68 °C sprinkler: glass bulb colour Red, fusible link colour code Renksiz / colour-free, maximum permitted ambient roughly 38 °C.
Summary
| Property | Value |
|---|---|
| Nominal operating temperature | 68 °C |
| Glass bulb colour | Red |
| Fusible link colour code | Renksiz / colour-free |
| Maximum ambient temperature (approximate) | 38 °C |
Where it is used
The most common rating. Offices, hotels, hospitals, retail, general production and storage ceilings.
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. 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 68 °C sprinkler can be manufactured in both quick response and standard response classes.
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 68 °C sprinkler?
Red. On a fusible link type the colour code is Renksiz / colour-free.
Up to what ambient can a 68 °C sprinkler be used?
Up to roughly 38 °C maximum ambient. 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) · BS EN 12845:2015+A1:2019 · EN 12259-1. Colour codes and temperature ranges are for information; the manufacturer's approval document governs product-specific values.