Design And Principle Of Operation - Samson 3301 Mounting And Operating Instructions

Design and principle of operation

3 Design and principle of op-
eration
The controller mainly consists of the controller
housing containing a nozzle and flapper sys-
tem, pressure gauges for supply air and out-
put pressure as well as the temperature sensor
with an outer tube (11) and Invar rod (12).
The different expansion properties of the In-
var rod and tube materials produce a de-
flection each time the temperature at the sen-
sor changes. This deflection causes the differ-
ential plate (3) mounted on the plate spring
(9) to tilt on the ball (5), and causes the dis-
tance between the nozzle (2) and flapper (4)
to change. The supply air p
flows through the restriction (1) to the nozzle
(2). These two components act as a pressure
p p
Z
Fig. 1: Functional diagram of Type 3301
6
(1.4 ± 0.1 bar)
Z
A
divider controlled by the flapper. As a result,
the output pressure p
to 1 bar) is regulated proportional to the sys-
tem deviation and in relation to the fixed op-
erating point of 0.6 bar.
The set point is adjusted at the screw (8) con-
nected to the set point pointer (7). The pro-
portional band is adjusted at the adjustment
screw (6). The position of the red dot on the
screw (6) indicates the operating direction ad-
justed.
Position in scale range
sure p increases as the controlled variable
A
increases.
Position in scale range
sure p decreases as the controlled variable
A
increases.
1 Restriction
2 Nozzle
3 Differential plate
4 Flapper
5 Ball
6 Adjustment screw for Xp
(proportional band)
7 Set point pointer
8 Screw for set point adjustment
9 Plate spring
10 Base plate
11 Outer tube
12 Invar rod
p Supply air (1.4 ± 0.1 bar)
Z
p Output pressure (0.2 to 1 bar)
A
(controlled variable 0.2
A
^
: The output pres-
^
: The output pres-
^
EB 7065 EN