B00-100
• B1 • 09/22 • GB • p. 8 of 20 • www.armano-messtechnik.com
Operating Instructions Pressure Gauges
Selection Criteria, Measuring Arrangements, Installation and Operation Manual
Corrosive atmosphere:
In corrosive atmospheres, suitable casings
and components made of resistant materi-
als must be provided.
Special surface treatments serve as exterior
protection.
5.
Additional Accessory
Shut-off valves for pressure gauges:
It is recommended to install a shut-off de-
vice between measuring point and pressure
gauge, which allows for an exchange of
the pressure gauge and a zero point check
while the system is running. Depending on
the intended application, either cocks or
valves are used.
Cocks have three positions:
• Ventilation:
The feed line is closed, the measuring element
is open to the atmosphere. The zero point can be
checked.
• Operation:
The feed line is open, the measuring element is
pressurised.
• Blow-out:
The feed line is open, the medium is vented to the
atmosphere. The measuring element is not in use.
For valves (e.g. according to DIN 16270 and DIN 16271),
a vent screw is usually provided between valve seating
and pressure gauge.
IMPORTANT! Ventilation to the atmos-
phere shall be arranged in a way that em-
ployees are not endangered by escaping
medium.
Potential environmental damage is to be
avoided. In certain applications (e.g. steam
boilers), the shut-off valves require a test
connection, so that the pressure measuring
instrument can be checked without being
disassembled.
Gauge holder bracket:
A suitable gauge holder is to be provided if
the measuring line is not rigid enough for
a vibration-free installation of the pressure
measuring instrument.
Siphons:
Use measuring lines with an adequate
length or siphons to protect the shut-off
valves and the pressure gauges against
heating due to hot media (e.g. steam).
Chemical seals:
For aggressive, hot, highly viscous or crys-
tallising media, which must not enter the
pressure element, chemical seals can be
mounted to Bourdon tube pressure gauges
to provide separation.
For transmission of the pressure to the pressure el-
ement, a neutral liquid is used, which is chosen to
match the measuring range, temperature, viscosity
and other influences by taking into account the com-
patibility of this liquid with the medium.
Chemical seals are available in various construction
types (
chapter 3.1.3 “Construction Types Chemical
Seals”), whereas the diaphragm seal is the most com-
monly used model.
For in-line seals and flange type chemicals seals, the
pressure gauge has to be mounted to the chemical
seal by the manufacturer in accordance with the given
installation position.
The connection between pressure gauge and chemi-
cal seal must not be separated.
Potential errors, influenced by mounting a chemical
seal to a pressure gauge have to be regarded.
Overrange protection devices:
CAUTION! If the indication range has to
be lower than the maximum operating
pressure due to operational reasons, the
pressure gauge can be protected against
damage by fitting an overrange protection
device.
In the event of a pressure stroke, the protection device
closes instantly. If the pressure rises slowly, it closes
gradually. The closing pressure to be set thus depends
on the temporal pressure profile.
However, highly viscous and contaminated media might
impair or disable the function of the protection device.
Capsule gauges and diaphragm pressure gauges can
also be produced overrange protected (3-fold, 5-fold
or 10-fold).