How to Replace Aerospace Cleanroom Filters

How to Replace Aerospace Cleanroom Filters

A cleanroom with ineffective filters isn’t a cleanroom at all. That’s why it’s important to perform regular inspections and routine maintenance on your cleanroom filtration system. 

Depending on your unique application and ISO classification requirements, your cleanroom filters’ maintenance schedule and routine may look a bit different than others’. In this article, let’s take a look specifically at when and how to replace aerospace cleanroom filters. 

What Are Aerospace Cleanroom Filters?

Aerospace cleanroom filters are used to effectively and efficiently maintain air quality throughout the space, removing various hydrocarbon, silicone, and microbiological contaminants. In most cases, these filters consist of three components: a fan, a pre-filter, and a HEPA or ULPA fan filter unit (FFU) — which all work together to treat the cleanroom so it continuously meets a certain cleanliness level, or ISO classification. There are usually many filters that work together to form a comprehensive filtration system, which is installed in the ceiling grid of the cleanroom. 

Most aerospace cleanrooms require an ISO classification of 7. This means that the maximum allowed number of particles 0.5µm or larger is 352,000. To achieve this, the cleanroom must have 15-20% of ceiling coverage dedicated to filtration and an average air change rate of about 60-90 completed changes per hour. 

However, for some highly sensitive applications like spacecraft hardware and fine electronics, this classification could be lower and more stringent, requiring even more ceiling coverage dedicated to filtration and even faster air change rates. 

How to Replace Aerospace Cleanroom Filters

Regularly inspecting, maintaining, and replacing your aerospace cleanroom’s filters is important in ensuring your cleanroom meets those required levels of cleanliness. If left unchecked and dysfunctional, both your products and your end consumers could suffer dangerous and costly consequences. Here’s how to access and replace aerospace cleanroom filters to ensure optimized, safe operations within your facility. 

Where to Access Aerospace Cleanroom Filters

As mentioned previously, most filters are housed in your cleanroom’s ceiling grid. However, many cleanroom manufacturers (like us at Angstrom Technology) want to make accessing and replacing cleanroom filters as simple as possible — and climbing up a ladder to breach the ceiling isn’t all that easy. 

Therefore, these manufacturers will instead separate the prefilter from the FFU housing and place it in a low wall grille near the floor where it’s more accessible. This way, the ceiling doesn’t need to be regularly accessed and the cleanroom doesn’t need to be recertified with each prefilter replacement. 

How Often Aerospace Cleanroom Filters Should Be Replaced

Each part of your aerospace cleanroom filter requires maintenance and replacement at different times. 

Pre-filters are the outermost filters, and are therefore exposed to the most contaminants. On average, they’ll need to be replaced six times per year. It’s important to stick to this schedule so that your innermost (and most expensive) filter, the HEPA/ULPA filter, is kept safe for longer periods of time. 

Since they are the innermost filters, HEPA and ULPA filters don’t need to be replaced as often as pre-filters. With proper prefilter maintenance, they usually have a lifespan between 7-10 years. However, it’s important to check them more regularly than that to ensure they are in fact functioning properly. 

It’s also important to note that your aerospace cleanroom’s location can affect how often your filters need to be replaced. If your facility is located in an area that experiences more air pollution or contaminants (e.g. next to a railroad track or factory), your cleanroom filters may require more frequent inspections and replacements. 

Trust a Professional to Replace Your Aerospace Cleanroom Filters

Hiring a professional to inspect, service, and replace your aerospace cleanroom filters can bring many benefits to your facility. They’ll have the knowledge and experience needed to ensure your equipment meets stringent ISO standards, and they’ll help you maintain a consistent maintenance schedule — leaving you with a few less things to worry about. 

Looking for someone to service your aerospace cleanroom and get it back in top shape? The experts at Angstrom Technology can help! We’d be happy to put you on our schedule for filter replacement, HVAC upgrades, and more. Contact us for more information. 

How Cleanroom Airflow Patterns Are Designed

How Cleanroom Airflow Patterns Are Designed

Every cleanroom is designed to uphold a certain cleanliness level and ISO classification — and a major component of meeting those standards is establishing and maintaining a proper airflow pattern. In fact, ISO 14644-4 designates an entire annex section to discussing the necessary airflow patterns for maintaining low contaminant and particle counts. 

But what goes into achieving the right airflow pattern for your cleanroom? Below, we’ll provide an overview for how cleanroom airflow patterns are designed, and how you can ensure yours are meeting all necessary cleanliness requirements. 

Types of Cleanroom Airflow Patterns

Cleanrooms employ a number of HEPA and/or ULPA fan filters in order to limit how many contaminant particles enter the clean environment. Generally speaking, the more filters installed, the more treated your cleanroom will be. However, HEPA and ULPA filters are also capable of creating different airflow patterns, which can also affect cleanliness levels. 

The two main types of airflow patterns are turbulent airflow and laminar airflow. 

Turbulent Cleanroom Airflow Patterns

Turbulent, or non-unidirectional, airflow occurs when air flows in various currents throughout your cleanroom. It’s mostly commonly caused by non-uniform air speeds or obstructions in the air’s path. 

Turbulent airflow patterns can threaten the cleanliness of your environment. They can cause uncontrolled movement of contaminating particles, or they can cause dead zones where no air is moving — allowing those particles to build up over time. 

Laminar Cleanroom Airflow Patterns

Laminar, or unidirectional, airflow occurs when air flows in flat, uniform layers throughout your cleanroom. Typically, laminar airflow patterns follow a vertical path from the ceiling straight down to the floor. They require as little disturbances as possible in order to maintain a uniform pattern. 

Laminar, uniform airflow patterns are important in achieving the most controlled cleanroom environment possible. They work to keep particle movements consistent, and to prevent dead zones from popping up. 

How to Achieve Cleanroom Airflow Uniformity

To achieve a uniform airflow pattern, you first need to install HEPA and/or ULPA fan filters in the ceiling of your cleanroom. Make sure you have the correct amount of fan filters for your desired level of cleanliness. Then, those filters will push treated air out vertically, downward toward your work surfaces and eventually to the floor of your cleanroom. 

An important step of ensuring airflow uniformity is to minimize, remove, or account for any factors that could cause turbulence. You can do this by designing your cleanroom airflow pattern to accommodate your layout, equipment, furniture, and personnel. 

Need some tips on how to accommodate each of these factors? Try some of these:

  • Ensure large equipment or furniture pieces aren’t blocking fan filter units
  • Adjust equipment with aerodynamic attachments or design features
  • Use perforated cleanroom tables to allow air to pass through uninhibited
  • Modify behavior of personnel to not block airflow within critical zones

The Benefit of Expert, Custom Cleanroom Airflow Design

As your cleanroom’s ISO classification becomes more stringent, hiring an expert to design your cleanroom airflow pattern becomes more critical. They have the tools and experience needed to design a layout that optimizes airflow to meet your requirements. 

In many cases, a custom cleanroom designer or engineer will use fluid dynamics to map out your cleanroom. Then, they’ll place fan filter units and outlets appropriately to meet necessary standards. This process allows them to visualize the airflow patterns and make adjustments for systems, equipment, furniture, and personnel in order to achieve uniformity. 

Whether you want to install your own cleanroom or have it installed professionally, your cleanroom airflow pattern is something you need done right. Angstrom Technology can help! Our experts design every inch of your modular cleanroom before it’s built and delivered to you. We provide detailed instructions for installation in case you choose to DIY — but we also offer professional installation services to set it up quickly and effectively for the best possible results. Contact our team to learn more. 

Understanding Biological Safety Levels

Understanding Biological Safety Levels

In any cleanroom application, safety is top priority — for the benefit of both operators and end consumers. In order to ensure the safety of all, various industry authorities have created guidelines for cleanliness and protection.  When it comes to applications that require working with potentially hazardous biological microorganisms, the Centers for Disease Control and Prevention (CDC) have established the leading regulations: biological safety levels (BSLs). Let’s explore more about what BSLs are, and how they may be applied in your cleanroom. 

What Are Biological Safety Levels? 

BSLs are sets of biocontainment precautions required to isolate potentially hazardous biological microorganisms in enclosed, controlled environments. They’re intended to ensure operator safety by outlining recommendations for safe operating procedures and atmospheric controls. BSL protocols are used everyday in a number of industries and applications, from medical, to microbiology, to environmental testing. 

The Four Biological Safety Levels

The CDC has proposed four BSLs, each of which is associated with a varying degree of danger, and a set of appropriate operational protocols. These levels range from Biosafety Level 1 (least hazardous) to Biosafety Level 4 (most hazardous). Below, we’ll explain the basics of BSL 1, 2, 3, and 4. 


BSL-1 requires a basic level of protection against agents that aren’t known to cause disease in healthy, non-immunocompromised humans. This could include non-pathogenic and non-infectious bacteria like E.coli. Usually, there are doors that separate a BSL-1 lab from the rest of the facility, but within those doors, operators can do open-bench work with just the most standard regulations in place: personal protective equipment (PPE), hand washing, and decontamination of work surfaces after use. 


BSL-2 requires a level of protection appropriate for handling moderate-risk agents, known to cause varying degrees of disease in humans. This could include the microbial organisms like Staphylococcus aureus or Salmonella. A BSL-2 cleanroom is restricted from the rest of the facility behind self-closing doors, and features various biological safety cabinets (BSCs) to perform procedures safely in. Operators are required to wear additional PPE, including a face shield, and follow each of the standard cleanliness regulations as in BSL-1. 


BSL-3 requires protection against “exotic” airborne microbial agents that are known to sometimes cause fatal reactions in humans post-ingestion. An example of one of these agents is Mycobacterium tuberculosis. Because of the potentially deadly nature of these microbes, BSL-3 cleanrooms require even more enhanced protection protocols, including:

  • The lab must be restricted behind two sets of doors.
  • Operators must be immunized and wear PPE, plus respirators. 
  • All work must be performed in a BSC. 
  • Filtered room air must be exhausted appropriately. 


BSL-4 requires the maximum amount of preventative measures and protection. It’s recommended in labs that handle agents that have a high risk of airborne transmission and are frequently fatal for humans. Often, this includes microbial agents that we don’t yet have a treatment for, such as Ebolavirus. BSL-4 necessitates that operator and environmental protection is at its highest level, meaning the following protocols are in place:

  • The lab is located in a completely separate building. 
  • Operators must wear PPE, including a full-body, positive-pressure cleanroom suit. 
  • Operators must shower after exiting the lab. 
  • All work must be performed in a Class III BSC. 
  • All material must be decontaminated before exiting the lab. 

Biological Safety Levels vs. ISO Classifications: What’s the Difference?

While BSLs and ISO classifications are both withheld in cleanroom environments, there isn’t much correlation between them because they deal with different issues: protection of operators from biological exposure vs. protection of sensitive product materials from contaminant exposure. That being said, BSLs work in tandem with ISO classifications, with most requiring ISO Class 7 cleanrooms with separate gowning and degowning rooms. It’s best to have a conversation with your cleanroom manufacturer to get a sense of how to accommodate both needs and keep your operators, products, and environment safe all at once.  Maintaining a controlled, biosafe environment is critical for many environmental and medical cleanroom applications. If you need a cleanroom that’s designed to meet specific design or cleanliness requirements, contact Angstrom Technology. Our team of experts is happy to help you build the solution you’re looking for. 

Medical Cleanroom Terminology: What Are Hoods?

Medical Cleanroom Terminology: What Are Hoods?

Many cleanrooms require the implementation of additional features in order to perform their specific application safely and efficiently. One of the most common additions is a cleanroom hood. Below, we’ll outline the basics of what a cleanroom hood is, what it’s used for, and how it can be maintained for maximum efficiency and durability. 

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): 

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. 

How Much Does a Plastics Industry Cleanroom Cost?

How Much Does a Plastics Industry Cleanroom Cost?

In the plastics industry, quality is critical. No matter which industrial application you’re manufacturing for, a controlled cleanroom environment is critical for the efficient production of safe, durable, reliable plastic products. But with all that emphasis on quality and cleanliness, you may be left wondering, how much is all of this going to cost me? 

In this article, we’ll explore the answer to that question. After we discuss what a plastics industry cleanroom consists of, we can discover how much one may cost you, depending on your unique specifications. 

What Is a Plastics Industry Cleanroom?

Plastics industry cleanrooms are used for researching, developing, and assembling plastic components in a controlled, clean environment. Plastic products can be used for a number of industrial applications, so their cleanrooms vary in stringency based on that. For example, if your plastic components are used to make medical devices, you’ll need much more cleanliness regulation than another facility that uses plastic components to make furniture. 

Regardless of the application, there is still some amount of regulation for each of them. This helps ensure the quality of end products and the safety of operators throughout various methods of plastic manufacturing, including:

  • Injection molding – Melted plastic is injected into a set mold, fills the shape, and cools to permanent form. 
  • Extrusion molding – Melted plastic is pushed through a die, then cools in the desired shape. 
  • Rotational molding – Plastic powder is placed into a mold, then rotated until the plastic creates an outer layer with a hollow interior. 
  • Blow molding – Air pressure is used to shape melted plastic around a pre-shaped hollow plastic piece, which creates a cavity where the plastic has expanded around it. 

Changes in temperature, humidity, pressure, or static during any of these processes can result in product defects and failures — potentially wasting your facility’s time and money or putting end consumers at risk of harm. A plastics industry cleanroom mitigates that risk by controlling all the environmental factors you need, to the amount you need them. 

How Much Does a Plastics Industry Cleanroom Cost? 

All that being said, it’s apparent that a plastics industry cleanroom could look like a lot of different things — and the same goes for the cost of that cleanroom. Because of this variation, it can be difficult to get a sense of what your cleanroom may cost before you outline your specific needs to an expert manufacturer. However, there are some key considerations that you can look at to give you a general guideline:

ISO Classification

Plastics industry cleanrooms are regulated by standards created by the International Standards Organization (ISO) — specifically by the ISO 146441-1 standard, which provides the particle count, air change rate, and ceiling coverage requirements for all cleanroom environments. ISO 146441-1 is split into nine separate classes, with 1 being the most filtered air, and 9 being equivalent to regular room air. Most plastics industry cleanrooms require an ISO Class of 7 or 8, but some applications that are more sensitive to contamination may bump requirements up to Class 5 or 6. 

How does this relate to the cost of your cleanroom? The general rule is, the more stringent your cleanroom is, the more equipment it usually requires, and the more it will cost you. 


Another factor that determines your cleanroom cost is your choice between these three types of cleanrooms, which is heavily based on which ISO requirements you need to meet: 

  • SoftWall – Meets ISO Class 5-8 requirements, and is completely versatile and customizable to fit whatever space is needed. 
  • HardWall – Offers the highest level of control over the environment, and can uphold even the most stringent ISO Class 1 requirements. 
  • RigidWall – Meets ISO Class 5-8 requirements, and features a modern, transparent panel design. 


In most cases, SoftWall cleanrooms are the most affordable cleanroom option, and you’ll pay extra for the additional structure, control, or design benefits of HardWall and RigidWall types. 


As you can probably imagine, size is the most easily understood factor to account for in terms of cleanroom cost. Simply put, the bigger your cleanroom is, the more expensive it will be. Cleanroom manufacturers usually account for the biggest piece of equipment (in terms of both width and height) that will be stored in it to determine your ideal sizing. 

Design Complexity and Additional Features

The least expensive cleanrooms have basic layouts and no additional features or technologies. However, for many plastics industry applications, this just isn’t feasible. From added equipment, process piping, furniture, static control, access controls, and even attached gowning rooms, your cleanroom will likely need to accommodate specific design complexities that come at an additional cost. 

Get the Most Out of Your Cleanroom at Angstrom Technology

All this being said, it’s important to get the cleanroom you need in order to manufacture, test, assemble, or package products safely and effectively. Budget is an important consideration in the design process, but you need to be sure to make a budget that accommodates all your needs — otherwise, you’ll end up wasting on a space that doesn’t work for you. 

Trying to save on the costs of your cleanroom? Contact one of our experts at Angstrom Technology! Our team of experts will create custom designs to your exact specifications — both for your cleanroom classification and your budget. 


types of cleanrooms