Valves

Valves are placed in the line of flow and are used to block flow in a tube or pipe.  Around the lab, you will find several types of valves.  Some are electrical and are used with Process Controller and some are manual, controlled by the user.  Below are the ones you will find.

Manual

Ball Valve

Below is a PVC ball valve. It is open when the handle is inline with the flow. When the handle is perpendicular to the flow path, the valve is closed. The push-to-connect valve (used with tubing) in the following image is in the closed position.

Check Valve

Check valves only allow flow in one direction. For the swing check valve in the second image, there is a flap that opens and closes. When flow is AWAY from the viewer, the water pushes the flap open. When flow is TOWARD the viewer, the flap closes, causing the valve to close and no water to flow through. The spring check valve is similar but the flow must overcome the force of a spring applied to a flat disk to flow through the valve.

Swing Check Valve

Spring Check Valve

Elecromechanical Valves

Solenoid Valves

Solenoid vales have a valve component and a solenoid component. When a current is applied to the unit, a magnetic field is created and opens the valve component. When current is removed, the valve returns the closed position. Thus, the default position of the valve is closed.

Pinch Valves

These pinch valves are similar to the solenoid valves above. There is a solenoid component that creates a magnetic field to move the valve component. The different is the valve mechanism. For a pinch valve, special tubing is inserted into the slot and the valve pinches the tubing closed or releases to open and allow flow through. The valve pictured below has a normally open (NO) and normally closed (NC) section. To operate the valve manually, push the black disk at the end of the valve. You should see the valve pinch and release the tube.