The VMH type valve is a safety shut off valve for gas with a hydraulic actuator. It is suitable for air or gas blocking and releasing controls, required in the main pipe of gas power burners, atmospheric gas boilers, industrial kilns, and others gas-consuming appliances. See Tab. 2 for maximum operative pressure for every model.
- The valves are made of aluminum alloy with a range for connections from DN 65 up to DN 300. Pipe connections meet group 2.
- Suitable for use with air and non-aggressive gases included in the 1st, 2nd and 3rd families (EN437).
- Special versions for aggressive gases.
- The valve is open only when energized: if for any reason, the power supply goes down, the valve closes immediately (intrinsic safe).
- Qualified for continuous service (100% ED).
- Size DN65-80 is equipped with a flow rate adjustment.
- An incorporated fine mesh filter protects the valve seat and disc as well as downstream components and prevents dirty contamination.
- Provided with G1/4 pressure gauge on two sides in both inlet and outlet chamber to connect manometers, pressure switches, leakage tester or other gas equipment.
- The actuator is provided with ISO 4400 plug for easy cabling. The protection class is IP65 (EN60529).
- The actuator is provided with a led to visualize when it is energized.
- All components are designed to withstand any mechanical, chemical and thermal condition occurring during typical service.
- Effective impregnation and surface treatments have been used to improve mechanical sturdiness, sealing, and resistance to corrosion of the components.
- Valves are 100% tested and fully warranted.
Functioning and application
The VMH type valve is a safety shutting device using an auxiliary power supply. When it is de-energized, the spring pushes on the sealing disc, keeping the gas passage closed. In this condition the inlet chamber is filled with pressurized gas that forces on the disc, improving the seal.
When the actuator is powered, the relief valve closes, the pumps start, and the pressurized oil pushes the piston. The disc opens against the combined force of spring and gas pressure.
When the disc reaches the end stop, the pump is turned off and only the relief valve is consuming power.
If the power supply is shut off, the relief valve opens and the disc closes rapidly, interrupting the gas flow. Fig. 1 shows a sketch of a VMH valve.
This kind of valve is normally installed as safety and regulating device in gas trains, for industrial applications and gas firing systems. Fig. 2 shows an example of installation, in combination with other Elektrogas devices.