B00-100
• B1 • 09/22 • GB • p. 10 of 20 • www.armano-messtechnik.com
Operating Instructions Pressure Gauges
Selection Criteria, Measuring Arrangements, Installation and Operation Manual
Shut-off valves at the pressure gauge:
Shut-off valves at the pressure measuring instrument
serve to check the zero point or to exchange the meas-
uring instrument during operation (
chapter 5 “Addi-
tional Accessory”).
Pressure measuring instrument:
The pressure measuring instrument needs
to be mounted vibration-free and positioned
for easy readability.
Parallax errors are to be avoided when reading the
dial. It has to be ensured that any blow-out devices
on the pressure gauge are protected against blocking
(
DIN EN 837-1, 9.7). The pressure gauge shall be ar-
ranged in a way that the temperature does not fall be-
low or exceed the permissible operating temperature
(
chapter 4.4 “Operating Conditions” and chapter 8
“Intended Use”). Here, the influence of convection
and thermal radiation has to be regarded. If the meas-
uring element of a pressure gauge is filled with water
or a water mixture, the instrument has to be protected
against freeze. The pressure gauge is generally mount-
ed with vertical dial. In all other cases, the position
symbol on the dial according to DIN EN 837 applies.
A height difference between measuring port and
pressure gauge causes a shift of the measuring
start value if the medium in the measuring line does
not have the same density as the ambient air. This
shift of the measuring start Δp results from the den-
sity difference (ρM − ρL) and the height difference
Δh:
10
-5
·
(ρM − ρL) g · Δh
Δ = shift of measuring start
[bar]
ρM = density of the medium
[kg / m³]
ρL = density of the air (1.205 at 20 °C)
[kg / m³]
Δh = difference in height
[m]
g = gravitational acceleration
[m / s²]
(medium gravitational acceleration 9.81 m / s²)
The indication is decreased by Δp if the pressure
gauge is positioned higher than the pressure measur-
ing port, and increased by Δp if it is positioned lower.
7. Installation
The mounting of pressure measuring instruments
shall be carried out by qualified personnel only.
For the measuring arrangements, please refer to chap-
ter 6.
During installation or removal, the pressure gauge
should never be held at the case, but at the wrench
flat of the socket.
It must be ensured that the matching pro-
cess connection has been selected (nominal
width, if required, suitable sealing face etc.).
For instruments with thread connection, an installation
with clamping sleeve or union nut is recommended, in
order to position it for proper readability. Instruments
with flange connections are fitted to the counter flange
and secured with suitable screws. It must be ensured
that the screws are firmly tightened.
The connections need to be leaktight.
Therefore,
sealings made of suitable medium-resistant material
should be used for the connection. For the sealing
of pressure measurement connections with cylindri-
cal thread spigots, e.g. flat sealing rings according to
DIN EN 837-1, profile packings or lens-type sealing
rings for corresponding high pressure connections
have to be applied at the sealing face. Conical threads
(e.g. NPT threads) are sealed with additional sealing
materials such as PTFE tape (
DIN EN 837-2).
sealing face
wrench flat
sealing in
the thread
cylindrical threads
conical threads