BS/EN 437-2018 pdf download.Test gases-Test pressures – Appliance categories.
3.2
distributed gases
gaseous fuels used on the territory of the CEN members and affiliated members
Note 1 to entry This definition corresponds to the one given in the Directive 2009/142/EC on gas appliances
(article 2.2).
Note 2 to entry The list of CEN members Is given In Annex B and the one of afliliated members Is given In Annex D.
3.3
test gases
gases intended for the verification of the operational characteristics of gas appliances. They consist of reference gases and limit gases
3.4
reference gases
test gases with which appliances operate under nominal conditions when they are supplied at the corresponding normal pressure
3.5
limit gases
test gases representative of the extreme variations in the characteristics of the gases for which appliances have been designed
3.6
test pressures
gas pressures used to verify the operational characteristics of gas appliances. They consist of normal and limit pressures
Note 1 to entry The gas pressures used are expressed In millibars (mbar) 1 mbar = 102 Pa.
3.7
normal pressure (pn)
pressure under which the appliances operate in nominal conditions when they are supplied with the corresponding reference gas
limit pressures
maximum pressure: pmax; minimum pressure: pmin
pressures representative of the extreme variations in the appliance supply conditions
3.11
relative density (d)
ratio of the masses of equal volumes of dry gas and dry air under the same conditions of temperature and pressure: 15 °C or 0°C and 1 013, 25 mbar
3.12
calorific value
quantity of heat produced by the complete combustion, at a constant pressure equal to 1 013,25 mbar, of a unit volume or mass of gas, the constituents of the combustible mixture being taken at reference conditions and the products of combustion being brought back to the same conditions
A distinction is made between:
— the gross calorific value Hs: the water produced by combustion Is assumed to be condensed;
— the net calorific value Hi: the water produced by combustion is assumed to be in the vapour state
Note 1 to entry The caloriilc value is expressed:
— either in megajoules per cubic metre (MJ/m3) of dry gas under the reference conditions;
— or in megajoules per kilogram (MI/kg) of dry gas.
3.13
Wobbe Index
gross Wobbe index Ws; net Wobbe index Wi
ratio of the calorific value of a gas per unit volume and the square root of its relative density under the same reference conditions. The Wobbe index is said to be gross or net according to whether the calorific value used is the gross or net calorific value
Note 1 to entry The Wobbe indices are expressed in megajoules per cubic metre (MJ/m3) of dry gas under the reference conditions.
3.14
heat input (Q)
quantity of energy used in unit time corresponding to the volumetric or mass flow rates, the calorific value used being either the net or gross calorific value
Note 1 to entry The heat input is expressed In kilowatts (kW).
Note 1 to entry The volume flow rate is expressed in cubic metres per hour (m3/h), litres per minute (I/mm). cubic decimetres per hour (dm3/h) or cubic decimetres per second (dm3/s).
3.18
gas family
group of gaseous fuels with similar burning behaviour linked together by a range of Wobbe indices (see Table 1)
3.19
gas group
specified range of Wobbe index within that of the family concerned (see Table 1); this range is determined on the general principle that appliances utilising this gas group would operate safely when burning all gases within this range without adjustments
Note 1 to entry Adjustment of the appliance may be permitted in accordance with the special national or local conditions that apply in some countries (see B.4). For gases corresponding to national or local conditions, see Tables B.5, 116 and B.7.
3.20
appliance category
means of Identifying the gas families and/or gas groups that a gas appliance is designed to utilize safely and to the desired performance level (see individual appliance standards)
Note 1 to entry General appliance categories are described in 6.1. Special appliance categories marketed nationally or locally are described in B.4 and Annex D.
4 Gases
4.1 Classification in gas families and groups
Gases are classified Into three families, each family may be divided into groups, (themselves being divided into ranges, see Annex B), as a function of the Wobbe index, according to the values given in Table 1.
NOTE The classification given In Table 1 Is used by Member states for the communication of the types of gas used in their territory according to Article 2.2 of the Gas Appliances Directive 2009/142/EC.BS/EN 437-2018 pdf download.