Samson 3730-4, Mounting And Operating Instructions

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3 Connections
3.1 Pneumatic connections
NOTICE
The threads in the positioner housing are not
designed for direct air connection!
The screw glands must be screwed into the
connecting plate, the pressure gauge mount-
ing block or the connection block from the
accessories. The air connections are option-
ally designed as a bore with ¼ NPT or G ¼
thread.
The customary fittings for metal and copper
pipes or plastic hoses can be used.
Note:
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 tubes and hoses thor-
oughly prior to 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 di-
aphragm chamber of the actuator, depend-
ing on the actuator's fail-safe action "Actua-
tor stem extends" or "Actuator stem re-
tracts".
For rotary actuators, the manufacturer's
specifications for connection apply.
3.1.1 Signal pressure gauges
To monitor the supply air (Supply) and sig-
nal pressure (Output), we recommend that
pressure gauges be attached (see accesso-
ries in Tables 1 to 5).
3.1.2 Supply pressure
The required supply air pressure depends on
the bench range and the actuator's operat-
ing direction ( action).
The bench range is registered on the name-
plate either as spring range or signal pres-
sure range depending on the actuator. The
direction of action is marked
FA
or
FE
, or by
a symbol.
Actuator stem extends FA
(air-to-open
ATO)
Fail-safe position "Valve Closed"
(for globe and angle valves):
Required supply pressure = Upper bench
range value + 0.2 bar, minimum 1.4 bar.
Actuator stem retracts FE (air-to-close ATC)
Fail-safe position "Valve Open"
(for globe and angle valves):
For tight-closing valves, the maximum signal
pressure pst
max
is roughly estimated as fol-
lows:
pst
max
= F +
d p
A
2
4
⋅ ⋅
⋅
π ∆
[bar]
48
EB 8384-4 EN
Connections