Test gases

BS EN 437:2021 pdf free.Test gases一Test pressures一Appliance categories.
The values of the test pressures, i.e. the static pressure to be applied at the gas inlet connection to the appliance whilst in operation, are given in Tables 5 and 6.
NOTE The test conditions are specified in the individual appliance standards.
However:
— for the combustion test in still air with G 21 the appliance is first adjusted on G 20 to give an increase of 5 % in the nominal heat input where a gas pressure governor exists, and an increase of 7,5 % in the absence of a governor. Gas G 21 is then substituted for G 20 without altering this adjustment;
— tests for ignition and crosslighting should be carried out at an inlet pressure of 0,7 times the normal pressure (pa) using the reference gas(es) for the first and second families.
6 Classification of appliances
6.1 Appliance categories
6.1.1 General
Appliances are classified into categories defined according to the gases and the pressures for which they are designed.
The definition of the categories follows from 6.1.2, 6.1.3 and 6.1.4.
In each country, taking account of the local gas distribution conditions (gas composition and supply pressures), only some of the categories defined in 6.1.2, 6.1.3 and 6.1.4 are marketed. In addition, some of these categories are used only for certain types of appliances as specified in the individual appliance standards.
The conditions concerning the marketing of these appliance categories in each country and the corresponding supply pressures are given in Tables B.1, B.2 and B.3 (see also B.4 for the categories marketed locally and nationally, corresponding to the gases and specific supply pressures given in Table B.5; B.6 gives the particular conditions specific to certain countries).
NOTE See also Annex C – Guidelines for extension to other categories.
6.1.2 Category I
6.1.2.1 General
Appliances of category I are designed exclusively for the use of gases of a single family or of a single group. 6.1.2.2 Appliances designed for use on first family gases only
Category ha: appliances using only gases of group a of the first family at the prescribed supply pressure (this category is not used).
6.1.2.3 Appliances designed for use on second family gases only
Category l2H: appliance using only gases of group H of the second family at the prescribed supply pressure.
Category lzL: appliances using only gases of group L of the second family at the prescribed supply pressure.
Category l2E: appliances using only gases of group E of the second family at the prescribed supply pressure.
Category l2E: appliances using only gases of group E of the second family, and operating with a pressure couple without adjustment of the appliance. The appliance gas pressure regulating device, if it exists, is not operative at pressures in between the two normal pressures of the pressure couple.
Category l2N: appliances using only second family gases at the prescribed supply pressure and that automatically adapt to all gases of the second family.
Category IZR: appliances having a pressure regulator which can be manually adjusted in order to utilize each of the following gas groups: H, E, L, K and LL (see also Table B.6).
6.1.2.4 Appliances designed for use on 3rd family gases only
Category l3B,p: appliances capable of using the third family gases (propane and butane) at the prescribed supply pressure.
Category I3: appliances capable of using gases of the third family (propane and butane) and operating with a pressure couple without adjustment of the appliance. However, for certain types of appliances specified in the particular standards, adjustment of the primary combustion air may be permitted when changing from propane to butane and vice versa. No gas pressure regulating device is permitted on the appliance.
Category l3: appliances using only gases of group P of the third family (propane) at the prescribed supply pressure.
Category l3B: appliances using only gases of group B of the third family (butane) at the prescribed supply pressure.
Category l3R: appliances having a pressure governor using all the gases of the third family which can be adjusted manually in order to utilize the various gases of a group of the third family under the local condition of distribution (see Table B.7).
6.1.3 Category II
6.1.3.1 General
Appliances of category II are designed for use on gases of two families:
6.1.3.2 Appliances designed for use on gases of the first and second families
Category H1a2H appliances capable of using gases of group a of the first family and gases of group H of the second family. The first family gases are used under the same conditions as for category I ia.The second family gases are used under the same conditions as for category 2H
6.1.3.3 Appliances designed for use on gases of the second and third families
Category ll2113B,p: appliances capable of using gases of group H of the second family and gases of the third family. The second family gases are used under the same conditions as for category ‘2H The third family gases are used under the same conditions as for category 3B/P.
Appliances of category III are designed for use on gases of three families.
This category is not used in general.
The categories III accepted in specific countries are given in Annex B (see B.4).
6.2 Operations permitted for a change of gas or pressure, adjustment and regulating devices
The individual appliance standards should specify:
—the operations permitted for a change of gas or of pressure (as far as possible the permitted conversion operations should be limited so as to ensure that the conversion may be effected without difficulty);
—the conditions applicable to adjustment and regulation devices.
7 Choice of test gases and test pressures
According to the appliance category:
—the tests are carried out with the gases given in Table 7;
—the test pressures are chosen from Tables 5 and 6, as appropriate, as a function of the test gas and in accordance with the requirements given in the individual appliance standards.
8 MarkIng
The marking of a catieguty comprises:
— In Roman numerals, the number of utilizable gas families;
— in an Arabic numeral suffix, the number assigned to the gas family considered, La I for the first family. 2 for the second and 3 for the third;
— in the suffix following that numeral, the letter or letters designating the utilizable gas group or groups, respectively.
The suffix to the Roman numeral denotes all the families with all the gas groups usable by the appliance, with or without making adjustments and/or adaptations appropriate to each group.
In cases where the appliance Is capable of using gases belonging to one of the groups £ or B/P that completely or partially encompass more restricted groups. the breadth of which is expressed by a Wobbe number range, the supply pressure may be set according to the pressure couple principla This supply condition for the gas group considered Is symbolised by the + sign following the letter £ or the dIgit 3 for group B/P; In the latter case, the symbol for the group itself Is replaced by the digit 3, whIch denotes the third family.BS EN 437 pdf download.Test gases