Air showers can greatly enhance your cleanroom’s performance by removing surface contamination from clothing and cleanroom garments. Gowning/changing room areas are the interface between a dirty “street clothes” environment and a clean room environment. Unfortunately, the changing or gowning process itself releases contaminants from street clothes that can settle onto the “clean” garments. Air showers blow off and remove much of this contamination preventing it from entering the clean space. For more specific information on different air shower applications, see the Engineers Guide to Air Showers section on the website.

[ top ]How does an Air Shower Work?

The air shower produces high pressure air, filters this air through a HEPA/ULPA filter, then flows the air through adjustable nozzles which exit at a high velocity, so air is directed towards the individuals waiting to be cleaned. This high-velocity air removes surface particles and also “flaps” the garments to dislodge more firmly attached particles. After cleaning, the air is re-circulated back to the high-pressure blower, where it is prefiltered, then HEPA/ULPA filtered and then ducted back to the adjustable high-velocity cleaning nozzles. The air shower utilizes an adjustable microprocessor controller to allow easy on-site adjustment of the cleaning cycle time and other critical process controls.

[ top ]How does Garment Type Influence Cleaning Effectiveness?

The cleaning effectiveness of the air shower is affected by the type of garments, the size, shape and type of contamination. Large light particles such as lint, hair, dander, and skin flakes are the easiest to remove. Particulate contamination adheres to garments in two basic ways: Either by mechanical entrapment or by an electrical attraction.
Mechanical bonds between the garment and particulate contamination are reduced when smooth surface garments are utilized. These include “cleanroom-designed” garments and those made from synthetic materials such as Tyvex, Gortex, polyester, and nylon – to name a few. These materials are low-shedding and minimize the mechanical bond, making it easier to blow the surface contamination off the garments.
Natural fibers, such as cotton, tend to shed particles and their surface finishes tend to have a higher mechanical bond with particles, making them harder to clean. Synthetic garments can develop a static charge. This charge can “hold” particles to the surface of a garment. To help reduce this charge, garments can be laundered with an “anti-static” agent in the final rinse. This will help reduce the level of static charge on the garments, allowing particles to be more readily removed. Some garments are available with special built-in conductive fibers that can assist in keeping the surface charge to a minimum. Consult your garment supplier for details.
Point Ionization (static neutralization) can be installed on the inside walls to dissipate some of the charge on the garments, helping to reduce the holding charge (force) of the garment, making it easier for the air to blow the particles off. In many cleanroom applications, much of the contamination in the room is carried in on the garments of the individuals working within the room. Typically they bring it to the most critical area.
Without using an air shower, individuals are often cleaner when they leave the clean space because a large portion of the contamination they had on their garments will have fallen off within the clean space. Using an air shower is an effective way to remove much of the contamination that would otherwise come off within the clean space.

[ top ]What makes the CAP701 Air Shower Superior?

An air shower in many ways can be compared to vacuum cleaner. They are available in a variety of sizes, capacities and features; some work very well while others just seem to make noise. To be effective, they need to have high cleaning force and power.

1. Superior Performance

A good vacuum cleaner has high suction and airflow to pick up dirt. A small vacuum with low suction and airflow does little more than pick up a few crumbs. The same can be said for air showers. Some air showers (not made by Clean Air Products) have a small blower/motor, low airflow and low pressure. These under-powered devices give air showers a bad name. The CAP701 air shower has a high velocity and a large air volume rate for fast, efficient cleaning. The Clean Air Products’ CAP701 air showers offer the highest velocities combined with a large airflow rate to provide an air shower that quickly and efficiently cleans particulates from the surface of clean room garments.

2. Superior Construction Materials

The CAP701 air shower is constructed of an all-metal, painted steel shell with no wood or plastic laminate and is entirely silicone free. The standard shower has a 16-gage steel shell, heavy-duty glass door and door closer. The shell and concealed air ducts are finished with a white powder coat paint which provides a strong, durable cleanroom-compatible finish. The all-steel shell design will stand up to the rigors of shipping, installation, use, and the occasional abuse of a high-traffic entry system. While we don’t recommend it, you could hit the metal shell of the air shower with a hammer. It may dent or scratch the paint, but you would not break the cabinet as you would with laminated types of construction.
The steel construction also reduces the chances of biological growth and contamination caused by systems using laminated particle board in the construction. Laminated particle board construction is fine for a simple table, but not for an important piece of equipment that is being integrated into your cleanroom system.
NOTE: A typical laminated particle board air shower has the plastic laminate on the outside – but often the interior concealed air ducts are just painted over the raw particle board – leaving a rough surface finish that harbors dirt and biological contamination. As the particle board ages and deteriorates, parts will flake off, becoming another source of contamination. All-metal (painted steel or stainless steel) air showers are the best type of air shower to purchase.

3. Superior Service Access

Service to the mechanical equipment, blower, motor, HEPA filter and prefilter is easily done from the inside of the air shower through a hinged access panel located in the interior ceiling of the air shower. This is desirable because you don’t have to penetrate the clean room ceiling surrounding the air shower for maintenance. Often the area around the air shower is not accessible because of ceiling filters, lights, ducts, pipes, walls or other equipment. Exterior-mounted service panels would make maintenance difficult or impossible in those cases. The unit’s electrical control panel is conveniently mounted on the outside of the air shower above one of the entrances (see the website for details), and is serviced from outside the air shower.

[ top ]What are the Different Types of Air Shower Designs?

Straight Thru Air Showers

The entry door and exit door are straight across from one another. This is the most common type of air shower.

90-Degree Air Showers

The air shower can be provided with the doors in a 90-degree configuration for those applications where a Straight Thru path will not work.

3-Door Air Showers

This air shower has three doors. The typical configuration is one
entrance door and two doors exiting to two different cleanrooms.