Filter Tests using an automated ULPA and HEPA Filter Test System

Applied Physics, Inc.

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Applied Physics, Inc.

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Wafer Size Standards

Clean Room Foggers

Ultrapure Foggers

PSL Spheres, Silica Particles


Aerosol and Wind Generator Information

ULPA HEPA Filter Testing

Particle Generator, Air Flow Generators, Laser Particle Counters, X/Y Scanning capabilities, Diluters, Computer Control.

A filter test system for ULPA and HEPA filter test and certification requires x-y scanning, filter leak detection for pin hole leaks and efficiency measuring. In order to achieve this the filter test system has to have automated scanning capabilities, which in most cases will be used in production and certification of the filters. PSL spheres are used as the aerosol particle challenge, rather then oil based particles. The advantage of PSL is a narrow size peak at the point of filter specification, as well as high volume of particle challenge in order to speed up the filter test requirements. One to 5 laser particle counters are used to scan the downstream side of the filter; while 1 laser particle counter would be used to monitor the upstream particle count. The data collected should be used to create a surface filter profile with real time particle counting to show X/Y locations of pin hole leaks as well as a 4 color profile of each square inch of filter surface monitored. Dat4e collected also allows for the calculation of the filter efficiency, which would be measured to the specification of the filter for pass fail certification. The system should be capable of detecting pin hole leaks, based on a specification required for that quality of filter. Thus the filters can be analyzed over every square inch of surface area, edges in order to accurately certify ULPA and HEPA filters. ULPA is typically a 99.9999% efficiency level usually referred to as 6/9 filter, while HEPA filters are specified for filter effiency at 99.999? and 99.99%, 5/9 and 4/7 respectively. In order to achieve best results, the filter test system should have automated computer control for each type and size of filter, based on a recipe control (software control) operation. Data collection, data analysis and data presentation would make this filter test system ideal for testing high efficiency filters in the production environment. Each machine needs to be custom-designed to meet the needs of the individual customer. The system should include an x-y scanner with control based on 2 x 2 foot filters requiring a 26" x 26") X/Y scan. Filters at 2 x 4 foot dims require a 26" x 50" X/Y scan, while 3 x 6 filters would need a 38" x 74" X/Y scan. Computer control is needed to manage all the sensors for airflow, particle count, X/Y movement, blower control, etc. Particle challenge should be provided by one or two high output particle generators for the upstream challenge. One or two airflow blowers with 1000cfm capacity should be included in the upstream air management.

FILTER TEST GOALS, APPLICATIONS

  • Leak detection and efficiency certification of ULPA and HEPA filters
  • Efficiency certification to the 99.9999% level
  • 1 x 10 8ft3 PSL sphere challenge would normally be required
  • high volume particle output with computer control of the particle generator

Operating Goals

An ULPA and HEPA Filter Test System needs to be custom-designed to meet the individual needs of 1 or more sizes of filters with a varieity of filter specifications. The following filter test, performance guidelines are desired.

(subject to change without notice)

PSL sphere size range 0.1 - 0.5 µm
PSL output rate 7.2 x 1010 per min @ 0.10 µm
Maximum filter size 3' x 6'
Maximum flow rate 1000 cfm (optional 2000cfm)
Compressed air or N2 required 8 scfm @ 80 - 100 psig
Size, weight and power consumption Depends on specific configuration