Application Note
A brief look at
ATEX and its
impact in the US
What is “Intrinsically
Safe?”
Intrinsic safety is a protection
standard employed in poten-
tially explosive atmospheres.
Devices that are certified as
“intrinsically safe
” are designed
to be unable to release suffi-
cient energy, by either thermal
or electrical means, to cause
ignition of flammable material
(gas, dust/particulates).
Intrinsically safe standards
apply to all equipment that can
create one or more of a range
of defined potential explosion
sources:
•
Electrical sparks
•
Electrical arcs
•
Flames
•
Hot surfaces
•
Static electricity
•
Electromagnetic radiation
•
Chemical reactions
•
Mechanical impact
•
Mechanical friction
•
Compression ignition
•
Acoustic energy
•
Ionizing radiation
What industries are
intrinsically safe
products designed f
or?
•
P
etro-chemical
•
Oil platforms and refineries
•
Pharmaceutical
•
Bulk materials (e.g. grain)
•
Mining
•
Pipelines
•
Any environment where
explosive gases are present
What organizations
are defining intrinsically
safe standards?
ATEX
The primary intrinsically safe
standard has been set in the
European Union with the
Directive 94/9/EC, commonly
called ATEX (“Atmosphères
Explosibles,” French for explo-
sive atmospheres). The stated
goal of the guidelines is to
“help ensure the free move-
ment of products in the
European Union” by “minimiz-
ing the number of safeguard
clause applications, at least
those originating from diver-
gent interpretations.” ATEX
is intended to serve as total
harmonization directive, laying
down essential health and
safety requirements, and
replacing existing divergent
national and European legisla-
tion which covers the same
subjects.
The A
T
EX rules ha
ve b
een
in place as a voluntary stan-
dard since March 1, 1996. The
rules are mandatory on electri-
cal and electronic equipment
for use in environments subject
to explosion hazard sold in the
E
U as of July 1
, 2003.
IEC
The International Electrotech-
nical Commission (IEC) is
responsible for setting interna-
tional standards for electrical
technology. Its technical com-
mittee T
C3
1 deals w
ith
explosion protection for electri
-
cal apparatus. It has introduced
a procedure, the IECEx Scheme,
which is intended to become a
globally recognized test and
c
ertification proc
edure for
explosion protection.
The objective of the IECEx
Scheme is to facilitate interna-
tional trade in electrical
equipment intended for use in
explosive atmospheres by:
•
reducing testing and certifi-
cation c
osts to manufacturers
•
reducing time to market
•
providing international
confidence in the product
assessment process
•
providing one international
database listing
The IECEx has not yet been
ratified.
Factory Mutual
In The United States, Factory
Mutual Research, managed by
Factory Mutual (FM) Global, is a
not-for-profit scientific and
testing organization that has
tested and certified over
40,000 products in the last 165
years. FM Research has set cer-
tification guidelines for
equipment used in potentially
explosive atmospheres.
NEC
The NFPA (National Fire
Protection Association)
70,
National Electrical Code
, also
known as the NEC, is the basis
for all electrical codes in the
United States
. Classifications
and related product markings
for hazardous areas are c
overed
in NEC 500 and 505. These are
similar to, but not exactly the
same as, those in A
TEX.
OSHA
O
S
H
A (O
c
cupational Safety &
Health Administration of the
U
.S. Department of Labor) par-
ticipates in the
US-EU
Cooperation on Workplace
Safety & Health
. This is a proj-
ect of the U.S. DOL, OSHA, and
the EU European Agency for
Health and Safety at W
ork
. The
Application Note
From the Fluke Digital Library @ www.fluke.com/library