Selection criteria
Bourdon tube, capsule, diaphragm,
spring diaphragm pressure gauges
13
Corrosive atmosphere
In the case of a corrosive atmosphere, use suitable housings
and assemblies made of resistant materials, for example, spe-
cial surface treatments against external influences.
4.4
Overload
Overloads cause tension in the elastic measuring element which de-
creases its services life and deteriorates the measuring accuracy.
1.
Use a pressure gauge whose full scale value is greater than the
maximum static pressure.
The pressure gauge is less sensitive to overload and load
changes (see also see chapter 4.1, page 11).
2.
If, for operational reasons, the range must be smaller than the
maximum operating pressure, install an overpressure safety de-
vice, see chapter 9.5, page 34.
Spring-diaphragm pressure gauges may be used up to a maximum
static pressure of 25 bar.
Use a pressure gauge whose full scale value is greater than the
maximum differential pressure.
4.5
Accuracy classes
The accuracy class is the error limit in percent of the measuring
range. The error limit applies to both positive and negative devia-
tions, based on the measured value.
EN 837-1, chapter 6 specifies the error limits of Bourdon tube pres-
sure gauge, EN 837-3, chapter 6 specifies the error limits of capsule
pressure gauges and diaphragm pressure gauges.
Classes 0.1 to 0.6 pressure gauges are primarily used for precision
measurements in laboratories and workshops. Classes 1.0 and 1.6
pressure gauges measure the pressure at machines and production
facilities. Classes 2.5 and 4 pressure gauges are used for monitoring
purposes without special accuracy requirements.
When selecting the accuracy class, take into account the as-
signment of the classes to the nominal sizes (EN 837-1/-3,
chapter 6, table 1).
