What is air changes per hour What is CFM how they are related to cleanness of Pharmaceutical Manufacturing Aria
What is ACPH, Air Changes per hour
Importance of CFM and ACPH (air changes per hour).
How ACPH is related to cleanness of room. How to calculate Air changes per hour ACPH in what is CFM in AHU
Is it true that higher degree of clean room requires high number of ACPH?
In pharma industry manufacturing facility area are classified depending up on ther requirements of dosage forms.
Manufacturing of Tablets dosage form area requirement is of Class 100000
Class 10000 area is required for Liquid oral dosage form and Topical Cream and Ointment manufacturing.
Injectable dosage form is required to have class 100 area at the point of filling, adjacent area is required to meet class 1000.
Air supplied in the core manufacturing room is required to be filtered through HEPA filters which ensure exclusion of particles and contaminants from the clean room.
To achieve higher degree of cleanness level, more and more amount of air in the room must be filtered through HEPA filter and supplied in the room.
The process happens when air leaves room carrying particles in the room with it and enter back through HEPA filter where these particles are filtered out, more will be such cycles more will be the number of particles removed from the manufacturing area with time.
In quantitative manner if we want to discuss then we will have to use term AIR CHANGESP PER HOUR (ACPH) is the number of times in one hour of time that entire air in the room is filtered out.
For an example a room of 500 ft. 500 ft. manufacturing are is said to be having 20 ACPH means in one hour of time 20 times entire air in the room is filtered out.
More is the CFM more will be the ACPH ( Air changes per hour)
What is CFM: it the measure of amount of air coming out from the filter in the cleanroom, in other words it’s the rate at which air is supplied in the room.
It is amount of air supplied per minute in unit of cubic feet, number of cubic feet air filtered through terminal filters inside the clean room per minute.
CFM is also a measure of capability of AHU blowers, manufacturers rate the AHU
blowers or AHU to be of supplying xyz number of CFM of air if installed.
How to calculate ACPH (air changes per hour)
Air changes per hour in a clean room is also a measure of capability of cleanness level to which an AHU is capable to maintain in a clean room, its number of times the entire air in the clean room is changed with filtered air, it may be the same air getting in after filtration or some part of fresh air taken by the AHU as per its design. Therefore, dimension of room is important in calculation of ACPH.
Following formula is used to calculate air changes per hour.
ACPH = CFM X 60 / Volume of the clean room
Volume of the clean room = Length x Breadth x Height of the Clean room, 60 stands for 60 minutes in one hour, CFM value the measure of flow rate is taken perm minute
ACPH (Air changes per hour is always read and referred in number of times)
In Pharmaceutical Manufacturing a 20 ACPH is considered to be of optimum.
As the requirement of cleanness increases, the ACPH value too is required to increase.
More is the CFM, more will be the ACPH, more will be the ACPH, level of cleanness achieved will be of greater degree.