The classification of a cleanroom is determined by the amount of particulate matter (PM), a descriptor for particles and liquids in the air, per cubic meter. The air we breathe has about 35 million particles in a cubic meter with an estimated size of 0.5 μm, micrometers or one millionth of a meter.
Cleanrooms are classified by the International Organization of Standards (ISO) that uses a grading system of ISO 1, for extremely clean, to ISO 9, satisfactorily clean. The determination of the classification is decided by the size and numbers of particles in the room's air.
The United States classification system for cleanrooms was and is Federal Standard 209E published by the Institute of Environmental Sciences and Technology (IEST) in 1963. The IEST used a classification system that ran from Class 1, an ISO 3 class, to Class 100,000, an ISO 8 classification. Though several countries still use the IEST system, it was formally retired in 2001 as being obsolete.
For many years, scientists, engineers, and designers had attempted to create an uncontaminated atmosphere but failed due to problems with uncontrollable particles and airflow. In 1960, Physicist Willis Whitfield developed a filtration system that led to the development of the modern cleanroom.
Requirements for a Cleanroom –
Cleanrooms are used by specialized industries, such as pharmaceutical, biotech, semiconductors, laboratories, microchip producers, and photovoltaic. Any manufacturing process requiring strictly controlled production and product handling will have some form of cleanroom. The nature and delicacy of a product determines the level of cleanroom required.
The requirements for a cleanroom begin with staff protection, who wear protective clothing and accessories to prevent contamination. Those specialized items are made from a synthetic material that is wear and tear resistant and are used only once. Anything that enters the cleanroom has to be specially classified and approved down to the smallest detail.
Cleanrooms do not have furniture. Surfaces are free of bolts, nuts, visible joints, or places that may collect dust particles. Equipment and surfaces are smooth and highly polished, usually made of plastic or high grade stainless steel. The design and construction of cleanrooms is minimalistic and uncomplicated.
Lighting for a cleanroom provides enough light for a smooth operation and follows strict hygienic requirements. It is very important that lighting does not require frequent cleaning and be longevous since interior cleaning of a cleanroom means that it has to be recertified.
The most important feature of cleanrooms is their air circulation system. Airflow comes from the ventilation system that strictly controls air movement. Some designs have air enter from the ceiling and exit through the floor, which is referred to as unidirectional. Negative pressure is applied to prevent the escape of contaminants from dangerous materials and the intrusion of contaminants from the outside atmosphere. The items being handled determine the type and kind of airflow system.
Cleanrooms are very expensive to maintain and construct with an average cost between $100 to $150 per square foot. A ten foot by ten foot cleanroom, about the size of a small bedroom, has a cost of $10,000 to $15,000, which can be lower or higher depending on the air control system and instrumentation.
A more flexible type of cleanroom is the modular version that is adaptable, easy to construct, and can be effortlessly changed and modified. They have all of the benefits of more expensive types and produce the same contaminate free environments but at a lower cost.
Clean Room Applications
During the COVID-19 scare of 2020, cleanrooms were and are an essential part of the treatment process. Since their inception in 1960, cleanrooms have found use in several industries, including some that may seem a bit unexpected. Below is a description of some of the uses of cleanrooms.
Isolation Rooms for Hospitals
Isolation rooms are a special form of clean room that is designed to separate patients with unique or unusual symptoms away from other people. The requirements for an isolation room are very similar to those for all other forms of clean rooms and may have an ISO rating depending on the function of the room. Patients placed in isolation rooms have specific medical conditions or infections on their skin, in their lungs, or intestines. This special form of clean room prevents the spread of disease and includes patients that get easily infected.
The type of air pressure for an isolation room varies in accordance with the type of illness the patient has. Negative air pressure is used to prevent contaminants from escaping the room. Air is pulled into the room and filtered before it is forced outside. In cases where a patient has a weakened immune system, positive air pressure is used to prevent contagious diseases from entering the room. Positive air pressure pumps air through a set of HEPA filters into the room.
These unique rooms have been designed by the collaboration of healthcare workers and clean room engineers. They have alarms to detect pressure loss, hands free showers and toilets, and no circulating air. They use high efficiency particulate air (HEPA) filters that are designed to remove dust, pollen, mold, bacteria, and any particles that are 0.3 µm.
Semiconductor and Microelectronic
The sensitive and delicate nature of electronics manufacturers' equipment demands very stringent environmental controls. Any defects or deficiencies in a clean room can greatly affect a production run. The clean rooms for these manufacturers are air tight, have UV filtered light, and control mechanisms for electrostatic charges. Unlike most clean rooms, ones for the electronics industry are larger and more spacious.
The integrity of products for the semiconductor and microelectronics’ industry can severely suffer if contaminated with microscopic particles. One minute particle can cause significant problems such as haze on optics, which increases cleaning costs. Clean rooms for semiconductors and microelectronics have to consider every aspect of clean room construction including wall materials, air flow, power, lighting, storage, and production areas. This is further exacerbated by the size of the clean room that houses several workers.
The goal of clean rooms for the semiconductor and microelectronics industry is an ISO level 3 or 5 rating and includes the use of gowning rooms, anterooms, air locks, pass throughs, and specialized window modules. To achieve the desired clean room level, strict controls are maintained, which is difficult and a constant issue.
Every clean room constructed for semiconductors and microelectronics is unique and needs to be installed in accordance with the types of products being manufactured and the processes being used. This requires the use of design specialists that are familiar with the parameters of semiconductor and microelectronics’ construction, which, in many cases, involves working with products assembled under magnification and conducted in a noiseless environment.
Medical Device Manufacturing
Medical devices are assembled and manufactured in controlled clean room environments to ensure their integrity. Since the goal of medical devices is to help patients and prevent illness, where the devices are manufactured has to have the highest standards for cleanliness. This factor makes clean rooms used in their production a key element in the process.
Unlike other clean rooms for manufacturing, medical device clean rooms come under intense scrutiny by regulatory agencies that monitor any form of tool that will come in contact with the public. Although ISO standards determine the classification of a clean room and have specific standards for medical device manufacturing, companies still have to comply with governmental oversight. This aspect of medical instrument production creates complications and regular inspections.
Aside from the standards established by governmental agencies, there are international standards that must also be followed that are administered by the World Health Organization (WHO). The specifications and standards for medical device clean rooms cover the most minute details regarding the size, contents, location, filtration, and clothing of workers that have to be strictly followed in order to continue production.
Medical device clean rooms are designed to control airborne particulates and microorganisms. Additionally, they have to be checked for their bioburden rate, the number of bacteria living on a surface. The demands and regulations for medical device manufacturers has steadily risen over the last few years. Class III medical devices, ones that are implanted or sustain life, are the most stringently controlled.
Compounding Pharmacies
Stipulations for pharmaceutical clean rooms follow similar stringent standards as those set for medical devices since they have the same relationship with the public. The standards for pharmaceutical clean rooms are set by the United States Food and Drug Administration (FDA) that regularly adjusts and edits its standards. Clean rooms for the pharmaceutical industry are designed to control humidity that can impact product integrity, air pressure, microorganisms, and temperature.
Meticulous detail and minute scrutiny are a common aspect of pharmaceutical clean rooms to ensure the safety and effectiveness of its products. The adherence to high quality is necessary to prevent medications from being a danger to the public. As with food, drink, and medical instruments, any thing that comes in contact with the public has to be closely regulated.
The compounding pharmacy business has been growing over the last several years and has had restrictions placed on it due to the chemicals and compounds they produce requiring clean rooms. The unique nature of a compound pharmacy is their ability to mix, produce, and sell drugs specifically designed to meet a customer’s needs. The nature of the materials they use makes it necessary for them to have an enclosed sanitary environment. Their clean rooms need to meet the ISO standards levels 7 or 8.
Ballrooms
The ballroom clean room concept makes it possible to scale up or scale down according to the needs of a process. Multiple processes are completed at the same time. Operations or functions are placed on wheels and wheeled to where they are needed. Additionally, a ballroom does not have to be a single large space but can be adjacent smaller spaces connected with through the wall connectors, a concept that is known as a dance floor.
The use of ballrooms maximizes the use of space while lowering capital expenditure. The focus of ballroom clean rooms is to be flexible to meet the changing requirements of products and customers. All personnel and equipment are located in one space with easy access to all operations. The design of a ballroom clean room makes it possible to have a sealed and enclosed space that is capable of completing a full set of operations without having to shift products to various sealed locations.
This class of clean room is used for full scale production operations for precision products. They are unlike mini environments that are designed for the production of one tool or process. Ballroom clean rooms are large with complete production operations. Their major problem is their ability to produce a completely contained environment that is free of contaminants.