16
MT 235 – EN ed.2015 (Rev.A)
5.2
GAS FEEDING, CHECK OF EXTERNAL TIGHTNESS AND CALIBRATIONS
Pressure feeding to the equipment shall be performed very slowly. When a speed-limiting procedure is not in place, it is
recommended to keep the gas speed in the feeding piping under a value of 5 m/sec during the pressure feeding phase.
In order to prevent the equipment from being damaged, the following shall be absolutely avoided:
Pressurization through a valve positioned downstream of the equipment itself.
Depressurization through a valve positioned at inlet of the equipment itself.
The external tightness is assured when by applying a foam medium on the element under pressure no bubbles are produced.
The regulator and any other devices (slam-shut valve, monitor) are normally supplied already calibrated to the required value.
Moreover, it may happen that due to several reasons (e.g. vibrations during transport) the calibrations may be subject to slight
changes, though remaining within the range of the values allowed by the springs used. Therefore, it is advisable to verify the
calibrations according to the procedures outlined here below.
In installations consisting of two lines, it is recommended to commission one line at a time, starting from the one with the lower
calibration value, i.e. the so-called "spare","backup" or "standby" line.
Before commissioning the regulator, it is necessary to verify that all on-off valves (inlet, outlet, and bypass - if any) are
closed and that the gas has such a temperature as not to create malfunctions.
5.3
COMMISSIONING THE REGULATOR
If on the line there is also a relief valve, refer to par. 4.1 to check it.
Figure 15: Dival diagram (internal sensing line)
Figure 16: Dival diagram (internal and external sensing line)
1.
Partially open the relief valve 6 located on the outlet piping;
2.
Very slowly, open the inlet on-off valve V1;
3.
Once the inlet and outlet pressure values have stabilized, using the pressure gauge 5, check that the outlet pressure
shows the desired calibration value. Should this not be the case, adjust the calibration by acting on the proper internal
ring nut (fig. 1), turning it clockwise to increase and counterclockwise to decrease the value;
4.
Close the relief valve and check the tightness of the regulator and the value of its lockup overpressure;
5.
With a foamy substance, check the tightness of all the joints present between the on-off valves V1 and V2;
6.
Very slowly open the outlet on/off valve V2 until reaching the complete filling of the piping.
