ISO 23551-9-2022 pdf free download – Safety and control devices for gas burners and gas-burning appliances — Particular requirements — Part 9: Mechanical gas thermostats.
4? Classification
4.1 Classes of controls
ISO 23550:2018, 4.1, is not applicable.
4.2 Groups of controls
Shall be in accordance with ISO 23550:2018, 4.2.
4.3 Types of DC supplied controls
ISO 23550:2018, 4.3, is not applicable.
4.4 Classes of control functions
ISO 23550:2018 4.4, is not applicable.
5 Test conditions
Shall be in accordance with ISO 23550:2018, Clause 5, with the following addition:
Where applicable, the thermostat shall be mounted in an appropriate test fixture and the tests conducted with the thermal sensing element immersed in the intended medium (e.g. water, oil or air) for the application, as specified in the installation and operation instructions.
6 Construction
Specific regional requirements shall be as specified in Annex G.
6.1 General
Shall be in accordance with ISO 23550:2018, 6.1.
6.2 Construction requirements
6.2.1 Appearance
Shall be in accordance ISO 23550:2018, 6.2.1.
6.2.2 Holes
Shall be in accordance with ISO 23550:2018, 6.2.2.
6.2.3 Breather holes
ISO 23550:2018, 6.2.3 is not applicable.
6.2.4 Vent limiter
ISO 23550:2018, 6.2.4 is not applicable.
6.2.5 Screwed fastenings
Shall be in accordance with ISO 23550:2018, 6.2.5.
6.2.6 Moving parts
Shall be in accordance with ISO 23550:2018, 6.2.6.
6.2.7 Sealing caps
Shall be in accordance with ISO 23550:2018, 6.2.7.
6.2.8 Dismantling and reassembling for servicing and/or adjustment for controls Shall be in accordance with ISO 23550:2018, 6.2.8, with the following addition.
If, in accordance with the manufacturer’s instructions the thermostat can be dismantled for servicing,such action shall not result in a change in temperature calibration exceeding the declared maximum set point deviation (see 7.6.1.1).
Suitable means for maintaining all adjustments shall be provided. Lock nuts or adjusting nuts held by springs or compression are considered satisfactory, except where their adjustment can be accidentally disturbed.
6.2.9? Auxiliary? channels? and? orifices
Shall be in accordance with ISO 23550:2018, 6.2.9.
6.2.10 Pre-setting device
Shall be in accordance with ISO 23550:2018, 6.2.10.
6.3 Materials
6.3.1 General material requirements
Shall be in accordance with ISO 23550:2018, 6.3.1.
6.3.2 Housing
Shall be in accordance with ISO 23550:2018, 6.3.2.
6.3.3 Springs providing closing force and sealing force
Shall be in accordance with ISO 23550:2018, 6.3.3.
6.3.4 Resistance to corrosion and surface protection
Shall be in accordance with ISO 23550:2018, 6.3.4.
6.3.5 Impregnation
Shall be in accordance with ISO 23550:2018, 6.3.5.
6.3.6 Seals for glands for moving parts
Shall be in accordance with ISO 23550:2018, 6.3.6.
6.3.7? Jointing
Shall be in accordance with ISO 23550:2018, 6.3.7.
6.4 Connections
Shall be in accordance with ISO 23550:2018, 6.4.
Further requirements for GQC shall be in accordance with Annex D.
6.5Gas controls employing with electrical components in the gas wayISO 23550:2018,6.5 is not applicable.
6.6Flow characteristics
Subclause specific to this document.
An adjustable bypass shall be set by means of a variable pre-setting device or shall be adjusted by meansof a fixed pre-setting device.Bypass rate adjustments shall be independent of pilot rate adjustments.When specified by the manufacturer, it shall be possible to gain access to any fixed bypass or bypassadjusting device for cleaning without changing the calibration temperature set-point.
The opening and closing of the thermostat closure member with a total shut-off function shall happenby snap-action between the off position and the reduced flow position.
Figure 2 shows typical operating curves of a modulating, snap-acting and modulating on-off thermostat.The flow rate at the moment of snap-action shall not be less than the value as specified in the installationand operating instructions.
6.7Temperature adjustment of adjustable thermostatsSubclause specific to this document.
6.7.1 Range adjustment
The allowed temperature setting range of an adjustable thermostat shall be limited by stops. Whereapplicable, the operating instructions shall state the limits in which the temperature setting range maybe adjusted using appropriate tools.The temperature setting range stops shall not change on their ownaccord.ISO 23551-9 pdf download.