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he VML type valve is a slow opening single-stage solenoid valve, normally closed (open when
energized). This type of device is suitable for air or gas blocking and releasing controls, required  
in gas power burners, atmospheric gas boilers, industrial kilns and others gas consuming
appliances.

The VML type valve is a safety shutting device using auxiliary power supply.  
When it is de-energized, the spring pushes on the seal disc, keeping the gas passage closed.
Now, the inlet chamber is under the gas line pressure, and it forces on the disc too, improving
the seal. 
When the coil is powered the valve opens slowly because of the hydraulic brake, against the
strength of the spring and gas pressure. The rapid stroke may be adjusted using the regulating
screw on the top (see the installation and service instructions), to adjust the initial gas flow.
Main flow and opening time can be adjusted also. 
If the power supply is shut off, the valve rapidly closes, interrupting the gas flow.