Taken from
http://www.sba.co.uk/content/doc_11.pdf
European Standards - an overview
Powered Air Respirators
EN 146 (rev) & EN12941
There are two core European Standards covering the operation and technical specifications for Powered Air respirators, these are
prEN146 (rev) and EN12941.
In brief, prEN146 (rev) describes (a) the main components that make up the powered respiratory device: a helmet or hood, covering at
least the face (eyes, nose, mouth & chin), a power operated fan (turbo unit) and one or more filters, (b) the respirator’s operation: the
fan should provide a flow of filtered ambient air to the wearer in excess of the wearer's demand, with the exhaled air being discharged
outside the respirator by exhalation valves or other outlets and (c) the classifications of respirator: powered respirators are classified
into three categories depending on the levels of protection they offer the wearer: THP1, THP2 & THP3. (TH = Turbo Hood or Helmet)
In addition to the requirements set out in prEN146 (rev), EN12941 requires a compulsory low flow warning device to be incorporated
within a respirator system*; see descriptive text for the Jupiter Turbo unit as an example of this approval.
* not required for EN12941 TH1 devices