Schools Fume Cupboard Repairs

We get called to test schools fume cupboards on a regular basis. We find that most of the older schools have ducted fume cupboards, however many of the newer school builds have re-circulating fume cupboards. This is mainly due to the perceived cost savings relating to the installation costs of ducted fume cupboards, and the added flexibility of mobile units to be used in multiple locations.

While upfront costs are reduced when opting for a mobile recirculating fume cupboard the ongoing costs are usually much higher than a ducted fume cupboard.
As a result of this high ongoing cost of filtered recirculating fume cupboards many schools are not maintaining their fume cupboards to the minimum safe levels, as the carbon filters are not being changed on a regular basis.

CLEAPSS recommend the active carbon filters are changed every 2-4 years depending on the usage. However we have found that in many cases these guidelines are not being kept to. Either through lack of available money or a lack of knowledge regarding the different types of fume cupboards and the specifics on how they function.

The Carbon filter is designed to absorb the nasty chemical fumes from experiments performed within the fume cupboard. After a certain amount of time the carbon filter will become saturated. When a carbon filter becomes saturated there is no longer any space for the fumes to attach to the carbon. At this point they pass through the filter and get ejected back into the room.

This is the major danger with re-circulating fume cupboards. They are only as good as the filter. In some of the worst cases we have found carbon filters that are 15 years old. At this age the filter will most certainly be saturated, and the seal may also have deteriorated causing fumes to pass through and around the filter and being blown back into the room.

It is very difficult to tell when a filter has become saturated, and a large chemical spill in a fume cupboard could saturate the filter (even if it is only a few months old). It is for this reason we have the option to carry out a filter seal test and filter saturation test on schools fume cupboards especially when no regular filter changing has been set up.

With the cost of a new carbon filter being between £180 and £280 The filter seal and saturation test is usually more cost effective. However if the filter is over 4 years old we would always urge the school to invest in new filters.
If your service records do not show a carbon filter change or a filter test in the past 4 years we would highly recommend a filter test is carried out so you can make sure the filter is working correctly. (We have seen some filters that have failed after 6 months due to high usage like wise we have been testing some for up to 5 years without them needing changing.)