Purpose and function of the Jockey Pump

A jockey pump, or pressure maintenance pump, is the low-flow pump that keeps the fire protection network pressurized within preset limits while no water is flowing, replenishing allowable leakage and normal pressure drops. That is how NFPA 20 defines it, and the Brazilian standard NBR 13714 describes it as a centrifugal pump intended to keep the system pressurized within that range. It does not fight the fire: when a hydrant or sprinkler opens, pressure falls below the main pump start setting and the main fire pump starts.

By flow and by pressure. For flow, NFPA 20 requires capacity to replenish allowable leakage and normal pressure drops, never less than the normal leakage rate of the network. The annex explains that large underground mains are allowed some leakage and need a larger jockey; on aboveground-only sprinkler and standpipe piping, the jockey should deliver less flow than a single sprinkler, so that an open sprinkler makes the main pump start. One guideline in use is to make up the allowable leakage in 10 minutes, or 1 gpm (3.8 L/min), whichever is larger. In Brazil, São Paulo's IT 22 and NBR 13714 cap the jockey at 20 L/min. For pressure, the discharge must maintain the desired system pressure, and the Brazilian rules set the jockey's maximum operating pressure at the main pump shutoff. A fixed percentage of main-pump flow does not replace this calculation.

The main pump delivers the design fire-fighting flow and pressure; the jockey only keeps the network pressurized while there is no flow. NFPA 20 does not allow the primary or standby fire pump to be used as a jockey pump, except where the standard itself permits. Controls also differ: under the Brazilian rules (São Paulo's IT 22 and NBR 13714), the jockey starts and stops on its own through a pressure switch, while the main pump only starts automatically and, once running, stops only at its own controller in the pump room. Under NFPA 20, the jockey controller must be listed, though listing for fire pump service is not required.

NFPA 20 covers the jockey pump in the general chapter on fire pumps: definition, flow, pressure, relief valve, steel piping, sensing line and controller; the annex gives the setting sequence. NFPA 25 covers inspection, testing and maintenance. In Brazil, NBR 13714, for hydrant and hose systems, and IT 22 of the São Paulo Fire Department set a maximum flow of 20 L/min, a maximum pressure equal to the main pump shutoff and automation by pressure switches, and recommend about 100 kPa between starts. In other states, the local fire department rule applies, and the specification states the required edition.

It depends on the rule that applies to the installation. São Paulo's IT 22 requires a jockey on hydrant or hose systems with more than six outlets and waives it when the fire water tank is elevated; NBR 13714 requires it when the network must be kept pressurized within a preset range. For pressure-actuated fire pumps, NFPA 20 requires a means to maintain system pressure: a jockey pump, a positive displacement water mist pumping unit or another approved means that is not the main fire pump. Without it, allowable leakage would drop the pressure to the main pump start setting. Removing the jockey is a decision for the responsible designer, with the local rule in hand.

Yes, and it is the type the standards describe. NBR 13714 defines the pressure maintenance pump as a centrifugal pump, and the NFPA 20 annex considers a centrifugal type preferable. NFPA 20 also allows a turbine vane (peripheral) pump, but requires a relief valve on the discharge whenever the jockey is peripheral or when the centrifugal pump shutoff exceeds the working pressure rating of the components. Suction and discharge are steel pipe, with a check valve and isolation valve on the discharge, and the suction can come from the tank filling line, which allows the network to stay pressurized even with the tank empty for repairs. Model, material and motor come from the selection and the data sheet.

That the jockey cannot make up what the network is losing, or that pressure does not reach the stop setting. NFPA 20 sizes the jockey for allowable leakage and normal pressure drops; if it does not stop, the loss has exceeded that or the stop setting is above what the jockey reaches at zero flow. The symptom alone does not identify the cause: the maintenance team looks for the loss in the network, checks valves, pressure switches and the sensing line, and compares the settings with the design. The informative annex of NFPA 25 lists the jockey controller data that support this analysis: total starts and run time since the last reset, start and stop pressures and duration of the last run.

It depends on the duty point and the scope. To get a quote, state the make-up flow (with the 20 L/min cap of the Brazilian rules, where they apply), the intended stop pressure and the main pump shutoff, the minimum and maximum suction pressures, the available voltage and whether the jockey ships loose or on the skid with the main pump. The FB Bombas proposal identifies the pump, motor, controller and accessories included and the installation responsibilities; in the electric and diesel FBFS configurations, the jockey is part of the fire pump package.

It keeps the fire protection network pressurized without starting the main pump. The network loses some pressure through allowable leakage and normal pressure drops; the jockey starts when pressure falls to its start setting and stops when it reaches the stop setting. The network thus stays full and pressurized, and the main pump starts only when the drop is larger than the jockey can make up, as when a hydrant or sprinkler opens. The NFPA 20 annex recommends a jockey where a uniform or relatively high pressure is wanted on the fire protection system.

In the fire protection system, the jockey is the first of a sequence of pumps that start on pressure drop. It keeps the network between its stop setting, which the Brazilian rules cap at the main pump shutoff, and its start setting. If pressure keeps falling, the main pump starts at the next setting and the standby pump, where provided, at an even lower one; the Brazilian rules recommend about 100 kPa (10 m of water column, 1 bar) between these sequential starts. The jockey does not replace fire-fighting capacity: fire flow and pressure come from the main pump.

Under the Brazilian rules (São Paulo's IT 22 and NBR 13714), the jockey's maximum operating pressure equals the main pump pressure at zero flow (shutoff), and about 100 kPa (10 m of water column, 1 bar) is recommended between sequential pump starts. The NFPA 20 annex proposes: jockey stop equal to the main pump churn (shutoff) pressure plus the minimum static suction pressure; jockey start at least 10 psi (0.69 bar) below the stop; main pump start 5 psi (0.34 bar) below the jockey start, plus 10 psi (0.69 bar) for each additional pump. Final pressures must not exceed the pressure rating of the components, and settings are confirmed on test gauges. The worked example, in psi and bar, is on the jockey pump application page.

Through pressure switches. The jockey pressure switch starts it when network pressure falls to the start setting and stops it at the stop setting; the main pump switch only starts it, at a lower setting. Under the Brazilian rules, the pressure switches sit on the automation manifold, wired to the controllers and motor starters of each pump, and the main pump, once running, stops only manually at its own controller in the pump room; opening any hydrant is enough for automatic starting. NFPA 20 requires an individual pressure sensing line for each controller, including the jockey's, connected between the discharge check valve and the discharge isolation valve of each pump.