系列選型兩位兩通防爆電磁閥ode，ODE技術(shù)特性
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系列選型兩位兩通防爆電磁閥ode，ODE技術(shù)特性
The danger areas are the places in the system where a dangerous atmosphere could be created during normal
operation or because of breakdowns. In Italy the classification of danger areas is regulated by the CEI 60-2
standard, some notes on which are given as follows:
DANGEROUS ATMOSPHERE
系列選型兩位兩通防爆電磁閥ode，ODE技術(shù)特性
系列選型兩位兩通防爆電磁閥ode，ODE技術(shù)特性
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系列選型兩位兩通防爆電磁閥ode，ODE技術(shù)特性
The danger areas are the places in the system where a dangerous atmosphere could be created during normal
operation or because of breakdowns. In Italy the classification of danger areas is regulated by the CEI 60-2
standard, some notes on which are given as follows:
DANGEROUS ATMOSPHERE
A dangerous atmosphere is an atmosphere formed, or reasonably liable to be formed, by the mixing with air, at
atmospheric conditions, of inflammable substances in the form of gas, vapours, smoke or powders in such
proportions that a thermal phenomenon (excessive temperature, electric arc or spark) may cause them to
explode.
DANGEROUS PLACE
Dangerous places are subdivided into the following four classes (in function of the substances present):
- C0 (CLASS 0 places): places containing explosive substances.
which may occur. The temperatures are referred to a room temperature of 40°C.
N.B.: the term "billion" in Italy, Germany and Britain has the meaning of 10 whereas in
U.S.A. and France it has the meaning of 10 . Therefore, if this term should be used, it is advisable to request an clear explanation of its meaning so as to avoid mistakes.
sometimes the power absorbed by coils is expressed in volt-amperes (VA). This measurement
unit does not have a fixed correspondence with the S. I. measurement unit (Watt). This non-correspondence is because of the voltage-current phase displacement which, when the coil is energized
with alternating current, varies as the coil and the valve on which it is mounted vary.
An APPROXIMATE value for VA-Watt correspondence is 0.6: 1 VA = 0.6 Watts
- episodic or for short periods of time (ZONE 2)
- present for periods of less than 0,01 hour a year. (ZONE R)
The safety required depends on the CLASS combined with the ZONE rating.
For CLASS 1 (C1) equipment, the standards provide for a further classification based on the installation place
and the gas type that may be present. Therefore, there are 2 subgroups:
GROUP I - Equipment to be used in mines
- C1 (CLASS 1 places): places containing inflammable substances in the form of gas or vapours in minimum
quantities indicated by the standard.
- C2 (CLASS 2 places): places containing inflammable powders (E-electric conductors; NE-non-electric
conductors).
- C3 (CLASS 3 places): places containing inflammable substances in quantities which are lower than the
minimum indicated for class 1.
By the legislative provisions, in dangerous atmospheres, in Italy only equipment conforming to the "EEx"
European standards can be used which have been certified by an authorized laboratory and which bear the
distinctive community mark.
As in some countries there are local protection methods which are not recognized by CENELEC, some of these
are listed as follows:
- (CEI 79-15) "N" non-incendiary protection method for zone 2 (Netherlands and United Kingdom)
- "H" hermetic protection method (Netherlands)
- "S" protection method (Netherlands and Germany)
- ICS-6 A NSI/NEMA 7.9 Standard (U.S.A.)
PARAMETERS FOR THE CHOICE OF THE PROTECTION METHOD
The choice of protection method depends on the place where the equipment is to be installed (class and zone)
and subsequently on the type of atmosphere present.
DANGEROUS ZONES
A zone where the presence of a dangerous atmosphere is possible. There are four types of dangerous zone
depending on the fact that the dangerous atmosphere is:
- permanent or for long periods of time (ZONE 0)
- intermittent in normal service (ZONE 1)
TEMPERATURE CLASSES
For all GROUP II equipment, the standards also provide a classification based on the maximum surface
temperature that the same equipment can reach both during normal operation and because of any breakdowns
GROUP II - Equipment for surface installation.
GROUP II is further subdivided based on the atmosphere to which the equipment is destined. For protection
modes "d" and "i", the standards define three subgroups (A-B-C) which identify the gases with which the
equipment comes into contact.
系列選型兩位兩通防爆電磁閥ode，ODE技術(shù)特性
