Careful with low pressure and vacuum

When plumbing compressed air under 25 PSI, or when controlling vacuum, careful that the air valve you pick can operate at those pressures.

A direct acting solenoid valve will operate, regardless of the pressure. Usually these are limited in size, however.

Larger air valves are, most commonly, solenoid air piloted.

This means that compressed air, sourced from that air valves supply line, is being directed through a small valve to operated the bigger valve with compressed air. This type of valve has a Minimum Operating Pressure of around 25 PSI, and the valve will not work if the supply line air pressure is below that, or if you are trying to plumb vacuum.

Most of the solenoid air pilot valves will have an air port on the small direct acting solenoid valve that is piloting it, to allow the plumbing of an external source of higher pressure air. Now, with this supply at a higher pressure installed, the big valve can be used to plumb low pressure or vacuum.

Swivel Fittings

A swivel fitting is usually an elbow, and the part of that fitting that connects to the incoming air line can be rotated after the threaded part of that fitting is screwed securely into a component. This allows the air line connecting part to be rotated to it’s optimal position for plumbing the air to the fitting, and ultimately to whatever the fitting is threaded into.

Swivel fittings are (for the most part) not designed to provide continuous rotation. For example, if the air line coming to the fitting is attached to another component that is dynamic, moving continuously, then the swivel portion of the elbow fitting could be rotating continuously as the component connected to it moved.

This would result in fairly rapid fitting failure.

If you have a situation where you need to plumb air to a moving component, talk to your fitting supplier about using a Rotary Fitting in this application. A rotary fitting is one that’s designed to allow continuous, and often high speed, movement of the fitting to accommodate air line movement due to the operation of the machine.