Series
KNAR/F, KNARP/F, KNAR-D/F, KNARP-D/F,
Page
8
KNAR-S/F, KNARP-S/F
ASME
9520-032-en
Revision 15
TM 9549
Edition 11/2018
3
Safety notes for applications in potentially explosive areas
based on the Directive 2014/34/ EC (ATEX)
The valves are intended for use in a potentially
explosive area and are therefore subject to the
conformity assessment procedure of the directive
2014/34/EC (ATEX).
As part of this conformity assessment, an ignition
hazard analysis to EN 13463-1 to satisfy the
fundamental safety and health requirements was
conducted with the following result:
♦
The valves do not have any ignition source of
their own and can be operated both manually
as well as mechanically/electrically.
♦
The valves are not covered by the scope of
application of the ATEX directive and therefore
do not need to be identified accordingly.
♦
The valves may be used in a potentially
explosive area.
Supplementary notes:
♦
Electric/mechanical
actuators
must
be
subjected to their own conformity assessment
to ATEX.
It is imperative to observe the individual points of
intended use for application in a potentially explosive
area.
3.1 Intended use
Inadmissible modes of operation, even for brief
periods, may result in serious damage to the unit.
In connection with explosion protection, potential
sources of ignition (overheating, electrostatic and
induced charges, mechanical and electric sparks)
may result from these improper operation; their
occurrence can only be prevented by adhering to
the intended use.
Furthermore, reference is made in this connection to
the Directive 95/C332/06 (ATEX 118a) which contains
the minimum regulations for improving the
occupational health and safety of the workers who
may be at risk from an explosive atmosphere.
A difference is made between two cases for the use of
chargeable liquids (conductivity < 10
-8
S/m):
1. Chargeable liquid and non-conductive
lining
Charges can occur on the lining surface. As a
result, this can produce discharges inside and
outside the valve.
a) Discharges inside the valve
However, these discharges inside the valve cannot
cause ignitions if the valve is completely filled with
medium.
If the valve is not completely filled with medium,
e.g. during evacuation and filling, the formation of
an explosive atmosphere must be prevented, e.g.
by superimposing a layer of nitrogen. It is recom-
mended to wait 1 hour before removing the valve
from the plant in order to permit the elimination of
static peak charges.
This means that, to safely prevent ignitions, the
valve must be completely filled with medium at all
times or else a potentially explosive atmosphere
must be excluded by superimposing a layer of inert
gas.
b) Discharges outside the valve
At the points where the non-conductive lining e.g.
protrudes on the sealing surfaces to the outside or
gets contact with the atmosphere on the outside, it
may lead to discharges from the lining to nearby
valves or attachments.
To safely avoid explosion hazards and accidents,
therefore, the atmosphere surrounding the valve
must not be explosive.
2. Chargeable liquid and conductive lining
No hazardous charges can occur as charges are
discharged direct via the lining and shell (surface
resistance < 10
9
Ohm, leakage resistance < 10
6
Ohm).
Static discharges of non-conductive linings are
only produced through the interaction with a
non-conductive medium and are therefore the
responsibility of the plant operator.
Static discharges are not sources of ignition
which stem from the valves themselves!
♦
The temperature of the medium must not exceed
the temperature of the corresponding temperature
class or the maximum admissible medium temper-
ature as per the operating manual.
♦
If the valve is heated (e.g. heating jacket), it must
be ensured that the temperature classes pre-
scribed in the Annex are observed.
♦
For safe and reliable operation, it must be ensured
with regular inspection intervals that the unit is
properly serviced and kept in a perfect technical
condition.
♦
Increased wear to the valve can be expected with
the conveyance of liquids containing abrasive
constituents. The inspection intervals are to be
reduced compared with the usual times.
♦
Actuators and electric peripherals, such as
temperature, pressure and flow sensors etc., must
comply with the valid safety requirements and
explosion protection provisions.
♦
The valve must be grounded.
This can be achieved in the simplest way via the
pipe screws using tooth lock washers.
Otherwise grounding must be ensured by different
measures e.g. a cable link.
