KROHNE H250 M9 NEPSI Ex nA - Manual (Page 6)

2
DEVICE DESCRIPTION
6
H250 M9
www.krohne.com 03/2013 - 4002616501 AD H250 M9 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
The flowmeters are designed according to GB 3836.1-2010 and GB 3836.8-2003.
2.6 Types of protection
The variable area flowmeter is designed in protection type "non-sparking" Ex nA. Explosion
protection is ensured by the absence of sparking contacts and hot surfaces during normal
operation.
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.
The marking Ex nA IIC T1 - T6 Gc contains the following information: The marking Ex nA IIC T1 - T6 Gc contains the following information: The marking Ex nA IIC T1 - T6 Gc contains the following information: The marking 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 Suitable for gas groups IIC, IIB and IIA
T1 - T6 T1 - T6 T1 - T6 T1 - T6 Suitable for temperature classes T6 ... T1
Gc Gc Gc Gc EPL, suitable for zone 2
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