KROHNE H250 M40 ATEX II3G Ex nA EN - Manual (Page 6)

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DEVICE DESCRIPTION
6
H250 M40
www.krohne.com 01/2012 - 4001485201- MA H250/M40-Ex-II3G-AD 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 condititions: Installation condititions: Installation condititions: Installation condititions:
Variable area flowmeters operate outside of atmospheric conditions, which means that
explosion protection according to Directive 94/9/EC (ATEX) – 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 Equipment category
Variable area flowmeters are designed in accordance with EN 60079-0 and EN 60079-15 in
Category II 3 G or EPL Gc designed for use in zone 2. The inside of the measuring unit is also
permitted for zone 2.
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 acc. 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.
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