Over the years, medical device cleanrooms have become more cost effective in both initial cost and operating cost due to advances in technology and methods. My first experience with cleanrooms was in 1967 with the first laminar flow room built for Honeywell's Solid State Electronics Center in Plymouth, Minnesota. That room has been in constant use for 39 years. There were no filter changes in those 39 years. The system was upgraded with ULPA (ultra low penetration air) filters in 2004 even though the HEPA(high efficiency particulate air) filters were not loaded.
Then in the early 1970s, Medtronic built their headquarter campus on the north side of the Twin Cities. Manufacturing was moved from St. Anthony to the new campus and a new cleanroom. This room was the first cleanroom for medical device manufacturing in the area. It was a "unidirectional" cross flow design. It has been in continuous use since it was constructed. In the beginning, a cross flow design was selected because all the manufacturing was done in one room, with the dirtier operations in the return end and the final assembly, cleaning and packaging near the supply wall.
Throughout the next 15 years or so, rel=nofollow [http://www.gerbig.com]medical device cleanrooms used ducted modular HEPA filter systems and walls constructed of gypsum and coated with epoxy paint. The Class 10,000 room was the norm for medical device manufacturing. The filtration system began to change in the 1980s with the introduction in 1983 of the fan-filter unit by Envirco, Inc. in Albuquerque, NM. At first, it was thought this system would be too noisy for most operations, but over time this objection disappeared as the new unit proved to be very quiet. Today, over 90% of medical device cleanrooms use the fan-filter system. The reasons are straightforward:
Lower first cost.
Lower energy consumption.
Easier to add or subtract HEPA filtered airflow to any space.
Easier to take the investment in filtration to a new location.
Fan-filter units today have two basic motor-drive systems: a) permanent split capacitor motor and b) DC motor with built-in rectification from AC supply voltage. The DC motor option lowers energy consumption while maintaining airflow throughout the life of the HEPA filters. The motor automatically adjusts rpm to deliver constant flow through the HEPA filter. One change in medical device cleanrooms that we are beginning to see in our market area is the use of a low cost control system that offers unoccupied set-back of the system airflow. For systems with 40 hours per week peak flow usage, this system pays back the investment quickly. The system also identifies units that are not working and allows for setting individual fan speed from the control console.
Another change we have seen in the past eight years in medical device cleanrooms is the use of modular wall systems. Typically, a large manufacturing area is defined by occupancy separation walls with interior walls being constructed of a cleanroom panel system. This technique is being used because the device manufacturer can't afford down time for changes to the wall systems. One large manufacturer of implantable devices modifies their wall systems about 20 times per year. Walls are added, moved, and removed all while the cleanroom maintains the cleanliness rating. Technicians are gowned up appropriately and all materials and tools cleaned outside the room before the wall modification begins. By using a modular wall system, the cost of the walls disappears when compared to shutting down a large manufacturing operation for a day or so due to dust created by gypsum walls and painting.
rel=nofollow [http://www.gerbig.com/Workstation_Home.html]The Clean Workstation
The class 10,000 room has be the standard for medical device manufacturing for the past 30 years or so. But this too may be changing. About four years ago, Medtronic asked Gerbig Engineering to develop and manufacture a clean workstation specifically for medical device assembly. After a couple of prototypes were constructed the design was finalized. The new workstation offered many new ideas in device assembly.
Double sided airflow with two fans and two HEPA filters. More assembly area per dollar invested.
Smaller HEPA filter area; only the first few inches above the work surface has HEPA filtered airflow. This reduces heat gain and total energy, but still offers contamination protection superior to conventional assembly stations.
Putting the airflow at the work surface means fewer HEPA units in the ceiling. In our prototype test, particle counts below 3000 were recorded in an office environment. Less than 100 particles were measured in a Class 10,000 room. Using the clean workstation approach, the room could be designed as a Class 100,000 or unclassified with HEPA filters in the air handling system, while the work area itself can be class 10,000 or better.
The assembly workstation has quick connects for compressed air and electrical circuits to pass from station to station eliminating drops from the ceiling.
Using a shorter HEPA filter allows for storage or monitors to be mounted at a more usable height.
Today, with the advances in clean room construction and controls, a manufacturer needs to make sure that they are considering all options before investing in a clean room. A little time researching and using an expert system designer work out the specifications, one could realize thousands of dollars in startup as well as on going costs,.
Fred T. Gerbig, PE, has been involved with both the cleanroom industry and HVAC systems for the past 33 years. In 1985, Fred started Gerbig Engineering Company specializing in contamination control. The Company designs, builds, and certifies cleanrooms. In addition, the company performs validation work for GMP facilities and designs high purity gas and water systems. Mr. Gerbig has a Bachelor of Science in Mechanical Engineering and Bachelor of Science in Electrical Engineering, both from Iowa State University (1964).
As an active member of the Institute of Environmental Sciences (IES), he was the secretary of subcommittee RP-50 for updating Federal Standard 209B to 209D and was the Secretary for IES subcommittee RP-006 to standardize the testing of cleanrooms. Mr. Gerbig was awarded the 1986 "James R. Mildon Award" for outstanding contributions to the Institute of Environmental Sciences Contamination Control Division. He holds a patent in the field of air filtration.
Article Source: [http://EzineArticles.com/?Technologies-Impact-on-Medical-Device-Clean-Rooms&id=568004] Technologies Impact on Medical Device Clean Rooms
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