PALAS Aerosol Spectrometers

Mercer Type Cascade Impactor

Mercer Impactor is designed to sample at low air flow rates, between 0.5-1 lpm, making it ideal for inhalation exposure applications where the test article is dispensed at low volumetric flows. During operation, aerosol is drawn through a series of successively smaller jet openings and impacted on collection surfaces (impaction plates). The aerosol mass collected on each stage is then gravimetrically determined. The results are analyzed by plotting the data on log probability graph paper or by using a computer program to determine the Mass Median Aerodynamic Diameter (MMAD) and Geometric Standard Deviation (GSD) of the aerosol sampled.

Aerosol Spectrometers made by Palas all utilize white light to give the most accurate representation of a large size distribution of aerosol. They are capable of accurately sensing particles as small as 120 nm up to 100 mm, with minimal coincidence and boarder zone error.


These spectrometers can measure particles in a wide temperature range (-120° - 470 °C) and up 10 bar of back pressure. Measurements can be made at intervals as small as 10 milliseconds. Using fiber optic cables, Welas® sensors – equipped with measurement volumes of varying sizes – can be easily attached to the Welas® digital 2000 and 3000 and exchanged at will. These sensors make possible a reliable measurement in the concentration range from less than 1 P/cm3 to 100 P/cm3. The sensors are available for measurements in gases as well as in liquids. These devices can also function safely in laboratory (BSL III and IV), explosive, and corrosive environments.

47mm Gravimetric Sampler

The 47mm Filter Holder has been the standard general purpose filter unit for a wide variety of scientific sampling applications for over 40 years. This design originated in the air filtration research department of a major university and has been the quality standard for this type of device since 1962.

The key to this device is the application of the overlapping seal principle combined with a very open pore, etched stainless steel screen. The conical shape of the outlet allows for the more homogeneous distribution of the collected material on filter pad, thus avoiding overloading at the center.

The 25mm and 37mm Filter Holders were developed to meet constant requests for these other two standard sizes. The overlapping seal principle has been retained. While the 47mm models have always been threaded ¼ inch NPT, the 25 and 37 mm models use ⅛ inch NPT.