Connections; Pneumatic Connections; Pressure Gauges; Supply Pressure - Samson 3767 Mounting And Operating Instructions

Connections

4 Connections
4.1 Pneumatic connections
The pneumatic connections are optionally
designed as a bore with ¼ NPT or G ¼
thread. Customary fittings for metal or cop-
per tubing or plastic hoses can be used.
NOTICE
The supply air must be dry and free
from oil and dust. The maintenance
instructions for upstream pressure
reducing stations must be observed.
Blow through all air pipes and hoses
thoroughly before connecting them.
If the positioner is attached directly to the
Type 3277 Actuator, the connection of the
positioner's output pressure to the actuator is
fixed. For attachment according to
IEC 60534-6 (NAMUR), the signal pressure
can be routed to either the top or bottom
diaphragm chamber of the actuator,
depending on the actuator's fail-safe action
"actuator stem extends" or "actuator stem
retracts".
Exhaust air
Models with index 3767-x...x.03 and higher
are equipped with a hinged cover without its
own exhaust air hole. The exhaust air con-
nections for these models are included in the
accessories.
The vent plug is located on the plastic cover
of the actuator for direct attachment, where-
as for NAMUR attachment, it is located on
the adapter housing. The vent plug is located
34
on the intermediate piece or reversing ampli-
fier for attachment to rotary actuators.
NOTICE
If you intend to replace older models
with index 3767-x...x.02 or lower,
the mounting parts may need to be
replaced as well.
4.1.1 Pressure gauges
To precisely tune the positioner, we recom-
mend installing pressure gauges for the sup-
ply air and signal pressure.
The required parts are listed as accessories
in Table 4, Table 5 and Table 7.
4.1.2 Supply pressure
The required supply air pressure depends on
the bench range and the actuator's operat-
ing direction (fail-safe action).
The bench range is written on the nameplate
either as the spring range or signal pressure
range. The operating direction is marked FA
or FE, or by a symbol.
Actuator stem extends (FA):
Fail-close
(for globe and angle valves)
Required supply pressure =
Upper bench range value + 0.2 bar,
at least 1.4 bar.
EB 8355-2 EN