An outline of the various validation tests done in regards to HVAC system
1.0 Introduction
Heating, ventilation and air system comprise heating, ventilation & air conditioning system which is a crucial system in pharmaceutical facilities. In order to prevent cross contamination & accumulation of air, proper temperature & continuous flow of air is to maintained which further ensures cooling of air.
Validation of HVAC systems includes evaluating various parameters like particle count, filter leak test, viable monitoring, fresh air determination, air flow velocity, air flow pattern, air changes per hour, temperature uniformity & recovery test, humidity uniformity & recovery test, pressure difference.
The heating, ventilation and air conditioning system is important as it helps to maintain quality of drugs. HVAC system ensures proper temperature, air conditioning and ventilation in the facility.
HVAC system is often defined as the system that fulfills four core objectives like control of air quality, air humidity, air circulation & temperature.
1.1 Validation
Validation includes compiling documents of design, drawing of the design and its plan, Master plan of the validation process, TAB – testing, adjusting, balancing, reports on execution of protocols for validation
HVAC validation includes installation qualification, operational qualification, and performance qualification.
IQ ensures that each aspect of installation is in compliance with manufacturers approved design, appropriate codes & recommendations.
OQ ensures that systems and its subparts are uniform throughout the specified operation range
PQ ensures that systems, utilities, equipment’s are in compliance with the specifications provided
1.2 Following are the validation tests
i) Air flow/ Smoke Pattern
Here a titanium tetrachloride stick is burnt and placed before AHU and distribution of smoke is observed for its uniform pattern
ii) Air flow velocity and its rate of change
Here HVAC is divided into 4 grids and air velocity is measured at every grid and average air velocity is calculated
The area of HEPA filter inlet (A) is measured in feet and total air volume is obtained by multiplying area of the inlet and average velocity of air (V)
T = A x V
Later volume of room is calculated. The rate of change of air (per hour) is calculated by dividing total air change with volume of room
iii) Filter Leak test
A filter leak test is done by velometer. It is placed before the air handling unit and air velocity is checked at corners. The air velocity should be within the upper limit of HEPA filter, if it exceeds then the gas cut is used to lower the leakage.
iv) Particle count
This test is done by particle counter. Before operation and during working condition particle count is taken and it should be within the standards given as Grade A, B, C & D area
v) Viable monitoring
This test is done regularly by using swab test & nutrient agar medium for incubating microorganisms. The media plate is exposed at every manufacturing section along with HEPA filters reverse air duct at the back of cubicle. CAPA is initiated if the microbiological count is found to be out of limits for two times consecutively.
vi) Filter integrity test
Using PAO aerosol in this test the integrity of the HEPA filter is tested. Ensuring the aerosol moves in upward direction 100% this test is performed. Later the receptor probe of HEPA filter is checked to know the quantity of aerosol reversed. the limit should not cross the upper limit of the HEPA filter. Before this test was carried out using DOP but due its carcinogenicity it is replaced by PAO.
vii) Pressure difference
Pressure difference is calculated by using manometer which is attached to the walls of adjacent area. The pressure difference is usually maintained between 5 and 20mmHg.
viii) Recovery test
Temperature and humidity are checked at the off position of HVAC system in this test. Later the temperature is increased to 400oc and humidity is raised to 75%. Then the temperature and humidity are measured by switching on the HVAC system and the time in which the temperature & humidity are stable is noted.
ix) Uniformity test
Temperature and humidity are monitored by this test by using a thermometer and manometer.
They are monitored on regular basis and documented and the stability is to be maintained within the limits specified.
x) Fresh air determination
At the fresh air dumper inlet the intake of fresh air is observed. The total air change is calculated. The intake fresh air is divided by total air change in room and later multiplied by 100 to give the fresh air intake percentage in each cycle in HVAC system in all individual rooms
1.3) Related Documents
1) http://www.asiapharmaceutics.info/index.php/ajp/article/view/349/333
Validation tests, hvac system, air flow/ smoke pattern, filter leak test, viable monitoring, pressure difference, fresh air determination
