EN 12941/A2 This European Standard specifies minimum requirements for powered filtering devices incorporating a helmet or a hood with gas, particle or combined filter(s). It does not cover devices designed for use in circumstances where there is or might be an oxygen deficency (oxygen less than 17% by volume). Also it does not cover respiratory protective devices designed for escape purposes.
EN 12942/A2 This European Standard specifies minimum requirements for power assisted respiratory protective devices which incorporate a full face mask, half mask or a quarter mask together with gas, particle or combined filter(s). It does not cover devices designed for uses in circumstances where there is or might be an oxygen deficiency (oxygen less than 17% by volume). Also, it does not cover respiratory protective devices designed for escape purposes. It must protect the user even if the PAPR is off.
EN 14594:2005 This European Standard specifies minimum requirements for continuous flow compressed air line breathing apparatus and a hood or a mask.
What is an Occupational Exposure Limit – OEL? The Occupational Exposure Limit (OEL) is the safety level for dust, fumes, gases and vapours, below which you may not need to wear respiratory protective equipment. For each known hazard, the Health & Safety Executive or equivalent national authority has set a safety limit, a concentration above which the user need to wear respiratory protective equipment. These safety limits are reviewed regularly and tend to increase rather than decrease. The OEL can be expressed as a long term limit relating to exposure by the operator for the 8 hours. This is more realistic of a working shift and is, therefore, the more common OEL. Short term limits relate to an exposure of 10 minutes in a day.Both are time weighted averages and take the average concentration over the 8 hour or 10 minute period.
How is the OEL expressed? Particulate or fume – mg/m3 : which means that the concentration is measured by weight in milligrams per cubic metre of air. This is the weight of dust in this volume of air. Gases which have no significant weight are measured in parts per million. Ozone = 1 ppm : which means that the safety limit of ozone is 1 molecule of ozone in 1 million molecules, which is equivalent to .000001%.
Protection Factor – What does this mean? This is the concentration above the Occupational Exposure Limit that the respirator will protect up to. For example : The OEL of general welding fume is 5mg/m3. A respirator with a protection factor of 10 will provide protection up to10 x 5mg/m3= 50mg/m3 provided that 50mg/m3 is still below the IDLH of the given substance. A respirator with a protection factor of 50 will provide protection up to 50 x 5mg/m3= 250mg/m3 provided that 250mg/m3 is still below the IDLH of the given substance.
Nominal Protection Factor This is the protection factor assigned by the European Standard Authorities to the class of respirator. A Class of 2 powered respirator with a hood (TH2) under EN12941 has a nominal protection factor of 50. A Class 2 disposable face mask (FFP2) under EN149 has a nominal protection factor of 12.5.