Selection criteria
12
Bourdon tube, capsule, diaphragm, spring diaphragm pressure gauges
2.
Due to the limited selection of materials for the elastic measur-
ing elements, it may be necessary to use suitable diaphragm
pressure gauges or to install chemical seals made of resistant
materials (see chapter 9.4, page 34).
4.3
Ambient conditions
Mechanical shocks
Pressure gauges must not be subjected to mechanical shocks.
If the installation point is subject to mechanical shocks, install
the pressure gauge in a separate location and connect it by
means of flexible lines.
Vibrations
Vibrations are be indicated by ongoing and frequently unsteady vi-
brations at the tip of the pointer.
The installation site of the pressure gauge is subjected to me-
chanical vibrations.
Install a liquid filled pressure gauge.
In the case of heavy or unsteady vibrations at the installation
point, install the pressure gauge in a separate location and con-
nect it by means of flexible lines.
Ambient temperature
The error limit indicated on the dial applies to an ambient tempera-
ture of +20 °C. Different temperatures have an influence on the accu-
racy; the influence depends on the measuring system.
According to EN 837-1, a deviation of the indication caused by tem-
perature influences is permissible up to the following value with ref-
erence to the full scale value:
•
Bourdon tube pressure gauges: 0.04 %/K
•
Capsule pressure gauges: 0.06 %/K
•
Diaphragm pressure gauges: 0.08 %/K
•
Spring diaphragm pressure gauges: 0.05 %/K
Protect the pressure gauge from atmospheric influences in out-
door applications in order to avoid icing up of the gauge at tem-
peratures below 0 °C.
The viscosity of the filling liquid in pressure gauges with liquid filling
increases at decreasing temperatures. This causes a considerable
delay in indication.
