GP · HEPA · ULPA
Fume Cupboard Filters
GP Plus!, acid, mercury, ammonia and formaldehyde grades, plus HEPA and ULPA. Supplied on their own or supplied and fitted, with the spent media taken away under licence.
On a ductless cupboard, the filter is the containment
A ducted cupboard sends its exhaust outside the building. A ductless recirculating unit does not — it cleans the air and returns it to the room the operator is standing in. Everything therefore depends on the media doing its job.
Carbon does not fail visibly. It saturates, and once saturated it stops adsorbing and starts letting vapour straight through. The airflow reads perfectly normal throughout. The first sign is usually somebody noticing a smell, by which point breakthrough has already happened.
This is why filter life is assessed against actual use rather than a date on a chart, and why the media has to match the chemistry. A general purpose carbon filter will not hold ammonia or formaldehyde.
A smell means stop Any odour from a ductless unit should be treated as breakthrough. Take it out of use and call us before it is used again.
Life depends on use, not age Light teaching use can give several years. Sustained solvent work can exhaust the same filter in months. We set the interval from what you actually do in the cupboard.
Spent media is controlled waste A used filter holds everything it captured. We remove and dispose of it under our waste carrier licence, with a transfer note for your file.
Filter types
Media matched to the chemistry
Tell us what is used in the cupboard and we will specify the filter. If the work has changed since the unit was installed, the filter specification probably needs to change with it.
Other formulations are available, and where more than one chemical family is involved a multi-layered filter may be the answer. Quote the grade currently fitted and we will match it; otherwise describe the work and we will specify it with you.
How the stages work together
A recirculating unit filters in stages, and each stage protects the one behind it. Configurations can be combined to cover acids, bases and particulates in the same cupboard.
Stage 01 — pre-filter
Electrostatic
Catches aerosols, mists and dust so particulate loading does not blind the main filter. Cheap to change and it extends the life of everything downstream.
Stage 02 — main filter
Carbon or HEPA / ULPA
The working filter, specified from the grades above. Carbon for vapours, HEPA or ULPA for particulates, or both where the work demands it.
Stage 03 — safety filter
Optional second line
A further filter downstream of the main one, giving margin if the main filter reaches breakthrough between service visits.
Where carbon filtration is the wrong answer
We would rather tell you this before you buy. Activated carbon is not suitable where very large quantities of contaminant or highly toxic substances are produced — acid digestions and evaporating solvents to dryness are the two that come up most often. In those cases you need a ducted cupboard, and we will say so.
Two other points worth knowing. Where several chemicals are used, retention capacities are not additive — the filter has to be assessed as a weighted average across the whole workload, not chosen for the worst single substance. And after any significant spill or release, the filter should be replaced rather than assumed to have survived it.
Ductless units are also not intended for explosive, flammable or radiological materials unless your chemical safety officer has assessed and approved the application. Final responsibility for chemical suitability rests with your safety officer and employer; our job is to give you accurate information and the right filter for what you have signed off.
Supply or supply and fit
Two ways to buy, one of them safer
We supply filters to in-house teams every week and there is nothing wrong with changing your own consumables. But a filter is only doing its job if it is seated correctly, and a poor seal lets air take the easy route round the media rather than through it.
On a ductless unit that failure is invisible. The fan still runs, the monitor still reads, and nothing indicates that the air returning to the room is untreated.
Where we fit, we verify performance afterwards and record the change against the unit’s asset number, so the next person knows what media is in there and when it went in.
Supply only
Correct media identified for your unit and application, quoted and dispatched. You handle fitting and the disposal of the old filter.
Recommended
Supply and fit
Fitted and seated by a DBS-checked engineer, performance verified afterwards, old media removed under our waste carrier licence with a transfer note, and the work recorded.
On a maintenance contract
Filter condition assessed at every visit and replacement scheduled on interval at agreed rates. Servicing & maintenance
Where ductless wins
Filtration where ductwork is not an option
Recirculating units exist because plenty of buildings cannot take a duct to atmosphere. Getting the filtration right is what makes them a legitimate answer rather than a compromise.
If you are weighing ducted against ductless for a particular room, we will give you a straight answer about which suits the work.
LISTED BUILDINGS
Where external ductwork or roof penetrations are not permitted.
SCHOOLS
Older estates where running duct through occupied floors is impractical.
MOBILE & TEMPORARY
Units that need to move between rooms, sites or projects.
LIMITED VENTILATION
Internal rooms with no external wall and no route to atmosphere.
Not by looking at it. Carbon gives no visual indication of saturation. We assess condition, recorded usage and elapsed time at each service visit and advise on a replacement interval for your specific work. Waiting for a smell means waiting for breakthrough.
No. GP Plus! covers solvents, organics and alcohols, but it is not formulated for inorganic acids, ammonia, formaldehyde, mercury or iodine — each of those has its own grade. Fitting a general purpose filter where specialist media is required gives no meaningful protection against that substance.
Both capture particulates rather than vapours; ULPA captures a higher proportion of the very smallest particles. HEPA suits most laboratory powder and dust work. ULPA is specified where containment requirements are more demanding, typically cleanroom and pharmaceutical applications.
No. A spent filter holds everything it has captured, which makes it controlled waste, and your duty of care as the producer applies. We remove it under our waste carrier licence and issue a transfer note. Details on our removal and disposal page.
Yes. We supply compatible filters for most major ducted and ductless fume cupboards, fume hoods, laminar flow cabinets and biosafety cabinets, including UK, European and USA manufactured units. Send the make and model, or a photograph of the data plate.
Very possibly. Filter media is specified against the substances in use at the time. A cupboard commissioned for one process and later used for another may have entirely the wrong media in it. It is worth telling us if the work in a ductless unit has changed.
Request a quote
Request a filter quote
The two things that determine the filter are the unit and the chemistry. Tell us both and we will specify it.