KROHNE H250 M9 ATEX II2G Ex i EN - Manual (Page 6)

2
DEVICE DESCRIPTION
6
H250 M9
www.krohne.com 11/2012 - 4000345604 MA H250/M9-Ex-II2G-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 Device category
Variable area flowmeters are designed according to EN 60079-0 and EN 60079-11 in category II 2
G for use in zone 1. The inside of the measuring unit is also approved for zone 1.
2.6 Types of protection
The variable area flowmeter is designed with protection type intrinsic safety, protection level "ia"
as per EN 60079-11.
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 1 as per EN 1127-1, Appendix B:
An area in which an explosive atmosphere may occasionally occur as a result of the mixture of
flammable substances in the form of gas, steam or mist with air under normal operation.
The marking II 2G Ex ia IIC T6 Gb II 2G Ex ia IIC T6 Gb II 2G Ex ia IIC T6 Gb II 2G Ex ia IIC T6 Gb contains the following information:
II IIII II Explosion protection Group II
2222 Device category 2
G G G G Gas explosion protection
Ex ia Ex ia Ex ia Ex ia Intrinsically safe, protection level "ia"
IIC IIC IIC IIC Suitable for gas groups IIC, IIB and IIA
T6 T6 T6 T6 Suitable for temperature classes T6 ... T1
Gb Gb Gb Gb EPL, suitable for zone 1
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