It all comes out in the wash

It all comes out in the wash

Class 1 laundry processing facility uses state-of-the-art technology to keep contamination out of the cleanroom

by Jerry Martin

When you think of a commercial laundry facility, you probably envision the neighborhood laundromat with its walls of washers and dryers and an attendant folding garments on a table in back. But the Class 1 cleanroom laundry at Prudential Cleanroom Services (PCS; Milpitas, CA) makes such facilities seem as archaic as a tub and washboard. The new facility, which opened last month, employs high-tech computerized passthrough washers — capable of computing variable basket speeds, providing faster and more accurate temperature control, and performing gentle and accurate water extract steps — and passthrough dryers with variable speed baskets and blowers, built-in particle counters, and sophisticated static dissipative design and control systems. But there`s more to the facility than the washers and dryers.

The facility is 12,000 square feet of classified cleanroom space, ranging from Class 1 to Class 100,000. The Class 1 space includes four packaging rooms, a quality assurance lab, a body box testing chamber, and gowning rooms. The facility is 40,000 square feet and is situated on three acres. Initially the facility will employ 109 employees with a projected 30 percent increase within six months of opening. The facility will initially handle 5.2 million processing pounds per year.

Product flow

Customers` reusable garments and other launderable items enter the facility in a Class 100,000 soil sort room (5,000 square feet) equipped with ceiling-mounted HEPA filters. All items are bar-coded by trained garment inspectors/soil sorters using a proprietary computerized tracking system. Garments are scanned in the soil sort room. The bar-code system has been designed to convert to RF chip technology when the cost and reliability presents itself. The bar-code system is able to provide a complete detailed analysis of all garment usage by size, audit trail, repairs carried out on each garment and any special treatment given to a garment. The computerized bar-code tracking system can also be installed at a customer`s site.

After being scanned in soil sort, garments continue through four independent production flow lines; each line containing a passthrough washer, a passthrough dryer, a dedicated packaging room, and a distribution area.

Garments are placed in the passthrough washers in the soil sort room, and once washed, they`re unloaded from the Class 10 wet room on the other side. Passthrough machines prevent clean garments from being in the same area as soiled ones. The L-Tron washers, which can handle loads as small as a few pounds or as large as 500 pounds, were developed in partnership with their manufacturer, American Washer, and PCS. These are the first units built from the prototype in use at another PCS facility. The washers were designed to yield increased quality and extend garment life by providing for programmable wash speed, water levels, and chemical dosage of cleaning agents. A state-of-the-art computer on every washer computes variable basket speeds, faster and more accurate temperature control, which extends garment life, and gentle and accurate water extract steps. In addition, the wash drum and basket have been completely redesigned to match the computerized controls, and to provide for thorough, but delicate wash cycles. The built-in disk drives allow for data storage and automated maintenance procedures. They are programmed to provide views of historical data for wash cycles. Machine schematics and preventative maintenance capabilities are built in. For example, a digital readout could notify the operator that a bearing will require greasing within a specific period of time.

In addition, the 120-pound-capacity FASA 660 open pocket pony washer by Dubix is also the first of a new generation of all-stainless steel passthrough washers, similar to the L-Trons, which are designed for smaller specialty loads. “Open pocket” means that garments have “free fall” within the wash cylinder, providing a more thorough agitation. It is the first passthrough pony washer used at PCS, matching the capabilities of the larger L-Trons.

Once unloaded into the Class 10 wet room, garments enter the passthrough dryers. The PCS dryers are critical to product integrity. The exacting requirements of the dryers used in Milpitas are the result of a 33-year partnership with PCS`s customers. These state-of-the-art dryers by Challenge contain the elements of a standard cleanroom dryer (ULPA-filtered air, static control, stainless steel basket, steam heated and non-contaminating gasket material) plus a variable speed basket, variable speed blowers, built-in particle counter, and sophisticated antistatic design and control system. The computer system delivers exact controls on garment rotation, temperatures, humidity, and particle counts. If it is beneficial to continue the cool ULPA filter air cycle, the controls will extend the cool air blow time to further reduce particles on the garments. If a high particle count is detected, the drying cycle continues in an attempt to reduce particle count. If this doesn`t work, the garments are re-processed. In addition, the dryers are connected to a PC, continually downloading parameters. This assists in data gathering, account verification, and statistical process control (SPC).

Garments are then unloaded from the passthrough dryers into the Class 1 packaging rooms where they are folded and packaged. Packaging is accomplished in four identical but separate Class 1 cleanrooms (100-percent ULPA filter coverage), each with independent airflow and control.

The packaging rooms use only 316-grade electropolished, 48-percent bullnosed, stainless steel tables and completely enclosed, high quality, extra wide, auto cycling sealers. Ceiling mounted, pulsed DC ionizers are positioned at six-foot intervals ensuring overlapping coverage. This keeps potential charges to a minimum and allows remaining particles to be released to the floor.

After garments are folded and packaged, they are passed through to the Class 100 distribution area. All final products are placed in oversized bags — to ensure Class-100 double packaging, account integrity, and efficient and clean distribution — before being deposited into dedicated, covered delivery carts and delivered to the clean staging area.

Finally, clean and packaged cleanroom reusable garments are staged in the Class 10,000 clean staging area before being loaded onto their dedicated route trucks for delivery to the customer.

Construction challenges

The building shell construction was delayed by weekly El Ni&#241o rains, which pushed back the date the cleanroom could be started inside the building.

KTEC Cleanroom Systems (Round Rock, TX) could not start the cleanroom installation until the building shell work was completed to a point which would minimize dust, but did not have the luxury of waiting until all shell activities were complete before starting cleanroom erection. KTEC had to closely coordinate the requirements of men and material access to the cleanroom site with the needs of the building construction, such as pouring driveways and parking lots, and finish out of other support areas inside the building.

All the rain contributed to a high water vapor permeance potential up through the building slab, which was discovered through testing. Special vapor barrier treatment of the slab prior to installation of the finished floor was required.

Also, Prudential has an industrial laundry facility, close to the new building site, which remained in full operation throughout the construction process. Utility tie-ins and building erection had to be tightly controlled to allow uninterrupted service. The two facility`s compressors, air/steam, and waste water treatment are connected so they can serve as back-up to one another.

Cleanroom equipment and components

The cleanroom is of modular, prefabricated design, which allowed for speed of installation and the ability to remove or rearrange panels in the future. The self-supporting cleanroom shell was manufactured by KTEC Cleanroom Systems, and uses steel framing with a composite wall-panel skin of a baked acrylic enamel paint finish over aluminum. The skin does not produce powder when cut or drilled, and is non-outgassing. The cleanroom system provides air return capability as well as a mechanical space deck area above for all the fans serving the cleanroom.

The general approach uses ducted HEPA and ULPA filters, fed by recirculation fans located on the mechanical deck, which is located above the cleanroom and below the roof of the building. A return air plenum above the cleanroom ceiling eliminates return duct and provides a leak-free ceiling in the cleanroom.

All but the Class 100,000 areas of the project have raised-floor air return (600 air changes per hour), manufactured by Tate Access Floors. This portion of the cleanroom is installed in a recessed slab to allow the raised floor to be flush with the surrounding space with no ramps or steps required. There is even an expansion area designed into the slab to allow for increase production in the future.

The clean staging area is also equipped to handle future needs. Currently running at Class 10,000, the mechanics are in place to upgrade this area to Class 100 simply by adding HEPA filters. This approach also allows the adjacent Class 100 area to be expanded simply by relocating a partition wall.

The 32 recirculating fans serving the cleanroom were purchased from a decommissioned cleanroom and refurbished with new motors and prefilter bases to match the needs of the facility. The fans are direct drive type with all-aluminum housings. PCS realized a substantial savings with this approach vs. new equipment. The arrangement and quantity of these fans and motors provides primary airflow redundancy in the cleanroom operation.

Eight independent zones of control serve the cleanroom with a central water cooled chiller serving the cleanroom facility. Each zone has a dedicated fan coil unit, and air does not mix between zones.

Energy savings was addressed in the design as well. The design features 100- percent reuse of process and condensate water by the industrial laundry. Therefore, there is no sewer line for the waste water in the cleanroom laundry facility, and all water will be reused within the industrial laundry processing facility for such items as towels and mats. The industrial laundry is one building removed from the cleanroom laundry facility and separated by a common parking lot. Also, the cleanroom has an air side economizer system that provides free cooling during cold winter days. The control system compares the indoor and outside air enthalpy and switches the cleanroom to as much as 100-percent outside makeup air, allowing the chiller to idle. Barometric relief dampers maintain pressure relationships during these periods. Three stages of prefiltration at each fan coil unit maintain HEPA filter life even with this feature.

In addition, 100-mm-deep HEPA and ULPA filter media was selected for its lower pressure drop, reducing operating fan horsepower requirements. The night setback feature of the control system reduces airflow and relaxes temperature control during unoccupied periods. Finally, the cleanroom lighting uses solid state electronic ballasts and polished aluminum reflectors to maximize lighting efficiency.

Additional process systems installed in the facility include deionized water, hot water, steam, and automatic soap dispensing. The DI water make-up of the facility is 18 megohms water filtered to 0.2 micron at point of use.

A sophisticated direct digital control and reporting system is provided to allow the cleanroom operators to have real-time information on all critical cleanroom functions. The system, manufactured by Alerton, has a graphical PC interface which displays cleanroom functions such as fan, chiller and pump status, temperature, humidity and pressure for all zones, and lighting control. The dial-up feature allows the PCS engineering staff to work with the system from the company`s corporate headquarters in Irvine, CA, just as if they were on-site.

Besides the cleanroom control, Lighthouse Worldwide Solutions is providing a real-time process-monitoring and reporting system. Laundry functions that impact garment quality — such as wash and dry temperature, soap dispensing, DI water flow and resistivity and room particle counts — are continuously monitored and reported. This greatly enhances and automates the quality assurance functions of the facility.

Quality control lab

Garment testing facilities are incorporated into the facility. The Class 1 lab is equipped with analytical and test instrumentation for in-process testing and certification needs. Typical services available are:

1) Microscopic particle detection and ASTM-F-51 testing;

2) Helmke drum testing;

3) Liquid particle counting as low as 0.2 micron; and

4) ESD testing including

a) surface resistivity

b) static decay

c) garment sleeve-to-sleeve

d) Humidity- and temperature-controlled chamber is available to meet special conditioning requirements.

Body box testing is performed in a dedicated Class 1 chamber designed per IEST-RP-31, with an electropolished stainless steel plenum. Unlike others, particle measurement is taken at three discrete locations, which provides

an accurate source for shedding (boots/soles vs. garment). Simultaneous monitoring of each port allows three times data collection and graphical representation of each channel.

The facility is geared and capable of providing service to customers with sterile processing requirements. The facility will be qualified to service sterile accounts at 10-6 SAL (Sterility Assurance Level). PCS`s Fremont facility currently offers this validation level.

More on process control

Emphasis has been given to reach a world-class process control by using a programmable logic control system to control and monitor critical nodes of production and the environment. Constant monitoring capability, unlike hourly sample inspection, provides a wider bandwidth for data collection and SPC initiatives thus capturing the true process capability index.

Airborne particle detection in critical zones are as low as 0.1 micron. Data collection points (DCPs) are located above work surfaces to collect the airborne particle count during the operation.

Special contamination control features

While there are no toxic substances used in the cleanroom laundry facility, features were added to further control contamination. Automatic sliding doors with touchless sensors reduce contamination of gloved hands as well as aid smooth product flow through the cleanroom. Pulsed DC ionizers are installed in the ceiling above the folding and packaging areas to reduce static charge on garments and packaging materials. All cleanroom furniture is electropolished stainless steel, and epoxy flooring in the non-raised floor areas provides for ease of maintenance and a low wear surface. A 24-station intercom system allows personnel from all areas of the facility to communicate without violating clean

protocol procedures.

All those entering the controlled space surrounding the cleanroom are required to wear shoe covers and bouffant caps. Separate gown rooms are provided for people entering the Class 1 and Class 10 areas, and those working in other areas of the cleanroom. There are separate men`s and women`s pregown areas with private dressing stalls, which allow employees to don inner garments at the facility immediately prior to entering the gown room at the beginning of each shift. As with the cover garments, the inner garments are laundered on-site, further eliminating contamination brought in from the outside. All garments and consumable products are items offered by PCS.

Finally, garments are kept in a cleanroom environment from the moment they enter the facility until they are loaded on the route trucks for delivery. Ultimately, stated processing and contamination control methods will produce cleaner cleanroom garments thus assuring PCS`s customers that its portion of their contamination control process is satisfied.

This article was written by Jerry Martin, director of sales and marketing at Prudential Overall Supply (Irvine, CA), in cooperation with Stefan Schurter, vice president of engineering, Prudential Overall Supply (Irvine, CA); Shahn Jafari, quality assurance manager, Prudential Cleanroom Services (Irvine, CA); Peter Travis, general manager, Prudential Cleanroom Services (Milpitas, CA); and Mark Wells, vice president, KTEC Cleanroom Systems (Round Rock, TX).

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KTEC Systems modular cleanrooms fit into any high tech environment.

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above: Cleanrooms rated at Class 1, with raised-floor installations and flow-through lighting, provide full vertical laminar flow and Class 1 conditions.

right: Prefabricated wall panels install quickly with no on-site sawing, cutting or finishing.

below: Modular walls and top deck panels form the sealed cleanroom envelope.

Key facts

Design/Build Cleanroom contractor: KTEC Cleanroom Systems (Round Rock, TX)

Size of facility: 12,000 square feet of classified cleanroom space, ranging from Class 1 to Class 100,000.

Purpose of the facility: To provide cleanroom reusable garment laundry processing for customers operating or manufacturing in critical/controlled environments.

Cost of the project: $2.7 million (the entire building project cost $5.9 million.)

Completion time: 18 months


The $5.9 million Milpitas,CA, project took 18 months to complete. The total facility cost does not include land, which was purchased by PCS 20 years ago. The cleanroom laundry is located on a parcel adjacent to an existing Prudential Overall Supply industrial laundry processing facility. The cleanroom laundry processing facility is completely independent from the industrial facility.

Company background

Prudential Cleanroom Services`s (PCS) new Milpitas, CA, facility replaces the existing Class 10 Fremont, CA, location, which opened in 1987. In 1996, PCS projected that the Fremont facility would exceed production capacity by the year 2000 and committed to begin construction of the Milpitas facility in June 1997. The Milpitas facility is designed to handle a production capacity three times greater than the Fremont facility.

The Milpitas facility marks PCS`s fifth cleanroom laundry processing facility in the United States with the other facilities located in Los Angeles, CA, Mesa, AZ, Austin, TX, and Albuquerque, NM. The next facility opening is scheduled for June 1999 in Richmond, VA.

PCS, established in 1960, is a division of Prudential Overall Supply, established in 1932. Prudential is a privately held company with corporate headquarters in Irvine, CA.

Did you know …

a complete bunny suit (hood/coverall/boots) makes up two processing pounds? Since PCS will process 5.2 million processing pounds per year, that`s the equivalent of 2.6 million bunny suits per year, or about 7,123 bunny suits per day.*

*assuming the facility operates seven days per week.


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