Phase Doppler particle analyzer (PDPA)

When high-value risks need fire protection, manufacturers turn to UL for accurate, comprehensive fire-extinguishing tests. In UL's dedicated test laboratory, engineers use phase Doppler particle analyzer (PDPA) technology to perform non-invasive evaluation of fire sprinklers, fixed nozzles and water mist nozzles to determine precisely how they perform in different environments. PDPA testing assures manufacturers, their customers and insurance companies that the liquid sprays that flow through these components display specific discharge characteristics.

The PDPA is a highly specialized technology used to measure any liquid spray with transparent/semitransparent droplets. The equipment combines a laser-based optical transmitter, an optical receiver, an electronic signal processor and software for capturing and analyzing data. Water is discharged through a pump rated at 250 psi capacity at up to 500 gallons per minute. As it passes through a nozzle or sprinkler, it produces a distinctive spray pattern. As droplets reach the intersection of the PDPA's laser beams, the equipment measures the size and velocity of these droplets in two dimensions. The PDPA equipment can measure a droplet's diameter between 0.5 and 7,000 microns, and measure velocity up to 800 meters per second.

Test Standards

UL tests to the current editions of the following Standards:

• UL 2167, Water Mist Nozzles for Fire Protection Service
• IMO Resolution A.800(19), Revised Guidelines for Approval of Sprinkler Systems Equivalent to That Referred to in SOLAS Regulation II-2/12
• NFPA 750, Water Mist Fire Protection Systems

A dedicated test environment

UL has a 24-foot by 30-foot dedicated test laboratory with an 18-foot-tall, sloping ceiling to perform PDPA tests. A special 10-foot by 10-foot moveable vertical traverse allows test professionals to position the PDPA laser beams deep within a spray nozzle's flow field, without disrupting the spray pattern.

The UL advantage

Highly specialized sprinkler applications require active measurements of how components perform under specific test conditions. UL has made the technology investment to help manufacturers develop products that meet or exceed current standards. Leading-edge equipment, engineering expertise and more than 100 years of standard development, testing and certifying experience make UL a valuable resource for product development and performance analysis.