validation of air handling units (HVAC)

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VALIDATION OF AIR HANDLING UNITS(HVAC SYSTEM) Under the guidance of Mushraff Ali Khan sir. Presented by, HUSNA KANWAL QURESHI.


INTRODUCTION: Heating ventilation and air conditioning (HVAC) systems are used in the pharmaceutical plant to prevent contamination and used to provide comfortable working conditions. Ambient air may have different contaminants, the most common being the dust. Dust can be roughly classified by size: Coarse dust (particle size 50 to 500µ) Fine dust (particle size 1.0 to 50µ) Ultra fine dust(particle size 0.5 to 1.0µ) Coarse dust settles rapidly. Fine dust settles slowly. Ultra fine dust remains constantly suspended. Normally bacteria settles themselves on dust particles. Environment is one of the sources which can cause bacterial contamination. For proper working, a comfortable temperature is required. For this reason air may be required to be heated or cooled. Therefore, air handling systems are often called HVAC SYSTEMS.


CLEAN ROOM Air will be required to be filtered to bring down particulate matter. This lead to the emergence of clean room concept. A clean room is an area or zone where the particulate and bacterial contamination is limited to specified level. Air borne particulate matter and degree of filtration is a critical parameter with reference to the level of product protection required. There are three levels of protection. LEVEL 1: General- an area with routine house keeping and maintenance. LEVEL 2: Protected- an area where steps have been taken to protect the exposed drug substances from contamination and degradation. LEVEL 3: Controlled- an area in which specific environmental conditions are defined, controlled & monitored to prevent contamination or degradation of drug. For each increase in clean room classification, air change rates should be increased proportionately.


LAMINAR FLOW: This occurs when the paths of the molecules of air move parallel to one another. US federal standard indicates that this occurs when air velocity is 90 feet per minute(fpm). Importance of laminar flow is that a particle moving within a laminar stream line tends to remain in this stream line and is not deposited on surface it might encounter. The laminar stream lines tend to bend around obstacle and keep the Particles entrained. LAMINAR FLOW

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A significant difference of air change rate should be maintained in the following areas: - as built: condition relates to carrying out room classification tests on the room without any equipment or personnel. - at rest: relates to carrying out room classification tests with normal production equipment in the room but without operations. -operational: with normal production process with equipment and the operators.

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Achievement of clean room depends on the following criteria like: Building structure and finishes Air filtration Air change rate Room pressure Location of air terminals Temperature Humidity Flow of materials Flow of personnel Movement of equipment.


AIR HANDLING UNITS(AHU): AHU comprises of air supply, coarse filtration, heating or cooling and HEPA filtration. AHU producing class A, class B and class C HEPA filters may be located in the air handling units. In less clean rooms they may be located terminally. There may be alternative location for return air i.e low level return air and ceiling return air.


RECIRCULATION SYSTEM: In this, bulk of air is recirculated and a small percentage of fresh air is introduced. Depending upon the airborne contaminants in return air, recirculated air is used. If recirculated air is used, HEPA filters should be installed in the supply air stream to remove contaminants. Where AHU is servicing a single product, there is no need of HEPA filters as there is no chance of cross contamination.

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Ventilation with recirculated air + make-up air Central Air-Handling Unit Return air Exhaust Unit HVAC


FULL FRESH AIR SYSTEM: These are designed with 100% supply of fresh. These are designed where toxic substances are handled. The relative pressures between supply and air exhaust system should be such that air exhaust operates at a lower pressure compared to supply system. If production process requires environment with low humidity , it can be achieved by drying the air. Dessicant is used.

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Containment of contamination can be achieved by the following: Displacement concept( low pressure differential, high air flow): A low pressure differential can separate clean and less clean adjacent zones by means of low turbulent displacement air flow greater than 0.2 m/s. This displacement airflow should be calculated as the product of the door area and the velocity. Pressure differential in such designs may vary between 5 to 20 Pa. Because of high airflow, it may be cost effective to use this air as cooling medium. Example: if a cubicle temperature of 25©C is required the corridor can be maintained at 21©C giving temperature difference of 4©C to provide room cooling.

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Pressure differential concept (high pressure differential, low air flow): The high pressure differential between the clean and less clean zone can be generated by leakage through the gaps of the closed door to the cubicle. Pressure differential should be of the magnitude that will ensure containment and prevention of flow reversal. The most widely accepted pressure differential between two adjacent zones is 15 Pa. Pressure control systems can be either active/ automated or passive/ manual. Passive/manual pressure control system tends to be more stable.

Pressure cascade solids Protection from cross-contamination HVAC


CLEAN ROOM CONSTRUCTION: Depending on the parameters for a desired clean room an engineering design is prepared. While preparing layout the designing team must examine raw materials receiving, storage & transport to the clean facility as well as finished product transport, storage and shipping, walls, floors and ceiling. WALLS: include stick built using a dry wall system on steel studs. This has been used for number of years and has low cost. A variety of coatings and cladding for clean rooms. Modular systems are also used, which r quick to install.

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WINDOWS: Generally made of glass to permit supervision from outside. It should be flush to the wall on the clean side to prevent the accumulation of particles. Designs are also available for flush windows on both sides of the wall. Such windows are installed between adjacent clean rooms.

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FLOORS: frequently covered with a high solid epoxy finish, applied to concrete surface. Vinyl tiles and vinyl sheeting with properties like static, standard, dissipative or conductive properties are used. In class 100 or more stringent clean room, a raised floor should be considered. It may be forged aluminium construction perforated to permit airflow from clean room to the return plenum space below the floor. CEILING: Most common one is an inverted T support grid made of extruded aluminium. Ceiling supports filters, blank panels and lights. In p’cal industry generally monolithic design ceiling is used (to eliminate seems).

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LIGHTS: Typical fluorescent fixtures. DOORS: Made of non shedding material and may have full or half glass. Have sealing an all four edges to minimize loss of clean air.

HVAC Control and monitoring system validation: : 

HVAC Control and monitoring system validation: HVAC SYSTEM DQ PROTOCOL: Scope: The scope of this document is to demonstrate that functional requirements have been incorporated into the HVAC design specifications and equipment selection. Objective: provides the verification of the conformance of the selected components design. System description: like class of cleanliness, category of products to be manufactured, room design criteria, equipment and material selection etc. IQ PROTOCOL: Scope: to verify that all components have been installed in accordance with their approved design and engineering specification. Responsibility: name and designation of persons responsible for approving and execution . Manufacturer’s equipment and workmanship verification: Inventory of the equipment installed. Means to verify proper installation of system.

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Calibration verification: A list of instruments which require calibration is prepared and calibrated. SOP verification: List of sops and manuals are prepared. Utilities connection verification:Utilities connections supporting HVAC system should be verified to ensure that it has been properly installed. Change parts and replacement parts verification Maintenance procedure verification: ensure that a maintenance program exist, by the manufacturer. Lubricant verification: approved lubricant to be used. As built drawing listing and verification: built drawing is the one which has been physically verified through inspection, signed and dated by the person performing inspection.

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OQ PROTOCOL: Objective: verifies that given system operates as specified and are in agreement with acceptance criteria. Responsibility: names and designation of persons who are responsible for approval and execution. System description: includes how the system operates and sequence of controls. Instrument calibration and verification: all the instruments specified have been installed and calibrated. Testing equipment calibration verification: verify operation of the system. Verify calibration. SOP verification: SOPs required for operating system shd be verified. Operators shd be trained in the operation of the system. OQ tests: includes series of tests designed to prove proper operation of HVAC system. Like:

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AIR SYSTEM BALANCING AND PRESSURE DIFFERENTIALTEST: for achieving proper environmental conditions, the distribution of the air among various sections is controlled. System dampers(valves) are used. Control damper for air flow The data is obtained through thermo-anemometers, electromanometers, airflow meters. Following data is obtained like Airflow under full HVAC operational conditions at filters, AHU supply etc. And also pressure differentials to ambient air or adjacent or interconnected classified environment. The data obtained should be compared with design specifications. Control dampers for airflow

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AIR VOLUME FOR NON-UNIDIRECTIONAL AIRFLOW TERMINALHEPA FILTER TEST: Its important to find out the volumes of air supplied by individual terminal heap filter. This will demonstrate that the filter operates within design range. Volume of recirculation air through filters defines the dilution ratios or air changes per hour. HEPA FILTER INTEGRITY TEST (DOP Test): to test the filter integrity, the filter is challenged with an air generated or mechanically generated aerosol using dioctylphthalate (DOP). The passage of aerosol through filter is detected using a light scattering photometer. Usually the condition under which aerosol is generated provides a consistent concentration of 10µg/l of air. This concentration i equivalent to 3*10^10 droplets per cubic meter.

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PRESSURE DIFFERENTIAL STRESS TEST: demonstrates how the system performs under stress condition. Proper design of experiment should be designed in consultation with designers and contractors. Pressure differentials are measured and recorded between interconnecting environments. Pressure readings are compared against approved specifications. START UP AND SHUT DOWN TEST: used to test start up and shutdown Sequence of the operation of the AHU as controlled by the control system.

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CONTROL AND MONITORING DEVICE TEST: the object of this test is to verify the proper performance of the HVAC control, monitoring and alarm system. If the control and monitoring system is computerised, this is dependent on the configuration of the control system for both software and hardware system. The procedure should outline the sequence to be followed and the devices which intervene. POWER FAIL AND RECOVERY TEST: the object of this test is to verify that the control system can maintain the components of the AHU within the specified range after a power failure. The steps included in this test are : simulate power failure; bring system to complete halt; wait for the required time before start; record the time it takes for the system to re-establish the approved conditions. AIR FLOW VELOCITY AND UNIFORMITY TEST: object of this test is to determine that the uni-directional air flow devices meet the criteria for air flow and uniformity as set in the design specifications. The environment is divided by a grid (2ft*2ft) depending on configuration and classification of the room. Velocities are measured at the centre of each square.

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AIR FLOW PARALLELISM TEST: to verify parallelism of the air flow through the work area. This test is carried out by generating visible smoke upstream from the work area. A reference point is established. Direction of the airflow is videotaped to determine the direction of the airflow. Air should flow in parallel stream to prevent the flow of outside air into the critical environment.

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PQ PROTOCOL: In this HVAC system is assessed for its performance with in the area it is serving. This is done by simulating the process or by actually conducting it. Data is collected under static conditions as well as under dynamic conditions. TEMPERATURE- HUMIDITY CONTROL TEST: This is carried out to verify that system is capable of maintaining the design conditions under “in use” conditions. This test is also indicative of malfunctioning of HVAC system. Seasonal conditions can effect the temperature and humidity levels. Occasionally seasonal variations can be simulated during validation. Data collected should be documented. AIR CLEANLINESS TEST (NON VIABLE PARTICLE COUNTING): there are two types of particles in environment, viable (microbes) and non viable. Air borne particles are counted with particle counters. The classification of air cleanliness is determined on the basis of number of particles ranging in size between 0.5 to 5.0µ in specified volume of air. The sampling points, size of samples and acceptance criteria should be carefully decided.

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AIR-BORNE BIO-BURDEN TEST: The object of this test is to determine whether all the component of the system are capable of performing in accordance with the process functional requirements for airborne bio burden. For this an adequately qualified microbiologist is required. The test could be qualitative or quantitative. Commonly used techniques included are: settle plates; contact plates; glove points; air samplers. SURFACE BIOBURDEN TEST: this test is done on the surface of either premises or equipment. Assessment of bio burden on surface can be made by considering pre cleaning conditions as challenge and assessing bio burden at pre cleaning stage and after cleaning. The assessment of bio burden on surfaces can be made by test like swab test, contact plates (RODAC).

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Revised schedule M also recommends that the parameters listed below should be verified at the time of installation of AHU and thereafter at periodic intervals: Particulate monitoring- 6 monthly HEPA filter integrity testing- yearly Air change rates- 6 monthly Air pressure differentials- daily Temperature and humidity- daily Microbiological monitoring- daily.

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