Siemens P technical specifications 152, Response time, Recommendations

© Siemens AG 2008

SITRANS P measuring instruments for pressure

Remote seals for transmitters and pressure gages

Technical description

	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
2	•	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 remote seal:

•Choose 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 process connections, certain remote 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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Siemens FI 01 · 2009