The 2019 NFPA 20 standard defines the essential criteria for installing, operating, and testing stationary fire pumps utilized in fire protection systems. It encompasses various pump types such as centrifugal and positive displacement, powered by electric, diesel, or steam turbine drives, to ensure dependable water flow during firefighting. This document is vital for professionals designing, installing, and servicing fire pump setups in buildings and industrial environments.
Overview
The 2019 NFPA 20 standard defines the essential criteria for installing, operating, and testing stationary fire pumps utilized in fire protection systems. It encompasses various pump types such as centrifugal and positive displacement, powered by electric, diesel, or steam turbine drives, to ensure dependable water flow during firefighting. This document is vital for professionals designing, installing, and servicing fire pump setups in buildings and industrial environments.
Audience
Contents
Structure
This section outlines the extent of NFPA 20 pertaining to the design, installation, and testing of stationary fire pumps within fire protection systems. It includes single-stage pumps, vertical lineshaft turbine pumps, and self-regulating variable speed units, powered by electric, diesel, or steam turbine drives. Requirements for water supply sources, acceptance testing, reliability parameters, and key components such as brake horsepower and pipe sizing are also described.
Provides essential definitions to clarify terminology used throughout NFPA 20 including terms like drawdown duration, system designer roles, discharge cones, vertical lineshaft turbine pump configurations, variable speed drives, and critical components that affect pump operation. It also covers pump classifications, testing procedures, component dimensions, control valve specifications, and data recording systems.
Details the general mandates including incorporation of referenced documents, required documentation such as engineering calculations and test records, and stipulations for existing installations to conform to certain sections. It also presents key formulas for calculating pump capacity, pressure head, and power requirements necessary to verify performance compliance.
Defines alternate power as an independent energy source distinct from the primary supply, which must automatically energize fire pump drivers upon primary power failure. Typical sources include emergency generators and battery systems, with specifications for power capacity, run duration, and adherence to electrical codes. Design considerations and advantages of various alternate power options are discussed.
Covers flow capacity ranges for centrifugal pumps with conversion tables, methods for calculating net discharge suction pressure, velocity pressure adjustments, and flow through orifices. It includes formulas and parameters essential for proper pump sizing and performance evaluation.
Highlights minimum submergence requirements adjusted for elevation to ensure sufficient NPSH and prevent cavitation, lubrication guidelines for lineshaft bearings, performance curve characteristics, motor specifications tailored for vertical turbine pump use, and insights on variable speed pump advantages. Includes formulas and selection flowcharts.
Describes positive displacement pumps capable of delivering fixed volume per cycle, suitable for steady flow and high-pressure scenarios. Discusses types like gear, screw, piston, and diaphragm pumps, selection criteria based on flow and pressure needs, key operational formulas, and safety features like relief valves.
Specifies general provisions for electric motors powering fire pumps, including requirements for intermediate equipment and exclusions. Details criteria for part-winding motors, locked rotor current ratings for single- and three-phase motors, and requirements for motors paired with variable speed controllers. Also addresses flow measurement devices for performance verification.
Specifies voltage ratings, marking requirements for short-circuit current capacity, current limits for safe operation, backup controller provisions, and mandatory electrical diagrams and instructions. Addresses critical components, external control operations, and transfer switch specifications to ensure reliable controller function.
Defines diesel engines as compression ignition units and outlines performance expectations including ramp-up and ramp-down timing to avoid mechanical stress. Contains installation requirements ensuring operational readiness, fuel supply continuity, starting systems, and cooling provisions. Includes power calculation formulas and minimum fuel capacity guidelines.
Covers manufacturer responsibilities for emergency operating instructions, types of engine drive controllers including variable speed pressure limiting controls, relevant electrical and control specifications, and compliance with current limits. References tables for maximum controller currents and stresses the importance of including instructions in emergency manuals.
Details speed regulation requirements maintaining turbine speed within a ±3% range, ordering data parameters such as pump load, speed, boiler pressure, and steam characteristics. Describes steam consumption estimates, minimum steam pressure needs, and controller automatic return functions. Summarizes typical operational parameters for steam turbine drives.
Outlines acceptance testing procedures including comparison with manufacturer certified curves, flush and hydrostatic tests, attendance by manufacturer and authority representatives, and control system verification. Describes performance testing parameters, requirement for calibrated instruments, vibration and temperature monitoring, and maintenance protocols including record-keeping and component inspection.
Frequently Asked
NFPA 20 encompasses a variety of stationary fire pumps utilized in fire protection, including electric fire pumps where reliable power exists, diesel engine-driven pumps for locations with unreliable electric supply, multistage and multiport pumps tailored for specific fire suppression needs, variable speed pumps with self-regulating capabilities, and pumps arranged in series with requirements for control wiring and communication safeguards. This ensures comprehensive coverage for different power sources and applications to guarantee dependable firefighting water supply.
Diesel engine-driven fire pumps must utilize compression ignition engines as specified. Controllers powering auxiliary equipment such as pump room dampers or oil heaters must be factory-equipped with dedicated terminals and overcurrent protection. Additionally, pressure relief valves are mandated when the combined net rated shutoff pressure and maximum static suction pressure adjusted for elevation exceed the component's pressure rating. These requirements ensure safe, reliable operation and compliance with NFPA 20 standards.
Variable speed fire pumps must undergo tests at multiple load points in variable speed mode, including no-flow, 25%, 50%, 75%, 100%, 125%, and 150% of rated load. Additional testing at rated speed includes minimum, rated, and peak load assessments. Self-regulating variable speed pumps require two certified test curves representing constant discharge pressure and constant boost pressure modes. The installed pump’s performance must align with certified shop test data within acceptable accuracy, following the controller’s operating sequences to verify compliance.
Each fire pump must have its own dedicated transfer switch if one is required. If the transfer switch is self-contained, it must be housed within a barriered compartment in the fire pump controller or in a separate attached enclosure clearly marked as the fire pump power transfer switch. Automatic operation must not be impeded by any remote devices. Arrangement II requires individually listed fire pump controllers and transfer switches to ensure compatibility and adherence to the standard, providing reliable and automatic power switching.
NFPA 20 mandates that high-rise buildings have at least one alternate power source unless a backup fire pump with independent power is installed. Alternate power is required if the normal power source is deemed unreliable, characterized by no extended outages or overhead supply limitations. When alternate power is provided, an across-the-line fire pump controller and transfer switch must be installed per the electrical requirements. This framework ensures fire pumps remain operational during power interruptions, maintaining fire safety system integrity.
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