Compressed Air Preparation and Regulation

What is Air Preparation?

In pneumatic circuit terms, air preparation refers to the treatment of compressed air to remove water, oil and particles from the air stream that could damage downstream components. Pressure regulation and filtration components can be fitted at point of use for operator air tools and where automation circuits connect to the air distribution network.

Reducing the pressure at point of use by means of a pressure regulator or filter regulator, allows the downstream circuit to operate at the optimum pressure without increasing the potential for leakage losses. Using a single filter regulator to achieve this function allows one unit to both remove water and reduce the pressure with minimal installation time.

Regulation, Relieving or Non-Relieving?

Both pressure regulators and filter regulators are available as relieving types, which means that when the downstream pressure exceeds the setpoint, the valve closes and the excess is vented to atmosphere.

This may not be allowable where the regulator is being used on flammable or noxious gases and in that case a non-relieving type could be specified.

Relieving regulators can be used on these gases when they have threaded bleed ports so that the excess gas can be piped to a safe area or catchment.

Which Drain Type?

All pneumatic filters have a bowl that surrounds the filter element to act as a reservoir for the water or oil collected. There may or may not be a means to view the liquid level but there will be a method of allowing the water/oil to drain out.

The manual drain is the simplest that works by means of a fastener at the bottom of the bowl. When it is unscrewed a little way, an internal drilling allows the liquid to drain out so that the operator can collect it for disposal.

This method is simple and cost effective but wholly reliant on regular checks by operators as a flooded bowl will cause big problems for the downstream circtui components.

Automatic and semi automatic drains use a float principle to lift a valve so that the water drains out as the level rises. This would seem to offer reduced maintenance but the floats can stick or puncture and they also reduce the maximum working pressure for the filter. Note that some of these drain types only allow the bowl to drain when the supply pressure has been removed and internal pressure vented.

Another alternative may be to use a manual drain unit, unscrew the drain plug and pipe the bowl to a small solenoid valve operated by a timer. This offers regular draining of the bowl under pressure, would be more reliable than some float type drains and not limited to a reduced working pressure.

Air Preparation Products