What is NFPA 37? NFPA 37 vs NFPA 110 for Stationary Engines

Engineering Scope: What is NFPA 37 and Why Does it Matter?

The technical objective of NFPA 37 is to minimize the fire hazards associated with the installation and operation of stationary combustion engines and gas turbines. This standard applies to engines used for a variety of purposes, including emergency power generation, driving fire pumps, and providing mechanical power for compressors or pumps in industrial settings.

Failure to comply with NFPA 37 can lead to significant life safety risks and property damage. Because stationary engines involve high-temperature exhaust systems and flammable fuel supplies, they are inherent ignition sources. Compliance ensures that if a mechanical failure or fuel leak occurs, the resulting fire is contained and prevented from spreading to the rest of the facility.

Key Fire Protection Requirements of NFPA 37 for Stationary Engines

The fire protection strategy within NFPA 37 relies on a combination of physical separation, structural fire resistance, and automated safety controls. For engineers, understanding the "Fire Area" concept is vital for determining the necessary protection levels.

Fire Resistance Ratings and Containment

If an engine is located inside a building, NFPA 37 requires that the engine room be separated from the remainder of the building by walls, floors, and ceilings with at least a 1-hour fire resistance rating. This rating must increase to 2 hours if the engine is part of a mission-critical system where the failure of one engine could impact others.

Critical NFPA 37 Installation Rules for Engine Rooms and Enclosures

One of the most frequent points of inspection for NFPA 37 compliance is the clearance between the engine (or its enclosure) and the surrounding structures. These rules are designed to prevent radiant heat from igniting adjacent buildings.

The 5-Foot Clearance Rule in NFPA 37

Engines installed outdoors must be located at least 5 feet (1.5 meters) from openings in walls and at least 5 feet from structures having combustible walls. There are exceptions to this NFPA 37 rule if the wall has a fire resistance rating of at least 1 hour or if the engine is housed in a non-combustible weatherproof enclosure that has been tested for fire spread prevention.

Integration with ASME and Mechanical Codes

While NFPA 37 governs the safety aspect, the mechanical design of the fuel piping systems must often adhere to ASME B31.3 (Process Piping). The standard requires that fuel lines are robustly supported and protected from vibration-induced fatigue, which is a common occurrence in stationary combustion engines.

Essential Benefits of NFPA 37 for Industrial Facility Safety

Adhering to NFPA 37 provides a multi-layered safety net for facilities that rely on stationary combustion engines. Beyond simple regulatory compliance, the standard offers tangible engineering benefits that safeguard long-term operations.

• Risk Mitigation: By enforcing strict fuel shutoff and exhaust temperature controls, NFPA 37 significantly reduces the probability of a small mechanical failure escalating into a facility-wide fire.
• Insurance Compliance: Most industrial insurers require proof of NFPA 37 compliance before underwriting policies for power plants or data centers.
• Operational Continuity: Proper ventilation and exhaust design prevent engine overheating and the ingestion of hot exhaust gases, ensuring the Emergency Power Supply Systems (EPSS) remain available during a grid failure.
• Personnel Safety: Standards for egress and engine room construction ensure that technicians have clear, safe paths for maintenance and emergency exit.

Technical Comparison: NFPA 37 vs NFPA 110 Explained

A common point of confusion for facility managers is the distinction between NFPA 37 and the NFPA 110 Standard. While both are critical for emergency power, they govern entirely different aspects of the system.

Fuel System Integrity: NFPA 37 Guidelines for Gas and Liquid Fuels

The fuel supply is the most significant fire hazard in a stationary combustion engine installation. NFPA 37 mandates specific hardware and layout requirements to ensure that fuel can be quickly isolated in the event of a fire.

Gaseous Fuel Supply Piping Requirements

For gas turbine installation and natural gas engines, NFPA 37 requires a manual shutoff valve located outside the engine room. Additionally, an automatic shutoff valve must be provided that closes when the engine is stopped, whether by manual shutdown or by a safety trip (such as overspeed or high temperature).

Liquid Fuel Containment and Safety

For diesel engines, Fuel Supply Piping must be constructed of steel or other non-combustible materials. NFPA 37 also requires that day tanks located inside a building have a capacity limit (typically 660 gallons) and be equipped with spill containment to prevent leaking fuel from reaching ignition sources.

Exhaust System and Ventilation Standards Under NFPA 37

Exhaust temperatures on a stationary combustion engine can exceed 500 degrees Celsius (932 degrees Fahrenheit). Proper management of this heat is a cornerstone of NFPA 37 compliance.

• Termination Points: Exhaust pipes must terminate outside the building at a point where they will not ignite combustible materials or enter building openings.
• Clearance to Combustibles: Exhaust systems must maintain a minimum clearance of 9 inches (229 mm) from combustible materials, or be properly insulated to maintain a surface temperature that does not exceed the ignition point of the surrounding environment.
• Ventilation: The engine room must have sufficient ventilation to provide combustion air and to remove the heat radiated from the engine.

Combustion Air Calculation Logic

Engineers must calculate the required air flow to prevent the engine room temperature from exceeding 40 degrees Celsius (104 degrees Fahrenheit). A simplified logic for ventilation requirement (CFM) based on heat rejection (H) and temperature rise (T) is:

Frequently Asked Questions about NFPA 37 Standards