Article 113 of the Turkish Fire Protection Regulation (BYKHY) sorts liquids into six classes by flash point: the flammable liquids, Classes IA, IB and IC, and the combustible liquids, Classes II, IIIA and IIIB. Almost every later rule in the liquids chapter keys off this class: notification and permits (Article 114), the quantities allowed inside buildings (Article 115), the basement ban and warehouse limits (Article 118) and tank bunding (Article 119).
Which text is this based on? This article follows the consolidated text of the Turkish Fire Protection Regulation (BYKHY) as amended up to 09.07.2015 (Official Gazette no. 29411), read together with the BYKHY Guide issued by the Ministry of Environment, Urbanisation and Climate Change in December 2024. The regulation has been amended since 2015, and the Guide itself states that the legislation in force prevails where the two differ. On a real project, check the latest text published in the Official Gazette and confirm with the local authority or fire brigade.
Two families: flammable and combustible
The Turkish text uses two different words on purpose. A flammable liquid (parlayıcı sıvı, Class I) has a flash point below 37.8 °C and a vapour pressure at 37.8 °C not exceeding 276 kPa. A combustible liquid (yanıcı sıvı) has a flash point of 37.8 °C or higher; Classes II, IIIA and IIIB sit here (Article 113(1)(a) and (b)). The distinction matters: the stack rule in Article 118(2), for example, is written for flammable liquids.
The 276 kPa limit separates liquids from liquefied gases. A substance whose vapour pressure at 37.8 °C is above it is not a liquid class under this chapter; the regulation's gas provisions apply instead.
The Article 113 class table
| Class | Family | Flash point | Boiling point | Clause |
|---|---|---|---|---|
| IA | Flammable | Below 22.8 °C | Below 37.8 °C | 113(1)(b)(1) |
| IB | Flammable | Below 22.8 °C | 37.8 °C or higher | 113(1)(b)(2) |
| IC | Flammable | Above 22.8 °C, below 37.8 °C | No criterion | 113(1)(b)(3) |
| II | Combustible | 37.8 °C or higher, below 60 °C | No criterion | 113(1)(a)(1) |
| IIIA | Combustible | 60 °C or higher, below 93 °C | No criterion | 113(1)(a)(2) |
| IIIB | Combustible | 93 °C or higher | No criterion | 113(1)(a)(3) |
Boiling point is used only to split the two most hazardous sub-classes, IA and IB. A liquid that boils at a very low temperature evaporates quickly at room temperature and forms a large ignitable cloud, which is why IA is the most onerous class. The boundaries are rounded Fahrenheit values: 37.8 °C is 100 °F and 60 °C is 140 °F, while 22.8 °C and 93 °C are roughly 73 °F and 200 °F.
The text leaves one small gap. Class IC is "above 22.8 °C" while IA and IB are "below 22.8 °C", so a flash point of exactly 22.8 °C is not covered. Where a product sits on a boundary, the safe reading is the more hazardous class.
The heated-liquid rule
Article 113(2) is short but important: Class II and IIIA liquids heated above their flash point are treated as Class I. A heated fuel tank, a preheated process line or a hot oil bath is judged by its operating temperature, not by the class printed on the data sheet. That flows straight into the basement ban and the warehouse quantities.
What changes with the class?
| Rule | Effect of the class | Clause |
|---|---|---|
| Notification and permit | IIIA and IIIB are outside the Annex 11 notification duty; separate thresholds apply to IA and to IB, IC and II | 114(1), Annex 11 |
| Filling in enclosed rooms | Where Class I and II liquids are filled indoors at more than 200 litres per hour and more than 1000 litres are present, a fire brigade permit is needed | 114(2) |
| Mixed storage equivalence | With Class I present, 5 litres of Class II or IIIA count as 1 litre of Class I | 114(3) |
| Small quantities | Storage rooms and retail premises: 100 litres for IA, higher limits for other classes | 115(2), 115(3) |
| Basements | No basement in a building storing Class I; no Class II in basements; at most 40,000 litres of IIIA and IIIB in a basement | 118(1) |
| Warehouse stacks | Per-stack limits by class; IA equivalence for mixed storage | 118(2), Annex 12/A |
The opening words of Article 114(3) also mention Class IIIB, but the ratio is given only for Classes II and IIIA. No factor for IIIB appears in that clause; the IA-equivalence divisors of Article 118(2) (dividing IIIB by 80) belong to a different context. Agree a project-specific approach with the fire brigade. Quantities are covered in detail in the Annex 11 and Article 115 article, warehouse tables in the Annex 12/A and 12/B article.
Table 113 in the Guide and example liquids
The December 2024 Guide turns Article 113 into a table and adds the Article 115 quantities and some example liquids (Guide p. 189). Its examples are acetone, petrol and ethyl alcohol for IB; diesel and kerosene for Class II; and biodiesel, antifreeze and lubricating oils for IIIB.
One row differs from the regulation. For Class IC the Guide gives a flash point "above 22.8 °C" and a boiling point "below 37.8 °C", whereas the regulation defines IC by a flash point between 22.8 and 37.8 °C, with no boiling-point test. The Guide's imprint says the legislation in force prevails in case of conflict, so classify against the regulation text. Rather than relying on an example list, use the product's own flash point data: products sold under the same name can differ in composition.
Where the chapter does not apply (Article 123)
- Storage and filling not carried out for a commercial or industrial activity, such as heating-plant boiler rooms and their fuel stores (123(1)(a)). Boiler rooms have their own rules: boiler room article.
- Vehicle tanks, mobile installations, fixed installations of up to 300 litres, and fuel containers that form an integral part of them (123(1)(b)).
- Liquids processed in production, or held briefly as a product or intermediate (123(1)(c)).
The last item is open to interpretation because "briefly" is not quantified. Settling the line between process buffer stock and permanent storage with the authority at design stage avoids a permit dispute later.
Common mistakes
- Treating diesel and petrol alike. Per the Guide's examples petrol is IB and diesel is Class II; notification thresholds, the basement ban and warehouse limits differ.
- Calling heated heavy fuel Class III. Class II and IIIA held above their flash point are Class I (113(2)).
- Mixing up the two Turkish words. In the regulation, parlayıcı means Class I.
- Guessing the class from the product name. The test is flash point, and blends vary.
For where the regulation expects foam, see the Articles 98 and 122 article.
Frequently Asked Questions
What is the difference between a flammable and a combustible liquid in BYKHY?
Under Article 113 a flammable liquid (Class I) has a flash point below 37.8 °C and a vapour pressure at 37.8 °C not exceeding 276 kPa. A combustible liquid has a flash point of 37.8 °C or higher and falls into Class II, IIIA or IIIB.
Which class are petrol and diesel?
The examples in Table 113 of the December 2024 Guide place petrol in Class IB and diesel in Class II (Guide p. 189). The actual class follows from the product's flash point.
How is a heated oil classified?
Article 113(2) treats Class II and IIIA liquids heated above their flash point as Class I, so the Class I basement ban and quantity limits apply.
Does a heating boiler's fuel tank fall under this chapter?
Article 123(1)(a) excludes storage and filling not done for a commercial or industrial activity, such as heating-plant boiler rooms and fuel stores. Boiler-room rules still apply separately.
Which prevails if the Guide's Table 113 and the regulation differ?
The Guide is guidance and states that the legislation in force prevails. For Class IC the Guide's table gives a boiling point, while the regulation defines IC by a flash point between 22.8 and 37.8 °C.
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Download MEP Calc on the App StoreRegulation on Fire Protection of Buildings (BYKHY), Official Gazette 19.12.2007/26735; consolidated text including the amendments of 09.09.2009/27344, 05.04.2012/28255 and 09.07.2015/29411: Articles 113, 114, 115 (pp. 42–43), 118 (pp. 43–44), 123 (p. 47). BYKHY Guide (Binaların Yangından Korunması Hakkında Yönetmelik Kılavuzu), Ministry of Environment, Urbanisation and Climate Change, December 2024: Article 113 and Table 113 (p. 189), Articles 114–115 (p. 190), Article 123 (p. 205). Page numbers refer to the 72-page consolidated text and to the Guide's own page numbering. The binding text is the regulation in force as published in the Official Gazette.