Richter NKP Series Butterfly Valves - Manual (Page 9)

Series NKL, NKLP, NKS, NKSP, NK, NKP
Page 9
9520-070-en Revision 04
TM 7113 Edition 05/2008
3 Safety notes for applications in potentially explosive areas
based on the Directive 94/9/ EC (Atex 95)
The valves are intended for use in a potentially
explosive area and are therefore subject to the
conformity assessment procedure of the directive
94/9/EC (ATEX).
As part of this conformity assessment, an ignition ha-
zard analysis to EN 13463-1 to satisfy the fundamen-
tal 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 explo-
sive area.
Supplementary notes:
Electric/mechanical actuators must be subjec-
ted to their own conformity assessment to A-
TEX.
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 inadmissible modes of
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 occupa-
tional 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 li-
ning
Charges can occur on the lining surface. As a re-
sult, this can produce discharges inside the valve.
However, these discharges 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 recommended to wait 1 hour before removing
the valve from the plant in order to permit the eli-
mination 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.
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 tempe-
rature as per the operating manual.
If the valve is heated (e.g. heating jacket), it must
be ensured that the temperature classes prescri-
bed in the Annex are observed.
To achieve safe and reliable operation, it must be
ensured in inspections at regular intervals that the
unit is properly serviced and kept in technically
perfect order
Increased wear to the valve can be expected with
the conveyance of liquids containing abrasive con-
stituents. The inspection intervals are to be redu-
ced compared with the usual times.
Actuators and electric peripherals, such as tempe-
rature, pressure and flow sensors etc., must
comply with the valid safety requirements and exp-
losion 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 other ac-
tion, e.g. cable bridges.
Attachments such as actuators, position control-
lers, limit switches etc. must satisfy the relevant sa-
fety regulations as regards explosion protection
and, if required, be designed in compliance with
ATEX.
Special attention must be paid to the appropriate
safety and explosion protection notes in the
respective operating manuals.
Plastic-lined valves must not be operated with car-
bon disulphide.