GB/T 20910-2025 Temperature and pressure safety valve for hot water supply system English, Anglais, Englisch, Inglés, えいご
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ICS 13.220
CCS H 57
National Standard of the People's Republic of China
GB/T 20910-2025
Replaces GB/T 20910-2007
Temperature and pressure safety valve for hot water supply system
热水系统用温度压力安全阀
Issue date: 2025-10-31 Implementation date: 2026-05-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Technical Requirements
4.1 Parameters
4.2 Structure
4.3 Valve Body
4.4 Valve Seat and Valve Disc
4.5 Spring
4.6 Temperature Sensing Element
4.7 Anti-loosening Device
5 Test Methods
5.1 Shell Strength Test
5.2 Set Pressure and Reseating Pressure Test
5.3 Seal Test
5.4 Pressure Relief Continuity Test
5.5 Set Temperature and Reseating Temperature Test
5.6 Temperature Relief Continuity Test
5.7 Temperature Relief Capacity Test
5.8 Pressure Relief Capacity Test
5.9 Mechanical Characteristics Test
6 Inspection Rules
6.1 Inspection Items
6.2 Factory Inspection
6.3 Type Test
7 Marking
8 Packaging, Transportation and Storage
9 Installation and Maintenance
1 Scope
This document specifies the technical requirements, test methods, inspection rules, marking, installation and maintenance, and packaging and storage for temperature and pressure safety valves used in pressurized hot water systems such as solar water heaters, electric water heaters, heat pump water heaters, gas water heaters, and fuel water heaters.
This document applies to temperature and pressure safety valves with nominal sizes DN15 to DN50, flow diameters not less than 11.1 mm, set pressures ranging from 0.1 MPa to 1.1 MPa, and set temperatures not exceeding 99°C.
2 Normative References
The contents of the following documents, through normative citations in this document, constitute essential provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 1047 Pipeline components - Definition and selection of nominal sizes
GB/T 7306 (all parts) 55° sealing tube threads
GB/T 12225 General valves - Technical conditions for brass castings
GB/T 12230 General valves - Technical conditions for stainless steel castings
GB/T 12243 Spring-loaded direct-load safety valve
GB/T 23935 Design and calculation of cylindrical helical springs
GB/T 29528 Technical conditions for brass forged valve parts
3 Terms and Definitions
The following terms and definitions apply to this document.
3.1 Temperature and Pressure Safety Valve
A type of automatic valve that opens automatically without any external force, utilizing the force generated by the medium pressure or the thermal expansion of the temperature sensing element to discharge a rated amount of fluid, preventing pressure and temperature from exceeding the predetermined safety values. When pressure and temperature return to normal, the valve closes and prevents the medium from continuing to flow.
3.2 Set Temperature
The inlet medium temperature at which the temperature and pressure safety valve is set to open.
3.3 Reseating Temperature
The inlet medium temperature at which the valve disc recontacts the valve seat after discharge.
3.4 Set Pressure
The inlet medium pressure at which the temperature and pressure safety valve is set to open.
3.5 Reseating Pressure
The inlet medium pressure at which the valve disc recontacts the valve seat after discharge.
3.6 Certified (Discharge) Capacity
The portion of the measured discharge that is allowed to be used as a benchmark for the temperature and pressure safety valve.
3.7 Temperature Sensing Element
A device or component that detects temperature changes and converts them into expansion force.
4 Technical Requirements
4.1 Parameters
The nominal size of the temperature and pressure safety valve shall comply with the provisions of GB/T 1047.
4.2 Structure
4.2.1 Typical structural types are shown in Figure 1.
4.2.4 A temperature sensing element shall be installed in the inlet of the temperature and pressure safety valve. The diameter (d) of the temperature sensing element shall not exceed the dimensions specified in Table 1.
4.2.5 The diameter (D1) of the flow passage (throat) of the temperature and pressure safety valve shall not be less than 11.1 mm.
4.2.6 The distance (h) between the centerline of the drainage pipe of the temperature and pressure safety valve and the sealing surface of the valve seat shall not exceed the dimensions specified in Table 1.
4.2.7 Except for the following conditions, the minimum cross-sectional diameter (e) of the flow area of the temperature and pressure safety valve shall not be less than 4.8 mm (as shown in Figure 1):
a) The flow area (a) between the valve body and the valve disc shall not be less than 1.6 mm;
b) The flow area (b) between the valve wall at the flow passage and the temperature sensing element shall not be less than 3.2 mm;
c) The edge (H) in the A-A cross-section of Figure 1 cannot be contained by a 4.8 mm diameter circle and must be tangent to the flow area (grid surface).
4.2.8 The flow direction of the medium in the temperature and pressure safety valve shall have a permanent marking.
4.3 Valve Body
The valve body design shall ensure that the temperature and pressure safety valve does not rupture or undergo permanent deformation under strength test conditions and operating conditions.
4.4 Valve Seat and Valve Disc
The sealing surfaces of the valve seat and valve disc are generally flat or conical. When a conical sealing surface is used, the angle of the sealing surface to the valve axis should be approximately 45°. The material can be the same as the body material or an elastic non-metallic material embedded.
4.5 Spring
The spring design shall comply with the provisions of GB/T 23935 and GB/T 12243.
4.6 Temperature Sensing Element
The temperature sensing element shall ensure that the expansion force generated by heating is greater than the total force tending to close the valve disc under set pressure. The temperature sensing element should be of automatic return type.
4.7 Anti-loosening Device
A locking device to prevent loosening shall be set on the mechanism for adjusting the spring compression.
4.8 Pressure Release Performance
4.8.1 The maximum set pressure shall be 1.1 MPa.
4.8.2 The preferred series of set pressures (MPa) are: 0.10, 0.15, 0.25, 0.50, 0.70, 0.85, 1.00, 1.10.
4.8.3 The deviation of the set pressure shall comply with the provisions of Table 2.
