How to Calculate the Number of Fire Extinguishers: A Step-by-Step Guide Under Turkish Regulation

You are walking through a new site for the first time, or a client calls just before an inspection: "How many extinguishers do we actually need?" It sounds like a simple question, but the answer is never a single number. Working out how many fire extinguishers a building needs means looking at several things together: the floor area, the hazard class of that area, how floors and sections are laid out, and how far people have to walk to reach a unit.

What happens on site all too often is that the number is set by eye. Two units go on every floor, the corners get covered, and the job is considered done. An inspector, however, does not ask whether there are extinguishers; they ask whether the number and distribution comply with the regulation. A site that has enough units by floor area can still fall short on travel distance, and the right number of units can be useless if the wrong type was chosen.

This article covers the legal basis for the calculation under Turkish regulation, how to determine the hazard class, a step-by-step calculation method, the travel distance check, choosing the right type, and the most common mistakes. The goal is a number for every site that is defensible, written down and easy to re-check.

How to calculate the number of fire extinguishers: the legal basis

In Turkey, the calculation rests on Article 99 of the Regulation on the Fire Protection of Buildings (Binaların Yangından Korunması Hakkında Yönetmelik), which governs portable extinguishers. Its first paragraph sets the general principle: the type and number of portable extinguishers are determined according to the conditions and risks present in each space. In other words, the regulation does not leave the number to a formula alone; it requires the risk to be assessed.

The concrete ratio is in the second paragraph. In the low hazard class, one extinguisher is required for every 500 m² of building construction area; in the medium and high hazard classes, one for every 250 m². The unit is a suitable 6 kg dry chemical powder extinguisher or an equivalent gas extinguisher. This is the base ratio you will use. Two phrases deserve attention: "building construction area" and "6 kg or equivalent". The first tells you the calculation is done by area; the second tells you the ratio is built around a 6 kg unit.

The third paragraph adds a further obligation: car parks, storage areas, plant rooms and similar spaces must also have a wheeled extinguisher. The word "also" matters. A wheeled unit does not replace the portable units that come out of the area calculation; it is added to them. The fourth paragraph governs placement and states that the travel distance to an extinguisher must not exceed 25 metres. The calculation is not complete until all four paragraphs are read together.

Determining the hazard class correctly

Whether the ratio is 500 m² or 250 m² depends on the hazard class. That is why the calculation should start with classification, not with square metres. Article 19 of the regulation states that the hazard class depends on the characteristics of the building and the nature of the processes and activities carried out in it, and it defines three classes: low, medium and high hazard locations.

The definitions are as follows. Low hazard locations contain materials with low fire load and low combustibility, have at least 30 minutes of fire resistance, and have no single compartment larger than 126 m². Medium hazard locations contain combustible materials with a moderate fire load and combustibility. High hazard locations contain materials with a high fire load and combustibility that allow a fire to spread and grow quickly. Examples of each use are listed in Annexes 1/A, 1/B and 1/C of the regulation.

The point most often missed on site is that the low hazard class is narrower than people assume. In the Annex 1 lists, hospitals, hotels, residences, restaurants, schools and offices sit in the first group of the medium hazard class; only certain areas of schools and offices appear on the low hazard list. Car parks and laundries are also medium hazard. So the assumption "we are just an office, that is low hazard" and the 500 m² ratio that follows from it will, in most cases, leave the site short of units. For any use you are unsure about, check the Annex 1 lists; if you still cannot settle the class, use the stricter 250 m² ratio and record that choice with its reasoning.

Step-by-step calculation method

Building the calculation section by section, rather than once for the whole building, gives a more accurate result and makes it easier to defend during an inspection. The recommended order is:

• First, list the building's floors and sections, and take the construction area of each section from the project drawings or permit documents.
• Next, write down the use of each section and determine its hazard class from the Annex 1 lists.
• Then divide each section's area by the ratio for its class: 500 for low hazard, 250 for medium and high hazard.
• Round any fractional result up.
• Add the wheeled unit as a separate line for areas such as car parks, storage areas and plant rooms.
• Finally, check the 25 metre travel distance on each floor plan and increase the number if needed.

The reason for rounding up is simple: the regulation says "one unit for every 250 m²". On a 1,200 m² office floor in the medium hazard class, the division gives 4.8. The area left over after the fourth unit still has to be covered by a unit, so the answer is 5. Rounding down leaves that remaining area unprotected and cannot be defended at an inspection.

The same logic applies to sections. If a building has a 600 m² production area and a 300 m² office section, it is safer to calculate each separately than to add them up and divide once. The units end up where they are actually needed, and you can choose a different type for each section. A record kept this way also shows which line has to be updated when there is a renovation or a change of use later on.

How the 25 metre travel distance changes the number

The area calculation gives you a minimum; the travel distance tests whether that minimum is enough. The fourth paragraph of Article 99 states plainly that the travel distance to an extinguisher must not exceed 25 metres. This means that a person standing anywhere on the site must be able to reach the nearest unit within 25 metres of walking.

In long, narrow buildings, this rule often matters more than the area calculation. Think of sections lined up along a long corridor, a large warehouse, or a fragmented production floor. Even if the area calculation gives two units, placing them at the two ends of the corridor may leave one of the middle sections more than 25 metres away. In that case, the only option is to increase the number.

The most reliable way to check is on the floor plan. Mark the position of each unit, then measure the actual walking route from the furthest corners of the plan to the nearest unit. Use the path someone would really walk, around walls, shelving and doors, not a straight line. For every point beyond the limit, either move existing units or add a new one. Noting on the plan why an additional unit was placed keeps the answer to "why is this extinguisher here" ready for later.

The right type matters as much as the right number

The right number of units can still be ineffective if the wrong type is chosen. The first paragraph of Article 99 links the type to the fire class. Where a Class A fire is likely, multi-purpose dry chemical powder or water extinguishers come first; for Class B, dry chemical powder, carbon dioxide or foam; for Class C, dry chemical powder or carbon dioxide; and for Class D, dry metal powder extinguishers.

The same paragraph also states that water or clean gas extinguishers should be preferred in hospitals, care homes, nurseries and similar places. In practice, this means that even if the area calculation in these facilities is based on a 6 kg dry chemical powder unit, the type placed on site should be chosen with the occupants in mind. The effect of a powder cloud on patients, elderly people or small children, and the clean-up burden afterwards, are the reasoning behind this preference.

Choosing the type section by section also makes the calculation table clearer. A multi-purpose dry chemical powder unit for the office section, a carbon dioxide unit for a room with servers or electrical panels, a unit suited to the risk in the kitchen: each choice should be written on its own line. When deciding whether different types are equivalent, rely on the manufacturer's documents and the information on the unit's label; do not accept equivalence by eye.

Areas that require a wheeled extinguisher

Car parks, storage areas, plant rooms and similar spaces should be treated as a separate heading in the calculation. The regulation makes a wheeled extinguisher mandatory in these areas in addition to everything else. It does not reduce the number of portable units; the portable units from the area calculation stay in place and the wheeled unit is added to them.

Two mistakes come up often on site. The first is counting the wheeled unit in place of portable units: the attitude of "there is a big unit in the car park, so we do not need small ones" contradicts the word "also" in the regulation. The second is forgetting plant rooms. Boiler rooms, generator rooms and pump rooms often do not appear as separate lines in the calculation table, and the wheeled unit requirement is missed.

When choosing where to put a wheeled unit, think about the access route too. These units are heavy; if they are placed behind a threshold, a step or a narrow passage, they may be impossible to move during an emergency. Placing the unit near the entrance of the area, on level ground with the space around it kept clear, makes sure the number works on site and not only on paper.

Common calculation mistakes

Most calculation errors come from reading one paragraph of the regulation in isolation from the others. Before an inspection, review the table against these points:

• Setting the hazard class by assumption. Treating offices, schools or hotels as low hazard and using the 500 m² ratio often does not match the Annex 1 lists.
• Rounding fractions down. The area left over still has to be covered by a unit.
• Dividing the whole building area at once. When sections of different classes are calculated with a single ratio, some sections end up short.
• Skipping the travel distance check. A number that is sufficient by area can turn out to be insufficient against the 25 metre rule.
• Counting a wheeled unit in place of a portable unit.
• Not updating the calculation after a change of use. When a storage area becomes production space or an office becomes an archive, the class, and therefore the number, can change.

What these mistakes have in common is that the calculation was never written down. When the answers to which section, what area, which class, which ratio and how many units are not kept in one table, the calculation is redone from scratch at every inspection or renovation, and it produces a different result each time. Adding the name of the person who prepared the table and the date also shows when and on whose assessment the calculation was made.

After the calculation: inventory and periodic inspection

Finding the right number is not the end of the job; that number has to be maintained on site. Units go out for servicing, get moved, are taken away for refilling and sometimes are not put back. If the table shows five units on a floor and there are four on site, the facility is non-compliant even if the calculation itself is correct.

That is why the calculation table should be matched against an inventory. For each unit, the location, type, capacity, last refill and service date, and the next periodic inspection date should be recorded. During a periodic inspection, the technician should confirm not only the condition of the unit but also that it is in the location shown in the table. The same check reveals whether a spare was put in place of a unit taken for refilling.

Fire drills are a natural part of this check as well. Watching how long it takes staff to reach the nearest unit during a drill shows whether the 25 metre rule holds in reality and not only on paper. Points that turn out to be hard to reach are concrete findings to address in the next update of the calculation.

Conclusion

Calculating the number of fire extinguishers correctly means applying Article 99 of the regulation as a whole: the ratio for the hazard class, a section-by-section calculation, rounding up, the 25 metre travel distance check, choosing a type suited to the fire class, and wheeled units where required. Once these steps are gathered in a written table, the number can be defended on the same grounds at every inspection.

The calculation is done once, but keeping it true is ongoing. At Yangın Takip, we provide a system where fire safety companies keep their clients, sites and equipment inventory, along with periodic inspection and refill dates, in one place, so you can track whether every unit in the calculation table is actually in place and up to date on site.

Related reading

• Yangın Söndürücü Nasıl Kullanılır? 4 Adımda Doğru Müdahale — https://yangintakip.com/en/blog/yangin-sondurucu-nasil-kullanilir-adimlari
• Yangın söndürücü dolum süresi ne zaman gelir? (TS ISO 11602-2) — https://yangintakip.com/en/blog/yangin-sondurucu-dolum-suresi-ts-iso-11602-2-rehberi
• Periodic Maintenance Software — https://yangintakip.com/en/cozumler/periyodik-bakim-yazilimi