Bronkhorst EX-FLOW Mass Flow Manual de usuario descargar pdf (Pagina 11)

BRONKHORST HIGH-TECH B.V.

1.6 Control valve

1.6.1 Introduction

Control valves are not designed to provide positive shut-off, although some models have excellent

capabilities for this purpose.

It is recommended to install a separate shut-off valve in the line if so required. Also pressure surges, as may

occur during system pressurisation must be avoided. The following models can be distinguished:

Solenoid valve

This is considered to be the standard (direct operated) control valve. In general it

is a normally closed solenoid valve. The plunger is lifted by the force of the

magnetic field of the coil. The orifice under the plunger is removable for optimising

the orifice diameter. Also a normally opened solenoid valve is available.

Vary-P valve

For process conditions where up- and downstream pressure vary much,

a special type of valve, VARY-P has been designed. This valve consists

of two valves, a solenoid operated control valve and a fixed adjusted

pressure compensation valve.

Pilot operated valve

For high flow rates the pilot operated valve has been designed. A

solenoid driven control valve controls the pressure difference

across a piston, which lifts the main plunger.

flowcontrol

valve

pressure

compensating

valve

flowcontrol

valve

pilot valve

pressure

compensating

valve

flowcontrol valve

9.17.028 page 11

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Bronkhorst EX-FLOW Mass Flow Manual de usuario Pagina 11