PIETRO FIORENTINI REVAL 182, Use And Maintenance Instructions

Page: 42 / 404

42
REV
AL 182
EN
Use, maintenance and warning instructions
MEDIUM PRESSURE REGULATOR | DESCRIPTION AND OPERATION | REV. 00
4.5.2.1 - BUILT-IN MONITOR
The PM/182 monitor (1) is mounted in series directly on the service regulator body (2), converting the equipment into two
pressure regulators with a common valve body. The two regulators have the following characteristics:
• are governed by two separate pilots;
• they work on independent valve seats.
BUILT-IN MONITOR OPERATION
In depressurised conditions, the plug (3) is kept in a shut-off position by the spring (4) and rests on the reinforced gasket
(5).
The upstream pressure (Up), even if variable, does not change this position as the plug (3) is completely balanced, just like
the stem (6), as a result of the upstream pressure (Up), through the hole (A), in the chamber (B).
The position of the plug (3) is controlled by the movements of the diaphragm (7) on which the forces act:
• towards the shut-off position: the load of the spring (4) and the thrust resulting from the downstream pressure (Pd) in
the chamber (C),
• towards the open position: the thrust resulting from the loading pressure (Pm) in the chamber (D), supplied by the
pilot (8).
The weight of the mobile unit acts towards the shut-off or open position depending on the installation position of the
regulator (2).
1
2
8
7
9
10
3
5
6
B
C
A
D
3
4
U
pstream pressUre
D
ownstream pressUre
p
re
-
regULator pressUre
m
onitor LoaDing pressUre
Fig. 4.6. Built-in monitor operation
NOTICE!
To check the position of the plug (3), look at the position of the stroke indicator rod (9) referring to the
glass cover (10):
• fully open 100%;
• closed 0%.