Gas pressure regulators type 135-BV – with or with out incorporated safety
Gas pressure regulator type 135-BV is pilot operated gas pressure regulator for high pressure, which ensure a constant downstream pressure (p ). The regulator is controlled by a pilot. 2 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 type 135-BV in its initial position (no gas in the pipeline) is closed, i.e. the diaphragm forced by the spring is pressed against the seat. The pad unit of the shut off mechanism is spaced from the main seat allowing the gas flow through the nozzle. The pilot is in the closed position. When released in the installations, gas goes through the valve body and the nozzle. It acts on the membrane and tends to open the regulator and/or release the spring. The inlet pressure is delivered to the orifice from the valve body via the impulse line. Fine tuning of the choke valve at the outlet generates pressure that is further distributed in two directions: to upper membrane chamber and to the regulator pilot. The pressure that reached the chamber (together with the spring) tends to open the regulator, while the pressure at the regulator pilot acts on the seat and the membrane and opens it. The task of the pilot is to establish a control pressure required for the regulator operation. When the pressure at the regulator outlet reaches the set value, the balance of forces in the pilot and the regulator is established. This means that the control pressure reached the value required to realised the required position of the regulator membrane in relation to the seat. In the case of the outlet pressure increase, the pilot starts to close and the higher control pressure acts on the membrane and closes the regulator, thus reducing the outlet pressure to the set value. In the case of the outlet pressure decrease, the opposite happens.
Gas pressure regulators type 135-BV are equiped with a pilot type: 117. Pilot type: 117 is used for low and medium pressure control. In the absence of pressure, pilot is in open position, i.e. force of the spring, through stirrup act on the rod and maintain the nozzle 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, which together with spring 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 upper dipahragm housing of regulator. Further increase od 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 and the spring. 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 ÷ dn65)
Gas pressure regulator equiped with shut-off device is called 135-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:
– 0 – 2 bar type : GT.BM.VNP.02.65.P.Z
– 2 – 4 bar type: GT.BM.VNP.04.65.P.Z
– 4 – 6 bar type: GT.BM.VNP.06.65.P.Z
Shut-off device for protection against high pressure are:
– 0 – 2 bar type : GT.BM.VP.02.65.P.Z
– 2 – 4 bar type: GT.BM.VP.04.65.P.Z
– 4 – 6 bar type: GT.BM.VP.04.65.P.Z
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. Pressure increasing move the diaphragm assembly upper, through lever cause moving of rod which release the tooth from the rod . The rod under the spring load move the valve disc to close the nozzle. Increasing outlet pressure act uppon diaphragm assembly and overcome the high pressure spring load (VP). Decreasing outlet pressure move the diaphragm assembly down under the low pressure spring load (NP) and through lever move the rod and release the tooth from the rod. Activate pressure is realized by setting springs and by adjusting ring for VP and adjusting ring NP. Rotate adjusting ring clockwise for increase pressure or rotate adjusting ring counterclockwise to decrease activating pressure. Shut-off device is manualy reset by pulling handle. Shut-off device used only for protection against high pressure is equipied without spring NP and adjusting ring for NP.
Shut-off device operation (for regulators size dn65÷dn200)
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