Water Mist System Equipment Component Testing

Testing and Certification of Water Mist Fire Protection Systems and Components

How water mist systems work

Water mist fire suppression works by breaking water into tiny droplets that rapidly absorb heat through evaporation. As the droplets turn to steam, they cool the flames, displace oxygen near the fire and create a barrier that helps prevent the fire from spreading. This efficient use of water offers effective fire control with minimal water damage.

Types of water mist systems by pressure classification

NPFA 750 classifies systems based on their operating pressure. These classifications impact system design, droplet size, discharge pattern and application suitability.

• Low-pressure systems (under 175 psi): Low-pressure water mist systems operate below 175 psi and typically produce larger droplets. These systems are often used in applications where lower water pressure is sufficient, such as residential, light commercial or specific machinery enclosures. They can be simpler to install and maintain, making them cost-effective for certain risk profiles.
• Intermediate-pressure systems (175 psi to 500 psi): Operating between 175 psi and 500 psi, intermediate-pressure systems strike a balance between droplet size and system complexity. They are suitable for broader commercial or industrial applications where enhanced fire suppression performance is needed without the equipment demands of high-pressure systems.
• High-pressure systems (over 500 psi): High-pressure systems exceed 500 psi and generate ultra-fine water mist droplets. These fine droplets vaporize rapidly, efficiently absorbing heat and displacing oxygen to suppress fires. High-pressure systems are commonly used in high-risk or enclosed environments, such as data centers, engine rooms or tunnels, where minimal water usage and rapid suppression are critical.

Critical water mist system components

Water mist systems are made up of specialized parts, all integral to their effectiveness and reliability, including:

• Specialized nozzles and spray heads
• High-pressure pumps
• Control systems
• Pipes and fittings
• Detection and activation mechanisms

Water mist testing standards and compliance

Our fire suppression professionals test water mist equipment in accordance with several global standards, as well as under IMO regulations. The requirements for the installation and use of these products are specified in the National Fire Protection Association (NFPA) installation standard on water mist, NFPA 750.

We test to the following standards:

• UL 2167, the Standard for Water Mist Nozzles for Fire Protection Service
• UL 448C, Stationary, Rotary-Type, Positive-Displacement Pumps for Fire-Protection Service
• UL 321: Outline of Investigation for Pipeline Strainers
• UL 2167A, the Standard for Water Mist Residential System Units - Targeted Discharge
• IMO Assembly Resolution A.800(19): Revised Guidelines for Approval of Sprinkler Systems Equivalent to That Referred to in SOLAS Regulation II-2/12

Verification with report 

• Customized evaluation: We tailor the verification process to assess specific aspects of your water mist system, ensuring it meets your unique requirements.
• Regulatory and industry reference: Our verification aligns with applicable standards, including NFPA, EN and ISO guidelines, to guarantee regulatory compliance.
• Detailed report issuance: We issue a comprehensive report that documents the evaluation process, highlights key findings, and presents test results.
• Support for market readiness: We assist manufacturers in demonstrating product capabilities to customers, insurers, and regulatory bodies, facilitating smoother market entry.

Benefits of water mist firefighting testing and certification

Our testing and certification services offer several advantages to both manufacturers and users of fire suppression equipment.

• Accelerate your time to market with efficient, flexible services backed by UL Solutions’ leadership in fire safety certification.
• Access advanced testing capabilities and a knowledgeable technical team with deep expertise in fire protection codes and standards.
• The UL Mark signifies that a product has been tested and certified to meet UL Solutions’ safety, quality and security standards, trusted by fire safety professionals worldwide.