Labconco Precise Controlled Atmosphere and Basic Glove Boxes 5220131 - Manual (Page 25)

Chapter 3: Getting Started
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chambers. Figure 3-11 shows test results of the oxygen decay or oxygen level
increase as a function of time. Per ISO specifications, Class 1 controlled
atmosphere chambers have a specified hourly leak rate of less than 5 x 10
-4 per
Table 3-1 listed at the end of Chapter 3.
Precise CA Glove Box
Oxygen Decay Leak
ISO 10648-2 Test Method
0
20
40
60
80
100
120
140
0 10 20 30 40 50 60 70 80
Oxygen ppm
Ti
me
Mi
nu
te
s
Oxygen Decay
Barometic Pressure:
28.66 inches of Hg
Main Chamber Temp.:
77.6° F
Main Chamber
Pressure: -4 inches
H
2
O
Transfer Chambler
Pressure: 0 inches
inches Hg
Leak Rate Box 1.7 x
10 -4
Class 1 Leak Rate <= 5
x 10 -4
Figure 3-11
The validation requirements and required testing instruments for all
applications shall be determined by the end user and Safety Officer. Other
validation test methods such as pressure leak decay tests may be conducted per
ISO 10648-2 standards. The pressure leak decay test may be performed, but
the pressure inside the glove box must be adjusted accurately for temperature
and barometric pressure.
These pressure leak decay tests are conducted under negative pressure of -
250 Pa (-1" water gauge) for operational use or -1000 Pa (-4" water gauge)
for the acceptance test; the pressure leak decay tests are usually performed
under stable barometric pressure and temperature conditions to minimize the
effect of these variables.
A 0.1°C fall in temperature results in an equivalent pressure change of -34
Pa or -0.14 inches of water gauge. A 0.01 inches of mercury rise in
barometric pressure results in an equivalent pressure change of -34 Pa or
-0.14 inches of water gauge.