HEPA Laminar Flow Filters

TECHNICAL SPECIFICATION

Filter Class - H13
Filters global efficiency % for MPPS particles - ≥ 99.95 %
Local Efficiency % for MPPS particles - 99.75%

Filter Class - H14
Filters global efficiency % for MPPS particles - ≥ 99.995 %
Local Efficiency % for MPPS particles - 99.98%

MEDIA - Glass fibre paper
SEPARATORS - Hot melt glue
FRAME - Anodized aluminium profile 68-115 mm deep or MDF wooden frame
FACE GUARDS - Metal frame has epoxy painted expanded aluminium grids on both sides. Special Grid lock keeps the mesh away from the filter pack. Not fitted as standard to wooden frame, optional extra.
SEALANT - Two components cold moulded polyurethane

FAQs

What are HEPA filters?

HEPA (High Efficiency Particulate Air) filter can remove a minimum of 99.97% of dust, pollen, bacteria, mold and any other types of airborne particle with a size of 0.3 micron which is generally known as the MPPS (Most Penetrating Particle Size).

It is at this point that people start scratching their heads and looking a little confused, what is MPPS and why haven't I heard this term before? MPPS is a term that is used with HEPA filters but not with many other types of filter such as pleated panels or Procart extraction filters as these filters will capture particles to a certain size and anything smaller will, in theory, pass through. So they are Top Down filters, they capture big things but not small.

HEPA filters, on the other hand, will capture both big particles and small particles and they can do this as they capture the different sizes in different ways. Firstly, the largest particles fly into a HEPA filter but they are too big to get through the fibres so they get stuck. This type of filtration is called 'straining' and is generally for particles of around 10 microns. For smaller particles that can pass through the fibres, the larger ones will follow the flow of air but will be too heavy therefore too slow to pass all of the way through the panel so will drop out of the airflow and be captured. This type of filtration is called 'interception'. Then we have the smallest particles which are generally below 0.3 microns. These are very small and have such little mass that they don't travel in straight lines with the flow of air, they rebound when they hit gas molecules so they move in random patterns which results in them bouncing around and hitting the fibers of the HEPA filter and getting stuck. This type of filtration is called 'diffusion'.

This all sounds great, and it is, however there is a size of particle that falls between the filtration methods and this weak spot is known as the MPPS. This is around 0.3 microns which is too small for straining and too large for diffusion and so this is why we show the MPPS filtration efficiency percentage of our HEPA filters.

When should I replace a HEPA filter?

Its very hard to give a definite time for when to replace an old HEPA filter as there are many elements involved, for instance, humidity, filter location, usage time, the quality of air entering the HEPA and the quality of air filtration required.

In general terms, the HEPA filter should be changed every 3 to 6 months, which is a relatively broad average. When a filter's capacity to capture a large number of particles is reduced, it should be replaced. Let’s say, if you keep using a filter that is only 50% effective, that means it would take about double amount of time to clean the air in the same room compared to a normal HEPA filter. This is something that should be remembered when your HEPA starts to age.

Which depth of HEPA air filter should I choose?

There is not much difference in air filtration when comparing the depths of HEPA air filter apart from airflow and pressure drop. Generally your choice of depth of HEPA filter will depend on the frame in which you are fitting it. If you are making your own frame, we recommend choosing the depth of filter based on your fan specifications. SPCB UK can supply most filter sizes and depths according to your requirements with a lead time of a few weeks. Standard depths depend on the type of filter:

Laminar Flow: 68mm, 78mm, 88mm, 110mm, 115mm - custom depths up to 125mm
Turbulent Flow: 150mm, 292mm - custom depths up to 305mm
Deep Pleat: 150mm, 292mm - custom depths up to 300mm

We recommend comparing fan specifications with the technical sheets on our website at https://spcb.co.uk/air-filtration/hepa-filters

If you require more information, then do please contact us

Should I use HEPA filters in my spray booth?

Please don't use these to filter air entering a spray booth. You will not require air that has been filtered to this quality for a booth in which you are conducting standard spraying. Our Pleated Panels or Protop will provide perfectly adequate air quality. HEPA filters will also offer far too much resistance for a spray booth so the extraction fan will not function properly.

What is the difference between a wooden and a metal framed HEPA filter?

The filter efficiency is the same whether you have a wooden frame or a metal frame so if your concern is filtration quality then you can choose either frame type and receive the same filtration levels. Whilst a wooden framed High Efficiency Particulate Air (HEPA) filter is generally cheaper than a metal cased alternative, there are some important differences.

A metal frame will be more rigid and robust than the MDF equivalent and will be moisture resistant. This is of value during the installation process. However, the metal frame also includes grills to support and protect the filter medium. Whilst grills are also optional on the wooden frame, this increases the price.

The wooden option is generally a great version for recycling and / or disposal by burning which would not be possible with a metal grill in place.

Why would it not be a good idea to clean a HEPA filter?

Some of you may be thinking of trying to clean your HEPA filter yourself in order to save a little money but cleaning a HEPA filter is not the best of ideas for many reasons. Firstly, a HEPA contains many extremely thin mesh fibres which enable the filter to function but they are very delicate so any form of brushing or wiping could, very easily, cause damage. Even you could be certain that the filter would not be damaged during the cleaning process, there are other reasons why cleaning a HEPA filter is not a good idea.

Cleaning a filter is a very dirty job. There is a high possibility that you will bring some airborne contaminants into your home or workspace unless you undertake the cleaning outside. Getting rid of those pollutants would be your biggest reason using a HEPA filter in the first place. Any contaminants from the filter, that are introduced back into the air, may lead to new microbial growth or you may inhale some of the contaminants which could result in breathing difficulties.

What is the minimum / maximum particle size that will pass through this filter?

As detailed in the Technical Specification section, HEPA filters work in a different way to a standard filter which means that the filters will collect all size of particles. There is a weak point, however, at 0.3 microns which is known as MPPS (Most Penetrating Particle Size). This is why we show the filtration efficiency for this size of particle as this is the minimum quality of filtration. For further information please look in the Technical Specification section