KROHNE H250 M40 ATEX II2D Ex t-II2G Ex d EN - Manual (Page 8)

2
DEVICE DESCRIPTION
8
H250 M40
www.krohne.com 07/2012 - 4002069601 - MA H250/M40-Ex-II2GD-AD R01
2.7 Ambient temperature / temperature classes
Due to the influence of the product temperature, variable area flowmeters with built-in electrical
equipment (electric variants) are not assigned to any fixed temperature class. In fact, the
temperature class of a device is a function of the temperature of both the product and the
environment. The classification is outlined in the following tables.
The tables take into account the following parameters:
• Maximum value P
i
• Ambient temperature T
amb.
• Product temperature T
m
• Nominal DN
• Standard or high temperature version (HT)
• Standard or heating jacket version
• Heat resistance of the connecting cable
The permitted ambient temperature range is indicated on the nameplate; depending on the
device version it is T
amb
= -40...+60°C / -40...+140°F or T
amb
= -20...+60°C / -4...+140°F.
The minimum product temperature is -40°C / -40°F.
For certain device version, lower values apply due to differing boundary conditions (e.g. lining
materials). Here the user should consult the technical data sheet.
INFORMATION!
The maximum permissible product temperatures listed in the tables are valid under
the following conditions:
• The measuring device is installed and operated in accordance with the manufacturer's
installation instructions.
• It must be ensured that the flowmeter is not heated by the effects of additional heat radiation
(sunshine, neighbouring system components) and thus operated above the permissible
ambient temperature range.
• Insulation must be limited to the piping.
Unobstructed ventilation of the indicator part must be ensured.
To do this, the variant with a projecting indicator (HT version) is preferable.
• For device versions with a heating jacket, that the temperature of the heating medium does
not exceed the maximum permissible product temperature.
INFORMATION!
The following conditions must be met for all versions:
• Standard connecting cable, temperature resistance min. 70°C / 158°F.
• Heat-resistant connecting cable, temperature resistance min. 90°C / 194°F.
AD_H250_M40_II2GD_R01_en_4002069601_PRT.book Page 8 Friday, July 27, 2012 8:17 AM