If you’re considering a cleanroom, you’re probably trying to gather as much information as possible. What type of cleanroom is right for you? What industry standards do you have to meet? Where will your cleanroom go? You get the picture. Well, it might be helpful for you to understand the difference between a positive and negative air pressure cleanroom. As you probably already know, airflow plays a leading role in keeping your cleanroom to standard, but you may not have known that air pressure can also have a big effect on that. So here’s a broken-down explanation of each positive and negative air pressure.
POSITIVE AIR PRESSURE CLEANROOM
Positive pressure means the air pressure inside your cleanroom is greater than outside. You achieve positive pressure by pumping clean, filtered air into the cleanroom — generally through the ceiling. In the event of a leak, or a door opening, clean air would flow out of the cleanroom, preventing unfiltered air from flowing into the cleanroom.
A balloon popping is a perfect illustration of positive pressure. When you pop a balloon, air rushes out because the air pressure in the balloon is higher than the ambient air pressure.
Positive pressure cleanrooms are used primarily for industries where the primary goal of the cleanroom is to keep the product clean and safe from particulates, like in the semiconductor industry, where even the tiniest particle can damage the integrity of the microchips or wafers.
NEGATIVE AIR PRESSURE CLEANROOM
In a negative air pressure cleanroom, the air pressure in the room is lower than outside pressure. If the goal for your environment is to keep contamination from escaping the cleanroom, you likely need a negative-pressure cleanroom.
Negative pressure is created by filtering air out of the room at a higher rate than the supply air. In most situations, air enters through filters near the floor, then removed through filters in the room ceiling.
Windows and doors need an airtight seal to prevent air outside the cleanroom from flowing into it rather than out of it.
CONTACT THE CLEANROOM EXPERTS AT ANGSTROM TECHNOLOGY
If you have any more questions regarding negative and positive air pressure cleanrooms, call the experts at Angstrom today! We custom design all of our cleanrooms to meet your exact specifications and standards. Call us at 888-768-6900, or contact us online.
If the humidity is too high, bacterial growth can flourish, metal products or equipment can corrode, photolithographic degradation can occur, and condensation and water absorption can occur. This can cause real issues for processes with moisture-sensitive products, like semiconductor manufacturers.
If the humidity is too low, static buildup and discharge can become an issue, possibly causing shorts for products in electronics cleanrooms. Plus, poorly controlled humidity can make working conditions uncomfortable for your employees.
So, what are some of the methods you can use to control humidity in your cleanroom? In this blog, the experts at Angstrom Technology are here to answer that question.
Air conditioning/mechanical refrigeration
Humidity is relative, meaning that the lower the temperature is, the lower the relative humidity is. It makes sense then that lowering a cleanroom’s temperature will decrease humidity. When using air conditioning systems to dehumidify a space, the system reduces the temperature of a surface within the condenser unit to a temperature below the dew point of the airstream in the cleanroom. That surface is then exposed to the airstream in the cleanroom, and the water vapor in the airstream condenses, subsequently dehumidifying the space. The air must be re-heated to the desired room temperature and piped back into the cleanroom.
Desiccants
Desiccant systems draw air through a desiccant medium, which adsorbs moisture. The dehumidified air is then routed to the cleanroom. Consumer-grade desiccant systems collect condensate in a receptacle that must be emptied. On the other hand, commercial systems exhaust humid air through the ductwork out of the building. Vented systems can dehumidify to lower relative humidity levels at lower temperatures.
These systems are not mutually exclusive. In fact, where temperature control is also important, they work best when used in conjunction. Using a desiccant system in addition to air conditioning can also help reduce the load on the HVAC system, saving energy, wear and tear on the HVAC system, and, of course, money.
Humidity control is critical in some cleanroom applications, such as semiconductor manufacturing and pharmaceutical manufacturing, but it is an important consideration regardless of your application. Monitoring and controlling your cleanroom humidity, whether through air conditioning or mechanical refrigeration, a desiccant system, or both, is necessary to meet your cleanroom’s specifications and to ensure cleanroom integrity.
BATTERY DRY ROOM DESIGN & BUILD PROJECTS WITH ANGSTROM TECHNOLOGY
As Angstrom Technology are cleanroom specialists, our dry rooms can also achieve ISO classification. Not only that, but they 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.
Many materials and processes used in battery production are susceptible to moisture damage. For that reason, humidity control is critical in a battery dry room. The experts at Angstrom Technology can create a stable low dewpoint production environment to meet your requirements. In this blog post, we explain how.
Battery dry room construction
Battery dry rooms require a constant supply of ultra-dry air to create and maintain low-humidity conditions for the R&D and production of solid-state and lithium-ion batteries.
We can develop an energy-efficient dry room to protect your critical process in any of the following applications. We do this by combining airtight envelope systems, dehumidification systems, and HVAC design.
Small-scale battery research
Pilot plants
Mega / Giga-factory
Single-zone facilities for testing the chemicals and processes during battery R&D.
Multi-zoned facilities for scaling up production to manufacture at volume.
Large-scale battery production facilities for high-volume battery production.
Battery dry room manufacturers
As battery dry room facility manufacturers, we deliver complete dry room systems. Working with specialist humidity control partners, we provide bespoke solutions that include industry-leading energy-efficient HVAC systems.
A typical clean room environment operates at 20.0°Cdb, 50% Relative Humidity — which is a dewpoint of 9.3°Cdp. Due to the materials’ sensitivity in the process, solid-state battery dry rooms can require control to minus 40.0°Cdp at the room’s exit point. A lower dewpoint of minus 50.0°Cdp is required for Lithium-ion battery dry rooms, and the next generation may have even tighter requirements. The battery chemistry may need the environment to reach minus 80.0°Cdp at the point of supply into critical areas, such as Electrolyte Fill.
Look at how we can custom-build your perfect battery dry room.
Footprint & zones
Establish a suitable layout for your process, featuring multiple zones, each with the optimum dew point temperature and ISO class.
Dehumidification systems
Single or multi-rotor low dewpoint AHU options to suit your budget, space, and specification needs.
Internal airflow distribution methods
Horizontal unidirectional airflow with a supply and return air plenum or a high-level distribution system with uni or non-unidirectional airflow.
Airflow modelling
Using Computational fluid dynamics (CFD) studies to verify HVAC design with equipment and furniture layouts.
Scalable HVAC designs
With specialist AHUs designed for deployment in battery facilities, airflows range from 2,000 m³h to 50,000 m³
Energy-efficient design
Airtight envelope systems and recirculated air manage energy efficiency.
Battery dry room design & build projects with Angstrom Technology
As Angstrom Technology are cleanroom specialists, our dry rooms can also achieve ISO classification. Not only that, but they 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.
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.
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.
Cleanrooms are designed to maintain strict control over environmental factors, but they’re only effective if they have an expertly designed airflow pattern to help them reach the desired cleanliness level and ISO classification standard. ISO document 14644-4 describes airflow patterns to be used in cleanrooms at the different classification levels in order to maintain strict airborne particle counts and cleanliness.
Cleanroom airflow must allow the air within the cleanroom to be completely changed to remove particles and potential contaminants before they can settle. In order to do this properly, the airflow pattern must be uniform — ensuring every part of the space can be reached with clean, filtered air.
To break down the importance of cleanroom airflow uniformity, we need to start by looking at the three main types of airflow in cleanrooms.
3 Types of Cleanroom Airflow Patterns
Cleanroom airflow can be unidirectional, non-unidirectional, or mixed — a combination of both. The best cleanroom airflow type will depend on the cleanroom classification. Generally, cleanrooms of an ISO Class 6 or greater can use a mixed or non-unidirectional airflow pattern, while ISO Class 5 (or cleaner) cleanrooms rely on unidirectional airflow.
#1 Unidirectional Cleanroom Airflow
This type of cleanroom air moves in one direction across the room, either horizontally or vertically from fan filter units to the exhaust system that removes “dirty” air. Unidirectional flow requires as little disturbance as possible to maintain a uniform pattern.
#2 Non-Unidirectional Cleanroom Airflow
In a non-unidirectional airflow pattern, air enters the cleanroom from filter units located in multiple locations, either spaced throughout the room or grouped together. There are still planned entrance and exit points for air to flow along more than one path.
Although air quality is less critical compared to unidirectional airflow cleanrooms, special attention should be paid to make sure air is changed thoroughly, minimizing the potential for “dead zones” within the cleanroom.
Dead zones are areas where air is turbulent or not being changed and may result in deposited particles or a buildup of contaminants.
#3 Mixed Cleanroom Airflow
Mixed airflow combines both unidirectional and non-unidirectional airflow. Unidirectional airflow may be used in specific areas to boost protection around working areas or more sensitive materials, while non-unidirectional airflow still circulates clean, filtered air throughout the rest of the room.
Why Cleanroom Airflow Uniformity Matters
Whether a cleanroom airflow is unidirectional, non-unidirectional, or mixed, having a uniform cleanroom airflow pattern matters. Cleanrooms are meant to be controlled environments where all systems should work to prevent areas where buildup of contaminants can occur — via dead zones or turbulence.
What is Turbulent Air?
Turbulent air, or chaotic air, in a cleanroom is a serious threat to cleanliness. Turbulent air occurs when the airflow pattern is not uniform.
Think of a current moving through water. If the flow was uniform, all of the water would move steadily at the same speed. Obstructions or varying speeds, like rocks or rapids, impede the uniformity of the flowing water. Similarly, when you sweep your hand through water and see eddies and whirlpools form to the side of the current, that’s turbulence.
Eddies in water may be harmless, but turbulence in cleanroom airflow can cause the uncontrolled movement of contaminating particles — or dead zones where no air is moving at all, where contaminants can build up and threaten sensitive processes in the cleanroom.
What Causes Turbulent Air in Cleanrooms?
Turbulence in cleanroom airflow can be caused by non-uniform speeds of air entering the room or obstructions in the path of incoming or outgoing air. Airflow uniformity is about preventing unnecessary turbulent air so the cleanroom can perform at peak efficiency.
Minimizing Turbulence in Cleanrooms
You can minimize turbulence by designing the cleanroom airflow pattern to work with your layout, equipment, furniture, and personnel. The cleanroom should be removing air at the same or similar speed as it enters. This gives air a clear path to flow to prevent turbulence and dead zones.
Obstructions can also cause turbulent air, so make sure that no large furniture or equipment is blocking fan filter units or exhaust. Adjust equipment with aerodynamic attachments or design features to facilitate airflow, use perforated cleanroom tables to allow air to pass through uninhibited, or modify behavior of personnel to not block or impede airflow within critical zones.
Cleanroom Airflow and Pressurization
Another way to minimize contamination using a uniform airflow pattern to establish positive or negative air pressure. Cleanroom pressurization creates a natural barrier to protect or isolate cleaner or less clean zones, respectively. Using negative and positive pressure can be especially useful for sensitive applications such as the manufacturing of healthcare products, medical research, microelectronics, and more.
Custom Cleanroom Airflow Design
Cleanroom airflow patterns should be designed to work with each unique cleanroom layout and all the furniture, systems, and personnel in the cleanroom for optimal cleanliness during operation.
A cleanroom engineer uses computational fluid dynamics to map out the cleanroom and place fan filter units and outlets appropriately to meet your classification requirements. This system allows the designer to visualize the pattern of air and make adjustments for cleanroom systems, equipment, and personnel in order to achieve uniformity. It also allows you to anticipate your energy requirements and make your facility as efficient as possible.
As your ISO cleanroom classification gets lower, having an expertly designed airflow pattern becomes more and more crucial. Work with an expert to make sure your cleanroom airflow is as uniform as possible for your application.
Trust the Angstrom Technology Cleanroom Airflow Design Experts
Designing your cleanroom and need a little help establishing an efficient, uniform airflow pattern? Call the experts at Angstrom Technology. From cleanroom airflow design to HVAC and filtration maintenance, we can help you make the best choices for your budget and your classification.
Pressurized cleanrooms are used in a range of industries and applications. Varying levels of pressure determines the way air naturally moves in a space. High and low pressure, or positive and negative pressure, can be used as a tool in cleanroom environments to help cleanrooms reach their cleanroom classifications and protect their products and people. Let’s explore air pressure in cleanrooms to discover how it works.
How Does Air Pressure in Cleanrooms Work?
It’s a well-known natural process for air to flow from high to low pressure. Examples of this are found around us every day. Wind and weather are formed from the uneven heating of the earth’s surface, which generates pockets of high and low pressure air. If you’ve ever witnessed the sudden closing of a door as air is sucked out of a room where no breeze was felt, what you experienced was the high pressure air moving to a low pressure area to achieve stasis. Air escaping from a balloon is traveling from a high pressure environment to the relatively low pressure of the surrounding air.
What happens in all of these situations is that when air is moving in one direction, it’s not moving the opposite direction. When air is moving out of the balloon, there isn’t also air moving into the balloon, as long as the air inside the balloon is more pressurized. This concept can be applied to cleanrooms, to stop the flow of air into a cleanroom, or out of it, limiting particle transfer via the air and maintaining a cleaner environment.
To state this more plainly, higher pressure air within a cleanroom (compared to the air outside the room) blocks against contaminants entering the cleanroom, as air naturally wants to flow out. Conversely, lower pressure air within a cleanroom can trap contaminants and prevent them from leaving a cleanroom, as the natural flow of air wants to move in.
Using pressure in cleanrooms, either higher pressure (positive pressure), or lower pressure (negative pressure) can be extremely useful in many cleanroom applications — but how do you implement it in the cleanroom design?
Using Pressure in Cleanroom Design
Positive and negative pressure in cleanrooms is achieved by controlling how much air is put into the cleanroom, and how much is withdrawn.
In a positive pressure cleanroom, clean, filtered air is consistently pumped into the room through the HEPA filtration and cleanroom HVAC system. In the event that a door or window was opened in the cleanroom, air would rush out into the outside environment.
This positive pressure ensures that in the event of a breach or leak in the cleanroom, the products and processes within the cleanroom are protected. Because the cleanroom has positive pressure, the air is forced out of the cleanroom, preventing contaminated or unfiltered air from seeping in.
To achieve negative air pressure, external exhausts pull air from the cleanroom at a faster rate than air is introduced over a span of time. The resulting negative pressure means air will want to flow into the cleanroom to fill the low pressure area, effectively stopping contaminants from going against that natural movement in order to escape the cleanroom.
To maintain either positive or negative pressure in cleanrooms, adjacent spaces must be maintained at a lower or higher pressure than that of the cleanroom, respectively.
If you implement a pressurization system into your cleanroom design, having a pressure monitoring system is important to ensuring balance and consistency within your cleanroom. The monitoring system will check and maintain consistent pressure, which can be adjusted manually or automatically.
Positive Pressure Cleanroom Applications
High pressure, or positive pressure cleanrooms are extremely useful in applications where the slightest particle interference could disrupt processes within the cleanroom. Semiconductor cleanrooms, microprocessor cleanrooms, and aerospace and defense cleanrooms are just a few examples of industries that benefit from positive pressure cleanrooms, as they are extremely averse to contaminating particles. Many medical cleanrooms use positive pressure, to protect sensitive patients and maintain a controlled space.
Even when the stakes aren’t quite as high, using slightly positive pressure in cleanrooms can help reach cleanroom classifications and maintain a cleaner environment.
Negative Pressure Cleanroom Applications
Low pressure cleanrooms, or negative pressure cleanrooms, are ideal for applications that need to isolate substances, particles, or fumes inside the cleanroom environment to protect the space outside of the cleanroom. They are widely used in medical cleanrooms, for medical research, testing, and the development of treatments using sensitive substances.
Pharmaceutical applications also use negative pressure in cleanrooms as part of a segmented layout. One room is kept at a lower pressure, while the ante room immediately outside it is maintained at a slightly higher pressure. This allows employees to transition into the negative pressure room with minimized disruption.
High and low pressure, or positive and negative pressure, can both be used as tools in cleanroom environments to protect against entering contaminants (in positive pressure cleanrooms) or contaminant leakage (in negative pressure cleanrooms). Using the natural movement of air due to pressure, we can build safer, more effective cleanrooms.
Think a negative or positive pressure cleanroom is right for you? Reach out to Angstrom Technology. Our cleanroom experts can design the best air flow patterns and containment systems for your application.
