Water Mist Nozzles

shall be tested for degradation at least annually. Biodiesel fuel might need to be tested for degradation more frequently.

Water Mist Nozzles

Automatic water mist nozzles that have been installed for 10 years (5 for harsh environments) shall be replaced, or representative samples shall be tested.

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Why Water Mist Nozzle Compliance Matters

Water mist nozzle performance can change throughout a system’s service life in ways that may not be identified through visual inspection alone. Periodic testing provides objective performance data that can be used to evaluate nozzle conditions and determine whether maintenance or replacement may be necessary.

NFPA 25 requires periodic testing of automatic and open water mist nozzles to evaluate continued performance against established acceptance criteria. Test results can be used to support maintenance decisions and demonstrate compliance with applicable inspection, testing, and maintenance requirements.

Water Mist Nozzle Testing Overview

We test all types of water mist nozzles, including automatic and open nozzles. Water mist nozzle testing is typically performed as part of periodic inspection, testing, and maintenance programs required by NFPA 25. Testing may also be performed when evaluating system conditions, investigating concerns about nozzle performance, or supporting maintenance and replacement decisions.

These services are commonly used by building owners, facility managers, contractors, consultants, insurers, and fire protection professionals responsible for the inspection, maintenance, and long-term performance of water mist fire protection systems.
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Key Testing Capabilities Include:

Sensitivity (Automatic Nozzles Only)to evaluate nozzle response characteristics under controlled test conditions and determine whether activation performance meets the applicable acceptance criteria.
Functionality to verify that nozzles fully operate at their minimum operating pressure during testing.
Discharge Coefficient (K-Factor) to evaluate the relationship between flow and pressure and determine whether discharge performance remains within the allowable tolerance of the manufacturer's published K-factor value.
Comprehensive Reporting to document test results and identify nozzles that meet or do not meet the applicable acceptance criteria.

If you are interested in the equations and RTI calculations used in the testing process, refer to our Testing Explanation sheets available under Resources.

Free Water Mist Nozzle Sample Kits

Quantity Needed

1 kit = room for 4 water mist nozzles (minimum of 4 water mist nozzles required by NFPA 25)

2 kits = room for up to 8 water mist nozzles

3 kits = room for up to 12 water mist nozzles

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Description

• Kits are shipped via UPS Ground at no cost in the contiguous United States (limited free 1-way shipping to Alaska, Hawaii, Puerto Rico, and Canada, inquire for details), payment information is needed when samples arrive for testing

• Each kit contains four sample tags for labeling, foam packing material, a return UPS label, and a return form

• Standard turn-around is 5 business days

• Expedited shipping and testing (24 hour) is available, please contact us for pricing

• Use this kit to test NFPA 25 – Water Mist Nozzle Testing

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How Water Mist Nozzle Testing Reduces Risk and Supports Compliance

Water mist nozzle testing helps reduce risk by providing objective information on nozzle performance. Automatic water mist nozzles are evaluated to determine whether they activate within the applicable response time requirements, while both automatic and open nozzles are evaluated for discharge coefficient (K-factor) and functionality. Testing can identify conditions such as loading, corrosion, paint, missing fluid in the glass bulb (where applicable), or debris obstructing the waterway or nozzle orifice.

Laboratory testing provides performance data that supports informed maintenance, replacement, and compliance decisions. Testing can help identify nozzles that do not meet applicable acceptance criteria and may require corrective action. In accordance with NFPA 25 (2026 Edition, Sections 12.3.1.5 and 12.3.2.5), where one water mist nozzle within a representative sample fails to meet the test requirements, all water mist nozzles represented by that sample are required to be replaced.

By proactively evaluating nozzle performance and documenting test results, water mist nozzle testing helps support system reliability, informed maintenance planning, and confidence in the readiness of water mist fire protection systems.

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

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Relevant Corrosion & MIC Standards and Test Methods

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

What types of samples are tested?

Automatic water mist nozzles and open nozzles.

When is Water Mist Nozzle testing typically required?

10 years after installation and every 5 years thereafter. Harsh Environments: Automatic water mist nozzle testing every 5 years, open water mist nozzle testing every year.

How are test results delivered?

Test results are delivered via email within 5 business days or less from the receipt of the sample(s). System tags are mailed via USPS if requested on the sample return form for passing samples.

Who should I contact to get started?

You can contact Dyne Fire Protection Labs to discuss your testing needs.

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Why NFPA Global Solutions Water Mist Nozzle Testing

Dyne Fire Protection Labs, an NFPA Global Solutions company, is a full-service NFPA 25 testing laboratory that combines fire protection industry expertise with specialized water mist nozzle testing services. Our approach focuses on delivering objective laboratory data that helps organizations evaluate nozzle performance, support maintenance planning, and make informed decisions related to system reliability and compliance activities.

With more than 25 years of testing experience, we understand the unique challenges associated with maintaining water mist fire protection systems. Our testing services are designed to help organizations assess nozzle conditions, document results, and maintain confidence in the performance and readiness of their fire protection systems.

Key Testing Advantages:

Test reports in 5-business days or less (with rush 24-hour turn-around available)
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)
Comprehensive reports and system tags
Online access to results and return forms
Immediate communication with our quality technicians and customer service staff

Order Your Water Mist Nozzles Kit

Request your free Water Mist Nozzle sample kit and connect with our team to discuss your testing needs. We can help determine sample requirements, answer questions about the testing process, and provide guidance on submitting samples for evaluation. If you have questions, contact us at (800) 632-2304 or dyne.lab@nfpaglobal.com.

Order today

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