Gas pressure regulator 143 for high gas pressure with or with out incorporated safety shut off device
Gas pressure regulator 143-BV is pilot operated gas pressure regulator for high pressure, which ensure a constant downstream pressure (p2). The regulator is controlled by a pilot. They can be provided with shut-off device for low and high pressure or for high pressure. They can be used with natural gas, LPG, air, nitrogen, etc.
Gas pressure regulator 143, 143-BV is initially (when there is no gas in the gas pipeline) closed (diaphragm 3 is pressed to the valve seat by the force of spring 4). The safety shut-off valve pad unit 8 is pulled from the seat thus opening access to gas through the seat 5 and to diaphragm 3. The pilot is in closed position. When the gas is fed, it flows through the housing 1 and through the seat 5, overcomes the spring 4 force, presses the diaphragm 3 and flows through the impulse piping into the flow-control valve, then enters the pilot regulator and upper pocket of the diaphragm chamber. The pressure in the upper part of the diaphragm combined with the spring 4 work to close the regulator, and the pilot regulates the pressure in the upper part of the diaphragm which, in motion, laps over the regulator seat responding to changes in outlet pressure and thus maintains the required operating pressure downstream of the regulator. To achieve smooth regulation of the outlet pressure р2, it is necessary to modify (adjust) the flow area of the flow control valve by rotating the flow control valve’s needle and secure it with a lock nut. The flow control valve is set up in such a way that even when the needle is entirely screwed up, some flow area still remains for gas flow between sub-diaphragm pocket and upper chamber of the diaphragm mechanism. To set the regulator for the required outlet pressure р2, use the regulating cone which is then secured with a lock nut and covered with a transparent visor.
Gas pressure regulator type 143, 143-BV are equiped with a pilot type: 119. Pilot type: 119 is used for high pressure control. In the absence of pressure, pilot is in open position, i.e. force of the spring (7), through stirrup (6) act on the rod (2) and maintain the nozzle (3) opened. Letting the gas (inlet gas in regulator p ) in installation, gas flow through the pilot and through impuls pipe act on upper side of regulator 1 diaphragm. Outlet pressure from regulator p2 , through impuls pipe, act on diaphragm (4), which together with spring (1) maintain the control pressure p constant. Control pressure is through impuls pipe bringed up at the upper side of regulator diaphragm. At the setted value of control pressure, pilot is still opened, and gas flow from upper dipahragm hosuing of regulator to lower dipahragm housing of regulator. Further increase pressure p2 close the pilot and pressure in uper and lower dipahragm housing is equalised. Regulator spring close the regulator. Set point of control pressure p is established by the adjusting screw (8) and the spring (7). In order to increase control pressure, rotate clockwise the adjusting screw , and to decrease the control pressure rotate counterclockwise the adjusting screw.
SHUT-OFF DEVICE OPERATION (FOR REGULATORS SIZE DN25 ÷ DN50)
Gas pressure regulator equiped with shut-off device is called 143-BV. Protecting the instalation and the consumers after regulator against extreme (high and low) pressure is the basic function of shut-off device (protection against only high pressure upon request).
Shut-off device for protection against high and low pressure are:
– 1 – 10 bar type : GT.BM.VNP.25÷50.100-06.P.Z.00.00
– 5 – 30 bar type: GT.BM.VNP.25÷50.100-20.P.Z.00.00
– 25 – 75 bar type: GT.BM.VNP.25÷50.100-75.P.Z.00.00
Operation shut-off device for protection against low and high pressure is explained in folowing text. Outlet pressure intake through the pulse pipe under the diaphragm assembly (1). Pressure increasing move the diaphragm assembly upper, through lever (2) cause moving of rod (11) which release the tooth (3) from the rod (4). The rod under the spring (5) load move the pad unit (6) to close the nozzle. Increasing outlet pressure act uppon diaphragm assembly and overcome the high pressure spring (7) load (VP). Decreasing outlet pressure move the diaphragm assembly down under the low pressure spring (8) load (NP) and through lever move the rod (11) and release the tooth (3) from the rod. Activate pressure is realized by setting springs (7) and (8) by adjusting ring for VP (9) and adjusting ring NP (10). Rotate adjusting ring clockwise for increase pressure or rotate adjusting ring counterclockwise to decrease activating pressure. Shut-off device is manualy reset by turning the wheel (12). Shut-off device used only for protection against high pressure is equipied without spring NP (8) and adjusting ring for NP (10).
SHUT-OFF DEVICE OPERATION (FOR REGULATORS SIZE DN65÷DN150)
The impulse line takes the outlet pressure gas p to the shut-off mechanism pilot, which is an actuator of the shut-off 2 mechanism. The pressure increase from p to p increases the force acting on the diaphragm (a) of the shut-off 2 blv mechanism pilot and releases the high pressure spring (b), which results in axial movement of the pilot lock stem (c),
which turns the key of the shut-off mechanism (e) by a puller (d). By turning the key, the space for the lock ball is provided (f) and the stem (g) forced by the spring pushes the lock head (h) against the seat stops the gas flow. A pressure drop from p to p decreases the force that acts on the pilot diaphragm of the shut-off mechanism, causing the low pressure spring (i) to move the pilot lock stem, which activates the shut-off mechanism as in the previous case. Deactivation of safety shut-off device (mechanism):
Protection against high and low pressure:
– close the globe valve at the outlet of the regulation line.
– turn the handwheel (clockwise) and equalise the pressure and then continue to turn the handwheel in order to
unlock the mechanism.
– gradually open the globe valve at the outlet of the regulation line.