Air compressor customers must identify tools or equipme […]
Air compressor customers must identify tools or equipment that will consume large amounts of air at the highest pressures. Linsheng - Auto parts manufacturing technicians have the knowledge to help customers make the right purchase decisions.
Your excellent "rule of thumb" is to always buy more air compressors than you need!
What is the delivery of CFM?
This will be one of the most important numbers when you buy a new air compressor. (Assuming the price has no object) Many air compressor manufacturers will release their DISPLACED CFM number. The displaced CFM should not be considered when purchasing an air compressor. DISPLACED CFM is a CFM produced by an air compressor that operates at 100% efficiency in a perfect environment. This is not the case in your store!
You want to know the CFM delivered!
Deliverable CFM is an available air made by an air compressor in a real-life environment.
Delivering CFM is running your tool!
When the PSI is reduced, the delivered CFM will increase.
As the PSI increases, the delivered CFM will decrease.
We recommend that you purchase an air compressor that is 1.5 times faster than the CFM of your shop's largest air consumption machine. If you will be using multiple pneumatic tools at the same time, you must add together the CFM requirements for the "in use" tool.
Make sure your delivery CFM requires a measurement equal to or higher than the correct PSI.
What size of MOTOR should I look for in Air Compressor?
This should not be the deciding factor when buying an air compressor. Some air compressor manufacturers (and car manufacturers) use false advertising to imply that their "peak" horsepower is the same as their "normal operation" horsepower. When the motor is started, the "peak" horsepower may be five times the "normal" horsepower. The correct way to rate the motor power is to measure horsepower after the motor is running at the specified RPM and the starter winding is detached.
A car may have more horsepower than another car (BIGGER MOTOR), but that doesn't mean that the car with the best horsepower is the fastest or most effective. There are many factors that contribute to the overall performance of the car and air compressor.
How compressor pumps and motors are related
Reciprocating air compressors use a single or two stage compressor pump to make compressed air. The most efficient compressor is the one that provides the most CFM at the slowest speed. Small or inefficient compressor pumps that rotate at very high speeds can generate a lot of air, but only in a short amount of time! Your Corvette can cruise at a speed of 50 mph for two! But how long does it last? The motor and compressor pumps need to be perfectly matched to allow the compressor to operate at maximum efficiency. If the motor is too small, the compressor pump will not "rotate" with the correct RPM. A motor that is too small may overheat (stall) and attempt to power an oversized compressor pump. If the motor is too large, the compressor pump may "rotate" with too much RPM and the compressor pump will have a very short life.
Of course, the size of the pulleys for the motor and compressor pumps can vary the RPM of the compressor pump. These pulley sizes can be varied to increase or decrease the compressor pump RPM. However, in order to maximize the performance and life of the air compressor, the motor and compressor should be properly matched.
Do I need a single stage air compressor?
A single stage air compressor pump draws into the atmosphere and compresses air in a single piston stroke. The single stage air compressor pump produces approximately 150 PSI of air at a time. It is normal for a single stage air compressor pump to deliver more CFM (lower PSI) than a two stage compressor pump. The single stage compressor pump produces compressed air during each piston revolution. A single stage air compressor can have one cylinder or multiple cylinders. After the complete piston stroke is completed, each cylinder delivers compressed air directly to the air receiver. If there are multiple cylinders on the compressor, they all have an air filter; then you have a single stage air compressor. All cylinders draw air into the cylinder. If your tool or equipment requires high capacity at lower pressures, a single-stage air compressor may be your answer.
Do I need a two-stage air compressor?
Many pneumatic tools require elevated air pressure, which can only be produced by a two-stage reciprocating air compressor. The two-stage air compressor pump works much like a single-stage air compressor pump. The difference is that the two-stage air compressor pump compresses the air in one cylinder and then moves the compressed air to another cylinder to compress again. The two-stage air compressor pump is capable of producing up to 200 PSI of compressed air. A two-stage air compressor pump must have at least two cylinders. A cylinder is usually larger than the other cylinder. The larger cylinder (first stage - cylinder with air filter) draws into the atmosphere and the piston compresses the atmosphere to approximately 150 PSI. The compressed air (heat transferred through the finned tube) is then transferred to a smaller diameter cylinder that recompresses the air to about 175 PSI. This "double compressed air" is forced into the air receiving tank. An inline check valve prevents compressed air from flowing back from the air receiver to the high pressure compressor cylinder. This online check valve is also used in single stage air compressors. A two-stage air compressor pump can have multiple cylinders. However, each two-stage air compressor pump must have at least one low pressure cylinder and one high pressure cylinder.
What size tank do I need?
The air tank stores compressed air made by an air compressor pump. The air compressor is "temporarily closed" when the PSI of the air in the tank reaches a preset air pressure determined by the setting on the pressure switch. When the PSI in the air tank drops below the minimum preset pressure, the air compressor automatically turns on and begins the process of "making compressed air." Aerodynamic tools that operate in short-term air consumption require only a small gas tank to meet their needs. Sandblasting cabinets, track sanders and other high volume air consumption tools require larger capacity air cans. The air stored in the air receiving tank is cooler than the air produced by the air compressor pump. When the desired pressure is reached, the air receiver tank maintains pressurized air and allows the air compressor pump and motor to stop (and cool). If your air compressor pump and motor are too small to provide enough CFM, a larger tank is actually a burden. The motor and air compressor pump are insufficient before the air is delivered to the pneumatic tool, and the air tank must be filled and pressurized. Since the compressor pump and motor are too small, a larger fuel tank is a burden. Bigger tanks = longer waiting!
Keep in mind that as air pressure increases, more available air can be stored in a fixed area. The pressure is related to the storage area. The "more air" in a 60 gallon receiver pressurized to 175 PSI is "more air" in an 80 gallon receiver pressurized to 135 PSI.
Why do some air compressors have magnetic starters... What are they?
The magnetic starter is the "thought ceiling" of the air compressor motor. Magnetic starters are electromagnetically operated switches that provide a safe method for starting certain motors under large motor loads. If the starter detects a motor overload condition, the overload relay in the magnetic starter will prevent the supply voltage from supplying power to the motor. The heater (in series) is responsible for allowing current to reach the motor (and start it) or to prevent current from reaching the motor (to prevent motor failure). The magnetic actuator will allow the motor (when the compressor pump is properly sized) to operate at 100% duty cycle. Heavy duty pressure switches (using some motors) can also be used to simulate the action of the magnetic starter.
What is the duty cycle and how does it affect the operation of my air compressor?
Many air compressor pumps and motors are rated for continuous operation. If they close from time to time, it will be fine. This is a 100% duty cycle. Other compressor motors need to rest regularly for about three minutes every ten minutes to prevent them from overheating. If the air compressor is running for 7 minutes and stays for 3 minutes, the duty cycle will be rated as 70%. If 70% is the factory recommended compressor duty cycle and the compressor run time exceeds 70%, the pump and motor will overheat, causing damage. A magnetic starter or heavy duty pressure switch will increase the duty cycle of most motors. Most commercial grade air compressors use heavy duty motors with a 100% duty cycle. (When the magnetic starter is connected to the motor) the heavy duty pressure switch also increases the duty cycle of most motors.