2/2 Air Valves Continued

This is the 2nd of two pages providing details about 2-2-air-valves. Here is the first page about 2-2-air-valves.

We had been writing about the use of 2-2-air-valves in a quality control application.

In a quality control application, for example, a product may be moving down a conveyor system. When the product moves through a quality checkpoint sensor (perhaps a weigh scale or some sort of colour scanner) if that product doesn't meet the quality set points, a signal is sent to a PLC which in turn sends a signal to an actuator on a 2/2 air valve.

That 2-2-air-valves shifts, and air flows through the valve to blow the defective part from the conveyor.

Quality Control

The graphic just above shows a small 2/2 air valve with a solenoid operator and a DIN electrical connection.

Cooling Devices

They are used to provide simplistic cooling to control cabinets where the application cannot use other forms of cabinet cooling such as fans or refrigeration.

When the temperature inside the cabinet reaches a set point, a signal is generated which, in turn, opens the 2/2 air valve. Compressed air flows to and through the cabinet cooler, and lowers the temperature in the cabinet to an acceptable level. When the low temperature set point is reached the air valve shifts closed until the high set point is again reached.

2-2 Valves & Air Motors

As an example, an air motor may be powering a fixture to turn tops onto bottles.

\When a bottle reaches the set spot in the assembly line, a signal is generated. The PLC fires the 2/2 valve which powers the air motor, and it turns the cap onto the bottle.

A regulator can be used to allow the air motor to stall out before it over torques the cap, or a simple timer may be used to time the cap installation and then lift the air motor to allow the bottle to carry on down the line. Then the cycle repeats.

Air Driven Pumps

For example, an submersible air pump in a tank. A float switch signals when the tank level reaches a set point, a signal is sent, and the pumps starts and runs until the level in the tank reaches a low set point.

Problem!

No 2/2 air valve can be used to supply air to any device that is a closed vessel.

Once the 2/2 air valve is shut off, compressed air in the air line from the valve to the application, and any compressed air in the application itself - both at full line pressure - cannot get back out if 2-2 air valves are used to supply air to that vessel.

Therefore, 2/2 air valves are normally only used when the working point ultimately leads to atmosphere. Then, when the valve is shut off, air in the downstream line can bleed off.

Sizes

Of course, as the need for more air flow for the application is determined, larger ported 2/2 valves are selected.

Economies Of Manufacturing

It is often more economical to make larger bodied valves multi-ported and then to have the unused ports plugged for different applications than it is to purchase tooling to manufacture many different body styles.

And, there are fewer applications for large 2/2 air valves over their 3/2 and 4/2 cousins too.

Where applications exist, 2/2 valves can be stacked, they can be sub-based, or they can be plumbed individually for each need.

Drawing The 2/2 Air Valve

Here's where you learn how to draw the schematic for a 2/2 air valve.

Questions?

Please use this form to ask questions about the 2-2 valve only. Thanks.