CAGE PROCESSING in Animal Facilities - Felasa

• An operation display (indicating “process running”, door release, warning light) at the loading and unloadingside is required.• Door control (gasket control via sealing pressure, “door closed” contact) and locking must be monitoredduring the gassing cycle.• The feedback signal of the valves must be monitored.• An electrical connection for the generator and an optional socket inside the chamber must be provided.• Emergency stop buttons must be applied to each side and safety measures (emergency release of doors)taken inside walk-in chambers.4.6.2.3 Processual requirementsPlease pay attention to the following aspects on process requirements:Leakage testBefore starting the gassing cycle, it is recommended that the lock undergo a leakage test. This test can beperformed with the H 2O 2generator.Safety monitoring / ambient monitoringH 2O 2is a mildly odorous gas heavier than air. Thus a monitoring probe with automatic notice of malfunction isbest placed 0.5 – 1.5 m above ground. The probe should be shielded from mechanical damage.H 2O 2gassing cycleFigure 4-11 shows a characterstic textbook H 2O 2gassing cycle. After dehumidifying and conditioning thelock, a vaporised H 2O 2air mixture is fed in (gassing) until a required degree of concentration is achieved. Whatfollows is the dwell phase where the H 2O 2concentration is kept on a more or less constant level. In the finalstep (ventilation) the lock is ventilated or the H 2O 2discharged with the exhaust air, which finishes the gassingcycle.Figure 4-18: Characteristic text book process scheme of a H 2O 2gassing cyclePlease note, however, in table 4-18 that evidence of the effectiveness of sanitization is only provided by biologicalindicators. Currently, changes in H 2O 2concentration (concentration curve) cannot be acquired bymeasurement techniques sufficiently accurate for operator demands.With each gassing and dwell phase, the lock is given a defined H 2O 2injection. Based on this injection rate, theeffective H 2O 2concentration during the dwell phase, other than shown in the textbook cycle, does not necessarilyhave to be constant. A rising or falling of the H 2O 2concentration level is more likely. Prolonging the dwelltime without revalidating the cycle, however, can cause problems, as a potential H 2O 2oversaturation mightlead to a condensation of H 2O 2.Loading volume and configuration influence the required H 2O 2injection rate, gas distribution, and ventilation.With H 2O 2absorbing materials, like plastics, a longer ventilation time might be necessary. Different loading34Cage Processing in Animal Facilities · 4th issue · 2013