Best practices: Ensuring NFPA 20 compliance with diesel-driven fire pumps

Fire pump insights

• Fire pumps can be powered via many different sources. Understanding which is correct for a project is important.
• By managing the entire process of designing a fire pump, fire protection engineers can ensure the design is code-compliant.

Over the past few years, a rise in the adaptive reuse of buildings has led to a rise in the use of diesel-driven fire pumps. The increase stems from updated fire codes: Buildings that lack a sprinkler system, a standpipe system or sufficient water supply to meet the required pressure in pounds per square inch must be brought up to the current code.

In cases where the building’s height is beyond the reach of the fire department’s equipment, an electric fire pump could solve the problem, but some retrofitted buildings do not have a reliable alternate source of power required by NFPA 20: Standard for the Installation of Stationary Pumps for Fire Protection.

Examples of alternate sources of power are an emergency generator, a dedicated service connection to the fire pump, an on-site power production facility connection dedicated to the fire pump and a dedicated feeder from a dedicated service directly linked to the fire pump. The clear alternative in such situations is diesel-driven fire pumps.

Although the decision to use diesel-driven fire pumps is straightforward, design and installation are not, especially given the intricacies of NFPA 20. The sections of the standard that address fuel supply and arrangement are especially complex. To avoid problems, fire protection engineers and specifiers should adhere to the following best practices:

Insist on shop drawings with all relevant details. Shop drawings from contractors should show tank elevation, centerline elevation of the fuel tank supply to the fuel pump on the diesel engine, flexible connectors, check valves, drain valves and isolation valves. The NFPA 20 Handbook provides a helpful figure (Figure A.11.4.4) that depicts the compliance standards for components and locations.

It is critical for building teams to provide this level of detail to the fire protection contractor before making any purchasing decisions. If detailed drawings are unavailable, the fire protection contractor should try to obtain them directly from the equipment manufacturer. Incomplete drawings could lead to inappropriate selections of equipment, which could fail inspections and necessitate a full redesign of a tank system. Clients will not look kindly on such a waste of time and money.

Figure 1: This shows bottom-fed fuel oil supply piping on a tank with the required filter. Courtesy: Syska Hennessy Group

Compare shop drawings with product data submittals. Once the engineer receives fully detailed shop drawings from the fire protection contractor, the next step is to verify the accuracy of the information. Does the information provided on the shop drawings align with the information on the product data submittals and with NFPA 20 details and requirements? This seems like an obvious step, but it’s easy to overlook.

The risk of skipping verification could lead to project change orders or significant delays in installation — extending timeframes that are already longer than normal because of supply chain issues. Again, clients will not welcome the wait or added costs.

Be prepared to coordinate extensively with trades during design. Avoid assumptions. Equipment specifications must take electrical power requirements into account. Here the fire protection engineer should let the electrical engineer know what the voltage and phase of the controller are.

The voltage and phase indicated on the controller product data sheet should agree with both the fire protection specs and panel schedules on the electrical drawings. The electrical engineer can then confirm that the facility is equipped with the right circuits. The fire protection contractor should also coordinate with the fire alarm engineer to ensure that the fire pump controller is specified to send alerts to the building’s fire alarm control panel for low fuel levels or leakage in the interstitial spaces between tanks; both signals are required by NFPA 20.

Another consideration for the fire protection engineer is meeting a client’s desire for additional alarms that would report to the building automation system (BAS). While not a requirement by NFPA 20, the client may wish to exceed the base requirements for signaling. The fire protection engineer should discuss this possibility with the facilities management team and/or the consultant responsible for a BAS.

Coordination of fire pumps and related equipment

That’s not all. The fire protection engineer should work with the architect and building owner to coordinate locations for fuel tank vent terminations. Normal and emergency vents are required to terminate outside the building and, per NFPA 20, vents must be arranged so the vapors are discharged upward or horizontally away from adjacent walls so that vapors will not be trapped by eaves or other obstructions.

Another requirement for vent terminations is that vents cannot be within 5 feet of any building opening. Architects also will want to ensure that the openings are aesthetically pleasing.

Figure 2: Shown is bottom-fed fuel oil supply piping. Courtesy: Syska Hennessy Group

If an owner chooses a single-wall tank, the fire protection engineer and the architect must work together to determine the height of the door to the room where the tank is housed for containment purposes. In many cases the architect will have to specify the room to either have a secondary containment basin around the bottom of the tank or elevate the door to the room to a height containment of the full volume of the tank.

Building owners and teams that view fire protection engineering as a basic commodity rather than an expert service risk running into significant difficulties during design and installation. This is particularly true of projects involving diesel-driven fire pumps, which require specialist knowledge.

To facilitate the integration of these fire pumps into a facility’s design, fire protection engineers should examine all drawings carefully, compare them with product data submittals and collaborate closely with other members of project teams. By taking these steps, fire protection engineers can guide clients and project teams to compliance without burning through the owners’ budgets.

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