Air and gas filters

The term "COGA" is protected by the Contec air and gas filtration division. It stands for Contec Gas and Air filters.

Contec adsorbers are used for fine gas cleaning that mechanical filtration cannot manage. An adsorber is a system that consists of an adsorber housing that encloses adsorbents. The adsorbents depend on the elements to be filtered (CO₂ or various halogens, for instance).

In addition to drying gases, adsorbers can remove the following:

• carbon dioxide and carbon monoxide
• sulfurous gases
• nitrous gases
• ammonia
• halogens
• heavy-metal composites and metallic mercury
• odorous substances, oil mist, petrol, tar condensate
• toxic and carcinogenic composites

Particle filters separate particles from gases or liquids when the fluid stream is routed into a housing with two connections and through a particle filter element. The filter element flow direction is from outside to inside.

The flow direction in coalescing filter elements is from inside to outside. A coalescing filter element essentially consists of two parts: a coalescing inner layer and a coarser outer layer for discharging the liquid. Aerosols and droplets are captured in the fine fibers of the inner layer, accumulate in the outer filter element layer during passage and move from there to a collection tray.

PTFE is the abbreviation for polytetrafluorethylene. PTFE is a linearly composed polymer made of fluorine and hydrocarbons. The semi-crystalline fluoroplastic exhibits extremely strong bonds between carbon and fluorine atoms. Colloquially, this plastic is often called "Teflon", a DuPont trade name. PTFE is very temperature-resistant.

PTFE's outstanding thermal and chemical resistance make it one of the most versatile plastics in air, gas and liquid filtration. It appears in the Contec filter range in diaphragm filters and candle filters and in the filter housing itself. PFTE is inert and cannot adsorb.

To select the right filter housing and element, consider the following:

1. maximum pressure
2. maximum/minimum temperature
3. chemical and physical characteristics of the filter medium
4. filter structure – inlet, particles, coalescence, bypass, diaphragm
5. type of contamination
6. maximum flow rate
7. line diameter and connection type
8. required filter fineness
9. cost parameters, reaction time, service life and interval

Points 1, 2 and 3 determine the construction material for the filter housing, filter element and seals.

Point 4 is crucial for housing configuration: One connection for intake filters, two connections for inline housings and three connections for coalescing, bypass and fast-loop housings.

Points 5, 6, 7, 8 and 9 determine filter size. This is generally a compromise between factors favoring a small filter (quick reaction time, small space requirements, low cost, minimized adsorption losses) and those favoring a large one (long maintenance intervals, low pressure loss). The decision therefore depends on the importance of these criteria and must be evaluated individually with each application.

Disposable filter elements offer low pressure losses, a long service life and very good filtration characteristics that are harmonized with the medium. It is generally a very economical solution. There is no cleaning and filter elements are replaced 1:1. If the medium is changed, the filter can be adjusted easily and individually to the new medium.

A differential pressure indicator indicates how much of a filter element is "taken up". It can be used to determine when the filter element should be replaced to ensure that the system works without problems and there are no expensive failures.