CEN Standard

Declare the conformity or non conformity of the particular flaw detector under test, in accordance with the criteria of CEN standards. 

In Europe, the gas safety controls must meet the requirements of CEN standards, including flame failure devices, solenoid control valve, pilot con trols, ignition and governor. Overheat-type thermostats and either a pressure switch or an airflow-proving device are fitted to ensure that the burner will cut off in the event of no air flowing through the heater, such as occurs with fan failure. 

Choice of program and input should be in accordance with the problem and the answers sought. For simple problems, adequate results may also be obtained with an adapted simple model. Many cases can be solved using a single-zone model various models are available.A single-zone model is also described in a CEN standard. 

In Germany, deflagration and detonation flame arresters are tested and approved by the German Federal Physical-Technical Institnte (PTB) in Brannschweig and the German Federal Institnte for Material Research and Testing (BAM) in Berlin. However, once the new Enropean Committee for Standardization (CEN) standard is approved, it will supersede the PTB and BAM procedures. 

The CEN standard has some significant differences and/or clarifications in comparison to the USCG, EM, and UL standards, such as ... 

With regard to in-line flame arresters the CEN standard clearly specifies minimnm operating pressnres as well as detailing of the operating pressnre on the test report. 

The CEN standard dictates the nse of temperatnre sensors on flame arresters not approved for continnons (endnrance) bnrning. 

The CEN standard rises the Enropean classificadon system for flammability which has more groups (based on the MESG of die vapor-air mixture) than the US classificadon system. 

The CEN standard specifically addresses the issue of endnrance bnrn tests. 

According to Wanben (1999) the CEN standard offers many differences and advantages to flame arrester risers, srich as ... 

The more comprehensive CEN standard makes it likely that an approved device is available for almost any application. In certain difficult applications it may be required to make modest design changes in order to accommodate the flame arrester and its capabilities, but this is preferable to being stuck with an application where no approved flame arresters are available. 

Thomas (1998) presents an overview of the contents of the CEN standard and comparison of it with other existing test standards. 

In Germany flame arresters are tested in accordance with the TRbE standard (Technical Rules for Inflammable Liquids) and approved by the German Eederal Physical-Technical Institute (PTB) and the German Eed-eral Institute for Material Research and Testing (BAM). However, this standard will be superseded by the new CEN standard. 

If a flame arrester is provided with cowls, weather hoods, deflectors, etc., it must be tested for the configuration involved if the test is done to meet the UL, USCG, or CEN standard (see Chapter 8). Maintenance of a flame arrester should be performed carefully to avoid any adverse impact on arrester performance (see Chapter 7). All flame arresters should be inspected regularly as operating experience dictates (see Chapter 7). 

Pre-Volume Vessel A process vessel or piping system (length to diameter ratio of less than 5) in which a confined deflagration occurs (as defined in CEN Standard EN 12874). 

The other two CEN standards, for the determination of dithiocarbamate/thiuram disulfide residues and for the quantitation of bromide, are also separated into parts, but, in contrast to the multi-residue methods, complete methods are presented in each different part. Owing to this different approach and the reduced number of analytes, it was possible to validate these methods fully. 

For standardised instrumental analytical methods, i.e. biomarkers, biosensors and bioassays, there are well-established standard protocols on the national level, e.g. under Association Francaise de Normalisation (AFNOR), British Standard Institute (BSI), DIN (German Organisation for Standardisation), etc., and all those standards are formed by ISO-Working Groups and by validation studies into ISO - and CEN - Standards. Normal accredited and well-qualified laboratories should be able to perform the monitoring. 

The GUM approach to uncertainty is rapidly gaining acceptance in metrological institutes and industry, and must be applied in ISO and CEN standards. It should be used in accredited laboratory work but chemists often find the implementation difficult and therefore hesitate [34], Additionally, sometimes, there is a fear that honest GUM uncertainty intervals, which may be wider... 

This analytical dilemma and the non-conformity of test results obtained for complex, heterogeneous measurands stimulated a movement towards standardization implemented by various international organizations such as the IFCC (Table 6). All these efforts tried to follow metrologically established rules according to the International Vocabulary of Basic and General Terms in Metrology (VIM) [38] and ISO-CEN standards (Table 7)... 

Table 7 ISO/CEN Standards essential for reference systems in laboratory medicine...

Once the method has been established and validated, it should be described in full detail such that it can be carried out by any other analyst. Besides the numerous experimental details relating to the chemicals, solvents and solutions used and the chromatographic parameters, important observations such as for instance the findings about the stability of standard solutions should be laid down appropriately in the method description as notes or remarks. But potential health risks to the analytical operator should also be addressed, for instance in a warning note at the beginning of the method description. The following structure of a method description, which was agreed upon as a CEN standard format, is a recommended example. 

Anon., 2003a), requires CN > 40, while those for biodiesel prescribe minimums of 47 for ASTM standard D 6751 (Anon., 2007a) and 51 for European Committee for Standardization (CEN) standard EN 14214 (Anon., 2003b). Due to the high CNs of many fatty compounds, which can exceed the cetane scale, the term lipid combustion quality number for these compounds was suggested (Freedman et al, 1990). 

Not as the CEN standards yet, the ISO standards foresee measurement of particles in the flue gas. In view of the problematic nature of nanoparticles in breathing air, the measurement of particles gains in importance. This is reflected in the European clean air act with the PM 10 standard, setting limits on particle emissions of the size less than 10 microns. In order to reduce the particle emissions, the formation of particles shall be decreased at the source. Wood burning appliances produce higher particle loads than... 

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