Test Representative of Routine Operations
Figure 2
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The integrity of each new bag was tested with a pressure decay leak test (ASTM F2095) before assembly with the shells and
sterilization by gamma irradiation. Three sterile Celsius FFT containers were filled with a colored solution to the recommended
nominal volume (6 L) and inspected. The containers were frozen in the upright freezer with a –70 °C temperature set point
for 24 h. Each container was then removed from frozen storage and immediately submitted to a handling test composed of five
series of lifting, 180° rotation along the Y-axis (Figure 2), and drop down to the bench. The containers were then thawed
in a 25 °C water bath and inspected. After drainage, each bag was dissembled from the shell and inspected. The bag integrity
was tested with the pressure decay leak method.
Test Representative of Accidental Conditions
The integrity of each new bag was tested with a pressure decay leak test (ASTM F2095) before assembly with the shells and
sterilization by gamma irradiation. Ten sterile Celsius FFT containers were filled with a colored solution to the recommended
nominal volume (6 L) and inspected. Five test containers were then submitted to a 50 cm free fall drop, flat on front ([+X]
on Figure 2) and five to a 50 cm free fall drop, flat on bottom ([–Z] on Figure 2). Three additional containers were prepared
as above and frozen in the upright freezer with a –70 °C temperature set point, for 24 h. The three containers were then submitted
to a 50 cm free fall drop, flat on back ([–X] on Figure 2). The containers were then thawed in a 25 °C water bath and inspected.
Figure 3
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The shell and the fasteners were inspected after each drop test. The film, the bag seam, the fill line, and the connector
were inspected after disassembly of the bag from the shell. The bag integrity was then tested with the pressure decay leak
method.
RESULTS AND DISCUSSION
Table 1: Freeze times of Celsius FFT 6 L in a –70 °C upright freezer (two freeze experiments with two Celsius FFT 6 L each)
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Two Celsius FFT containers were filled with 6 L of colored water and frozen in the upright freezer with a –70 °C temperature
set point. The freeze temperature profile of one container was recorded for each experiment. A typical freeze temperature
profile is shown in Figure 3. The freeze performance of two consecutive cycles are summarized in Table 1.
It took an average of 13 h to bring the product temperature from 23 to –60 °C and 22.6 h to reach a final temperature of 69
°C (Table 1). The product temperature graph is showing the expected profile with a phase change plateau at 0 °C, corresponding
to the release of the latent heat, followed by a sharp decrease of the temperature during the cooling of the ice. The leveling
of the temperature profile toward the end of the cycle is caused by the decrease of the temperature driving force.
Figure 4
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Thaw tests were performed in a water bath maintained at 20 °C. The temperature of the bath was adjusted at regular intervals
with the addition of hot water. No agitation was used to homogenize the water temperature or increase the heat transfer efficiency.
Water bath thaw was initiated following 15 min storage of the frozen container at room temperature. A typical thaw temperature
profile is shown in Figure 4. It took 93 min to bring the product temperature from –60 to +2 °C with an average bath temperature
of 20 °C.
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