KROHNE DK 32-DK 34 NEPSI Ex nA - Manual (Page 5)

DEVICE DESCRIPTION
2
5
DK32 DK34
www.krohne.com 05/2013 - 4002598301 AD DK32/34 NEPSI Ex nA R01 en
2.4 Flammable products
Atmospheric conditions: Atmospheric conditions: Atmospheric conditions: Atmospheric conditions:
An explosive atmosphere is a mixture of air and flammable gases, vapours, mists or dusts under
atmospheric conditions. The following values define it
T
atm
= -20...+60°C / -4...+140°F and P
atm
= 0.8...1.1 bar.
Outside of this range, no key data are available as to ignition behaviour for most mixtures.
Installation conditions: Installation conditions: Installation conditions: Installation conditions:
Variable area flowmeters operate outside of atmospheric conditions, which means that
explosion protection – regardless of the zone assignment – is fundamentally not applicable due
to the lack of key safety data for the interior of the measuring section.
2.5 Device category
Variable area flowmeters are designed according to GB 3836.1-2010 and GB 3836.8-2010.
For more information see the chapter entitled "Flammable products".
2.6 Protection types
Variable area flowmeters can be operated as protection type "non-sparking".
Protection against explosion is ensured in that no sparking contacts or hot surfaces lead to
ignition under normal operating conditions.
WARNING!
Operation with flammable products is only permitted as long as no explosive fuel/air mixture
builds up on the inside of the flowmeter under operating conditions. The operator is responsible
for ensuring that the flowmeter is operated safely as regards the temperature and pressure of
the products used. In case of operation with flammable products the measuring units must be
included in the periodic pressure tests of the system. When using the device version H250/C...
(PTFE-liner, nonconductive) the min. conductivity of the medium must be 10
-8 S/m, in order to
avoid the electrostatic charge.
INFORMATION!
Definition of Zone 2 according to EN 1127-1, Appendix B:
An area in which an explosive atmosphere as a result of the mixture of flammable substances in
the form of gas, steam or mist with air is not expected to occur under normal operation. If,
however, such an atmosphere does occur it only lasts for a brief period of time.
The marking Ex nA IIC T1-T6 Gc Ex nA IIC T1-T6 Gc Ex nA IIC T1-T6 Gc Ex nA IIC T1-T6 Gc contains the following information:
Ex nA Ex nA Ex nA Ex nA Non-sparking equipment
IIC IIC IIC IIC Gas groups IIA, IIB, IIC
T1-T6 T1-T6 T1-T6 T1-T6 Temperature classes T6 ... T1
Gc Gc Gc Gc Equipment protection levels (EPL)
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