Compressed air is used in more than 90 percent of the world’s manufacturing plants, so much so that it has earned the appellation of fourth industrial utility after electricity, gas and water. Along with the latter, it is a crucial element in production processes, and its proper implementation and maintenance have a profound impact on productivity, financial results, and the smooth operation of enterprises.
Companies and maintenance personnel make every effort to ensure that compressed air systems operate safely, efficiently and economically. To this end, filtration is a must for any purification system to ensure a continuous supply of high-quality compressed air. Filtration technologies for compressed air treatment use interchangeable filter elements that need to be replaced periodically, however, the reasons and timing of replacement are not always clear.
Below, we will review types and sources of contamination, filtration technologies and their function, frequently asked questions, myths about differential pressure monitoring, and recommendations for filter element replacement.
Contamination control
Contamination of compressed air comes from several sources:
- Contaminants in the atmosphere that enter the compressor.
- Contaminants introduced by the compressor.
- Contaminants introduced from the air tank and distribution piping.
There are at least 10 contaminants in a common compressed air system that need to be treated:
- Water vapor
- Microorganisms
- Atmospheric impurities
- Oil vapor
- Water aerosol
- Liquid water condensate
- Liquid oil
- Oil aerosol
- Rust
- Scaling
Coalescing filters represent one of the most important purification technologies as they can remove most of these contaminants, while water separators, dry particulate removal filters, and adsorption filters take care of the remaining aspects. The table below shows how each technology is used to ensure clean compressed air.
The filter elements have a finitado operating life.
All of these filtration technologies (with the exception of water separators) use a replaceable filter medium, typically in the form of a cartridge or element. Filter elements are subject to extreme and changing conditions in compressed air flow, including:
- Significant pressure variations.
- Pulse airflow demand.
- Temperature variations.
- Humidity values between 100% saturated air and dew points below zero.
- Chemical attacks.
Over time, these conditions lead to deterioration of the filter material and subsequent loss of effectiveness in removing contamination. Consequently, filter elements should be replaced periodically to ensure optimal performance at all times.
To ensure proper contaminant removal, Parker recommends replacing coalescing and dry particulate filters and float dischargers annually (every 12 months). Parker Domnick Hunter OIL-X coalescing and dry particulate filters are covered by an air quality warranty that is based on annual filter replacement using genuine replacement parts.
Although Parker clearly lays out maintenance requirements, there remains understandable uncertainty about the reasons for and timing of filter element replacement in filters, as each compressed air system has different characteristics. However, because conditions within the system can change rapidly, we recommend opting for a preventive approach toward maintenance.
Frequently asked questions
Why replace the compressed air filter element?
As illustrated above, the effects of the harsh conditions under which coalescing filter elements and dry particulate filters operate quickly compromise performance.
What happens if the filter element is damaged?
Over time, contaminants weaken the medium and cause tears and leaks to form, which rapidly enlarge, allowing contaminants to pass through the filter element.
In the case of plants operating at reduced hours, can the operating life of the filter elements be increased?
As mentioned, constant exposure to contaminants in the compressed air stream weakens filter elements. To avert the danger of spreading contamination, best practice suggests replacing the filter annually. Parker guarantees the performance of the filters for a period of twelve months.
Is it possible to wash the filter elements?
No, it is not possible to wash away contamination from filter media. The filter medium will be damaged if washed with hot water and detergents or solvents.
The filter element does not look particularly dirty, is it really necessary to replace it?
First, the visible part of the filter element is the drain layer, which prevents aggregate liquids from flowing downstream. The main filter medium is located below that layer and is visible only by disassembling the filter element. Second, coalescing and particulate filters capture aerosol particles and submicron-sized contaminants that are invisible to the human eye.
Myths about differential pressure monitoring
Most filter housings are equipped with differential pressure indicators, but it is a common mistake to base filter replacements on these devices. The gauges are not calibrated and usually indicate the upstream and downstream pressure change with a substantial margin of error. Although they may give some indication of any maintenance required due to clogging of the filter medium, they do not provide an accurate representation of the filter’s ability to remove contamination. Therefore, they are not a reliable tool for determining maintenance intervals of filter elements.
Myth
Differential pressure is an indication of air quality.
Reality
Differential pressure is a result of the collection of contaminants in the filter element, but it is not directly related to the quality of the air delivered.
Myth
The filter is equipped with a differential pressure gauge that indicates when to replace the filter element.
Reality
These devices serve only to get a general idea of pressure reduction since they are not subject to calibration and allow a level of accuracy of about +/- 25 percent. Gauges should not be used as indicators because of the need for maintenance, and it is best to follow the manufacturer’s instructions in this regard.
Myth
Filter elements of compressed air filters should be replaced only when the differential pressure increases.
Reality
Although it is good practice to keep the differential pressure low, the spread of contamination does not strictly depend on it. Consequently, it is not a particular indication of the need for maintenance of the filter element.
Conclusions
Filter elements should be replaced periodically to ensure a continuous supply of high-quality compressed air.
- Protection of adsorption dryer beds.
- Protection of downstream equipment, personnel and processes.
- Reduced operating costs.
- Increased productivity and profitability.
- Tranquility at all times.
This article was written with input from Mark White, Compressed Air Treatment Applications Manager – Parker Gas Separation and Filtration Division EMEA
If you enjoyed this article, you may also be interested in:
Why it always pays to install coalescing filters in pairs
Three moves to avoid costly downtime in compressed air systems
How compressed air redefines bottling processes
Compressed air is used in more than 90 percent of the world’s manufacturing plants, so much so that it has earned the appellation of fourth industrial utility after electricity, gas and water. Along with the latter, it is a crucial element in production processes, and its proper implementation and maintenance have a profound impact on productivity, financial results, and the smooth operation of enterprises.
Companies and maintenance personnel make every effort to ensure that compressed air systems operate safely, efficiently and economically. To this end, filtration is a must for any purification system to ensure a continuous supply of high-quality compressed air. Filtration technologies for compressed air treatment use interchangeable filter elements that need to be replaced periodically, however, the reasons and timing of replacement are not always clear.
Below, we will review types and sources of contamination, filtration technologies and their function, frequently asked questions, myths about differential pressure monitoring, and recommendations for filter element replacement.
Contamination control
Contamination of compressed air comes from several sources:
Contaminants in the atmosphere that enter the compressor.
Contaminants introduced by the compressor.
Contaminants introduced from the air tank and distribution piping.
There are at least 10 contaminants in a common compressed air system that need to be treated:
Water vapor
Microorganisms
Atmospheric impurities
Oil vapor
Water aerosol
Liquid water condensate
Liquid oil
Oil aerosol
Rust
Fouling
Coalescing filters represent one of the most important purification technologies as they can remove most of these contaminants, while water separators, dry particulate removal filters, and adsorption filters take care of the remaining aspects. The following table shows how each technology is used to ensure clean compressed air.
The filter elements have a finitado operating life.
All of these filtration technologies (with the exception of water separators) use a replaceable filter media, typically in the form of a cartridge or element. Filter elements are subject to extreme and changing conditions in compressed air flow, including:
Significant pressure variations.
Pulse airflow demand.
Temperature variations.
Humidity values between 100% saturated air and dew points below zero.
Chemical attacks.
Over time, these conditions lead to deterioration of the filter material and subsequent loss of effectiveness in removing contamination. Consequently, filter elements should be replaced periodically to ensure optimal performance at all times.
To ensure proper contaminant removal, Parker recommends replacing coalescing and dry particulate filters and float dischargers annually (every 12 months). Parker Domnick Hunter OIL-X coalescing and dry particulate filters are covered by an air quality warranty that is based on annual filter replacement using genuine replacement parts.
Although Parker clearly lays out maintenance requirements, there remains understandable uncertainty about the reasons for and timing of filter element replacement in filters, as each compressed air system has different characteristics. However, since conditions within the system can change rapidly, we recommend opting for a preventive approach toward maintenance.
Frequently asked questions
Why replace the compressed air filter element?
As illustrated above, the effects of the harsh conditions under which coalescing filter elements and dry particulate filters operate quickly compromise performance.
What happens if the filter element is damaged?
Over time, contaminants weaken the medium and cause tears and leaks to form, which rapidly enlarge, allowing contaminants to pass through the filter element.
In the case of plants operating at reduced hours, can the operating life of the filter elements be increased?
As mentioned, constant exposure to contaminants in the compressed air stream weakens filter elements. To avert the danger of spreading contamination, best practice suggests replacing the filter annually. Parker guarantees the performance of the filters for a period of twelve months.
Is it possible to wash the filter elements?
No, it is not possible to wash away contamination from filter media. The filter medium will be damaged if washed with hot water and detergents or solvents.
The filter element does not look particularly dirty, is it really necessary to replace it?
First, the visible part of the filter element is the drain layer, which prevents aggregate liquids from flowing downstream. The main filter medium is located below that layer and is visible only by disassembling the filter element. Second, coalescing and particulate filters capture aerosol particles and submicron-sized contaminants that are invisible to the human eye.
Myths about differential pressure monitoring
Most filter housings are equipped with differential pressure indicators, but it is a common mistake to base filter replacements on these devices. The gauges are not calibrated and usually indicate the upstream and downstream pressure change with a substantial margin of error. Although they may give some indication of any maintenance required due to clogging of the filter medium, they do not provide an accurate representation of the filter’s ability to remove contamination. Therefore, they are not a reliable tool for determining the maintenance intervals of filter elements.
Myth
Differential pressure is an indication of air quality.
Reality
Differential pressure is a result of the collection of contaminants in the filter element, but it is not directly related to the quality of the air delivered.
Myth
The filter is equipped with a differential pressure gauge that indicates when to replace the filter element.
Reality
These devices serve only to get a general idea of pressure reduction since they are not subject to calibration and allow a level of accuracy of about +/- 25 percent. Gauges should not be used as indicators because of the need for maintenance, and it is best to follow the manufacturer’s instructions in this regard.
Myth
Filter elements of compressed air filters should be replaced only when the differential pressure increases.
Reality
Although it is good practice to keep the differential pressure low, the spread of contamination does not strictly depend on it. Consequently, it is not a particular indication of the need for maintenance of the filter element.
Conclusions
Filter elements must be replaced periodically to ensure a continuous supply of high-quality compressed air.
Protection of adsorption dryer beds.
Protection of downstream equipment, personnel and processes.
Reduced operating costs.
Increased productivity and profitability.
Tranquility at all times.
This article was written with input from Mark White, Compressed Air Treatment Applications Manager – Parker Gas Separation and Filtration Division EMEA
If you enjoyed this article, you may also be interested in:
Why it always pays to install coalescing filters in pairs
Three moves to avoid costly downtime in compressed air systems
How compressed air redefines bottling processes
Parker Hannifin | Parker Hannifin