How is hose cabinet and hydrant flow calculated?
In Turkey the governing text for hose cabinets and hydrants is the Regulation on Fire Protection of Buildings (BYKHY). It sets flow and pressure by device type, ties duration to the building hazard class and describes tank pre-sizing through the Annex 8 tables. The calculation has three steps: add up the flow of the devices operating together, multiply by the duration to get the water volume, and carry the pressure needed at the critical outlet back to the source.
V = Qtotal × t · Psource ≈ Poutlet + ρ·g·h + frictionNumeric values in the Turkish regulation
| Item | Value | Article |
|---|---|---|
| Semi-rigid hose reel (EN 671-1), no fire-brigade outlet | 100 L/min at 400 kPa; hose 25 mm, ≤ 30 m | 94/1-b-4, 94/1-b-5 |
| Lay-flat hose cabinet (EN 671-2) | 400 L/min, at least 400 kPa; hose ≤ 50 mm, ≤ 20 m | 94/1-b-6 |
| Nozzle inlet pressure limit | pressure reducer above 900 kPa | 94/1-b-5, 94/1-b-6 |
| Hydrant system design flow | at least 1900 L/min, 700 kPa at the outlet | 95/2 |
| Duration by hazard class | low 30 · ordinary 60 · high 90 min | 92/3 |
| Perimeter hydrants only | at least 1900 L/min × 90 min; 5700 L/min × 60 min on Art. 7/12 sites | 92/7 |
Sprinklers + cabinets + hydrants: Annex 8/C
Where the building is also sprinklered, tank pre-sizing follows Art. 92/5: add the Annex 8/C cabinet and hydrant flows to the sprinkler flow (density × area from Annex 8/B) and multiply by the duration.
| Building hazard class | Cabinet allowance | Hydrant allowance | Duration |
|---|---|---|---|
| Low | 100 L/min | 400 L/min | 30 min |
| Ordinary 1, 2 | 100 L/min | 400 L/min | 60 min |
| Ordinary 3, 4 | 100 L/min | 1000 L/min | 60 min |
| High | 200 L/min | 1500 L/min | 90 min |
Art. 92/4 allows the tank to be pre-sized either this way or from the Annex 8/A table; where a hydraulic calculation exists it governs. The regulation treats the two as equivalent, so the calculator shows both pre-sizing results side by side in separate tiles and highlights the larger; the choice is the designer’s, and the cautious one is the larger. For a low-hazard dry or alternate system Annex 8/B says “use Ordinary-1”, so both the Art. 92/5 calculation (5.0 mm/min × 90 m²) and the Annex 8/A comparison (“Ordinary-1 – dry or alternate” row: 105/125/140 m³) use that class. The note under Annex 8/B says storage areas and occupancies with different characteristics follow EN 12845: do not use the table densities for storage, enter the sprinkler flow from an EN 12845 hydraulic calculation instead. Annex 8/B gives 7.7 mm/min for High-1 (EN 12845 says 7.5); the tool uses the regulation’s figure.
Where the regulation gives no number
The regulation does not say how many cabinets run at once; Art. 92/6 simply multiplies the cabinet design flow by the duration. It says hydrant flow is “increased with the hazard class” without an increment. Both are user inputs here. The default of 1 cabinet is the literal reading of Art. 92/6, not a written minimum; 1900 L/min is the explicit minimum of Art. 95/2. Art. 92/7 states the 90-minute duration only for the 1900 L/min base value, so for a higher hydraulic flow the tool keeps 90 minutes as a conservative assumption. Agree these assumptions with the authority. Pipe friction is also entered from your hydraulic calculation.
Art. 7/12 sites, cabinets + hydrants without sprinklers, and dry systems
The second sentence of Art. 92/7 requires a tank supplying at least 5700 L/min for 60 minutes (342 m³) for the external hydrant system on Art. 7/12 sites. It is not tied to the “hydrants only” case, so it also applies where sprinklers, cabinets and hydrants are installed together. Interpretation: the regulation does not say how this volume combines with the Art. 92/5 total. By default the tool adds the 342 m³ as a separate tank volume; the other reading, “hydrant item = max(Annex 8/C; 5700 L/min), at least 60 min, one tank”, is available as an option.
There is no explicit pre-sizing rule for a building with cabinets and hydrants but no sprinklers: Art. 92/6 covers “cabinets only”, Art. 92/7 “perimeter hydrants only”, and the Annex 8/C flows are defined in Art. 92/5 as additions to the sprinkler flow. Interpretation: the tool conservatively adds both volumes (cabinet flow × Art. 92/3 duration + hydrant flow × 90 min); Annex 8/C allowances × the Art. 92/3 duration can be selected instead.
For dry or alternate systems Annex 8/B moves Low hazard to the Ordinary-1 criterion and Ordinary-4 to High-1. Interpretation: the table changes only density and area, while Art. 92/3 ties duration to the building hazard class; the tool therefore takes duration and the Annex 8/C allowances from the selected class, with an option to use the higher class. All three readings should be agreed with the authority.
Where are cabinets and hydrants required?
In new buildings hose cabinets are required in high-rise buildings, in factories, workshops, warehouses, accommodation, healthcare, assembly and education buildings above 1000 m² of enclosed area, in enclosed car parks above 600 m² and in boiler rooms above 350 kW (Art. 94/1-b-1). For existing buildings the thresholds are 2000 m², 1000 m² and 500 kW (Art. 164/2). External hydrants are required where the combined footprint in a separately planned settlement exceeds 5000 m², and on Art. 7/12 sites (Art. 95/7).
NFPA 14 option
The Turkish regulation does not refer to NFPA 14. The NFPA 14 option is offered only as an alternative basis for projects where NFPA is additionally required by contract or insurer; in Turkey it does not replace BYKHY, and Art. 92–95 must still be met. For Class I and III systems NFPA 14 requires 250 gpm (950 L/min) at each of the two most remote 2½ in outlets on the most remote standpipe and 250 gpm for each additional standpipe (10.6.1.1). Where a horizontal standpipe serves three or more outlets on a floor, the first standpipe is 750 gpm. The total is capped at 1000 gpm in fully sprinklered buildings and 1250 gpm otherwise. Class II needs 100 gpm. Minimum residual pressure is 100 psi (6.9 bar) at the most remote 2½ in outlet and 65 psi (4.5 bar) at a 1½ in outlet (10.2.6.1), and the supply must last at least 30 minutes (5.2).
Worked example
- Ordinary Hazard 1, wet sprinklers, cabinets and hydrants: 5.0 mm/min × 72 m² = 360 L/min.
- Annex 8/C allowances: cabinets 100 L/min, hydrants 400 L/min → 860 L/min in total.
- 60 minutes → 860 × 60 / 1000 = 51.6 m³. The Annex 8/A table (h ≤ 15 m) gives 55 m³.
- Pressure: with the top cabinet 20 m up, 4.0 + 0.098 × 20 ≈ 6.0 bar; the grade-level hydrant needs 7.0 bar, so the hydrant governs (before friction).
Common mistakes
- Treating the Annex 8/C figure as the hydrant design flow: it is a tank pre-sizing allowance only; the hydrant system itself is designed for at least 1900 L/min at 700 kPa.
- Stopping at the outlet pressure: add elevation and friction to get the source pressure, and fit pressure reducers where lower floors exceed 900 kPa.
- Using lay-flat hose cabinets everywhere: EN 671-2 cabinets are for buildings that must keep trained fire staff.
- Applying existing-building thresholds to new work: the higher area and boiler limits of Art. 164 apply only to existing buildings; new projects follow Art. 94.
- Adding NFPA 14 hose flow on top of sprinkler demand: in a fully sprinklered combined system the supply follows the greater of the two, not the sum.
Frequently Asked Questions
What flow does a hose reel cabinet need in Turkey?
Under BYKHY Art. 94 a semi-rigid hose reel cabinet without a fire-brigade outlet is designed for 100 L/min at 400 kPa. A lay-flat hose cabinet (EN 671-2) needs 400 L/min at not less than 400 kPa.
What flow and pressure does a hydrant need?
Art. 95/2 requires a hydrant system design flow of at least 1900 L/min, increased with hazard class, and 700 kPa at the hydrant outlet. A building with perimeter hydrants only needs water for 1900 L/min over 90 minutes. On Art. 7/12 sites, sprinklered ones included, the external hydrants need a tank for at least 5700 L/min × 60 min (342 m³) (Art. 92/7).
How is the tank sized for sprinklers, cabinets and hydrants?
Under Art. 92/5, add the Annex 8/C cabinet and hydrant flows to the Annex 8/B sprinkler flow and multiply by the hazard-class duration (30, 60 or 90 min). For Ordinary Hazard 1: 360 + 100 + 400 = 860 L/min × 60 min = 51.6 m³.
How many hose cabinets operate at once?
The regulation gives no number; Art. 92/6 multiplies the cabinet design flow by the duration. In the calculator the number of simultaneous cabinets is a designer input; the default of 1 is the literal reading of Art. 92/6, not a written minimum, and should be agreed with the authority.
How is standpipe flow found under NFPA 14?
The Turkish regulation does not refer to NFPA 14; this calculation is only for projects where NFPA is additionally required by contract or insurer. For Class I and III, 500 gpm for the most remote standpipe plus 250 gpm per additional standpipe, capped at 1000 gpm in fully sprinklered buildings and 1250 gpm otherwise. The supply must meet this demand for at least 30 minutes.
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