What’s the Difference Between Horizontal vs. Vertical Laminar Flow Hoods?

What’s the Difference Between Horizontal vs. Vertical Laminar Flow Hoods?

Laminar flow hoods play a crucial role in minimizing contamination for sensitive products. In this blog, we’ll compare horizontal vs. vertical laminar flow hoods, providing insights into their configurations, pros, and cons. 

Whether you’re working with IV solutions, tissue culture, optics, or microelectronics, understanding these flow hoods is key to a contaminant-free workspace. Join us as we navigate the differences to help you make informed decisions for your cleanroom requirements.

Understanding Laminar Airflow and Its Crucial Role in Cleanrooms

Laminar airflow is air that constantly moves at the same speed in the same direction. In cleanrooms, a vertical laminar flow room is an enclosure where 100% of the ceiling provides filtered air downwards from the ceiling. Because of the 100% filter coverage, it creates an ultra-clean environment. But it’s much easier to achieve laminar flow in a smaller space, as equipment, personnel, and movement in a room cause turbulence that disturbs airflow.

A laminar flow hood is a device or enclosure commonly used as an ultra-clean workbench in laboratory applications. Filtered air sweeps particles in a uniform speed and direction from the hood’s most treated area (the filter) to its exit area.

Cleanroom airflow uniformity and laminar flow hoods are essential to ensuring that sensitive products placed under the hood are always upstream and, therefore, suffer little to no contamination. 

Horizontal vs. Vertical Laminar Flow Hoods

Flow hoods come in two configurations: horizontal and vertical. Both designs provide an effective sweeping action through the work zone and meet ISO Class 5 cleanliness standards. Your application and needs will help determine which is better for your facility.

Horizontal Laminar Flow Hoods

As their name indicates, horizontal laminar flow hoods direct air horizontally. Air is pushed through a HEPA or ULPA filter positioned on the back wall and moves forward across the work surface until it exits the enclosure.

By sweeping the air across the work surface and towards the operator, horizontal laminar flow hoods provide the highest protection from contaminating particles. No turbulence is caused by vertical air striking a perpendicular surface or the hands of the operator since they’re always further downstream than the materials they are working on.

However, the hood’s size, the filter’s positioning, and the airflow’s direction can also result in some negative consequences. Below you’ll find a helpful list of pros and cons for these types of hoods:


  • Low turbulence on the work surface due to air flowing parallel to the work surface
  • Easy to position products and materials close to the filter on the work surface
  • Little contamination from hands or gloves due to the operator being downstream from products and materials


  • Requires hood repositioning to gain rear access for filter changes and servicing
  • Objects can obstruct the flow and contaminate anything downstream
  • Operators could suffer from fume or powder contaminants blowing at them if they don’t use the sash correctly

Vertical Laminar Flow Hoods

In contrast, vertical laminar flow hoods take air from above the unit, push it through the HEPA or ULPA filter, and then direct it down onto the work surface, where it eventually disperses and exits the enclosure out of a front access area. They resemble the model of a laminar flow cleanroom with fan filter units on the ceiling, just on a much smaller scale.

Vertical laminar flow hoods are popular because of their size, layout, and operator safety. Since the filter is at the top of the unit rather than behind, these flow hoods require less floor space but can be taller to fit larger products and materials. Also, since the laminar air isn’t blowing toward the operator, they are less likely to suffer any contaminants.

Vertical laminar flow hoods are an excellent choice for many applications, including handling sterile, non-hazardous drug compounding in research labs, pharmacies, and microbiology. Here’s a quick overview of their pros and cons:


  • Require less floor space
  • Increased operator safety
  • Easy access to filter changes and servicing
  • Less cross-contamination of items on the work surface due to no parallel airflow
  • A taller system that can accommodate tall and large products and materials


  • May require overhead clearance for changing and servicing the filter
  • Increased work surface turbulence due to vertical air hitting a perpendicular surface
  • Products and materials could obstruct airflow when stacked

Which Laminar Flow Hood Is Right for Your Application?

Both horizontal and vertical laminar flow hoods can be utilized for many applications involving sensitive products and materials, including (but not limited to):

  • Injectable drugs
  • IV solutions
  • Tissue culture
  • Optics
  • Microelectronics

While both types of flow hoods are optimal for reducing contamination in a workspace, a few applications lend themselves more toward one or the other. Usually, the most important factors to consider include process location, clearance requirements, size of materials, work surface design, and operator safety.

That said, horizontal laminar flow hoods generally work best for applications that require minimal turbulence on the work surface and the highest level of object contamination control. If your application’s process is performed above the work surface, a vertical airflow configuration may be ideal; particles inside a vertical unit settle at the bottom of the work surface before exiting the enclosure. Vertical hoods are also a popular choice for any applications involving materials that could be especially large or dangerous to the operator.

Contact the Cleanroom Experts at Angstrom Technology

If your cleanroom requires laminar flow hoods, Angstrom Technology can design a cleanroom that will seamlessly meet your classification and industry requirements. Our experienced design engineers are ready to collaborate with you to create a tailored solution that ensures optimal performance and adherence to industry standards. Contact us today to initiate the conversation and enhance the efficiency of your cleanroom environment.


The best wall panels for a dry room for battery manufacturing

The best wall panels for a dry room for battery manufacturing

Our recent blog post discussed HVAC systems that deliver low dewpoint air to create a dry room for battery manufacturing. But we can’t overlook the importance of an envelope system in a dehumidification system. A fully sealed panel system with well-sealed doors will insulate and protect a dry room from moisture ingress. The experts at Angstrom Technology can create a stable low dewpoint production environment to meet your requirements. In this blog post, we explain how.

DRY ROOM for battery manufacturing wall PANELS: ROBUST & FLUSH

A critical building envelope decision is the fabric of the panel finish, which must consider cleaning regimes, robustness, and surface resistivity. The latter is often most important within the battery, semiconductor, and microelectronics industries.

A flush cleanroom system eliminates trapping points, allowing for the best particulate control possible. Vision panels and doors should have flush integrations to avoid dead zones in air flows and trapping points for particulate.


Static dissipative plastics have a surface resistance that allows electrical charges to dissipate within milliseconds. The use of static dissipative materials will allow charges to flow to the ground in a slow and controlled way, preventing discharge to or from human contact.


Anti-static materials usually have a surface resistivity that inhibits the build-up of electric charges created when two materials rub together. Suppressing initial charges prevents the build-up of static electricity and provides a very slow rate of static charge decay from a hundredth to several seconds. This method can control building envelope charges in micro-electronic facilities.


Electrostatic discharge (ESD) can cause lithium to catch fire or micro-electronic components to fry, so battery dry rooms must be designed and built to ground charges safely. Panels with PIR or PU cores are highly insulative, so they can trigger ESD, making them inappropriate for these environments. Instead, panels with an aluminum honeycomb core and either anti-static or static dissipative facings will help manage the grounding of charges.


Ultra-low humidity levels combined with highly combustible materials give battery dry rooms a high fire risk, which needs careful management. A low surface spread of flame tested to ASTM E84 is essential.



Whitepaper: Dry room design guide for lithium battery manufacturing




dry room design guide


As Angstrom Technology are cleanroom specialists, our dry rooms can also achieve ISO classification. Not only that, but a dry room for battery manufacturing from Angstrom can also meet any applicable international engineering and building standards and regulations.

We’ve developed proven envelope solutions and reliable cleanroom HVAC designs for many applications. The Angstrom Technology group pride ourselves on our in-house expertise and capability to deliver over 100 cleanrooms annually across America, the UK, and Europe.

Tell us about your new dry room project!



Fan Filter Units and Air Handling Units. What’s the Difference?

Fan Filter Units and Air Handling Units. What’s the Difference?

If you’re considering different options for filtering and treating the air in your cleanroom, you’ve likely come across fan filter units (FFUs) and air handling units (AHUs). What’s the difference, and how can you design a cleanroom filtration system that will offer you the control you need with maximum efficiency? Let’s break down fan filter units and air handling units in more detail.

Fan Filter Units and Air Handling Units: What’s the Difference?

Both FFUs and AHUs filter and treat the air in cleanrooms and controlled environments. However, they do this differently. The most significant difference between these systems is their connection to cleanroom HVAC.

Air Handling Units

An air handling unit is synonymous with the HVAC system and acts as a centralized unit for air processing and filtration. When an air handling unit is solely responsible for delivering clean air to the cleanroom, a fan pushes treated air through a filter positioned right before the plenum and into the room.

AHUs can be simple or complex, depending on the needs of the cleanroom. Simple AHUs consist of a HEPA filter, a heating coil, a cooling coil, and a fan to push air through the unit. More complex AHUs can also contain a sound attenuator, return fan, relief air section, humidifier, intakes for outside air, and a discharge plenum.

Fan Filter Units

Fan filter units sit in the cleanroom envelope, and to reach air cleanliness standards, you can increase or decrease the quantity as needed. They are individual units that each deliver filtered air into the cleanroom. The HVAC unit still controls temperature and relative humidity, but air enters the cleanroom after terminal filtration through the separate FFUs.

Fan filter units have a more straightforward construction multiplied across the cleanroom to reach peak effectiveness. They consist of a HEPA filter, a pre-filter, and a fan to push air through the unit. The more stringent the cleanroom classification, the more fan filter units are required to reach particle count requirements. For example, while an ISO Class 8 cleanroom may only need 5-15% of ceiling coverage dedicated to FFUs, ISO Class 3 cleanrooms may require 100% ceiling coverage with these powerful filtration units.

Fan Filter Units and Air Handling Units: Pros and Cons

While one system is not inherently better than the other, fan filter units offer some advantages over an air handling unit alone.

Drawbacks of Relying on an Air Handling Unit

AHUs deliver fresh, filtered air directly into the cleanroom. Because the entire system is in-house, all filters, heating, and cooling coils are maintained in one central location. It may seem like a more straightforward construction, but using AHUs to manage the treatment and filtration of air for an entire cleanroom requires more energy and becomes more inefficient (and expensive) as your ISO class gets lower.

Disadvantages of Relying on an AHU for Filtration

  • Higher Airflow Requires More Power: The entire system pushes air into the cleanroom through one or a few filtered openings. Depending on your cleanroom size and classification, a lot of air is forced through a limited space. Using an AHU to cool and filter the air in a cleanroom takes a lot of power, especially at lower ISO levels.
  • Inefficient Configuration for Low ISO Cleanrooms: As the ISO class gets lower, there’s more reliance on the AHU and filter to provide clean, cool air for the room. When cleanrooms get more complex and house large or sensitive equipment that generates a lot of heat, making it challenging to manage heat and ACH with just an AHU.
  • Vulnerable to Filter Loading: AHUs should run 24/7 to prevent filter loading. This is when particles settle on filter media and are forced through when the system is turned back on. Tears and filter loading can reduce filter performance and are challenging to spot and address.

Why Implement Fan Filter Units in Your Cleanroom

Many cleanrooms opt for modular construction with fan filter units installed in a grid ceiling. Especially those that must support sensitive processes at a lower ISO level. That’s not to say that an air handling system couldn’t do the job just as well. But the easy installation and maintenance of FFUs make them a more widespread, efficient, and cost-effective choice.

Advantages of Using Fan Filter Units

  • Modular and Customizable: Each filter and housing is an independent system mounted in a modular ceiling grid. FFUs are entirely customizable in size, flow rate, and filter options. When designing a cleanroom filtration system with FFUs, you have more flexibility to meet your classification, project, and budget requirements.
  • Thorough and Efficient Cleanroom Filtration: Fan filter units are 99.99% efficient with HEPA filters. Or 99.9995% with ULPA, making them ideal for various sensitive applications. They also produce less noise than a large AHU.
  • Easy to Modify: Fan filter units are ideal for projects that need room to grow. To meet increased cleanliness requirements, you can simply add more FFUs. With AHUs, this would require a certified contractor to reconfigure the system and run extra conduit.
  • Easy to Maintain: FFUs also present an advantage during maintenance. Self-contained units can be accessed and replaced as needed without having to disable the entire system.

To meet productivity demands, a reliable and easily accessible filtration system is a must. And the higher filtering power means that sensitive applications, such as those working with sensors or delicate electronics, are protected from the smallest particles with accuracy and consistency.


As Angstrom Technology are cleanroom specialists. We’ve developed proven envelope solutions and reliable cleanroom HVAC designs for many applications. The Angstrom Technology group pride ourselves on our in-house expertise and capability to deliver over 100 cleanrooms annually across America, the UK, and Europe.

If you’re interested in designing a cleanroom that runs at peak efficiency to cut unnecessary costs, get in touch with the cleanroom experts at Angstrom Technology. We’re happy to help design the right airflow pattern and install the solutions that will make your cleanroom cleaner.







Tips for Cleanroom Cleaning

Tips for Cleanroom Cleaning

You’ve spent the money, taken the time, and exhausted the resources needed to design and construct a perfect cleanroom for your facility’s application. It’s fully operational and exceeding your expectations, so now you can just sit back and enjoy the results, right? 

Well, yes — but your work isn’t done. All cleanrooms require constant cleaning because, no matter how robust of a filtration system they may have, they’ll always have some amount of exposure to contaminants. 

6 Tips for Cleanroom Cleaning

Regardless of your cleanroom’s ISO classification, adhering to proper cleaning protocols will help ensure its performance and longevity. There are a lot of factors that go into that cleanroom cleaning process, so we’ve compiled a list of six cleaning tips to help you keep track of the most important steps. 

1. Choose One of Two Cleanroom Cleaning Methods

For starters, there are two basic methods of cleanroom cleaning that you should be aware of: dry transfer and wet cleaning:

  • Dry transfer cleanroom cleaning involves wiping a surface with a collective, absorbent material. This material should be a cleanroom-specified cloth or wipe that won’t shed fibers, break apart, or redeposit contaminant particles. Depending on your cleanroom’s ISO classification, this could include knitted polyester cloths or cotton twill wipes. 
  • Wet cleanroom cleaning removes contamination with the use of a cleaning fluid. It’s a good choice when dry transfer isn’t enough to overcome particle adhesion to surfaces. However, it’s important to use only cleanroom-specified cleaning agents, such as deionized and distilled water, or neutral, non-ionic, non-foaming chemical solvents. 

Most of the time, proper cleanroom cleaning involves both types of cleaning. It’s just important to understand which is best for which kind of surface or application. 

2. Be Aware of Varying Industry Standards 

Depending on the industry you’re in, your cleanroom will have a unique layout, ISO classification, and cleanliness standard. Your cleaning routine needs to reflect those specifications. 

If your cleanroom has a lower ISO classification, it will need to adhere to more regular, comprehensive sanitation processes in order to keep tight control over particulate contamination. Cleanrooms with higher ISO classifications still need to keep up with regular cleanings, but they may be a little less involved. 

3. Adhere to Sanitation Protocols Before Entering Your Cleanroom

The best way to keep your cleanroom as clean as possible is to follow proper sanitation protocols before entering it. Make sure all of your equipment and tools are cleaned and disinfected before they’re allowed in. 

This step doesn’t just involve equipment though; it also involves your personnel. In fact, they’re usually the biggest contributor of outside contaminants coming into your cleanroom. Ensure all staff members are thoroughly trained on what steps they need to take — from washing and drying hands completely, to using sterile gloves, to following the proper gowning procedure. 

4. Implement Advanced Cleaning Equipment As Necessary

In some cases, dry transfer and wet cleaning can only get you so far, and you need to bring in more advanced cleaning technology and equipment. From portable HEPA filtration systems with UV-C light integration, to Dry Hydrogen Peroxide (DHP™), there are many technological cleanroom cleaning innovations to choose from — and they’ll all add a heightened level of filtration or sterilization to your environment. 

5. Follow a Top-Down Cleaning Pattern

How you clean is just as important as what you use while cleaning. Although they’re small, contaminant particles are affected by gravitational forces. To ensure any falling particles don’t recontaminate recently cleaned surfaces, you should sanitize your cleanroom from top to bottom, cleaning shelves or work surfaces first and the floor last. 

All of which brings up another good tip: don’t forget to sanitize your cleanroom’s floor! The floor is one of the most easily contaminated surfaces of your cleanroom, due to easily-forgotten shoe cleansing and gravity naturally pulling contaminants down. Invest in a shoe cleaner or sticky mat to minimize the number of particles before entering, but also remember to wipe the floor after the fact. 

6. Commit to a Regular Cleanroom Cleaning Routine

Maintaining a clean, controlled environment requires diligence. Your team needs to commit to a regular cleanroom cleaning schedule full of daily, weekly, and as-needed tasks. Depending on your ISO classification, these tasks may be done with more or less frequency, but a general schedule is as follows: 

Daily Cleanroom Cleaning Tasks

  • Before a shift begins, use a damp mop to sanitize floors. Dry them with a HEPA filter vacuum. 
  • Vacuum all walls with a HEPA filter vacuum.
  • Wash and dry all windows and pass-throughs. 
  • After each shift, wipe down all work surfaces.

Weekly Cleanroom Cleaning Tasks

  • Mop floors with a cleanroom-specified detergent and distilled water. Dry them with a HEPA filter vacuum.
  • Wipe walls with distilled water. Dry them with a HEPA filter vacuum. 

As-Needed Cleanroom Cleaning Tasks

  • Wash ceiling with detergent and distilled water.
  • Wipe off light lenses. 
  • Replace shoe cleaners and/or sticky mats. 

Have more questions about keeping your cleanroom clean? Get in touch with the experts at Angstrom Technology! We’re happy to walk through your specific requirements and help design, build, and maintain the ideal cleanroom for your facility.

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. 

How to Choose a Fan Filter Unit for your Cleanroom

How to Choose a Fan Filter Unit for your Cleanroom

In order to ensure your facility is meeting required cleanliness standards, fan filter units (FFU) are a critical component of your cleanroom design. Let’s explore more about fan filter units: how they work, what types there are, and how to choose the right one for your cleanroom.

What Is a Fan Filter Unit?

A fan filter unit is an independent filtration system mounted in a modular cleanroom ceiling grid that is used in conjunction with an air handling unit or HVAC system. It contains a fan, a pre-filter, and a filter (either HEPA or ULPA). In most cleanrooms, multiple fan filter units are installed in the cleanroom ceiling grid and are designed to provide a consistently treated workspace, minimizing dead zones.

Individual fan filter units can be added and subtracted according to the size and necessary ISO Class regulations. In general, the bigger your cleanroom, and the more stringent your ISO Class, the more fan filter units your cleanroom will likely need.

How Does a Fan Filter Unit Work?

Fan filter units work by continuously pushing clean, filtered air into your cleanroom. Air travels through a pre-filter, through the fan, and then through the HEPA or ULPA filter that treats and filters out airborne particles prior to entering your cleanroom.

When Do You Use a Fan Filter Unit for a Cleanroom?

Fan filter units provide a number of advantages over traditional air handling units. Here are a few reasons you may consider using fan filter units for your cleanroom:

  • Easy to install – Because they are mounted in the cleanroom ceiling grid, fan filter units are easy to install and are easily accessible from within the cleanroom.2
  • Easy to modify – As your facility grows and changes, your filtration system can too. Fan filter units can easily be added into the ceiling grid if you have to meet increased cleanliness requirements in the future.
  • Cost-effective – Fan filter units are generally less expensive than a completely new air system, both in terms of production cost and installation cost.

Types of Fan Filter Units: PSC vs. ECM

While all fan filter units function in generally the same way, there are two types of motors that commonly power a cleanroom FFU: permanent split capacitors (PSC) and electronically commutated motors (ECM). Each motor functions a little differently, providing distinct advantages depending on which option you choose. PSC motors operate at one consistent speed, while ECM motors have a variable speed drive and can adjust speed based on application requirements.

PSC vs. ECM: Which Fan Filter Unit is Right for Your Cleanroom?

Both of these are reliable options, guaranteed to provide the filtration your cleanroom needs. However, ECM units are often the best choice to help you meet your cleanroom goals and maximize treated space.

The Benefits of an ECM Fan Filter Unit

ECM fan filter units are known to be air-treating powerhouses for a range of applications — especially if those applications require varying filtration speeds. Its variable speed drive includes numerous benefits, including:

  • Smooth operation in inconsistent conditions
  • Great durability for big, long-haul projects
  • Energy-saving technology to help you reduce utility costs

Looking for a cleanroom that incorporates high performance filter fan units? Angstrom Technology can design a cleanroom to accommodate any equipment for your application. Contact us today to get started.