By George Ryder

A high percentage of existing cleanrooms are outfitted with lighting equipment that is not effectively sealed against leakage. The lighting equipment permits contaminants to enter the cleanroom space and it permits dangerous pathogens to escape containment areas.

This disclosure is well known and accepted by all lighting equipment manufacturers, many specifying engineers and most end users. How each group responds to this fact depends upon its degree of enlightenment, integrity and ingenuity.

Status quo

There are no universally accepted standards regulating the performance of lighting equipment used in cleanroom and containment environments. Much of this void has been filled with compliance to Federal Standard 209E statements. These compliance statements have given many cleanroom and containment professionals a false sense of confidence in the lighting equipment they manufacture, specify, install, or utilize and maintain.

This article places major focus on Federal Standard 209E only because this obsolete document continues to be the most cited standard in the lighting equipment sector.

ISO 14644 provides much more guidance in the design and construction of a facility that can support cleanroom and containment environments. Some lighting manufacturers are beginning to work with the Institute of Environmental Sciences and Technology (IEST; www.iest.org) certified testing laboratories to develop meaningful standards and testing procedures that reflect the product performance implications of this comprehensive document.

Lighting manufacturers—Nearly all manufacturers of cleanroom lighting equipment claim to provide equipment that conforms to Federal Standard 209E. An example of this is the following statement, which appears in some literature: In compliance with Federal Standard 209E for Class 100 applications.

The practice is decades old. This type of statement can be found on most manufacturers' product specification sheets. It is nearly impossible to gain access to the lighting equipment section of many lighting equipment schedules without this compliance statement. Although this practice is seldom intended to mislead, it does not provide sufficient product selection guidance.

Lighting equipment specifiers—Electrical engineers (specifiers of cleanroom lighting equipment) often use this same practice in their specification documents. Although many engineers are sophisticated enough to know it is not possible for lighting equipment to be in compliance with these federal and international standards, the practice is still common.

Until specifiers of lighting equipment understand the performance requirements of cleanroom and containment areas, they will be continually bombarded with inferior product reviews making unfounded performance claims.

End users—Even many major pharmaceutical manufacturing companies use this same practice in identifying lighting equipment acceptable for their cleanroom and containment areas.

First, it is imperative to establish that Federal Standard 209E is a testing and certification standard. It is not a standard for equipment design. Its primary purpose is to establish means of monitoring air cleanliness and certifying cleanroom environments.

Federal Standard 209E clearly states the following, “Scope: This document establishes standard classes, and provides for alternative classes, of air cleanliness for cleanrooms and clean zones based on specified concentrations of airborne particulates. It prescribes methods for verifying air cleanliness and requires that a plan be established for monitoring air cleanliness.” It further states, “Limitations: The requirements of this document do not apply to equipment or supplies for use within cleanroom or clean zones.”

The objective of Federal Standard 209E is to provide a consistent means of measuring contamination and establishing procedures for certification of compliance. Therefore, it is simply impossible for lighting equipment to comply with standards that were not intended to certify equipment.

Typical testing procedure

Although there are numerous variations of the following compliance statement procedure, the outcome is typically the same:

• Lighting equipment is tested in a horizontal laminar flow room certified to Federal or ISO standards.
• The lighting fixture is placed on a stand in front of the HEPA filter.
• Probes are placed behind the fixture.
• As the air flows past the fixture, the probes record particulates to Federal or ISO standards.

The only valid relationships between Federal Standard 209E and the lighting equipment are: the standard is adhered to in the design, operation and certification of the laboratory space used to test the lighting equipment and the standard is used to measure and record the resulting particulate count.

Therefore, the end result is a test that has measured if the lighting fixture is clean or dirty. This procedure does not test for leakage.

If compliance statements do not assure the most basic of end user expectations, what must the end user do to encourage the design and manufacture of lighting equipment that meets their needs? In one sentence: End users must articulate the performance requirements of lighting equipment for each of their processes—research, production, packaging and so on. These can be outlined as follows:

• It shall illuminate effectively and efficiently.
• It shall not leak.
• It shall not introduce toxicity, surface contaminants or corrosion to the environment.
• It shall be easy to clean and maintain.

The most direct means of achieving the above performance objectives is to identify universally accepted standards that clearly define the means of assuring required performances (see “Performance standards documents”).

Sugggested strategies for manufacturers

Use compliance statements only as certification. Compliance statements alone do not provide any assurance of meeting performance expectations (lighting levels, leakage, toxicity, corrosion and so on). Compliance statements without qualification and quantification are useless and often misleading.

Couple compliance statements with product features (triple gasketing, closed-cell gasketing, one-piece door frame and so on). Although features are important, they do not assure performance.

Let's review the range of performance within one feature—closed-cell gasketing. Gasketing is typically specified as closed-cell. The specifier's intention is to specify an impermeable material that is void of any surface cavities. But all too often, the supplied closed-cell gasketing is permeable to cleaning protocol and is riddled with surface cavities. Unfortunately, the surface cavities end up at the most demanding place of the lighting fixture—where the doorframe meets the ceiling structure (see Figure 1).

Figure 1. Closed-cell gasketing in die-cut strips.Click here to enlarge image

The correct application of this feature specification requires that the closed-cell material be selected according to its ability to stand up to the cleaning protocol of the end user and that the means of fabrication be selected by its ability to produce a smooth external skin. Simply stated: One-piece doorframe gasket—extruded NSF listed material with vulcanized joints (see Figure 2).

Figure 2. Extruded closed-cell gasket with vulcanized joints.Click here to enlarge image

Combine compliance statements and product features with non-standard oriented testing (hose down testing, PSI testing and so on).

Once compliance statements and product features have been acknowledged, the issue of performance can be addressed. All too often, lighting equipment is tested from a biased position—the manufacturer's. Performance tests that are not clearly defined and recorded are simply not valid. Testing that is quantified without description of conditions does not provide reliable data.

Manufacturers must design and manufacture the lighting fixture to pass testing in conformance with universally accepted standards that are directly related to performance requirements of the lighting equipment.

The only acceptable standards for cleanroom and containment lighting equipment must be based on end user performance expectations that are clearly definable by existing or new standards and tested by IEST-acknowledged or certified testing facilities.

Only IEC, ISO and NSF standards are available to define and measure lighting equipment performance required for cleanroom and containment area lighting applications. Hopefully, the future will provide helpful extrapolations and interpretations of these and other standards to establish the performance requirements of cleanroom and containment area environments.

George Ryder is vice president of Kenall Lighting (Gurnee, IL). He can be reached at [email protected].

Performance standards documents

Lighting Requirements: The Illuminating Engineering Society (IES)
Task Lighting Recommendations listed by application
Leakage: International Electrotechnical Commission (IEC)
IEC60598 Ingress Protection for Lighting Fixtures
Toxicity: National Sanitation Foundation (NSF)