Despatch 926E Equipment Manual (C-155)Rev 2/11 - Manual (Page 26)

21
To avoid moisture collection in the insulation after sustained operation at low
temperatures, the test chamber should be operated for at least one hour at 205

C (400

F) to evaporate the moisture. Do not exceed this temperature with the cryogenic
models which are insulated with high-temperature-resistant polyurethane (isocyanate)
foamed-in-place resin. This insulation will be damaged if temperatures in excess of 205

C (400

F) are sustained.
Safety Information
Operating and burst pressures for various hose assemblies are given in the following
table.
Component Operating Pressure Burst Pressure
kPa
2
PSI kPa
2
PSI
CO
2
20685
3000
68950
10000
LN
2
310
45
2586
375
Performance Characteristics
The following tables list the performance characteristics for the test chambers. The
tables are used topically as follows.
1.
Find approximate temperature of test chamber in left-hand column.
2.
Find temperature desired in second column from left.
3.
Determine the CO
2
consumption from the right-hand column under CO
2
CONSUMPTION.

Column AIR lists the amount of CO
2
needed to bring the air temperature in
the test chamber to the desired degree.

The AIR + WALLS column lists the associated amount of CO
2
needed to
bring the air and the chamber walls to the desired temperature.

Column RATE/HOUR lists the hourly rate of CO
2
consumption needed to
maintain the low temperature.

The CO
2
consumption in minutes may vary depending on the heat dissipated
by the size and material of the test object.