thuba PS 830 Manuel page 15

Manual BVS 19 ATEX E 080 X
d) Installer can also remove covers or
doors of internal housings if they pro-
vide adequate vent diameters alterna-
tively.
e) If the topics above are not applicable, a
separate piping must be added to the
internal compartment. The purge medi-
um flow through the compartment must
be high enough to make sure that the air
in the compartment is exchanged at
least 10 times higher.
For instance:
valve
nozzles for air
distribution
Ex pzc housing
2.3 Determination of pre-purging period
If its not sure, at power up, that the atmosphere
inside of the enclosure and the appropriate pipes
is below 25% of the lower explosive limit (LEL)
(IEC 60079-14 chapter 13.4), a prepurging of the
pressurized enclosure is necessary.
The pre purging of the housing is prohibited, by
an Ex pD system (pressurized enclosure in zone
22).
2.4 Purge medium requirements
1 The purging medium must not be derived
from hazardous area, it must be contamina-
tion free (dry, free of oil and dust)
2 The temperature of the purge medium
should not exceed 40°C.
3 If another purge medium than air is used, it
is important to regard the minimum oxygen
content of the ambient. Maybe it is neces-
sary to install a exhaust pipe from the PS
830 to out-of-door.
Edition July 2020
Copyright
internal compartment
PS840
d) 安装人员也可以拆卸内部腔体的盖子或
门，或者如果他们提供足够的通风口直
径。
e) 如果上述细目不适用，则必须在内部隔
间中添加一个单独的管道。 吹扫介质流
过隔间必须足够高，以确保隔间内的空
气至少交换高于10倍。
例如：
valve
nozzles for air
distribution
Ex pzc housing
2.3 预吹扫期的测定
如果不确定，在通电时，外壳和适当管道内的大
气是否低于爆炸下限(LEL)的25%(IEC60079-
14第13.4章)，则需要对正压外壳进行预吹扫。
对于防爆正压粉尘系统Ex pD（第22区正压外
壳), 禁止对外壳进行预吹扫.
2.4 吹扫介质要求
1. 吹扫介质不得来自危险区域，必须是无污
染的（干燥的，没有油和灰尘）。
2. 吹扫介质的温度不应超过40°。
3. 如果使用除空气以外其它吹扫介质，重要
的是考虑环境的最小氧含量。 也许有必要
安装一个排气管从PS830到户外。
11
internal compartment
PS840
thuba Ltd., CH-4002 Basel
Switzerland