This Recommended Practice (RP) addresses the sizing and counting of submicrometer liquid-borne particles using optical discrete-particle counters with a focus on applications in the semiconductor, flat-panel display, and data storage industries. Topics covered include the following:

• Overview of light-scattering technology

• Liquid particle counter (LPC) instrument types

• Data interpretation

• Coincidence level or maximum concentration limit

• Particle-size detection limit

• Bubble issue

• Refractive index effect

• Flow rate

• Calibration verification

• Instrument noise and false counts

• Practice of minimizing sensor contamination

• Sensor correlation

• Particle counting statistics