Air motors provide a flexible, efficient and inherently safe source of power compared with electric motors. The advantages of vane or piston type air motors are numerous:
- Infinitely variable speeds and torques
- Instant starting, stopping and reversing
- Will not overheat or burn out
- Safe operating in hazardous conditions
- Cool running characteristics
- Low maintenance
- Excellent design flexibility
- 150 degree to 300 degree temperature range
When selecting an air motor for a particular application it is important to remember the following design criteria:
Are smaller, lighter and less expensive than piston motors of similar power. Simple in design and construction, they can be operated in most any position. Vane motors are available in a broad range of speeds, torques and power and are the most widely used type of air motor.
Radial Piston Motors
Operate at lower speeds than vane motors. Have excellent starting and speed control. Especially good for managing heavy loads at slow speed. Standard operational position is horizontal.
Reversible/ Non Reversible Air Motors
Non-reversible air motors are rated at slightly higher speeds, torques, and horsepower than reversible motors of the same family.
When selecting air motors, remember that the specification listings show only one set of performance figures, at a particular pressure – 90 psig. Air motors are designed to produce optimum performance at this pressure. Many other speeds, torques and power can be obtained from the same motor by regulating the pressure, air supply or exhaust. While they will operate at pressures below 40 psig, their performance may not be consistent. They can also be operated above 100 psig, but often at the expense of increased maintenance. A good rule to follow is to size an air motor based on approximately 70% of the lowest available air pressure. This will allow additional power for starting and possible overloading.
Ungoverned air motors develop maximum horsepower at approximately 50% of free (unloaded) speed while governed motors reach their peak horsepower at about 80% of free speed.
Desired Operating Speed
The desired operating speed, not the free and unloaded speed should be considered when selecting air motors. Ungoverned air motors should not be run unloaded. The performance curves in the catalogue indicate the maximum speeds at which the motor should be operated. The nameplate stamped speed is present for identification only.
Equally important as the speed at which an air motor is to be run is the required torque. The combination of the two factors – speed and torque – determine the power of the desired motor. Care should be taken to differentiate between stall (maximum) and running torques when selecting air motors.
Air System and Supply
Once an air motor has been selected, it is important to ensure that the desired air pressure is available at the motor while the motor is operating. A pressure reading at the compressor does not mean that the same pressure will be available to an operating air motor, because of possible restrictions and friction losses in the air system. Exhaust restrictions can also affect air motor operation, and are often the cause of performance problems.
When installing reversible air motors, a four-way valve or two three-way valves should be used to prevent blockage of the secondary Exhaust Port. This is the opposite Rotation Port to that which is being pressurised.
Replacing Electric Motors with Air Motors
Electric motors, with the exception of series wound direct current motors, have entirely different performance characteristics than air motors. Therefore, their torque and speed curves will not match. Many electric motors are oversized to allow for overloading and lower power air motors can be used as replacements.
Creating sheer power from the natural environment, Ingersoll Rand and air motors are flexible, efficient alternatives to electric sources - perfect for a wide range of industrial applications:
Ingersoll-Rand produce well over 200 models of air motors, with an extensive range of options tailored to suit individual customer’s needs:-
- Reversible and non-reversible models
- Vane or piston configurations
- Geared and non-geared varieties
- 0.10 to 30 horsepower
- 23 rpm to 26,000 rpm speed ratings
- 0.10 ft-lb. to 1090 ft-lb. torque ratings
For more information contact us today.