79 °C sprinkler: glass bulb colour Yellow, fusible link colour code white; maximum permitted ceiling temperature 66 °C under NFPA 13 and 49 °C under EN 12845.
Summary
| Property | Value |
|---|---|
| Nominal operating temperature | 79 °C |
| NFPA 13 temperature classification | Intermediate |
| Glass bulb colour | Yellow |
| Fusible link colour code | White |
| Maximum ceiling temperature — NFPA 13 Table 7.2.4.1(a) | 66 °C |
| Maximum ambient — EN 12845 clause 14.4 (rating − 30 °C) | 49 °C |
Colour codes are taken from NFPA 13 Tables 7.2.4.1(a) and (b) and EN 12845 Table 37b (which refers to EN 12259-1). NFPA 13 Table 7.2.4.1(b) assigns white to 79–107 °C; in EN 12845 Table 37b the white range is 80–107 °C.
Where it is used
Areas with a slightly elevated ambient; some production lines and plant rooms.
The selection rule
A sprinkler's temperature rating is chosen above the maximum ambient temperature at its location. The margin exists so the sprinkler does not operate at normal working temperatures. EN 12845 clause 14.4 requires the rating to be at least 30 °C above the highest anticipated ambient; NFPA 13 Table 7.2.4.1 gives a maximum ceiling temperature for each rating. When measuring the ambient, allow for:
- Ceiling-level temperatures in summer, which are markedly higher than at floor level.
- Solar effect beneath glazed roofs and in roof voids, which must be measured.
- Local heating above heating and process equipment.
- Local heat generated near light fittings.
A higher rating is not always "safer". Choosing an unnecessarily high temperature makes the sprinkler operate late. The correct approach is to choose the lowest rating suitable for the ambient.
Do not confuse the temperature rating with RTI
The colour code shows only the operating temperature. RTI, which describes how quickly a sprinkler responds, is a separate property that cannot be read from the colour code and must be verified from the product approval document. A 79 °C sprinkler can be manufactured as either quick response or standard response.
Field checks
- Does the spare sprinkler cabinet hold spares at this rating?
- Have sprinklers of different ratings been mixed by mistake?
- Is there any cracked bulb, paint or corrosion?
- Has the ambient changed after refurbishment (new equipment, ventilation closed off)?
- Has a process change raised the local temperature?
Frequently Asked Questions
What colour is the bulb of a 79 °C sprinkler?
Yellow. On a fusible link type the colour code is white (NFPA 13 Table 7.2.4.1; EN 12845 Table 37b).
Up to what ambient can a 79 °C sprinkler be used?
NFPA 13 Table 7.2.4.1(a) gives a maximum ceiling temperature of 66 °C. EN 12845 clause 14.4 requires the rating to be at least 30 °C above the highest anticipated ambient, so the EN limit is 49 °C. The measurement should be taken at ceiling level and in summer conditions.
Does the colour code show the RTI?
No. The colour shows only the operating temperature. RTI is a separate property verified from the product approval document.
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Download MEP Calc on the App StoreNFPA 13 (2025) Tables 7.2.4.1(a)–(b) · TS EN 12845+A2:2026 (EN 12845:2015+A2:2026) clause 14.4 and Table 37b · EN 12259-1. Colour codes and temperature ranges are for information; the manufacturer's approval document governs product-specific values.