Compressed Air Filter Element

What Is a Compressed Air Filter Element?

A compressed air filter element is a component used to remove solid particles, oil, moisture, and microscopic contaminants from compressed air. These elements are usually made with a multilayer structure of borosilicate microfiberglass or other synthetic materials in order to ensure both high efficiency and low pressure drop. In the Iranian market, this group of filters is also commonly referred to as “microfilters.” They are used as final purification stages for compressed air. At this point you may be asking yourself why we need to filter compressed air at all. We will answer this question in detail in the following sections. First, let us look at the main components of a compressed air system.

Main Components of a Compressed Air System

• Compressor: The source of compressed air. In most cases, the primary contaminants (moisture and oil) also originate here.
• Aftercooler: The first cooling stage, used to reduce temperature and condense water vapor into liquid droplets.
• Water Separator: The first separation stage for liquid water and some coarse particles.
• Stage Filters for Compressed Air:
  • Pre-filter: Removes coarse particles and a portion of entrained oil.
  • Fine filter: Removes very fine particles and oil mist.
  • Activated carbon filter: Removes odor and oil vapors.
• Compressed Air Dryer:
  • Refrigerated dryer: Suitable for general industrial applications.
  • Desiccant dryer: Used in instrumentation, pharmaceutical processes, and applications requiring very dry air.
• Receiver Tank: Stores compressed air and helps dampen fluctuations and pressure peaks.
• Piping system: The pipework, which itself becomes a source of corrosion, rust particles, and secondary contamination.
• Point-of-use filters: Final filters located close to the point of consumption to ensure the required purity level.

Why Do We Need to Filter Compressed Air?

Compressed air is one of the most widely used energy carriers in industry, but it is not suitable for direct use immediately after leaving the compressor. It must always be treated (filtered and dried) before entering sensitive systems. The scientific and technical reasons for this necessity are as follows:

1. Increased concentration of contaminants due to compression

During isothermal or polytropic compression, the volume of air is significantly reduced (typically to 1/7–1/10 of its initial volume). Since the mass of the contaminants present in the air (moisture, solid particles, oil vapor, and hydrocarbons) does not change during this process, their concentration per unit volume increases in direct proportion to the compression ratio. For example, if the absolute humidity of the intake air is 10 grams of water per cubic meter and the air is compressed to 8 bar, the moisture concentration in the compressed air rises to around 80 grams per cubic meter. This is well above the atmospheric dew point and leads to rapid condensation of water.

2. Condensation of moisture due to temperature drop after compression

Compression causes a temperature rise, but in the subsequent stages (aftercooler, piping, and pressure losses) the temperature decreases. This temperature drop leads to condensation of water vapor and the formation of liquid water droplets, and sometimes water–oil emulsions, which are corrosive and harmful to pneumatic components.

3. Presence of solid particles and oil aerosols

The intake air entering the compressor contains suspended particles (dust, soot, metallic particles from wear, etc.). These particles, together with oil aerosols (in lubricated compressors), are present in the compressed air at much higher concentrations and can cause clogging of orifices, malfunction of control valves, damage to cylinder surfaces, and a reduction in the quality of the final product, especially in painting, food, and pharmaceutical industries.

4. Requirements of international compressed air quality standards

The ISO 8573-1 standard defines various classes of compressed air quality. Most industrial applications, particularly sensitive processes (painting, food industry, electronics, pharmaceuticals), require class 1 to 3 for solid particles, class 1 to 2 for moisture, and class 1 for oil. Achieving these levels is not possible without a multi-stage filtration system and an appropriate dryer.

ISO 8573-1 Standard

ISO 8573 is the official standard for assessing compressed air quality and specifies the acceptable levels of solid particles, moisture, and oil in compressed air. The most important part of this standard is ISO 8573-1, which defines the quality classes.

Three main quality indicators in ISO 8573

• Solid particles
• Water (dew point)
• Oil (liquid, mist, and vapor)

Each of these has numeric classes defined, and the lower the class number, the higher the quality.

Air quality classes – solid particles

• Class 1: Control of ultra-fine particles (down to 0.1 μm)
• Class 2: Control of particles up to about 1 μm
• Class 3: Particles up to 5 μm, suitable for general industrial use

Air quality classes – moisture (dew point)

• Class 1: Dew point down to −70°C (very dry air)
• Class 2: Dew point −40°C
• Class 4: Dew point +3°C (standard level for most industrial applications)
• Class 6: Limitation only on total water content, not on dew point

Air quality classes – oil

• Class 1: Maximum 0.01 mg/m³
• Class 2: Maximum 0.1 mg/m³
• Class 3: Maximum 1 mg/m³

What does Class 0 mean?

Class 0 means that the required quality must be better than Class 1. This class is used for ultra-critical applications, where the allowable contamination levels are defined by the user or equipment manufacturer, not by a fixed value in the standard.

In Which Grades Does Sepanta Palaye Pars Produce Filter Elements?

The specifications of the different grades of compressed air filter elements are summarized in the following table:

Why Sepanta Palaye Pars?

• 1. Genuine expertise in compressed air filtration and drying: The company is focused on a single domain and goes deep in that area. The result is correct selection of filter type, filtration class, capacity, and proper design of the compressed air system.
• 2. Products and solutions based on international standards: All products and solutions are designed in accordance with compressed air quality standards and can achieve the required ISO 8573 classes. This means the customer knows exactly what level of quality is being delivered.
• 3. Stable and reliable quality: The focus on durable materials, filtration media with real efficiency, and step-by-step quality control ensures that filter performance remains consistent throughout its service life, not only in the first few days.
• 4. Competitive pricing without compromising quality: The goal is to offer products that can compete in quality with imported brands while keeping replacement and maintenance costs low.
• 5. Fast and straightforward technical support: Troubleshooting, filter selection, contamination analysis, and monitoring of the compressed air system are performed quickly and accurately, so the customer does not lose valuable time.
• 6. Full support for industrial end users: From food and pharmaceutical industries to automotive and instrumentation, each sector’s requirements are evaluated specifically and tailored recommendations are provided. Solutions are not generic or superficial.
• 7. Long-term, predictable supply: Production and supply planning is maintained so that customers do not face stock shortages or production downtime. Replacement elements are always available.

Replacement Filter Elements with OEM-level Quality for Leading Brands

Sepanta Palaye Pars is capable of producing replacement compressed air filter elements with equal or superior quality compared to original elements for a wide range of brands, including: