What Are Cleanroom Hoods?

Cleanroom hoods (also called laminar flow hoods) are enclosures designed to guide filtered air in a uniform speed and direction, all in an effort to prevent contaminant particles from building up on the work surface, and to protect the product and operator. They can come in the form of workstations, work benches, and cabinets. 

Cleanroom hoods work in a circulatory process, pushing treated air from the fan filter unit to flow across the work surface until it reaches the enclosure’s exit area where it’s treated and circulated again. This ensures that any sensitive materials placed on the hood’s work surface are always upstream and suffer little to no contamination. 

Types of Cleanroom Hoods

There are two types of laminar flow hoods: horizontal and vertical. As their names suggest, each of them either blows air horizontally or vertically in relation to the hood’s work surface, and there’s some debate in the industry over which method is best. 

Horizontal laminar flow hoods direct air horizontally, or parallel across the work surface. This system helps reduce the amount of turbulence (random air movement) drastically, offering sensitive materials maximum protection from contaminants. 

Vertical laminar flow hoods direct air vertically, or perpendicular to the hood’s work surface. They resemble the design and operation of a laminar flow cleanroom, where air is treated through a fan filter at the top of the enclosure, then pushed downwards — just on a much smaller scale. The vertical flow of air is especially good at preventing any harmful particles from being blown at the operator. 

Cleanroom Hood Components

No matter if they’re horizontal or vertical flow, all cleanroom hoods have the same basic components. If you’re planning on using a hood for your cleanroom application, it’s important to be comfortable with each of the parts and their functions. 

• Sash – Located on the face of the hood, this is a transparent panel that shields internal materials from the outside environment, while also providing some protection to the outside environment and operator. 
• Airfoil – Usually located at the bottom front of the hood, this is a vent that allows room air to enter the hood enclosure. It helps prevent vapors from escaping and air imbalances in the workspace. 
• Baffle – Usually located on the hood’s ceiling, this is an adjustable partition that affects air force and direction within the enclosure. It works to ensure laminarity (uniformity) by controlling pressure in airflow. 
• Fan filter unit – This is the component that’s primarily responsible for the hood’s clean environment by filtering particles and maintaining consistent air change rates. For horizontal laminar flow hoods, this is located at the back of the enclosure. For vertical laminar flow hoods, this is located on top of the enclosure. 
• Plenum – This is the space underneath the work surface or behind the hood walls that balances and distributes air. Air usually enters the plenum from the airfoils and is pushed to the air filter before re-entering the enclosure. 
• Duct – This is an exhaust passage that’s used to transport contaminated air out of the hood’s clean environment — either into another room or outside of the building completely. 
• Gauges – These are meters that continuously monitor the hood’s air velocity, particle count, and air pressure. 
• Work surface – This is the main space where sensitive materials are placed and processes are carried out within the hood. Depending on which type of hood you have, this could be in front of (horizontal flow hood) or underneath (vertical flow hood) the hood’s fan filter unit. 

Which Cleanroom Applications Require Hoods?

Any process involving highly sensitive materials that can’t be contaminated may be carried out within a cleanroom hood. This includes a number of applications within a number of industries, including (but not limited to): 

• Pharmaceutical
• Medical
• Biological sampling
• Manufacturing
• Semiconductor

How to Clean and Maintain Cleanroom Hoods

Cleaning and maintaining your cleanroom hood is paramount in ensuring its effectiveness for years to come. Typically, certification of the hood is required annually or semi-annually, depending on your industry’s standards. In terms of cleaning, there are three levels of cleanliness that you can achieve: 

• Sanitized – Removing visible dirt and contaminants on the surface, reducing the amount of germs and chances of infection, illness, and/or contamination. 
• Disinfected – Eliminating virus, bacteria, and fungi from the work surface with a cleaning agent. 
• Sterilized – Completely eliminating any microorganisms and contaminants from the work surface, usually by means of chemicals, heat, and/or pressure. 

Angstrom Technology’s modular cleanrooms can be customized to meet the needs of your application. If your application requires special equipment like cleanroom hoods, get in touch with our team of design engineers. We’ll help explain the process and design a controlled space that accommodates all of your requests. 

All that being said, if your facility hosts one or more medical cleanrooms, you may also want to invest in some innovative technologies to ensure consistently sterilized air and surfaces. Below, we’ll explore some of the new medical cleanroom technology on the market, including various portable HEPA filtration systems and peroxide sanitizing solutions. 

Portable HEPA Filtration Systems with UV-C Light Integration

While your cleanroom may already host a number of HEPA filters, some of the newest trends in medical cleanroom technology deem portable HEPA filters a rewarding investment. New portable HEPA filters can be mobile, ceiling mounted, or standalone, and they usually contain a UV-C light integrated for extra cleansing power. This way, you’re able to sterilize any specific area or surface more quickly and effectively than ever before. 

How Do HEPA Filters with UV-C Light Integration Work?

HEPA filters are known for effectively capturing microscopic viruses and bacteria with ease. Generally, airborne viruses are moved through the air via particles with a diameter between 10-100 µm. HEPA filters are capable of capturing large infectious loads of particles that are responsible for virus transmission and exponentially reducing them. 

HEPA filters can remove many of the common human pathogens from air circulation, including (but not limited to) the following:

• Escherichia coli: Gastrointestinal infections
• Aspergillus brasiliensis: Sinus infections
• Mycoplasma pneumoniae: Pneumonia
• Haemophilus influenzae: Meningitis
• Mycobacterium Tuberculosis: Tuberculosis

When HEPA filters are combined with UV-C light technology, they can inactivate airborne-mediated microbial disease and microbial resistant bacteria even faster. UV-C lights and lamps are extremely effective, even against some of the most contagious airborne diseases. And while HEPA filters primarily cleanse the air, UV-C lights help sterilize water, hard surfaces, and nonporous objects as well. 

Portable HEPA Filtration System Features and Accessories

Along with your portable HEPA filtration system, you’re able to add on a variety of optional features and accessories for advanced performance, including:

• Portable UV torches – Portable UV disinfection torches are about 5 feet tall, and designed to sterilize objects and tools within a medical cleanroom. They stand on their own, include 8 UV-C bulbs, and are built with an open center that allows for comprehensive sterilization within a 10-foot radius. 
• Handheld UV light wands – Handheld UV light wands work similarly to portable UV torches, but are even more mobile. They have a lightweight, ergonomic design that is especially helpful in surface sanitation, and cleanroom inspection procedures. 

Dry Hydrogen Peroxide

Dry Hydrogen Peroxide (DHP™) is the true gas form of hydrogen peroxide, and it attacks microbes like viruses, bacteria, and mold before they can be damaging, both in the air and on surfaces. Developed by Synexis, this technology is designed to flow freely and constantly throughout your controlled space to effectively eliminate pathogens — without any reliance on air exchange rates. It works by taking the oxygen and humidity naturally present in your environment, then breaking them down in the Synexis device through a photocatalytic reaction (chemical reaction involving the absorption of light). Those molecules are then put together again, but as DHP™.

Not only is DHP™ cool and effective technology, but it’s also completely safe — falling far below safety limits for human exposure established by OSHA and meeting UL2998 certification requirements for zero ozone emissions. You can learn more about how DHP™ works and benefits various applications here. 

If you’re looking to upgrade your medical cleanroom technology to include some of the newest innovations, contact Angstrom Technology! Our cleanroom design experts can make sure your facility is outfitted with the best gadgets and gear to protect your work and workers.

Air Changes per Hour are important factors in determining the design and evaluating the performance of a cleanroom. The air changes per hour, airflow pattern, and exchange efficiency all have significant implications on cleanroom performance and cost, which in turn determines the return on investment for a cleanroom.

What are air changes per hour, and how are they accounted for in cleanroom design? We’ll break down the answers to these questions and more.

What are Air Changes Per Hour?

As defined by ISO 146144-4 standards, air changes per hour refers to the number of times per hour the air in a cleanroom is replaced with clean, filtered, and treated air. It’s calculated by dividing the volume of air sent into the cleanroom as a unit of time by the total volume of the cleanroom. 

Air Changes Per Hour or Air Change Velocity

Cleanrooms, by definition, require air changes in order to meet air quality requirements for particle count and more. As the environment gets more clean with lower ISO classes, more and more air changes are needed to reach stringent classification standards. 

ISO standards express air changes per hour differently for cleanrooms with unidirectional and non-unidirectional airflow. 

Non-Unidirectional Airflow = Air Changes Per Hour

Non-unidirectional, or mixed flow, refers to the airflow pattern in a cleanroom. Typically, cleanrooms that fall within ISO Classes 5 and above use this type of airflow. It is sufficient for removing the designated number and size of particles at a regular rate per their classification standard. 

For cleanrooms that comply with ISO Classes 4-9, hourly air changes per hour are sufficient to express how many times the air in the cleanroom is completely refreshed. Applications like pharmaceutical, packaging and manufacturing, biosciences and health typically fall in this classification range and comply with air changes per hour as described. 

Unidirectional Airflow = Airflow Velocity

As cleanroom classifications become more stringent, the air changes per hour must increase to remove particles and keep the air cleaner. Cleanrooms with unidirectional airflow, typically Class 5 and below, have the strictest cleanroom classifications. To maintain air quality, the air changes per hour is so rapid it is expressed instead as airflow velocity, either in meters per second or feet per minute. 

These cleanroom environments must remain extremely clean, so the constant flow of contaminant-free air, either vertically or horizontally, is vital to keep particles from settling on surfaces and maintain classification standards. 

Cleanroom applications such as microelectronics, sensor manufacturing, and other sensitive processes must be performed in such environments with strict air quality control and consistent removal of contamination.

Air Changes Per Hour and Cleanroom Classifications

air changes per hour are an essential component of cleanroom classification standards. They make it possible to reach the particle count and size restrictions each class sets. Let’s take a look how air changes per hour and classification are related.

As you can see from the chart above, classes are organized by three major factors: particle size and count, air changes per hour or airflow velocity, and percentage of ceiling coverage. Once the air changes per hour rises above 200, it is better expressed as airflow velocity in feet per minute. 

What’s My Air Changes Per Hour?

The best air changes per hour for your cleanroom is the one that allows you to reach the required cleanliness required by your cleanroom classification. The level of activity and actions that introduce contaminants in your specific cleanroom may affect the amount of particles generated, and thus the air changes per hour required to remove them.

Your cleanroom’s air changes per hour describes conditions when the room is in operation, but you may lower the air changes per hour when the cleanroom is not in use to save energy and operation costs.  

Designing Cleanrooms to Meet Air Changes Per Hour

Your cleanroom is designed to meet your cleanroom classification. All the systems that support air quality and cleanliness work together to achieve consistency.

To design a cleanroom that meets your classification with adequate air changes per hour, the cleanroom must contain enough fan filter units and a uniform airflow pattern. A greater percentage ceiling coverage of fan filter units is required to reach necessary air changes. 

Although the percentage of ceiling coverage for fan filter units isn’t a metric directly referenced by ISO standards, it helps estimate construction costs. What’s most important is that the cleanroom has the systems it needs to thoroughly and consistently change the air to reach its cleanliness requirements. 

Upgrading Cleanroom Classifications and Air Changes Per Hour

If you need to upgrade your cleanroom to meet stricter classification standards or adapt your facility to handle a more sensitive project, an important step is to increase or adjust the filtration and air changes per hour to remove more particles of a smaller size from the air. 

When moving from ISO Class 7 to ISO Class 6, for example, you’ll need to increase your air changes from 60-90 ACH to 150-240 ACH to filter all but 35,200 particles at 0.5 microns per cubic meter. Consider that, to support this shift, you may need to upgrade your HVAC system.

Meet Your Classification With Cleanroom Professionals

Think you need to update your cleanroom’s air changes per hour? The cleanroom design experts at Angstrom Technology can help! We can evaluate your space and systems to ensure they’re working effectively, and help you upgrade them to change air more efficiently. To learn more, give us a call or reach out online.

Every part of your cleanroom’s design should work for you, from its protective flooring and wall panels to the fume hoods and HEPA filters. Each element serves a purpose to change the air, reduce risk, or limit contamination. What about garments? What are they, and how do they serve you and your cleanroom’s work? Here is everything you need to know about cleanroom garments.

What Are Cleanroom Garments?

Cleanroom garments are pieces of clothing worn in a cleanroom to limit human contamination. They are essentially filters for people, blocking contaminates and shedding particles from entering the cleanroom environment as much as possible. Cleanroom garments are necessary in almost all class standards, though garment and material specifications may differ. 

What Are Cleanroom Garments Used for?

In your cleanroom, you can control almost every contaminating factor through isolation, careful cleaning procedures, and thorough sterilization — except humans. People are the most contaminating element of cleanroom environments, and the hardest to keep clean. From dead skin cells to hair, textile fibers and dust, and microbes from body oils, saliva, and other bacteria — even when practicing meticulous personal hygiene, humans are sloppily packaged messes. The average person sheds 10 million particles of skin alone in a single day. The more we move and talk, the more particles and microbes we shed, putting sensitive work at risk. While we have almost complete control over the rest of the environment, we’ll never be able to entirely eliminate human contamination of cleanrooms. 

Cleanroom garments are the best solution to this problem. They cover people up, limiting particle shedding as much as humanly possible. They significantly reduce our risk of ruining the cleanliness of our workspaces, and are absolutely essential to meet rigorous class standards.

Cleanroom garments have another important purpose. Not only do they block our contaminates from hurting our products, but they are protective for the wearer as well. In cases where the work could be caustic or hazardous, cleanroom garments can protect delicate skin, eyes, and respiratory systems from dangerous substances.

What’s Included? Common Cleanroom Garments

Cleanroom garments are essential for life-as-usual within almost all cleanrooms. They should be non-particle shedding, easy to put on, comfortable to wear for long periods of time, and be able to withstand the process of sterilization. Different cleanroom garments will be required depending on your class type. Your class will also specify the materials that can be worn. Some typical cleanroom garment items include: a coat and pants or coverall to cover the body; head gear like a mask, hood or both; goggles; shoe covers or boots; and, of course, gloves. 

Coat and Pants, or Coverall

The coat and pants or combination coverall must be made of an appropriate fabric type for your cleanroom class standard, either woven, spun-bonded, or laminated fabric. They will have as few seams as possible and fit a bit large but not baggy. All clothing must have adjustable closures at the openings, with no pockets.

Head Gear 

Cleanroom head gear will cover all hair completely to prevent any loose hairs from shedding into your cleanroom environment. Beard covers are available, too. If extreme control or protection is required, a hood with its own ventilation and filtering may be necessary.

Face Masks 

Cleanroom-specific face masks are either surgical-style with elastic or fabric straps, or a veil that is attached to the rest of the suit.

Goggles

If your cleanroom requires the use of goggles, they are used to prevent shedding of particles from the eyes or eyebrows, and also act as protection against sparks or splashing substances. 

Shoe Covers

Shoe covers are usually used when entering a gowning room. Before entering the cleanroom, more sterile footwear is donned to further limit possible contamination. Some low class standards might allow just shoe covers to be worn over appropriate footwear within the cleanroom.

Boots

Boots are typically used as a cleanroom garment to cover pant legs and are secured with straps to fasten over footwear. They have rubber or plastic soles for advanced protection against static electricity.

Gloves

Barrier gloves are the most common piece of cleanroom garments, and can be made from a variety of materials, depending on your cleanroom’s needs: Latex will fit well but may be allergenic; nitrile gloves are tear and chemical-resistant; vinyl is a low-cost glove material option but it can tear easily. All gloves must be powder free. They are pulled over the wrists to cover the sleeve of the garment. For extra protection, gloves can be layered.

Cleanroom garments will vary for different applications including pharmaceutical or laboratory applications, manufacturing cleanrooms, or grow rooms. Combined with good personal hygiene, slow and deliberate movement, and proper training, garments are effective defenses against cleanroom contamination by people. 

Your class standards will be the ultimate guide for what cleanroom garments your application requires. If you have questions about your cleanroom classifications or standards, talk to the experts at Angstrom Technology! We can help you design and install a cleanroom that adheres to any classification your application requires. Visit us online to reach out.