ISO 23550:2011 pdf free download – Safety and control devices for gas burners and gas-burning appliances一 General requirements.
ISO 23550 provides general requirements for controls and safety devices for gas burners and gas-burning appliances and is intended to be used in conjunction with ISO 23551 (all parts), ISO 23552-1 and ISO 23553-1 for specific types of controls, or for controls for specific applications.
This International Standard can also be applied, so far as is reasonable, to controls not mentioned in a specific standard and to controls designed on the basis of new principles, in which case additional requirements may be necessary.
Where no specific International Standard for a control exists, the control can be tested according to this International Standard and further tests which take into account the intended use.
Controls and safety devices for gas burners and gas burning appliances using fuel gases need to withstand the type of gas which is specified. Other ISO technical committees, e.g. ISO/TC 28, Petroleum products and lubricants and ISO/TC 193, Natural gas, deal with the testing and properties of fuel gases.
Note that, due to the differing properties of fuel gas depending on its source/region of origin, certain differences in regulations exist at present in different regions; some of these differences are presented in Annexes E, F and G. This International Standard intends to provide a basic framework of requirements until these differences can be harmonized.
3.16
diameter nominal
DN
nominal size
alphanumeric designation of size for components of a pipework system, which is used for reference purposes, comprising the letters DN followed by a dimensionless whole number which is indirectly related to the physical size, in millimetres, of the bore or outside diameter of the end connections
NOTE 1 The number following the letters DN does not represent a measurable value and should not be used for calculation purposes except where specified in the relevant standard.
NOTE 2 In those standards which use the DN designation system, any relationship between DN and component dimensions should be given, e.g. DN/OD or DN/ID.
NOTE 3 Adapted from ISO 6708:1995, definition 2.1.
3.17
type testing
conformity testing on the basis of one or more specimens of a product representative of the production
[ISO 8655-1:2002, definition 3.2.2]
4 Classification
4.1 Classes of control
Where appropriate, controls are classified by application (e.g. sealing force, performance characteristics,
number of operations during their working life). For classification of controls, see the specific control standard.
4.2 Groups of controls
Controls are grouped according to the bending stresses which they are required to withstand (see Table 4):
a) Group I controls — Controls for use in an appliance or installation where they are not subjected to bending stresses imposed by installation pipe work (e.g. by the use of rigid adjacent supports).
NOTE 1 In USA and Canada, group 1 controls are not used.
b) Group 2 controls — Controls for use in any situation, either internal or external to the appliance, typically without support.
NOTE 2 Controls which meet the requirements of a group 2 control also meet the requirements of a group 1 control.