NBR 16704: Stationary Fire Pump Sets — Requirements, Performance Curve and Acceptance

1. What NBR 16704 is and when it applies

ABNT NBR 16704 is the Brazilian standard for stationary pump sets serving automatic fire protection systems. The objective recorded in the ABNT catalogue is to establish the minimum requirements for selecting and installing these sets. The standard was published on 27 February 2019 and is currently in its 2020 corrected version, which incorporates Erratum 1 of 30 September 2020; ABNT confirmed it on 25 April 2024, and the catalogue lists it as in force.

It belongs to committee ABNT/CB-024 (Fire Safety) and has 89 pages. The full text is sold by ABNT and this guide does not reproduce it: what follows explains what the standard is, where it is required and what the cited sources say about the pump set.

Where it applies is set by each state's fire safety rules. In São Paulo, Technical Instruction 23 (IT 23) of the Fire Department, on automatic sprinklers, requires the stationary pump sets of sprinkler systems to follow Annex C of IT 22 and NBR 16704, and repeats, in its section on the fire pump, that the set must meet the requirements of the standard.

In Goiás, Technical Standard 23 (NT 23) of the Military Fire Department makes the same requirement, with Annex C of NT 22. Both instructions add that sprinkler pumps must be installed under positive pressure, and neither accepts a priming tank.

Within the family of standards, each document has a role. NBR 10897 (automatic sprinklers) and NBR 13714 (hydrants and hose stations) deal with the systems, and their design sets the flow and pressure demand; NBR 16704 deals with the pump set for automatic systems; and the state IT or NT defines what permitting requires.

The split has a practical consequence: in São Paulo, the hydrant instruction IT 22 does not cite NBR 16704, and hydrant network pumps follow Annex C of IT 22 itself.

2. Which pumps make up the set — and the role of each

NBR 16704 deals with pump sets; for pump types, NFPA 20, the US standard for stationary fire pumps, covers centrifugal pumps in two chapters. One covers overhung-impeller pumps, end-suction or in-line, with one or two stages, and impeller-between-bearings pumps, with axially or radially split casings and one or more stages; these pumps must not be used where a static suction lift is required. The other covers the vertical turbine pump, which is the standard's solution for that case.

In fixed systems, according to the Hydraulic Institute, positive displacement pumps are limited to water mist and foam. In FB Bombas fire configurations, the main pump is the FBCN normalized centrifugal pump, with back pull-out construction: the bearing assembly comes out of the volute without disconnecting or misaligning the piping (MTEC-03/00). This construction eases maintenance, but on its own it does not demonstrate compliance with NBR 16704.

The set has three roles. The main pump meets the fire demand; the standby pump takes over when the main pump or its power source fails; and the jockey pump keeps the network pressurized within a preset range, making up small losses so that the main pump starts only when there is firefighting flow.

In Goiás, Annex C of NT 22, which NT 23 extends to sprinklers, sets the minimum arrangement by pump function: a booster arrangement, with one main pump and a backup power source, or a fixed arrangement, with main and standby pumps, the standby having a backup power source and, where needed, a jockey pump.

In low-risk buildings (fire load up to 300 MJ/m²) with a fixed arrangement, the standby pump is waived, and the main pump must then have a backup power source. Main and standby pumps do not run at the same time, and minimum full-load autonomy ranges from 2 to 6 hours depending on the fire load.

The jockey pump deserves its own calculation. NFPA 20 does not require it to be listed, but requires it to be approved, and asks it to replenish the pressure lost through allowable leakage and normal pressure drops, with a rated capacity not less than the normal leakage rate.

The annex of the standard notes that, where it serves only aboveground sprinkler and standpipe piping, the jockey flow should be less than that of a single sprinkler, so that the main pump starts when a sprinkler opens, and cites a guideline that has been used successfully: make up the allowable leakage in 10 minutes, or 1 gpm (3.8 L/min), whichever is larger.

The rule of 1% of main pump flow is a practice of many designers, not a requirement of the standard. In São Paulo and Goiás, a hydrant network jockey pump is mandatory above six outlets, except with an elevated reservoir, has a maximum flow of 20 L/min and a maximum operating pressure equal to the main pump shutoff.

3. The performance curve the set must meet

The NBR 16704 text is sold through the ABNT catalogue, and this guide does not reproduce it; the numbers below are those of NFPA 20, which standardizes the shape of the fire pump curve. The pump is rated by the net pressure it delivers at 100% of rated flow, with standardized rated flows from 25 to 5,000 gpm (95 to 18,925 L/min) and a net pressure of at least 40 psi (276 kPa).

At 150% of rated flow, pressure must not drop below 65% of rated pressure: this is the overload capacity, which prepares the pump for a surge in demand during a fire. At zero flow, shutoff pressure does not exceed 140% of rated pressure for any type of pump; the Hydraulic Institute summarizes the range as 101% to 140%.

In selection, this changes the criterion: the whole curve must fit the envelope, not just the rated point. The largest single system demand connected to the pump must not exceed 150% of rated flow. In practice, ASPE advises against operating above about 140% or below about 90% of rated flow, and the duty point should preferably sit in the central part of the curve.

At acceptance, the manufacturer's certified curve for the pump supplied is what counts: NFPA 20 requires a copy of it for comparison with the field test, and the installed pump must match it at all flow conditions, including those tested, within the accuracy of the instruments. In São Paulo, the IT 23 model inspection report asks whether the performance curve, flow × pressure, prepared by the manufacturer before installation was presented.

4. Tests, installation and documentation: what proves compliance

The evidence is built in two stages. The first is the manufacturer’s documentation, with the curve of the pump supplied.

In the field, the acceptance test measures the installed pump: in the sample procedure in the NFPA 20 annex, the important points are shutoff, rated flow and 150% of rated flow, and at each point speed, suction and discharge pressures and flow are recorded, together with current and voltage for an electric motor or, for a diesel engine, engine data such as oil pressure and temperature.

In the documentation, separate what comes from the manufacturer from what comes from the installation. From the manufacturer, ask for the data sheet, curve, dimensional drawing and manuals; the installation provides the approved design and commissioning.

In São Paulo, the IT 23 model inspection report shows what is checked on the sprinkler pump set: pump installation and anchoring, the curve prepared by the manufacturer before installation and a curve produced within the last 36 months, a fire-protected room with no accumulation of combustible materials, no leaks, flow and pressure according to the approved design, isolation valves locked open, a flow meter and test header for the annual test, and pump supervision by the fire alarm panel.

For hydrant networks, the IT 22 model commissioning report has similar checks and is signed by the professional in charge, with their professional registration.

5. NBR 16704 × NFPA 20: how the two coexist in Brazilian projects

The question “do I follow NBR 16704 or NFPA 20?” is settled by the document that permitting and the contract cite. The two deal with closely related subjects — NFPA 20 is the standard for the installation of stationary pumps for fire protection — but they are different documents from different bodies, and this guide does not claim they are equivalent.

State rules show how the choice appears: in São Paulo, IT 23 requires NBR 16704 for the sprinkler pump set, and the hydrant instruction IT 22 cites neither; in Goiás, NT 23 requires NBR 16704 for sprinklers, and the hydrant standard NT 22 lists NFPA 20 among its references.

When the specification or the contract cites both, treat them as separate requirements: identify the edition of each, check the requirements of each and record with the designer and the authority how each discrepancy was resolved, before purchase. The NFPA 20 curve described in this guide does not replace whatever NBR 16704 requires, or vice versa.

FB Bombas works with both references: the set is designed in accordance with NBR 16704 or NFPA 20, as the project specifies, and the proposal states which documents demonstrate compliance.

6. Mistakes to avoid — and the correct specification path

Several specification mistakes go against written requirements and can be avoided before purchase. Selecting the pump by its rated point alone, without checking pressure at 150% of flow and shutoff, goes against the NFPA 20 envelope and shows up in the field test. Designing the sprinkler pump with suction lift or a priming tank goes against São Paulo's IT 23 and Goiás' NT 23.

Automating the stop of the main pump goes against Annex C of IT 22 and of NT 22, which only allow it to be stopped manually. Setting the pressure switches without staggering the starts ignores the recommendation of the same annexes: about 10 m of water (100 kPa) between the sequential starts of the pumps. And delivering the set without the manufacturer's curve leaves a question in the IT 23 inspection report unanswered.

The specification path follows the order of the standards. Demand comes from the system design: sprinklers under the state IT or NT and NBR 10897; hydrants under the IT or NT and NBR 13714. Selection checks the curve envelope and the suction condition; the drive, electric, diesel or both, and the backup power source follow the state rule; and the package of documents goes into the order.

For FB Bombas to assess the set, send the hydraulic calculations with required flow and pressure, suction data (reservoir type, minimum level and elevation difference), the state where the site is located, the adopted standards and editions, the available power supply and the list of required documents. Application engineering replies with the proposed configuration, electric, diesel or electric + diesel, with jockey pump, panels and base, and with the documents defined in the proposal.