Molecules are the chemical building blocks of everything in our world. Controlling airborne molecules is a very different proposition to particle filtration. Molecules are typically 1000 to 10,000 times smaller than the finest particles and the number of molecules in air is billions or even trillions times higher than the number of particles.
Airborne molecules can impact in several ways: -
- as odours or smells (rotting eggs, fertilizer, wet paint)
- as toxins or poisons (military gases, hydrogen cyanide, isocyanates)
- as corrosive agents (sulphur dioxide, chlorine)
- as oxidising agents (ozone)
- as irritants (onion smell)
Many molecules are known to be harmful to humans and the wider environment. Inhaled molecules do not remain in the lungs, they can pass into the blood stream and be distributed all around the body. Molecules can also enter the body via the skin.
Molecules can be seriously detrimental to sensitive manufacturing processes and can irreversibly damage sensitive artefact in museums and art galleries.
Airborne molecules cannot be controlled using particle filters. Instead we utilise adsorption processes that can be provided by activated carbon, activated alumina and ion exchange resins
Applications for molecular filters
The applications for molecular filtration are extremely diverse and can be found in each of Camfil Farr’s principal market segments
Comfort air- Protecting people
Our work and leisure activities mean that we spend increasing amounts of time inside buildings. The necessary ventilation of buildings means we are increasingly exposed to the particulate and gas pollution in the external air.
Exposure to pollution has been known to impact humans for some time. The common health symptoms of headaches, itchy eyes, reduced work efficiency etc have been termed Sick Building Syndrome (SBS). (see IAQ for more information). Molecualr filtration may be readily applied in ventilation systems to combat these issues.
Clean Process – Protecting processes
Some manufacturing processes and production control equipment are extremely sensitive and difficult to operate without molecular filtration to protect them. Examples include:
- Semiconductor manufacture (removal of low concentrations of various gases)
- Pharmaceutical manufacture (removal of an oxidising agent – ozone)
- Pulp and paper industry (removal of acidic gases).
Molecular filtration is also used to protect sensitive and valuable artefacts in museums, art galleries and document archives.
Safety and Protection – protecting the environment
Manufacturing processes can liberate chemicals that can create an odour nuisance or are harmful to human health and the environment. Such processes may be subject to local or national regulation. Routinely, the operating licence requires that effective and durable molecular filtration is applied to prevent releases of the harmful chemical under normal operation and in some cases under emergency conditions.
Examples include:
- Manufacture of flexible polyurethane foam (removal of isocyanates)
- Manufacture of pesticides (removal of multiple toxic agents)
- Processing domestic waste (removal of odour)