Fume hood filtration comes of age

As we all become increasingly “green aware”, one company has been working to solve a problem presented in laboratories around the globe

An essential part of most labs is a safety fume hood which allows users to work safely when handling dangerous chemicals. Whilst hoods do protect the user, they unfortunately consume enormous amounts of energy whilst doing it. They generally run 24 hours a day to maintain the air balance in a building and consequently waste energy by constantly expelling heated/cooled air as well as pumping noxious contaminants directly outside into the surrounding environment.

Whilst the energy benefits of ductless filtration fume hoods have been known for some time, the limitation has been the scope of chemicals that the filters can handle, making it complicated to ensure safety and requiring users to select from up to five different types of filter.

Cambridge laboratory supplier, Camlab offer a solution from ERLAB called Green Fume Hood. The company say the  range offers all the energy saving benefits of filtration but addresses the problem of filter selectivity and capacity offering over 99% coverage with one filter.

The heart of the Green Fume Hoods is Neutrodine – conceived and developed by ERLAB’s Research and Development Laboratory. It represents a major advance in terms of molecular filtration based on a new generation of activated carbon produced from recycled crop materials. It massively extends the potential of carbon filtration and thanks to its capacity to adsorb a wide spectrum of molecules, is without any equivalent.

Before Neutrodine, raw activated carbons available for air filtration were known to be efficient at adsorbing apolar pollutants with a molecular mass above 30M. To trap lighter apolar pollutants, activated carbon manufacturers have traditionally impregnated the carbon with chemical additives. This process increased the adsorption capacity for polar molecules such as HCl or HN3 but had the downside of decreasing the adsorption capacity for other chemicals such as solvents, due to clogging of the porous network by the chemicals used during impregnation. This has limited activated carbon filter usage and made it essential to carefully select the appropriate activated carbon depending on the chemicals you wanted to use in the hood.

ERLAB’s extensive research work with Neutrodine technology has focused in particular on increasing filter adsorption capacities and on widening the spectrum of pollutants that can be trapped by the filter.

Neutrodine activated carbon is elaborated without using toxic impregnations which are harmful to the environment. Its specificity is based on a surface treatment which creates functional clusters dedicated to polar molecule adsorption, without causing porous network clogging, leaving it available to adsorb other molecules.
It is this large range of use that was the deciding factor for Dr Thomas Knowles at the University Of Cambridge. Working on protein expression using micro fluidics, Dr Knowles and his team make their own photo resist wafers to produce different reaction arrays. They needed a hood that could handle a wide range of chemicals used in the manufacturer of the wafers and chambers.

Fitting a new hood in the basement presented a number of additional challenges in terms of access to ductwork. On discussing the problem with Camlab it was decided to go with a ductless solution due to its ease of installation and mobility should the team want to alter the lab setup or move in the future. Looking at the wide array of chemicals likely to be used it was felt that the best solution was the new Green Fume Hood from ERLAB.

“Now used extensively in universities across the USA, this was the first installation in the UK and we believe it is also the first time Cambridge University has allowed the installation of a ductless solution,” says Rowan Maulder, marketing director of Camlab. “This was allowed following extensive checks by the safety team and because it offered a real solution in a difficult location for a wide range of chemicals”.

At the end of ERLAB’s research program, tests run by an independent laboratory Intertek certified the polyvalence of Neutrodine filters. Retention capacities obtained for cyclohexane, isopropyl alcohol and hydrochloric acid were far superior to the results obtained with old generation carbons.

This filtration reliability is demonstrated by filtration tests performed in accordance with the AFNOR NF X 15 211:2009. This standard – the most stringent in the world – challenges the filtration of a ductless fume hood and guarantees a concentration of chemicals at the filter exhaust lower than 1% of the work exposure limit.
ERLAB tests all its activated carbon in Neutrodine according to the ASTM standard protocol. Using their own stringent internal controls ERLAB are able to guarantee  density criteria, granular size distribution, ash content, moisture content, butane activity and retentiveness to ensure their filters perform perfectly every time.

The Green Fume Hood with Neutrodine polyvalent molecular filters provides a safe solution to a wide majority of needs in terms of chemical protection for laboratories while allowing massive energy savings and a reduction of pollution in the local environment. The addition of HEPA filters –dedicated to particles – further improves the safety of the hoods over ducted versions as they can be safely used for powders without the build up of contaminants in ductwork.

Authors: Dr Cedric Herry and Rowan Maulder
Cedric is director of research and development at Erlab Ltd and Rowan is marketing director at Camlab