FAQ

 

To choose an air compressor that meet your needs, there are some key points for you to consider:

pressure, air discharge volume, power supply, environmental protection, installation type , cooling types, noise level, control system, required efficiency, etc.

Our air compressor expert will explain to you step by step as followings:

 

Key Point 1: Pressure

Air compressor’s discharging air pressure (kg/cm²) : 

In addition to consider the actual pressure used as a benchmark, you also need to add the pressure loss of the air flowing through pipes and the purifying system.

 

Pressure drops inside the pipes: 

The pressure loss of compressed air in the pipes is like a car driving on the road. When the road is wide and straight, it can speed up and reduce the loss of energy.  Generally, the loss of air pressure inside the pipes is about 0.5 kg/cm². Besides, the compressed air usually needs to be processed by the air purifying system, heat exchanger, dryer and will cause other pressure drops, which are about 0.3 ~ 0.5 kg/cm².

 

Key Point 2: Free Air Delivery ( F.A.D) and Displacement

It is important to understand the difference between the F.A.D and the

displacement.

 

F.A.D :

Use the required instruments and equipment to measure the air discharge volume of the air compressor by the standard detecting method.

 

Displacement:

Also known as theoretical displacement. The value is derived from the calculation

based on the theory that ignores mechanical energy loss and efficiency factors.

Generally, to obtain the F.A.D value, for single-stage compression, the displacement value will be multiplied by 0.65, and for two-stage compression, it will be multiplied by 0.8 . 

Therefore, decision of the air discharge volume should consider the following points:

  A:)Current required (100%)

 B:)Possible pipe leakage (10%)

 C:)Future expansion plan (20%~50%)

 D:) Allowable margin (10%~30%)

 

Hence, the total required air discharge volume = (A+B+C) x (1+D), when the value of C is larger, the value of D can be reduced. Pay special attention to the fact that

the measurement standard is based on the "actual air discharge volume".

 

 

Key Point 3: Power Supply

Regarding to the power supply, the motor used for an air compressor can be either single-phase or three-phase.

 

Single-phase: 

The general power voltages are 110V and 220V. For your safety and convenience, compressors under 1HP can use 110V. Compressors over 1HP can use 220V. Compressors of 5HP and above are not suitable to use a single-phase power supply.

 

Three-phase: 

The general power voltages are 220V, 380V, and 440V. Three-phase motors are typically used in compressors with higher HP.

Countries around the world have different power supplies, different voltages, different frequencies and different electrical regulations. When purchasing an air compressor, you must specify the voltage, frequency, and the number of phases used, so that the manufacturer can correctly assemble the air compressor with the electrical control equipment of the machine. Before you use the air compressor, it is necessary to confirm that the power voltage matches with the one displayed on the nameplate of the compressor motor.

 

Key Point 4: Environmental Protection requirements

According to different interior structures and designs, air compressors can be divided into the oil-lubricated type and the oil-less type. Users can choose between them according to their actual needs of the work.

 

Oil type: 

An air compressor that uses lubricating oil to lubricate the rotating and compressing parts inside it, is called oil type. The compressed air will contain a small amount of oil but it is still suitable for general industrial use. A filter can be installed to remove excessive oil if needed. Usually, after a new machine has been running for certain hours, the oil must be replaced completely, thereafter, it must be replaced regularly. If you fail to replace the oil regularly or an improper lubricating oil is selected, it will cause damage to the internal parts of the air compressor. Please refer to the manual for the correct selection of lubricating oil and the interval of regular replacement. Applicable industries: steel, plastics, mold, machine shops, and general manufacturing factories.

 

Oil-less type: 

The oil-less compressors are made of special self-lubricating materials, and the lubrication of the compressing parts can be achieved without the use of oil. Therefore, there is no oil in the compressed air, which can meet the oil-free requirements in industries like the precision industry, medical industry, food manufacturing, semiconductor industry, coating and other industries. The oil-less air compressors are without the problems of waste oil and oil pollution.

 

Key Point 5: Installation

Based on different usage types, you can choose: 

Mobile type: 

Small air compressors are all mobile, using two or four wheels to facilitate their mobility as required.

Fixed type: 

Larger air compressors are not easy to be moved due to their heavy weight, the need to be equipped with fixed piping and to reduce vibration and noise, therefore, most of them have to be installed fixedly. Pay attention to the fixing strength and the leveling of the machines during installation. 

 

Key Point 6: Cooling Types

The cooling functions can reach the followings: 

1. Lower down pump temperature, extend machine’s life and reduce oil content in the compressed air.

2. Reduce discharged air temperature and improve the drying efficiency of compressed air.

3. Provide safety protection and prevent dangers caused by overheating.

 

Cooling types of air compressors:

Water-cooled: 

A circulating cooling water tower must be installed. By using cooling water flow to achieve heat exchange between the cylinder and the exhausting air is an extremely efficient heat dissipating method. It is suitable for larger horsepower models.

Air-cooled: 

Using the cooling airflow generated by the cooling fan to achieve the heat exchange between the cylinder and the exhausting air. It is a simple designed heat dissipating system. Recently, with its efficient circulating airflow design, it has become a popular cooling system for both large and small horsepower models.

 

Recommendations for the installation space of the air compressor:

Good ventilation and sufficient space should be the first priority. In the configuration position of the machine, the distance between the cooling fan of the Piston compressor and the wall should be at least 30cm or above. For screw air compressors, the distance between the air exhausting port surface and the wall should be at least 1m, and the distance to the roof from it should be at least 1.5m.

 

Key Point 7: Noise Level Requirements

The noise of an air compressor usually comes from the followings: 

1. The operation of the body: during the compressing process, the mechanical impact sound in rapid running, the sound of airflow, the sound of rubbing between parts, and the noise of the cooling fan running.
2. Power source generation: the running noise generated by the electric motor or engine to drive the air compressor .
3. Unbalanced compressor body: poor balance correction or installation without leveling will cause the body and metal covers to vibrate and make noise.
4. Exhausting air leakage: the leakage of exhausting air and the high-pressure gas flow will cause noise. Due to different operations and structures, the noise levels could be different.
5. Open-type reciprocating air compressors: the noise from the reciprocating movement of the piston is not blocked, and it will spread to the environment along with the sound waves. Small horsepower has low noise and will not affect the environment, but higher horsepower is noisy and must be handled appropriately.
6. Cabinet-type reciprocating air compressors: although the compressor body of the cabinet type is the same as the open-type model, the sheet metal covers are specially designed, using high-grade sound-absorbing materials, shock-proof materials, together with the special design to block and insulate sound  sources, altogether will reduce considerable vibration and noise.
7. Rotary screw air compressor: Due to the different operating mode of the rotary screw air compressor from that of the reciprocating air compressor , the noise produced is different. The rotary screw type is usually with the cabinet-type design. Its sheet metal covers use high-grade sound-absorbing materials, anti-vibration materials, together with the special design to insulate sound source, so its noise value is usually lower than the reciprocating type.

 

The noise prevention does not mean to achieve a no-noise condition, but to reduce the excessively high noise level to an acceptable working environment noise level. Generally, it is required to be below 75 dBA. Based on economic conditions consideration , when environmental restrictions are not required so seriously, the open models are your wise choice. The cabinet type models will be recommended when the quality of life and work environmental restrictions are highly demanded.

 

Key Point 8: Control System

The control system of the air compressor should be properly selected and arranged according to different application conditions and required discharged air quantity, to maximize the compression performance and mechanical life. Taking air-cooled type compressors as an example, our currently used control methods are semi-automatic control and fully automatic control.

 

Semi-automatic control: Use the automatic unloading system to control the operation of the air compressor. Its operating procedure is that when the air pressure reaches to its upper limit, the automatic unloading system drives the unloader piston to keep the intake valve open and running under the un-loading state.

 

Fully automatic control: Use the pressure switch system to control the motor operation. When the air pressure reaches to its upper limit of the pressure switch, the switch turns off and interrupts the motor power supply to stop the air compressor  running. When the pressure drops to its lower limit, the switch turns on the motor power supply and the air compressor returns to run and resume compressing air. This control method is suitable for intermittent air supply and for small horsepower    compressors.

 

In the actual operation of the control system, the following methods can provide more flexible applications.

 

Recommendations: 

Full/semi-automatic selection control--- establish a control system to select the control method according to the actual situation.

 

Full/semi-automatic conversion control --- use the microcomputer control system to select the control mode automatically according to the operating conditions.

 

The control system of screw-type or large machine can be more diverse, we will explain it in another article later.

 

Key Point 9: Efficiency required

Different types of air compressors have their own preferred efficient running areas with regards to different structural design, operating pressure, displacement, and the number of compression stages:

 

Lower pressure and lower horsepower -- mainly choose the reciprocating type air compressors.

 

For compressors below 10HP and demand for a silent environment, you can choose either scroll type or cabinet type.

For above 20HP compressors: mainly choose rotary screw type or water-cooled type compressors.

For pressure above 12kg/cm2 compressors: two-stage compression, high-pressure reciprocating air compressor would be the best choice.

Why does compressed air contain moisture, and what problems may occur when using compressed air with moisture?

In industrial production lines, compressed air is an indispensable source of power for many manufacturing processes. However, many users have reported that compressed air unexpectedly “produces water,” which can even lead to tool jamming and failure, paint surface granulation, or abnormalities in product quality. These irregular conditions may be related to untreated moisture present in the compressed air.

The atmosphere naturally contains moisture. After being compressed by an air compressor, the air volume decreases and temperature changes cause water vapor to condense first in the compressor’s cooler and air receiver tank. When the compressed air is delivered to low-temperature environments or pipelines, further temperature changes affect the saturated moisture content of the air, causing additional condensation. The condensed water may then be carried along with the airflow into production equipment or become mixed into the products.

If the moisture content in compressed air is not reduced, the following problems may occur over long-term use:

1. Mixed with impurities, moisture forms sludge that causes pneumatic components to seize or cylinders to stick, reducing operational efficiency.

2. Moisture leads to corrosion of equipment and pipeline metal parts, generating additional contaminants and causing seal failure and air leakage.

3. Condensed water causes electrical control and sensing components to absorb moisture, resulting in system malfunctions or failures.

4. Condensed water contaminates production processes, affecting coating quality or altering cleaning and spraying performance.

5. Increased frequency of component failures, indirectly raising operational and maintenance costs.

 

Compressed Air Purity Class: ISO 8573-1:2010

	Solid particles — Particulate concentration (cn/m³)			Moisture and Water Content	Oil Content
	The maximum number of particles with a particle size d (μm) allowed per 1 m³.			Pressure Dew Point	Concentration
	0.1≤d≤0.5μm	0.5≤d≤1.0μm	1.0≤d≤5.0μm	℃ (℉)	mg/m³
0	Note: Stricter requirements than Class 1 may be specified according to customer needs or supplier agreements.
1	≤20,000	≤400	≤10	≤70(-94)	≤0.01
2	≤400,000	≤6,000	≤100	≤40(-40)	≤0.1
3	-	≤90,000	≤1,000	≤20(-4)	≤1
4	-	-	≤10,000	≤+3(+38)	≤5
5	-	-	≤100,000	≤+7(+45)	>5
6	-	-	-	≤+10(+50)	-

 

Before discussing the moisture content in compressed air, it is essential to first understand the compressed air purity standard ISO 8573-1.
According to ISO 8573-1, compressed air purity classes are defined based on three major parameters: solid particles, water (humidity and liquid water), and oil (total oil – liquid, aerosol, and vapor). The classification is determined by the concentration of these elements present in the compressed air.

For example, when compressed air purity is required to meet ISO 8573-1 Class 2,5,2, it means that both solid particles and oil must be treated with filtration equipment to comply with Class 2 requirements, while an air dryer must be used to control the moisture content to meet the Class 5 standard.

In industry, it is widely recognized that excessively moist or contaminated compressed air poses risks and potential damage to both equipment and products. However, determining how to select the appropriate air purification and air dryer equipment according to specific applications has become very significant in modern manufacturers.

Introduction to the Functions and Main Types of Air Dryers

The core purpose of an air dryer is to reduce the moisture content in compressed air, ensuring stable air supply quality. In general, air dryers on the market can be categorized into the following two main types:

1.Refrigerated Type Air Dryer

The refrigerated air dryer is currently the most common type of compressed air-drying equipment used in the industrial field. Its working principle involves cooling the compressed air, which changes its saturated moisture state and causes the water vapor to condense into liquid droplets. These droplets are then separated and discharged, thereby achieving the dehumidification effect.

To balance dehumidification efficiency and prevent pipeline freezing, most brands on the market operate with an actual heat exchange temperature ranging between +2°C and 15°C under normal conditions. Through proper equipment selection and effective management of airflow, pressure, and ambient temperature, it is possible to design a system that meets the ISO 8573-1 moisture content Class 4 to Class 6 requirements.

*The outlet pressure dew point ranges from approximately 2°C to 15°C, and the system can be designed and configured according to the required class for use in general industrial applications.
*Applicable industries: cleaning and packaging applications, general manufacturing, automotive maintenance, woodworking, plastic molding, general painting/coating processes, and as pre-treatment air sources for nitrogen generators and adsorption-type air dryers.
*Advantages: simple structure and easy configuration; when equipped with a no-loss drainer, it eliminates air consumption during the drying process.

 

2.Desiccant Type Air Dryer

When the compressed air treated by a refrigerated air dryer is still insufficient to meet the dryness requirements of the production line, an adsorption air dryer is commonly used as an enhanced treatment device.

Its working principle relies on adsorbents such as molecular sieves or activated alumina, which operate in a twin-tower alternating adsorption and regeneration cycle to continuously supply highly dried compressed air.For example, according to ISO 8573-1 moisture content Class 2, the corresponding moisture level is approximately 0.024 g/m³ or lower.

However, depending on the brand design and specified moisture class, an adsorption air dryer may require up to 20% of the airflow for desiccant regeneration. This represents a significant energy cost, as the compressed air itself is produced through energy-intensive processes.

To reduce compressed air consumption, system designs often adopt a hybrid approach — using a refrigerated air dryer for overall system drying, while installing adsorption air dryers only at critical production lines where higher air dryness is required.

*Pressure dew point: can reach -20°C to -70°C, suitable for industries with strict humidity control requirements.
*Applicable industries: powder coating, electronics manufacturing, medical equipment, food processing, laboratories, semiconductors, and others.
*Advantages: excellent drying capability; meets extremely low-humidity conditions and high clean air quality requirements.

The following lists the common applications across various industries and the recommended types of air dryers for each industry:

Industry type	Commonly configured models	Illustration
Traditional Machining and Hardware	Refrigerated Type Air Dryer	A basic drying process is enough to prevent rust and equipment failure.
Woodworking and Auto Repair	Refrigerated Type Air Dryer	Eliminate moisture at the tool end to maintain stable performance.
Food Processing and Packaging	Refrigerated Type Air Dryer/ Desiccant Type Air Dryer	Choose based on the cleanliness level required by the process.
Electronics and Optoelectronics	Refrigerated Type Air Dryer + Desiccant Type Air Dryer	Prevents component corrosion and static problems caused by moisture.
Medical and Laboratory	Refrigerated Type Air Dryer + Desiccant Type Air Dryer	The air quality must meet high cleanliness and moisture-free standards.
Semiconductor Process	Refrigerated Type Air Dryer + Desiccant Type Air Dryer	Requires air quality compliant with ISO 8573-1 Class 1 standard.

 

If there are no specific application requirements, a refrigerated air dryer is generally a suitable starting point for most factories. As operational needs expand, an adsorption dryer system can later be evaluated and upgraded accordingly.

With proper dryer configuration, it is possible to significantly extend the lifespan of the compressed air system, reduce maintenance frequency, and improve overall air quality and production stability.

SWAN air compressor and air dryer suggestion & recommendation

 

In practical applications, the selection of an air dryer is not determined by a single factor. It requires careful consideration of multiple elements, including the operating environment, compressor configuration, air quality standards, and budget balance. With our extensive practical experience in the compressed air industry, we can provide customized solutions tailored to the specific needs of different industries

* Air dryer type selection suggestion
* Complete Compressed Air System Setup
* On-site Assessment and System Optimization Services

Interested in finding the best air dryer and compressor solution for your needs? Contact SWAN Air Compressors today—we’ll help you design a smarter, more efficient, and more reliable compressed air system.

The automotive industries rely heavily on air compressors and are widely used for assembly, maintenance, repair, and detailing.  Despite the size of auto shops, stable, clean, and quality compressed air solution is essential for operation.  From small tasks like cleaning and powering pneumatic tools to big tasks like auto lifting and painting, compressed air is crucial for various applications.  Air compressors are the most basic equipment for auto facilities but play an important role. Energy efficient air compressors facilitate operation smoothly and reach the optimal performance.

Common Selection Questions

1. How to choose the right air compressor?

  1) Usage

• Low Usage → For auto repair shops mainly servicing sedans generally use 3 to 10 HP models.
• High Usage → For auto repair shops specializing in servicing large trucks or container trucks recommend high pressure 10 HP or higher hose power models.

  
  
  2) Working Pressure:

• Low Pressure → For auto repair shops mainly servicing sedans generally use 6 to 8 kg/cm².
• High Pressure → For auto repair shops specializing in servicing large trucks, container trucks, and offered wide ranges of services recommend high pressure 12 to 14 kg/cm².

 

2. To choose cabinet air compressors or open-type air compressors

• Mechanical noise is acceptable → Consider open-type models
• Low noise dB(A) is required → Consider cabinet type models 

 

3. When there are specific requirements regarding the moisture and oil content in compressed air

After air compressed, oil mist and moisture still exist in the final stage. Hence, installing dryers and filters is recommended for quality air output, especially for the painting department. Our professional technicians can help you evaluate and determine the most suitable air compressor configuration when required applications are provided.

 

4. Why SWAN brand air compressor?

SWAN Air Compressors are renowned for stable quality, reliable after-sales service, and diverse product selections. Our sales representatives will provide professional recommendations based on your needs.

 

Recommended Models

 

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Please contact SWAN certified technician for situations not mentioned below when the air compressor is out of order or malfunctions.

 

 

 

 

Professional skills and knowledge are required for air compressor maintenance. Please contact experienced technicians for services. Regular maintenance and checkup prevent malfunction from happening.

We have prepared a check list for your machines before and after the Holidays. Please follow it accordingly to ensure the machine is maintained at the highest efficiency.

 

Here are some precaution tips on air compressor shut off for a period.

1. Powering off main switch and unplug air compressor to save energy.
2. Clean air filter element with air gun to avoid clogged air filter.
3. Drain air and water out of air tank to prevent air compressor from rusting.  

Tips for Powering-On Idle Machine

1. Check if lubricating oil level is in the center of oil gauge and air tank drain valve is closed properly.
2. Inspect for any exposed wire before plug in electricity.
3. Monitor for any irregular sound when warming up air compressor. If there’s any abnormal noise, please refer to user manual or contact SWAN.