MBRAUN MB 120B-G, Operating Instructions Manual

Page: 34 / 105

Chapter 7: Purging the System
Glove-Box systems either newly installed or opened for reasons of service contain ambient air. For building up
an absolutely pure gas atmosphere within the box
,
a nitrogen, argon or helium atmosphere of medium purity is
the prerequisite for the gas purification. Thus, prior to the system’s commissioning
,
the ambient air should be
replaced by nitrogen, argon or helium.
Displacing the ambient air from the system is called purging. Working gas is used as purging gas.
On
average
, a system should be purged when the O2 portion in the box atmosphere exceeds 250 ppm.
The reasons for
excessive
oxygen values are as follows:
- first commissioning of a system
- servicing
- air influx due to faulty operation
- air influx due to damage (leaks)
Caution!
A Glove-Box system should be purged using working gas until the O
2
portion within the box
atmosphere has decreased to a value of <100 ppm. Operating the system with higher oxygen
value
s
may result in damaging the gas purification system.
Working gas is used for purging the system;
Nitrogen, argon or helium - medium purity - from bottles or any gas supply facilities.
Example
of
the purge gas consumption of a
n
MBRAUN System
!
General information
Chapter 7
Purging the System
When is purging necessary?
Purge gas
0.00
0.00 0.50 1.00 1.50
c = 1 vpm
c = 10 vpm
c = 100 vpm
c = 500 vpm
c = 1000 vpm
5.00
10.00
15.00
20.00
25.00
Purge gas consumption [cbm
]
Boxvolume [cbm]
30.00
gc = f (v,c)
35