Справочник Пользователя для Manfrotto 203

201/203 Series 

Page 14 of 20 

At flow rates higher than 30 slm, two valves are used in parallel.  A solenoid valve is used as a pilot 
valve to control a much larger pneumatic diaphragm valve.   The pilot valve is an “automatic 
metering solenoid” valve.  While most solenoids operate in either the fully open or fully closed state, 
the automatic metering solenoid valve is designed  to  control  flow  (see  Figure  3.5).    A  spring, 

connected to the plunger assembly, holds a magnetic plunger tightly against an orifice to shut off 
flow.  The magnetic plunger is surrounded by an electrical coil, which when energized with electrical 
current lifts the plunger off the orifice and allows flow to pass between the orifice and the plunger 
seat.  Controlling the current 
through the coil controls the distance 
between the orifice and the plunger 
seat, thus effectively controlling the 
flow through the valve. 

Figure 3.6 shows the combination of 
the two valves.  When pressure is 
first applied to the upstream side of 

the valve, flow will pass through until 
the chamber above the diaphragm is 
pressurized through a small bleed 
screw.  System pressure and spring 
force will then close the valve.  The 
pilot valve controls the pressure in 
the chamber above the diaphragm 
thus controlling the height of the 
large plunger above its seat. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FIG 3.6