An air handling unit (AHU) is a device that controls the circulation of air in a heating and cooling air conditioning system. An AHU is usually a large metal box containing a blower, hot and cold coils, a filter housing, a silencer and damper, and control equipment. AHUs are generally located in the ductwork of air conditioning systems, where the return air from the building must flow.
Air handling unit structure:
Usually, the air handling unit is made with metal frames and solid panels all around, according to the configuration of the system components. The internal parts are made of single-layer galvanized metal channels for long-term operation. In outdoor units, waterproof plates are used at the connection points to prevent water penetration.
Types of air handling systems:
– Package unit
– Hygienic
In the pharmaceutical industry, hygienic air handling units are used to supply air to clean rooms. For this purpose, hygienic air handling units are manufactured in accordance with WHO and GMP recommendations with the highest quality and according to the VDI6022 standard for use in controlled environments.
The difference between the ventilation system in conventional and hygienic systems is as follows:
– In conventional systems, only temperature and humidity are controlled, while in hygienic systems, in addition to the above, control of conventional particles and sometimes microbial particles is also carried out.
– The high amount of air supplied to the clean room is one of the most prominent features in the hygienic system. For example, the air exchange rate for a conventional system is between 0.5 and 2 times per hour, while for hygienic, this amount can vary between 10 and 600 times per hour depending on the space class.
– The use of HEPA or ULPA filters is another difference between conventional and hygienic systems
– In a clean room, a positive pressure difference between the space and the outside space must be maintained to prevent particles from entering the space. This is while in conventional spaces, positive pressure is not required.
Considerations that should be taken into account in the design of a clean room air handling system include
– Supplying air into the room in a way that maintains the cleanliness of the space.
– Distributing air in a way that the air is moving in all parts of the room and does not stagnate so that particles do not settle.
– Belt systems should not be used in clean room air handlers; only plug fans or low-noise direct coils should be used.
Validating the air handling system
Given that validation and quality assurance activities are carried out as a team, before starting the activity, a team consisting of technical and engineering experts performs all the following steps, which are briefly discussed for each of the cases.
– Design quality assurance
– Installation quality assurance
– Operation quality assurance
– Performance quality assurance
DQ Design Quality Assurance:
All documents and records are prepared to evaluate the design of air handlers and supporting facilities that must comply with GMP requirements and laboratory specifications, quality assurance and production. In the validation of consumer requirements systems (URS), they are reviewed. After the air handlers are designed, all design drawings, including mechanical, electrical and ductwork, classification, etc., are checked by the validation team with the initial request of the company for the provision of clean room air handlers, which is mentioned in the comprehensive validation plan. All deficiencies are noted and at the end of the final report is prepared and presented to the technical unit so that the deficiencies are resolved in the shortest possible time.
Quality Assurance of Installation Q:
All documents and records are reviewed to assess the structure or assembled parts of the air handlers, which must be manufactured and installed in accordance with the design specifications. After the air handlers are installed, quality assurance experts, along with technical engineers, check all air handlers and their components according to the prepared checklists to ensure that they are properly installed and are physically sound and free from any damage, dents, breakage, corrosion and rust. Similarly, all systems supplying air power, lighting and safety systems, fire extinguishing, alarms, vibration absorbers, control and computer systems (software and hardware) are also checked. All that the defects are eliminated in the shortest possible time. All the operational procedures for working with the device, cleaning, repair and maintenance of the air handling system are prepared by the technical and engineering unit, which are attached to the validation documents after approval by the quality assurance unit.
Verification of the quality of operation OQ:
In this phase, experiments and tests are performed that aim to examine the performance and efficiency of the air handlers. After the final installation and commissioning of the air handlers, the tests described in the section below are performed by the validation team in two conditions: At rest and In operation, and any errors and deviations that are observed are noted and prepared at the end of the final report and presented to the technical unit so that the defects are eliminated in the shortest possible time.
All parts of the air handlers and test devices must be calibrated and calibration certificates are attached to the validation documents.
All locations and points that have been tested are marked on the production site map and the maps are attached to the validation documents. In this phase, the air handling system operators are trained by specialists on how to work with the device and the training unit issues certificates to the operators, all certificates are attached to the validation documents.
The OQ phase tests are as follows:
– Air particle test
– Filter leakage test
– Inlet air volume test
– Air blowing speed test
– Ambient temperature control test
– Ambient humidity control test
– Air pressure control test
– Ambient air exchange test
– Air flow pattern test
– Sound test
– Air microbial control test
– Surface microbial control test
– Recovery test
PQ performance quality assurance:
In this phase, the air handling system is examined to ensure its performance and efficiency (continuous production of clean air). The tests described in the OQ phase are repeated periodically and according to a regular schedule for the air handling system.
All processes affecting the efficiency of the air handling system, including important changes in the structure and components such as filters, valves, etc. that directly and indirectly affect the quality of the ventilation system, must be quality assured and validated.
In Afashimi Pharmaceutical Company, hygienic air handlers (Hammer) are used in the production departments, which are designed in accordance with GMP and WHO standards, and tests related to the commissioning and quality of this system have been carried out with the help of technical and engineering units, laboratory and production, and have been approved by the Ministry of Health, Treatment and Medical Education.
. Air processing in such a way that the requirements related to temperature, humidity and filtration in the clean room are met –
