Technical·7 min read
Fire Pump: How It Differs from an Ordinary Pump, NFPA 20 Criteria and Redundancy
A fire pump is a special machine designed to run at the worst possible moment. The NFPA 20 performance curve, the 100% standby requirement of Turkish Fire Code (BYKHY) Article 93, when to prefer an electric versus a diesel pump, and the role of the jockey pump — we explain the lifeline of wet suppression from an engineering perspective.
A-Pro Engineering
The entire wet suppression system — sprinklers, fire hose cabinets, hydrants — rests on a single assumption: when it is needed, there will be water in the pipes at sufficient flow and pressure. The machine that turns this assumption into reality is the fire pump. No matter how correctly a sprinkler head is selected, if the pump behind it does not run, the system is nothing but a pile of pipes.
You can find which wet system is mandatory for which building in our general guide; in this article we focus on the pump itself: what sets a fire pump apart from an ordinary pump, which criteria NFPA 20 imposes, why and how it is backed up, and whether to prefer an electric or a diesel pump.
What sets a fire pump apart from an ordinary pump?
A booster or circulation pump runs many times a day; if it fails, it is noticed and repaired. A fire pump, however, is designed with a different philosophy: it may never run, but at the one moment it must run — the building’s worst possible moment — it has to deliver full performance on the first attempt. This single sentence gives rise to all the engineering differences between them:
- A proven performance curve. A fire pump is not chosen at random; it is selected according to a certified curve whose pressure varies with flow within specific limits (see NFPA 20 below).
- It does not stop by itself. Once a fire pump starts, it does not stop automatically; only authorized personnel stop it manually. Because it is unacceptable for a pump to say “my job is done” and stop while a fire is still going.
- Independent and redundant power. Grid electricity is the first thing to be cut in a fire; that is why the pump’s power is secured with an independent line, a generator, or a diesel engine.
- Redundancy is mandatory. A single pump is never relied upon; a standby pump is essential against the possibility of failure (Turkish Fire Code (BYKHY) Article 93).
In short, in a fire pump the priority is not efficiency but reliability.
What the fire system expects from the pump: guaranteed flow and pressure
A wet suppression system is calculated so that a specific flow and pressure are provided even at the most distant and highest head. The pump is selected precisely to meet the operating point that this hydraulic calculation demands — neither less (suppression falls short) nor more (unnecessary cost and pressure problems).
This demand does not end with the pump alone; the water the pump draws must also exist for a sufficient duration. Turkish Fire Code (BYKHY) Article 92 determines the fire water tank volume according to the hazard class: water to feed the system for 30 minutes for low hazard, 60 minutes for ordinary hazard, and 90 minutes for high hazard. The pump and the tank are a whole: the pump provides the pressure, the tank the duration.
NFPA 20 criteria: the pump performance curve
Fire pumps are designed internationally according to the NFPA 20 standard (and TS EN 12845 in Europe). The heart of this standard is the limits it places on the pump’s flow-pressure curve. The same criteria also appear verbatim in Turkish Fire Code (BYKHY) Article 93:
- The churn (shut-off, zero-flow) pressure must be at most 140% of the pump’s rated (nominal) pressure. In other words, when no water is flowing, the pump must not produce excessively high pressure and strain the system.
- The pressure at 150% flow must not be less than 65% of the rated pressure. In other words, even when demand rises far above expectations, the pump must still deliver a meaningful pressure.
These two limits keep the pump’s curve in a band that is “neither too steep nor too flat”; whatever operating point the system reaches, predictable and sufficient performance is obtained. In addition, NFPA 20 requires the pump to start automatically on a pressure drop, to be stopped manually, and to be tested automatically at regular intervals (typically weekly) — because an untested backup is not a backup.
The 100% standby requirement: why and how (Turkish Fire Code (BYKHY) Article 93)
A fire pump cannot be reduced to a single point of failure. That is why Turkish Fire Code (BYKHY) Article 93 explicitly makes redundancy mandatory:
- If a single pump is used in the system, a standby pump of the same capacity must be present — that is, 100% standby.
- If more than one pump is used, enough standby pumps are installed so that at least 50% of the total capacity is backed up.
The reasoning is simple: a fire does not choose the day you are servicing the pump or the day it fails. Even if the main pump is out of service for any reason, suppression water must continue without interruption. The standby pump is the insurance for this continuity. It is precisely at this point that the type of standby pump becomes a critical engineering decision.
Electric or diesel? The right choice
Fire pumps come in two main types according to their power source, and the choice rests on the reliability of the facility’s electrical supply:
- Electric pump — Runs on grid electricity; it is quiet, compact, and relatively easy to maintain. But its weak point is obvious: electricity is often cut in a fire. An electric pump can be sufficient on its own only if its supply is secured with an independent line or a reliable generator.
- Diesel pump — Runs with its own engine, completely independent of the grid. Water supply continues even when electricity is cut. In return, it requires a fuel tank, batteries, exhaust, and regular engine maintenance.
The most common and safest solution in the field is to combine the two: an electric main pump plus a diesel standby pump. Under normal conditions the electric pump feeds the system; if electricity is cut or the main pump fails, the diesel pump starts automatically. This way both the standby requirement of Article 93 is met and redundancy does not depend on a single power source. In facilities where electricity is reliable and solidly backed up by a generator, solutions with two electric pumps may also be preferred.
The jockey pump and the station as a whole
A fire pump station is the harmony of three components:
- Main pump — The actual pump that provides the exact flow and pressure the system demands.
- Standby pump — The (usually diesel) pump that takes over the same duty when the main pump is out of service.
- Jockey (pressure-maintenance) pump — The small pump that compensates for the small, normal pressure losses in the pipes. Its job is to protect the main pumps: instead of running the huge main pump for a tiny leak or pressure fluctuation, the jockey pump keeps the pressure constant. The main pumps start only when a real demand — a sprinkler head opening, a fire hose cabinet being used — drops the pressure significantly.
When you add the pump room, water tank, fuel tank, panels, and the test/pressure-relief line to this trio, the whole that gives the system its “ready at all times” quality emerges. At A-Pro, we design this station on the basis of TS EN 12845 and NFPA 20.
Summary
The fire pump is the invisible but decisive lifeline of wet suppression. What sets it apart from an ordinary pump is the obligation to run on the first attempt at the worst possible moment; that is why it is selected with the NFPA 20 performance curve, does not stop by itself, is fed with independent power, and is backed up under Turkish Fire Code (BYKHY) Article 93 (100% standby for a single pump, at least 50% for multiple pumps). The combination of an electric main plus a diesel standby is the safest solution against the risk of a power outage. You can review the system’s components on our fire pumps page, and reach out to us with a free site survey within Ankara for a pump selection and hydraulic calculation specific to your facility.
This content is for informational purposes only. A binding, facility-specific assessment requires project-based work with a fire engineer.
© 2026 A-Pro Mühendislik. This is original technical content produced by A-Pro Engineering; all rights reserved. Copying, reproducing or republishing it in whole or in part without attribution and permission is prohibited.
Frequently asked questions
Why is a fire pump different from an ordinary pump?+
An ordinary pump provides daily comfort; a fire pump, on the other hand, may run perhaps once a year, and it must run at full performance on the first attempt — at the building's worst possible moment. That is why fire pumps are certified to a specific flow-pressure curve, do not stop by themselves (they can only be stopped manually), and are installed with an independent power supply and a backup. Reliability comes before efficiency.
What does the NFPA 20 pump performance curve mean?+
NFPA 20 limits how the fire pump's pressure varies with flow: the churn (shut-off, zero-flow) head must be at most 140% of the rated value, and the head at 150% flow must not be less than 65% of the rated value. This curve guarantees that the pump safely meets the system's needs at both low and high flow. The same criteria also appear in Turkish Fire Code (BYKHY) Article 93.
What is the 100% standby requirement for a fire pump?+
According to Turkish Fire Code (BYKHY) Article 93, if a single pump is used in the system, a standby pump of the same capacity is mandatory (that is, 100% standby). If more than one pump is used, enough standby pumps are provided so that at least 50% of the total capacity is backed up. The goal is that suppression water is never cut off even if one pump fails.
Should an electric or a diesel fire pump be preferred?+
The decision depends on the reliability of the electrical supply. If the grid is reliable and backed up by an independent supply/generator, an electric pump may be sufficient. However, because the likelihood of a power outage during a fire is high, the common and safe solution is an electric main pump plus a diesel standby pump; the diesel pump runs independently of the grid and keeps the water flowing even when power is lost.
What does the jockey pump do?+
The jockey (pressure-maintenance) pump keeps the system pressure constant by compensating for small, normal pressure losses; this prevents the main pumps from starting and stopping unnecessarily. The main pumps run only when a real demand (a sprinkler opening, a hose reel being used) drops the pressure significantly.
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