JOB Bulbs GmbH

Technical Data


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RTI - Response Time Index

The Response Time Index is a calculated figure describing the actual operating time of a glass bulb mounted in a sprinkler or other devices in given standard conditions. The RTI is an indication of the thermal sensitivity of the glass bulb. The lower the value of the RTI, the faster the response time of the bulb. JOB THERMO BULBS are able to meet any RTI requirements the user may have by combining different actuating liquids (G or F) with various bulb diameters. Each JOB THERMO BULB can be identified regarding its Response time by the type classification marked on the bulb.




Standard Response Applications RTI >80

JOB THERMO BULBS G5 are used for all products requiring Standard Response functional properties are defined by local agencies or authorities in the USA, Europe and Asia.



Special Response Applications 80>RTI>50

JOB THERMO BULBS F5 and F4 are used for applications where Insurers Hazard classifications require sprinklers, which have an average RTI between 50 and 80.


Fast, Super Fast and Ultra Fast-Response Applications RTI<50

JOB THERMO BULBS F3, F3-Sp and F3-F are used for applications where products are used for Life Safety, e.g., Residential Sprinklers – and in cases where Insurers Hazard Classifications require Fast REsponse - or in Extended Coverage Sprinklers, which require faster operational times due to the increased distance between installed sprinklers.

The Super Fast and Ultra Fast bulbs F2.5, F2 and F1.5 are especially for use in high performance products where very early activation is essential such as ESFR Sprinklers or Water Mist products.



The latest Generation of Glass Bulbs

The latest developments in sprinkler design require glass bulbs having extremely low Response Times and very high strength characteristics. JOB has etablished a development team that continuously improve the quality and the characteristics of JOB THERMO BULBS in order to fulfill the needs for high quality and leading technology for life safety products.

THERMO BULBS with their unique bone shape design use reinforced ends are used to absorb loads from the mounting supports and to introduce these axially into a shaft of reduced diameter thus avoiding unfavourable shearing and bending stresses in the glass. Furthermore the outstanding tension condition allows a low mass structure, which, combined with the special filling liquid, provides very low Response Times. Because of these characteristics JOB is the world-wide leading company for the supply of glass bulbs with superior thermal response and strength.



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