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Qualification of Walking Type Stability Chamber

User requirement specification
User requirement specification (URS) is a list of all the requirements from the user, like equipment to be purchased. After the preparation of the list, the documents are sent to the manufacturer to get the required materials as per the given criteria.

The user department will raise the indent for his requirement regarding machine equipment or software. He/She will give all the requirements in the format of URS, which include the functional and technical specifications for the machine equipment or software. This specification in the written format is defined as URS. It shall be very specific.

There should not be any confusion during the preparation for approval. Functional as well as technical aspects shall be clearly mentioned. The number of spare change parts required shall be mentioned in URS.

Qualification of Walking Type Stability Chamber
  • For a chamber to receive a certification to conduct stability tests, it must undergo a three-part qualification process. The qualifications must also include calibration records of all instrumentation used and evidence of their calibrated state. 
  • The three qualification types are:
  1. Installation Qualification (IQ)
  2. Operation Qualification (OQ)
  3. Performance Qualification (PQ)
  • These tests are conducted by validation personnel using calibrated measuring and testing equipment; records are kept by the Quality Assurance department for a specified length of time.

Installation Qualification
  • The first step is to check the correct positioning of the chamber and then check if the chamber and all components are correctly installed, and also the presence of documentation. Documentation usually includes the user’s manual, certificates, and SOP's. Utilities can be verified at this phase: electrical feeding, water (pressure, pumps, filters and connections), and exhaust.
  • If the chamber has a control panel/ system, this can be checked too: buttons and commands, screens, etc. Finally, check for all components part of critical systems: measuring and control, ventilation, heating and cooling, and safety. All associate connections should be properly done.
  • The first qualification verifies whether or not the stability chamber meets its design specifications. All parts are accounted for and checked that they are correctly installed. Proper documentation must also be present, including the user manual and any certifications and standard operating procedures (SOPs).

  • All components must be properly installed and functional for a stability chamber to pass installation qualification. If the chamber has a control panel with a human-machine interface (HMI) or other pilot devices such as pushbuttons and selector switches, they must work as designed. All calibration and safety equipment also need to pass inspection.

Operation Qualification
  • At this phase, start by testing all individual functions of the stability chamber, including switches and controls, alarms, doors, etc. Check the sensors calibration if this was not covered on IQ. The final OQ test is to perform a thermal/humidity mapping of the chamber for the established set point. At this point, the mapping is performed with an empty chamber and for a determined period of time (not less than 24 hours).

  • The purpose of this study is to assure that temperature and humidity are evenly distributed inside the chamber and that the established acceptance criteria are met at any point of the chamber.
  • Use at least ten sensors evenly distributed inside the chamber. For example on the chamber’s corners and at the center, or 3 sensors on each shelf, depending on the size of the chamber. If you use thermocouples for temperature, assure that the chamber is prepared for it, or in case you pass them through the door, that the door is perfectly closed. The easiest is to use wireless probes, with the only disadvantage is that you will only see the results at the end of the study, instead of doing it online.
  • Program the sensors to acquire data for example every 5 minutes. Wait for temperature and humidity stabilization for a while and let it run for the established time.

Door Opening Study
  • At the end of the study, and before removing the sensors, perform a door opening study. This can be achieved for example by opening the door for a certain short time and keep recording temperature and humidity at a short-range (every 10 seconds for example). Once you close the door let it stabilize again. Usually, perform 3 door opening trials and at the end and calculate the chamber’s average recovery time.

  • The operation qualification tests the individual functions of the stability chamber and verifies that the systems and subsystems perform as intended under normal operating ranges including testing all doors, switches, controls, and alarms.

  • The operation qualification test verifies that temperature and humidity have equalized inside the chamber. To ensure accurate temperature and humidity readings, the operator waits a few minutes until they stabilize, then runs the test for the specified time.

PLC Validation Report

Performance Qualification
  • For performance Qualification, only perform a full load thermal/humidity mapping, using the same configuration for the sensors as in the empty chamber study. The minimum study time now is 24 hours. Again at the end of the study, we perform door opening trials and calculate the average recovery time.

  • The performance qualification verifies that the stability chamber meets performance specifications under a full load. Usually, the test is performed at the chamber’s operating setpoint with a simulated product loaded to replicate a typical environment. Temperature and relative humidity uniformities are measured using thermocouple and relative humidity (RH) sensors.

  • The stability chamber must perform under full load for at least 24 hours to pass performance qualification. After the initial study is complete, the trial gets repeated with a door-opened study to calculate its average recovery time.
  • The performance qualification process is done annually using the same procedures as past tests. After each requalification, the results should be compared with previous years to track the chamber’s overall performance.

  • Performance qualification is done on an annual basis, using the same sensor location and for the same time. You can use the same protocol or  SOP describing the method for mapping. After each requalification, it is recommended to compare the results with the previous qualifications to see if the chamber is maintaining its performance. If you eventually intend to change your temperature or humidity set points, both empty chamber and full load studies should be performed again using the new set point.

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