flow control valve

FLOW CONTROL VALVE

Flow control valves, also known as volume-control valves, are used to regulate the volumetric flow of the compressed air to different parts of a pneumatic system.

1. Construction and Operation

The construction and operation of a typical spring-loaded disk-type flow control valve is illustrated in Fig.12.7.

As shown in Figs.12.7(a) and (b), the spring loaded disk allows free flow in one direction and an adjustable or controlled flow in the opposite direction. A tapered brass stem controls the flow adjustment by controlling the flow through the cross hole in the disk.

2. Symbol

Fig.12.7(c) shows the graphic symbol of an adjustable flow control valve.

Note 

Time-Delay Valves: 

• In many pneumatic applications, intentional time delays are required to be introduced between specific operations. These time delays can be achieved using a pneumatic time delay valve. 

• Time delay valve is a combination of a pneumatically actuated 3/2 DC valve, an air reservoir and a throttle relief valve.

• The time delay function is obtained by controlling the air flow rate to or from the reservoir by using the throttle valve. Adjustment of throttle valve permits the control of time delay between the maximum and minimum times.

• Symbol: Fig. 12.8 shows the graphic symbol of a time-delay valve.

• A pneumatic time delay circuit using a time-delay valve is presented in Section 13.10, Chapter 13.