European Standard EN54-10
The European standard EN54 is a so called; “product standard”. Part 10 of this standard deals with the product requirements for flame detectors. In several European countries the national design standards refers to the standard EN54-10 for the quality requirements for flame detectors. The standard EN54-10 describes the quality requirements of the flame detector itself but not how the detector should be applied and if the detector is capable to detect a fire in a in a certain application. The standard EN54 part 10 describes which laboratory tests the flame detector should pass; these are especially ambient and electrical aspects. The standard also describes a number of test fires, the flame detector must be exposed to and, after the tests, classifies the detector in one of three sensitivity classes. All fire tests take place in a laboratory.
‘The national design standards and directives describe quality requirements of components and systems and also provides design guidelines for the fire safety in buildings.’
The phrase ‘buildings’ in design standards and/or directives always mean public buildings (offices, hospitals etc.) The design guidelines in these national design standards and directives are typically suitable for point smoke detectors. In public buildings flame detectors are hardly applied. Flame detectors are used in a versatile range of applications. The detection system design of flame detectors in an Alcohol storage in a Hospital differs significantly from the detection system design of flame detectors utilized for monitoring a Generator Room. When designing the flame detection system it is necessary to follow the instructions of the manufacturer, rather than following the guidelines of the national design directive and frequently ask for the assistance of the manufacturer or his representative. The supplier considers in its design guidelines also the features of the application, such as monitoring of the contamination of the detector window, sensor self test, and the aspects of detection of e.g. non-hydrocarbon fires.
‘It is possible to get an EN 54-10 approval for a simple UV flame detector in the highest sensitivity class, which is NOT suitable for 90% of the applications.’
UV flame detectors are typically used for the detection of light- or non-hydrocarbon fires. UV flame detectors also have their limitations making them not suitable for a number of applications: false alarm risk because of Electrical Welding, un-shielded Halogen Lamps or e.g. Corona. Blinding of the UV flame detector can take place by occurrence of Smoke, Gases, Vapors, Oil films, Silicone’s and Salt films.
These limitations which make UV flame detectors not suitable for a large number of applications are not mentioned in the standard EN 54-10. A certificate of conformity with the standard EN54 part 10 however, is not a guarantee that the UV flame detector is the right choice for a certain application.
For industrial objects a thorough analysis is necessary of the object and of the fires to be expected, the possible fire alarm sources and false alarm sources and also from pollution sources, which might negatively influence the sensitivity of the flame detector. In industrial applications in which hydrocarbon fires can occur in oily environments an IR flame detector, which is sensitive for radiation in the 4.3 micron range, will be more suitable than a UV flame detector. Whilst the IR flame detector might be classified in the lowest sensitivity class (3) and the UV flame detector in the highest (1). Therefore the sensitivity class in the standard EN54-10 is not a guarantee for a proper performance in a certain application.
‘The sensitivity classification in the standard EN54-10 might suggest that a flame detector which is classified in the highest sensitivity class is automatically the best flame detector in all applications.’
There is only a limited amount of applications where a very high sensitivity flame detector is important. Often the most sensitive flame detector is recommended presuming this is always the right choice. There are more important factors which determine what type and how many detectors are necessary for a certain project. Important factors are for example the shadow effect and zone classification.
For industrial projects it is necessary to follow the design guidelines of the manufacturer and to involve the know-how of the supplier. For the project the supplier can make a flame detection analysis by means of a project description of the application including a clear justification of the choice of the flame detector type. The national design standards and directives and the standard EN 54-10 are not of help for making a design of flame detection systems in industrial applications.
- Instead of stating suitability for “Buildings” the revised norm now states: “In- and around buildings”.
- The revised norm now makes a difference between flame detectors that are used mostly outdoors and mostly indoors.
- The revised norm practically excludes non-hydrocarbon fires such as Hydrogen, Munitions and Metals.
- A fourth sensitivity class is added: “X” for flame detectors that can detector the standard fires at a distance of more than 25 m.