Cleanroom Consulting Services - Dan Milholland

HEPA Filter Certification Testing

HEPA filter certification testing is critical to several industries including semiconductor cleanrooms. It is essential that HEPA and ULPA filters are tested efficiently and correctly. Milholland & Associates offers specialty products for the cleanroom and filter testing industry.

Microspheres (formerly known as Polystyrene Latex Spheres or PSL )

Microspheres are used as an aerosol challenge to test filter integrity at the filter manufacturer and in situ in cleanroom installation. Microspheres are specified where oils or oil vapor / outgassing is considered an Airborne Molecular Contaminants ( AMC ). The solution contains no cations and is safe to use in all classes of semiconductor cleanrooms.

The Milholland Microsphere Stock Solution is convenient and easy to use. Simply add 50 ml to 3.8 liters (one US gallon) of DI water and add to generator. 500 ml of stock solution makes 10 gallons (38 liters) of test solution.

Microsphere Size	Volume	Price*
0.1 mm	300 ml	US$400
0.1 mm	500 ml	US$600
0.3 mm	300 ml	US$500
0.3 mm	500 ml	US$750
Nalgene Graduated Cylinder†	50 ml	US$12

* Shipping is included for Continental United States. All international orders are shipped freight and import tariffs collect. This requires your UPS, FedEx, or DHL account number.

† The Nalgene Graduated Cylinder is shipped only with an accompanying order of Microspheres.

Aerosol Dilutor

When using a particle counter for filter integrity testing, filters and filter systems must be challenged with an excess of one six million particles per cubic foot of air (2.1e8 per cubic meter). Most particle counters are capable of only counting up to 100,000 particles per cubic foot of air before experiencing significant coincidence counting (counting two or more small particles as one larger particle). It is necessary to know the filter aerosol challenge concentration in order to properly quantify defects. Thus a reliable aerosol dilution device is required. This is the only NIST traceable dilutor on the market.

The Milholland & Associates aerosol dilutor has been refined and proved in over 10 years of actual cleanroom testing. It is designed specifically for PSL microsphere aerosols and uses capillary flow as the principle of operation. The unit is very durable and drift free. It does not rely on electronics, mass flow meters, transducers or orifices.

Inquire about other dilution ratios and OEM devices. We have provided two stage devices with dilution factors of up to 400,000:1, units with pressure transducers and A to D converters for computer interface, dilutors for 2.0 cfm particle counters, units compatible with VHP sterilization, etc. Contact us with you specific needs.

Dilutor Models	Price*
Model 450 AD (450:1 dilution)	US$2,275
Model 1000 AD (1000:1 dilution)	US$2,275
Calibration Service - Models 450 AD and 1000 AD**	US$350

* Shipping is included for Continental United States. All international orders are shipped freight and import tariffs collect. This requires your UPS, FedEx, or DHL account number.

** Calibration should occur at least one time each year. New dilutors are calibrated and NIST traceable.