The P442-2016 protocol is an NSF listing that references a series of minimum requirements for the design, construction, performance and certification of light fixtures for cleanrooms. Intended to protect the controlled environment from the common causes of particulate contamination related to or resulting from the use of lighting fixtures, this protocol first requires ingress protection IEC 60529/60598 (IP-65) and NSF-2 Food Equipment certifications.
New Performance Testing
In addition, there is a new performance testing requirement for pressure decay resistance. This new testing requirement is demanding: the sealed fixture is stressed with positive and negative pressure and acceptance is granted only after it is proven that no leaks are present. The pressure testing mimics the conditions found in actual installations where air handling equipment regularly induces dynamic positive and negative pressures, which can cause seal failure and ingress or particle passage in substandard fixtures. The pressure test is performed under controlled conditions by a nationally recognized independent testing lab, and calls for airtight fittings and pump to be secured to the fixture body to simulate the type of positive or negative pressures that the fixture will be exposed to during cleanroom use. The fixture is then pressurized to the prescribed level and sealed, with pressure readings recorded on a manometer at five-minute intervals.
To meet the P442 leakage prevention requirement, the fixture must be able to maintain 2 inches WC (498 Pa) of pressure, plus or minus 10 percent, for 30 minutes. While the test sounds relatively simple to pass, that is actually not the case. The seemingly small pressures (<0.1 psi) are made difficult by the size of the fixture in square inches. A typical 2x4 troffer presents over 1000 square inches of surface area; making a small pressure result in over 80 lbs of load on the doorframe and flange seals. This type of force must be anticipated by the fixture design.
P442 Cleanroom Light Fixtures
For two decades, Kenall has led the fight for the creation and adoption of specifications for cleanroom fixtures, while demonstrating the importance of proven compliance with standards that advance and provide safety to the industry. There are a number of governmental, educational and business concerns regarding the absolute reliability of controlled environments, including medical research laboratories, universities, semiconductor and pharmaceutical manufacturers, sterile packagers and biosafety labs.
Over the years, the lighting industry has recommended various construction standards and ratings, but they all required a certain amount of interpretation when judging the suitability of a fixture for cleanroom installations.
Now, with the development of NSF P442-2016, there is one protocol that encompasses the construction and rigorous testing of a sealed cleanroom fixture and requires independent verification of each aspect of the process.
This new protocol will help curtail the use of vague and slippery terms such as “meets standard x” or “complies with x” and replaces it with “Certified by”.