NFPA in USA

Supporting explainers

Technical explainers for calculator users

These pages support tool use and internal linking. Calculators remain the primary site experience.

All explainers

ExplainerEngineering useLinked toolsOpen

Hazen-Williams Formula for Fire Sprinklers Explained

NFPA 13

Hazen-Williams Formula for Fire Sprinklers Explained explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

NFPA 13 Hydraulic Calculation Step by Step

NFPA 13

NFPA 13 Hydraulic Calculation Step by Step explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

K-Factor in Fire Sprinklers: Complete Guide

NFPA 13

K-Factor in Fire Sprinklers: Complete Guide explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

NFPA 72 Battery Sizing: How to Calculate

NFPA 72

NFPA 72 Battery Sizing: How to Calculate explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Fire Sprinkler System Types: Wet, Dry, Preaction, Deluge

NFPA 13

Fire Sprinkler System Types: Wet, Dry, Preaction, Deluge explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Sprinkler Density and Area Curve Basics

NFPA 13

Sprinkler Density and Area Curve Basics explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Fire Pump Sizing Guide for Sprinkler Systems

Engineering

Fire Pump Sizing Guide for Sprinkler Systems explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

How to Read a Fire Hydrant Flow Test

NFPA 25

How to Read a Fire Hydrant Flow Test explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

NFPA 13 Occupancy Hazard Classification Guide

NFPA 13

NFPA 13 Occupancy Hazard Classification Guide explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Equivalent Pipe Length for Fittings Reference

NFPA 13

Equivalent Pipe Length for Fittings Reference explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Voltage Drop Calculation for Fire Alarm NAC Circuits

NFPA 72

Voltage Drop Calculation for Fire Alarm NAC Circuits explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Sprinkler Head Spacing Rules for Layout Checks

NFPA 13

Sprinkler Head Spacing Rules for Layout Checks explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

C-Factor Values for Sprinkler Pipe

NFPA 13

C-Factor Values for Sprinkler Pipe explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

NFPA 25 Flow Test: Calculate Available Water

NFPA 25

NFPA 25 Flow Test: Calculate Available Water explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Light vs Ordinary vs Extra Hazard

NFPA 13

Light vs Ordinary vs Extra Hazard explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Pipe Velocity Limits in Sprinkler Systems

NFPA 13

Pipe Velocity Limits in Sprinkler Systems explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Velocity Pressure in Sprinkler Hydraulic Checks

NFPA 13

Velocity Pressure in Sprinkler Hydraulic Checks explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Remote Area Setup for Sprinkler Calculations

Conversion

Remote Area Setup for Sprinkler Calculations explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Fire Pump Horsepower Formula

Engineering

Fire Pump Horsepower Formula explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Water Supply Curve Basics

NFPA 25

Water Supply Curve Basics explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Pitot Pressure to GPM Conversion

NFPA 25

Pitot Pressure to GPM Conversion explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

NAC Circuit Load Planning

NFPA 72

NAC Circuit Load Planning explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Fire Alarm Wire Resistance and Voltage Drop

NFPA 72

Fire Alarm Wire Resistance and Voltage Drop explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Detector Spacing Field Check

NFPA 72

Detector Spacing Field Check explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Strobe Candela Coverage Screening

NFPA 72

Strobe Candela Coverage Screening explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Pipe Schedule Selection for Sprinkler Calculations

NFPA 13

Pipe Schedule Selection for Sprinkler Calculations explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Hose Allowance in Sprinkler Demand

NFPA 13

Hose Allowance in Sprinkler Demand explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Elevation Pressure in Fire Protection Systems

NFPA 13

Elevation Pressure in Fire Protection Systems explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Dry Pipe C-Factor Screening

NFPA 13

Dry Pipe C-Factor Screening explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

CPVC Pipe Friction Loss Considerations

NFPA 13

CPVC Pipe Friction Loss Considerations explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Steel Pipe Roughness in Fire Sprinkler Systems

NFPA 13

Steel Pipe Roughness in Fire Sprinkler Systems explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Available Flow at 20 PSI Residual

NFPA 25

Available Flow at 20 PSI Residual explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Hydrant Test Data Quality Checklist

NFPA 25

Hydrant Test Data Quality Checklist explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Sprinkler Coverage Area Calculation

Conversion

Sprinkler Coverage Area Calculation explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Design Density Lookup Workflow

NFPA 13

Design Density Lookup Workflow explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Fire Pump Demand Margin

Engineering

Fire Pump Demand Margin explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

NPSH Screening for Fire Pumps

Engineering

NPSH Screening for Fire Pumps explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Pressure Unit Conversion for Fire Protection

Conversion

Pressure Unit Conversion for Fire Protection explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Flow Unit Conversion for Fire Protection

Conversion

Flow Unit Conversion for Fire Protection explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Pipe Dimension Lookup for Hydraulic Inputs

NFPA 13

Pipe Dimension Lookup for Hydraulic Inputs explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Length and Area Conversion for Sprinkler Layout

Conversion

Length and Area Conversion for Sprinkler Layout explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Common Mistakes in Hazen-Williams Calculations

NFPA 13

Common Mistakes in Hazen-Williams Calculations explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Common Mistakes in K-Factor Calculations

NFPA 13

Common Mistakes in K-Factor Calculations explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Fire Alarm Battery Sizing Common Mistakes

NFPA 72

Fire Alarm Battery Sizing Common Mistakes explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen

Water Supply Analysis Fire Protection

NFPA 25

Water Supply Analysis Fire Protection explains the calculation inputs, formula context, field checks, and limits engineers should confirm before using results in a project workflow.1 worksheets / 2 calculatorsOpen