Industrial ISO Clean Rooms 101: What You Need to Get Started

ISO clean rooms and industrial air filtration systems have been in use for many years in aerospace, defense, optical, and pharmaceutical production, and they are increasingly being used in biotech and food manufacturing and packaging. The global clean room market is expected to grow by 3.8% through 2027, driven by increased demand in manufacturing due to technological improvements and stringent regulatory standards.

It is important to understand the basics of industrial clean rooms and the standards for ISO clean room compliance. Compliance can be complicated, but it does not have to be overwhelming. It is also important to know custom-engineered, industrial air filtration solutions go beyond government compliance for shielding workers from dangerous airborne hexavalent chromium and VOCs. Done properly, industrial clean room systems are good for business, producing a higher-quality environment for production — especially for aerospace and aviation maintenance and manufacturing.

ISO Clean Rooms Achieve Success by More Thorough, Multi-layer HEPA Filtration

ISO clean rooms are designed for industrial environments to maintain extremely low levels of particulates, such as dust, airborne organisms, or vaporized particles. Air cleanliness is achieved by passing the air through HEPA filters. The more often the air passes through the HEPA filters, the fewer airborne particles are left in the room. The volume of air filtered in one hour divided by the volume of the room gives the number of air changes per hour (ACH).

A conventional office building or home system usually makes two to four air changes per hour, but an industrial clean room can range from 10 to 250 or more air changes per hour, depending upon the requirements.

An industrial clean room, such as one with a Duroair filtration system equipped with our patented Taper Draft Airflow, enables air to flow around the product being painted or worked on to keep particulates or paint off the side walls and moves into the air handling units' filters along the back wall of the enclosure.

Figure 1. Taper Draft Airflow to Meet ISO Clean Room Standards

Industrial clean rooms typically have a cleanliness level quantified by the number of particles per cubic meter by micrometer size ranging from 0.1 microns to 0.5 microns (shown as μm), as determined by the International Organization for Standardization regulation known as ISO 14644-1. For perspective, the width of standard notebook paper is about 70 μm, and the diameter of a human hair can be as small as 17 μm.

Compliance Standards Depend on ISO Clean Room Classification

An ISO clean room classification design is based on the amount of HEPA filtration and the number of air changes per hour. A class 100,000 clean room allows 100,000 particles at 0.5 micron within a cubic meter. A class 10,000 allows only 10,000 particles at 0.5 micron within a cubic meter and is therefore double the filtration and double air changes per hour. In the list below, ISO3 is the most stringent clean room, and ISO8 would be the least stringent clean room. The vast majority of industrial clean rooms are Class 100,000 or Class 10,000.

Figure 2. Common ISO Clean Room Classifications

For contrast, the ambient outdoor air in a typical urban area contains 35,000,000 particles for each cubic meter in the size range 0.5 μm and bigger.

In order to reach an ISO goal, a manufacturer must factor in the size of the room, the number of filters, and the frequency of the ACH. How many cubic feet of air must be filtered per minute to limit the number of particles to 10,000 or 100,000 per cubic foot in that size room?

Most Industrial Clean Rooms Apply a Similar Approach to Air Flow

More than 90 percent of industrial clean rooms installed are positive-pressure rooms, which are designed to capture particulates before they enter the room and eject air and any particulates that may arise within them from the manufacturing process.

There also are negative-pressure clean rooms, which are designed to trap contaminants in the room, such as when dealing with infectious diseases, pathogens, or other biohazards that need to remain in a controlled environment.

There are four primary designs of air flow in a clean room:

• Single pass design, which captures particulates in the ambient air as it flows into the room.
• Recirculating design, in which the air is recirculated through the filters multiple times.
• Negative pressure, which is designed to trap contaminants in the room.
• Containment, where air is recirculated within the clean room for additional filtration or exhausted to another area within the building.

Why Pressurization is So Important for Industrial-Level ISO Clean Rooms

With a positive-pressure clean room, air is forced to flow out of the room. This means that the air in the clean room will have a tendency to leak out of the room, preventing unfiltered air or air particulates from entering into it. The opposite is true for a negative-pressure clean room; air is more likely to leak into the clean room. Air moves from a higher pressure to a lower pressure.

To prevent contamination, Duroair can add an anteroom between the clean room and the uncontrolled space, and increase the pressure of this anteroom, which acts as an airlock. The pressure differential prevents contaminants and particles from moving from the lower pressure side to the high pressure side.

Key Air Filtration Terms to Add to Your Manufacturing Vocabulary

Other terminology you may encounter while learning about industrial clean rooms:

• HEPA vs. ULPA filter: HEPA is a type of pleated mechanical air filter. It is an acronym for "high efficiency particulate air” filter. This type of air filter can theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 µm. The “ultra low particulate air” filter is even more efficient at 99.9995% at a submicron size of 0.12 µm.
• Laminar vs. turbulent air flow: Laminar airflow is defined as air moving at the same speed and in the same direction (uniformly), with no or minimal cross-over of air streams, or “lamina”. By contrast, turbulent flow creates swirls and eddies that deposit particles on surfaces randomly and unpredictably.
• NESHAP 319: This refers to the National Emission Standards for Hazardous Air Pollutants. Method 319 is a testing protocol that verifies that an air filtration system has met minimum efficiency requirements, under laboratory conditions.
• UV lights: Clean rooms can also use ultraviolet light to disinfect the air, killing potentially infectious particulates, including 99.99% of airborne microbial and fungal contaminants.

Learn More About Industrial ISO Clean Rooms

Duroair’s compliant clean rooms are built to spec to meet your compliance needs, including:

• Protection to ISO level 5 to meet ISO clean room standards.
• HEPA filtration 99.97% capture rate.
• Filtration capable of capturing hexavalent chromium superior to NESHAP 319.
• Positive or negative pressure as required.
• Temperature and humidity control.
• Air quality monitor and magnehelic gauge to indicate when filters require changing.
• NFPA 33 compliant motor and electrical systems that work outside of the air stream.
• Air filtration ranging from 800 CFM to 80,000 CFM.