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- Environmental conditions or damage can impact activation reliability
- Corrosion or debris in the system can clog small orifices, reducing or preventing water flow and fire protection effectiveness.
Why Test with Dyne:
- Free Water Mist Nozzle sample kits
- Free shipping within the contiguous United States (limited free 1-way shipping to Alaska, Hawaii, Puerto Rico, and Canada, inquire for details)
- Test reports in 5-business days
- Rush 24 hour turn-around available
- Comprehensive reports
- System Tags
- Online access to results and forms
- Immediate communication with our quality technicians and customer service staff
NFPA 25 Standard for Inspection, Testing and Maintenance of Water-Based Fire Protection Systems 2026 Edition
Automatic Water Mist Nozzles:
12.3.1.4* A representative sample of water mist nozzles for testing per 12.3.1.2 or 12.3.1.3 shall consist of a minimum of four water mist nozzles or 1 percent of the number of water mist nozzles per individual water mist nozzle sample, whichever is greater.
A.12.3.1.4 Within the area represented by the selected sample, water mist nozzles of the same design produced by the same manufacturer can be considered part of the same sample, but additional water mist nozzles would need to be selected if produced by a different manufacturer.
12.3.1.2 Automatic water mist nozzles that have been installed for 10 years shall be replaced, or representative samples shall be tested and then retested at 5-year intervals.
12.3.1.3* Where water mist nozzles are subjected to harsh environments, including corrosive atmospheres and corrosive water supplies, they shall be either replaced or representative samples tested on a 5-year basis.
Open Water Mist Nozzles:
12.3.2.2* Where water mist nozzles are subjected to environments with residues, including corrosive atmospheres and corrosive water supplies, they shall be either replaced or representative samples tested on a 1-year basis.
12.3.2.3 Where the nature of the protected property is such that water cannot be discharged annually as indicated in 12.3.16.5 and not subject to the conditions in 12.3.2.2, open water mist nozzles that have been in service for 10 years shall be either replaced or representative samples shall be tested and then retested at 5-year intervals.
12.3.2.4 A representative sample of water mist nozzles for testing per 12.2.10.2 shall consist of a minimum of three water mist nozzles or 1 percent of the number of water mist nozzles per individual water mist nozzle sample, whichever is greater.
Dyne tests the response time of the automatic water mist nozzles to determine if they will release in a specified amount of time when exposed to a defined temperature and air flow. The acceptable response time is based on a response time index (RTI). A water mist nozzle could fail if the response time does not meet the RTI requirement.
For both automatic and open water mist nozzles, the k-factor is evaluated given the minimum operating pressure and manufacturer published k-factor value are provided. If the actual k-factor is outside the allowed deviation from the published k-factor (+/- 5% for open and +/- 10% for automatic), the water mist nozzle would fail. These failures may result from, but are not limited to, the following:
- Loading
- Corrosion
- Paint
- Missing fluid in the glass bulb (if applicable)
- Debris blocking the waterway/orifice
NFPA 25 Section 12.3.1.5 (automatic) / 12.3.2.5 (open) 2026 Edition Where one water mist nozzle within a representative sample fails to meet the test requirement, all water mist nozzles within the area represented by that sample shall be replaced.
Dyne helps you meet Water Mist Nozzle testing requirements in the following standards:
- NFPA 25 Standard for the Inspection, Testing and Maintenance of Water-Based Fire Protection Systems
- 2026 Edition Section 12.3.1.1
- 2026 Edition Section 12.3.2.2 or 12.3.2.3
