Air Motor Connection… The Basics

What does an effective air motor hook up look like?

The air supply piping to the air motor main supply should be at least one National Pipe Thread (NPT) size larger than the porting on the motor itself. This includes couplings, elbows, valves, tees and control accessories. The larger size keeps pressure loss to a minimum and helps maintain optimal performance.

It’s critical to check the valves in a system for proper size. While valves may manifest the correct, upsized NPT, the orifice inside may not be large enough. It needs to provide the correct amount of air flow in cubic feet per minute (CFM), for the air motor to operate correctly. This restriction will lower speed and reduce torque.

LINE ACCESSORIES – Filter/Regulator/Lubricator or FRL
A filter, regulator and lubricator should be placed in line on the air motor. These 3 items are critical to your system and its operation. They should be placed no more than 18” from the air motor itself. The FRL should be sized properly to prevent pressure loss. Newer LUBE-FREE air motors, like GAST’s NLP Series can be operated without lubrication or provide additional life with lubrication. TIP: The filter, regulator and lubricator should be exclusively dedicated to the pneumatic requirements of the air motor.

Because poor air quality is the #1 cause of air motor failure, the filter is absolutely critical. It removes debris and contaminants such as rust, pipe scale, Teflon tape and water. If rust is present, it will mix with oil from the lubricator. That can form a paste that prevents the vanes from moving freely in the rotor slots. The air motor will act sluggish or even fail. The air motor could simply lock up if foreign material gets into to it due to close internal tolerances. If water gets into the air motor, it can run sluggishly or ultimately corrode it enough to seize completely.

An air pressure regulator is common to most pneumatic systems. It helps maintain a constant pressure for a particular application when supply line pressure varies. It regulates air pressure to the air motor to control its speed and torque and operates by restricting air flow into its downstream leg.

There are several types of lubricators on the market today. They range from uncomplicated manual drip style to units with electronic controls that are far more sophisticated. The most common lubricators operate by a venture system. That’s where oil is entrained into the supply line compressed air as a fine, micro mist. Lubricators should be placed no more than 18” from the air motor and above or at the same level as the air motor inlet port. That will allow the lubricating mist to flow unimpeded. The lubricator should be adjusted to provide 1 drop of oil for every 50 cubic feet per minute of air consumed when the the unit is continuously running. A rule of thumb is 1 drop of oil per minute of continuous run time.

NOTE: There are many lubricants available and it’s critical that the proper lubricant is used. GAST recommends their Part #AD220, which is a 10WT High Detergent oil. Similar FDA-Approved “food grade” oil like Mobil “WHITE REX 425” must be used with lubricated air motors in food processing environments. As an alternative use GAST LubeFree NLP Series of air motors.

• Reduces internal friction within the air motor
• Helps seal the vanes
• Helps to control internal corrosion

Proper installation and maintenance is the key to efficient operation and unit life… and the key to an effective air motor hook up.

You can count on RG Group for excellent quality and service

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