On Fri, 28 May 1999 [email protected] wrote:
> A bit off the beaten path but maybe someone can interpret for me
> the basics of the Pressure Equipment directive 97/23/EC. For
> something to have to conform to it's requirements it needs to have
> a maximum allowable pressure greater than 0.5 bar... Is there
> also a requirement for the volume as well as with the Simple
> Pressure Vessel directive? Thanks for any help or a point in the
> right direction
Yes, volume also comes into play.
The Pressure Equipment Directive describes the perimeter of
several "Categories" of vessel and piping, from category I thru
category IV, with higher numbers being more hazardous. The
categorization considers the fluid (flammable, poison, oxidizing,
etc. being more hazardous) and the vapor pressure of the liquid at
the maximum rated temperature, in addition to the pressure * volume
value.
The quality control measures, including the extent of
notified body involvement, varies, depending on the category of the
equipment.
Piping is categorized according to its nominal inside
diameter (DN value) along with the pressure to be contained.
A different table is provided for equipment that intended to
generate steam. Pressure cookers are always category III.
Article 1 of the Pressure Equipment Directive has a
substantial list of exclusions. For example, category I pressure
equipment that falls under the Machinery Directive (for example, as
part of a machine, rather than as a "pressure only" apparatus) or
the Low Voltage Directive are expressly excluded from the Pressure
Equipment Directive.
Article 3, paragraph 3 says that those devices presenting
less hazard than defined as being in category I are NOT to be marked
for purposes of showing conformance with the Pressure Equipment
Directive.
Finally, an example of the pressure*volume limits as
described by Article 3, paragraph 1.1(a) and Annex II, Table 2:
- for "non-hazardous" fluids,
- where the vapor pressure is over 0.5 bar at the maximum
temperature of the equipment,
- category I begins at a volume of 1 liter (if < 1 liter
and < 1000 bar, it is Art 3, para 3), is limited to pressures below
1000 bar, and includes equipment from 50 bar*liter to 200 bar*liter.
Regards,
Chuck Seyboldt
Weinstein Associates
8 Lincoln Street
Brunswick, Maine 04011
(207) 725-2111
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