Achieving a specific cleanroom class requires not only clean physical design (non-particulating materials, etc.) but also a flow of clean, filtered air sufficient to both dilute existing particulates and to drive “dirty” air out of the controlled space.

Fan-filter units (FFUs) are generally used in LCGC LABS modular cleanrooms to provide HEPA- or ULPA-filtered air. FFUs provide air flow at velocities of about 90 to 110 feet per minute, fast enough to generate laminar flow but slow enough to prevent excessive turbulence.

Assuming a clean physical design, air flow determines the design cleanliness of a cleanroom. Cleanroom classes, ISO standards and LCGC’s general recommendations in terms of air-changes-per-hour are:

The cleanroom class is the number of particles >= 0.5 μm in diameter per cubic foot. For instance, a Class 1,000 cleanroom could contain an average of up to 1,000 particles per cubic foot of space.

The good news is that simply adding FFUs can generally lower the cleanroom class (make it cleaner). That assumes, of course, that the cleanroom has ceiling grid spaces not occupied by lights, FFUs or Power Distribution Modules.

Actual particulate levels are measured by taking a panel of readings with a particle counter at various points throughout the cleanroom. LCGC LABS sells such counters.

Both softwall cleanroom lines meet the same quality standards for design and materials. Within a class rating, both offer the same cleanliness. However, since LCGC LABS’s standard line softwall cleanrooms offer higher power for additional FFUs and teardrop lighting, they can be configured to Class 10, which is not available in LCGC LABS.

Each standard line softwall cleanroom is built to order, a process that takes generally four weeks or more. Standard line cleanrooms, then, can be made in virtually any reasonable size and can feature unusual materials such as stainless steel frames. Standard line softwall cleanrooms use LCGC-designed Power Distribution Modules (PDMs) that are hard-wired to the building’s electrical system in order to support larger numbers of FFUs, lights and in-room power outlets with higher power ratings.

LCGC softwall cleanrooms are preconfigured from standard components to produce ten standard sizes from 6’ x 6’ up to 12’ x 12’ in each of two heights (7’ and 8’). In place of PDMs, LCGC softwall cleanrooms are powered by a simple Power Supply Unit (PSU) that plugs into your standard wall outlet (20 amp free circuit required). The PSU switches a fused outlet box on the ceiling into which FFUs and lights are plugged, using standard 120V plugs. The PSU also provides one non-switched, light-duty outlet for in-room instrumentation.

LCGC softwall cleanrooms generally ship in a few days. The LCGC cleanroom arrives in one (large) crate that rolls on its own casters through 36″doors to the assembly area. Each LCGC cleanroom comes complete with all tools needed for assembly.

LCGC softwall cleanrooms do not include the decorative top trim included on standard line cleanrooms, which makes assembling the LCGC cleanroom easier. LCGC softwall cleanrooms do not include the flashing status indicators optionally provided on standard line cleanrooms.

LCGC softwall cleanrooms are significantly less expensive yet offer full cleanliness for operations that fit their sizes and power ratings.

LCGC softwall cleanrooms are assembled from off-the-shelf components and ship in a few days. In order to achieve this rapid service, only standard sizes can be offered. LCGC LABS can generally be custom sized at additional cost and with longer lead-times.

Class 10 requirements are generally provided by hardwall cleanrooms since they offer more complete airflow control and sealed cleanrooms. In addition, Class 10 airflow requirements usually require nearly continuous FFUs, more power than can be supplied by wall circuits and sometimes teardrop lights, none of which can be supplied in LCGC softwall cleanrooms. LCGC’s standard line softwall cleanrooms may provide Class 10 in some configurations.

A cleanroom provides a controlled, isolated environment for handling contamination-sensitive substances or for protecting the exterior environment from dangerous substances in the controlled area. The density of sub-micron and larger airborne particle contamination inside a cleanroom is kept within tightly controlled limits by forcing clean, filtered air into the cleanroom.

Controlling particulate contamination is a process, not an event. Contaminants are generated continuously by people, processes, facilities and equipment and must be continuously removed from the cleanroom. The allowable level of contamination is dictated by specifications for the operations being performed. In the US, particle counts per cubic foot are commonly given as “class ratings,” such as “Class 1000” specifying fewer than 1,000 particles, with a size greater than .5 μm per cubic foot. ISO standard 14644-1, however, provides more precise standards but is often used interchangeably in the US.

Contamination control requires controlling the total environment. Air flow rate and direction, pressurization, temperature, humidity and specialized filtration all need to be tightly maintained to remove particles from the cleanroom. Particles sources must be eliminated whenever possible.

Positive pressure modular cleanrooms provided by LCGC LABS typically use ceiling-mounted self-powered Fan-Filter Units (FFUs) to force HEPA or ULPA-filtered air into the cleanroom. This creates an internal air pressure greater than ambient pressure, which reduces particulate intrusion around doors, and minor un-sealed areas in walls, ceilings, etc. Wall venting near floor level exhausts cleanroom air with the particles it carries into the external environment and promotes laminar flow of incoming air. The ability to remove particles and thus create a particulate-controlled environment inside the cleanroom is measured by the number of air changes per hour; the more clean air, the cleaner the cleanroom. Basically, a positive pressure cleanroom protects the internal environment.

In a given cleanroom, cleanliness can generally be increased by simply adding more FFUs, and thus filtered air, in the correct locations. Positive pressure can be built with hard walls made of solid plastic or steel, or soft walls made from flexible plastic strips and curtains. In hardwall cleanrooms, temperature and humidity can be controlled to provide human comfort, protect processes and prevent static charges by adding air conditioners, humidifiers and dehumidifiers.

Negative-pressure modular cleanrooms provided by LCGC LABS are designed to keep contaminants from entering the external environment. A common design uses exhausting FFUs, or air handlers, and HEPA filters to remove internal air. The cleanroom’s in-room processes contaminate the air, that is then exhausted to a safe location. This exhaust system creates a negative pressure inside the cleanroom that draws external air into the cleanroom either directly or through filters. A common application for this design is a powder filling operation. A negative pressure cleanroom, then, protects the external environment but not necessarily the internal area.

Positive/negative pressure modular cleanrooms provided by LCGC LABS, a more complex design, typically use FFUs to inject clean air into the cleanroom and exhaust contaminated cleanroom air into a buffer area. An air-handling system then removes slightly more air from the buffer area than is supplied by the FFUs, thus creating a negative pressure with respect to both the cleanroom and the external environment. This negative pressure prevents cleanroom contaminates from entering the external environment and also prevents external particulates from entering the cleanroom. A positive/negative pressure cleanroom, then, protects both the cleanroom and external environments.