KROHNE H250 M9S ATEX II3D Ex t-II3G Ex nA EN - Manual (Page 6)

2
DEVICE DESCRIPTION
6
H250 M9
www.krohne.com 10/2012 - 4000646002 MA H250/M9-Ex-II3GD-AD-R06-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
The flowmeters are designed in category II 3G according to EN 60079-0 and EN 60079-15 and
category II 3D according to EN 60079-31 for use in hazardous areas, zone 2 and zone 22.
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.
AD_H250_M9_II3GD_R06_en_646002_PRT.book Page 6 Wednesday, October 17, 2012 8:03 AM