4
MT 235 – EN ed.2015 (Rev.A)
1.0
INTRODUCTION
This manual aims at supplying essential information on the installation, commissioning, disassembly, re-assembly, and
maintenance of the regulators
DIVAL 500
(fig. 1).
Moreover, it is deemed suitable to provide the reader with a brief description of the main features of the regulator and its
accessories.
1.1
MAIN FEATURES
The pressure regulator
DIVAL 500
is a pressure regulator for previously cleaned gaseous fluids, suitable for low, medium and
high pressure.
DIVAL 500
is a normally open regulator and, therefore, it opens in case of:
breakage of the main membrane;
lack of regulated pressure signal.
The main features of this regulator are:
Design pressure
PS
: up to 20 bar
Operating temperature: -20 °C ÷ + 60 °C;
Ambient temperature: -20 °C ÷ + 60 °C;
Range of the inlet pressure
bpu
: 0.2 to 20 bar
Possible regulation range
Wd
:
13 ÷ 100 mbar for BP head;
100 ÷ 300 mbar for MP head;
300 ÷ 2500 mbar for TR head;
Minimum differential pressure: 0.1 bar;
Accuracy class
AC
: up to 5 (depending on the outlet pressure range).
Range of the lockup pressure
SG
: up to 10 (depending on the outlet pressure range).
1.2
OPERATION OF THE REGULATOR DIVAL 500
In the absence of pressure and with loaded calibration spring, the obturator
211
is kept in the open position by the coupling of
the stem
201
by the lever mechanisms
305
.
The outlet pressure Pd is controlled by the comparison between the load of the spring
328
and the thrust that the outlet
pressure itself exerts on the membrane
322.
Also the weight of the moving equipment and dynamic thrusts acting on the obturator are considered in this comparison.
The inlet pressure, although variable, does not affect the balance of the obturator
211
, since the same - given the presence of
the hole
A
- finds itself between two equal pressures acting on equal surfaces.
The movement of the membrane
322
is transmitted by the lever system
305
to the stem
201
and, therefore, to the obturator
211
. The obturator is provided with a vulcanized rubber gasket in order to assure a perfect tightness when the requested flow
rate is zero.
If during operation the outlet pressure Pd decreases, the thrust it exerts on the membrane
322
becomes lower than the load of
the spring
328
; therefore, the membrane lowers, causing, through the levers
305
, the obturator
211
to move away from the
valve seat
102
. Consequently, the gas flow rate increases until the initial calibration pressure value is restored.
If instead the outlet pressure starts to increase, the force exerted on the membrane
322
exceeds the load of the spring
328
.
Therefore, the obturator is shifted toward the closed position, letting the outlet pressure return to the preset value.
Under normal operating conditions, the obturator
211
is positioned in such a way as to maintain the pressure Pd around the
chosen calibration value. The calibration pressure can be adjusted by appropriately turning the internal adjustment ring nut
318
clockwise to increase it and counterclockwise to decrease it.
The solution described in fig. 3 is adopted in order to protect the obturator against damages resulting from sudden increases in
the regulated pressure.
This solution allows, in fact, the membrane protection disc
323
to lean on the upper cover, thus overcoming the load of the
spring
329
, thereby relieving the obturator from the load caused by the abrupt pressure increase.
To prevent small leakages - at requested zero flow rate or due to sudden and temporary overpressures resulting, for example,
by abrupt maneuvers or gas overheating - from making the slam-shut valve trip, the solution of fig. 2 may be replaced, upon
request, by an embedded relief valve, removing the O-rings (fig. 3).
Its operation occurs as follows: with closed regulator, any overpressures lift the membrane protection disc
323
overcoming the
load of the springs
328
and
329
. In this way, a given quantity of gas is discharged through the seat
Z
.
