and the temperature error smaller

• Choose the filling liquid with the least viscosity and the small-

est coefficient of expansion. Make sure, however, that the fill-

ing liquid meets the process requirements with regard to pres-

sure, vacuum and temperature. And ensure that the filling

liquid and the medium are compatible with one another.

• Note the following points for use in the vacuum range:

- The pressure transmitter must always be positioned below

the lowest spigot.

- The operating range of some filling liquids is very limited with

regard to the permissible temperature of the medium.

- A vacuum-proof seal is necessary for continuous operation

in the low-pressure range.

• Recommendations for the minimum span can be found in the

section "Technical data".

Note

The remote seals listed here are a selection of the most common

designs. On account of the large variety of pr

ocess connections,

certain r

emote seals which are not listed here may be available

nevertheless.

Other versions can be:

• Other process connections, standards

• Aseptic or sterile connections

• Other dimensions

• Other nominal pressures

• Special diaphragm materials, including coatings

• Other sealing faces

• Other filling liquids

• Other capillary lengths

• Sheathing of capillaries with protective hose

• Calibration at higher/lower temperatures etc.

Please contact your Siemens Regional Office for more infor-

mation.

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