GB/T 39485-2020Safety and control devices for gas burners and gas-burning appliances - Particular requirements - Manual gas valves (English PDF)

4.1 Classification

Valves shall be classified, in accordance with the provisions of 4.1 in GB/T 30597-2014, into the following categories according to their construction type.

-- cock assembly for manual gas valve;

-- manual gas ball valve;

-- other manual gas valves.

4.2 Grouping

Valve grouping shall comply with the provisions of 4.2 in GB/T 30597-2014.

5.1 General requirements

The general construction of valves shall comply with the provisions of 5.1 in GB/T 30597-2014.

5.2 Construction

5.2.1 Appearance

The appearance of valves shall comply with the requirements of 5.2.1 in GB/T 30597-2014.

5.2.2 Holes

5.2.2.1 Holes used for assembling or installing screws, pins, etc., of valve components

shall not penetrate the gas passage, and the wall thickness between the hole and the gas passage shall not be less than 1 mm.

5.2.2.2 Process holes in the gas passage shall be permanently sealed with metal seals or

firmly sealed with metal seals marked as immovable. Connecting compounds may be used as supplements.

5.2.3 Breather holes

5.2.3 of GB/T 30597-2014 is not applicable.

5.2.4 Fastening screws

Fastening screws of valves shall comply with the provisions of 5.2.4 in GB/T 30597-2014.

5.2.5 Movable parts

Movable parts of valves shall comply with the provisions of 5.2.5 in GB/T 30597-2014.

5.2.6 Protective covers

Protective covers of valves shall comply with the provisions of 5.2.6 in GB/T 30597-2014.

5.2.7 Disassembly and reassembly during maintenance and/or adjustment

The disassembly and reassembly of valves during maintenance and/or adjustment shall comply with the provisions of 5.2.7 in GB/T 30597-2014.

5.2.8 Auxiliary channels

Auxiliary channels of valves shall comply with the provisions of 5.2.8 in GB/T 30597-2014.

5.2.9 Valve operating components

5.2.9.1 Except for the following cases, valves shall be opened by rotating

counterclockwise and closed by rotating clockwise.

a) Valves that supply gas to multiple burners;

b) When the valve is in the closed position, the valve rod or T-handle is at 90° to the flow direction; when the valve is in the open position, the valve rod or T-handle is parallel to the flow direction.

5.2.9.2 For a valve handle that can be removed without further disassembly of the valve, the removal of the valve handle shall not affect the leak-tightness of the valve; otherwise, a tamper-proof connection shall be used.

5.2.9.3 Valve operation shall be available without the use of tools.

5.2.9.4 When the operating spindle is pressed down to release the safety lock, no axial

pressure other than spring pressure shall be applied directly to the closure member.

5.2.10 Seating force

5.2.10.1 Cock assembly for manual gas valve and other manual gas valves shall be

maintained with a continuous seating force by means other than gravity to compensate for manufacturing tolerances, operational variations or lubricant displacement.

5.2.10.2 During normal use, the force applied to the closure member shall not cause the

closure member to be lifted off the seat or moved to a position that may cause the gas leakage to exceed the value specified in 6.3.1.

5.2.11 Tapered plug

The taper of the tapered plug of the cock assembly for manual gas valve shall be designed to be 1.4 ~ 1.7.The large-diameter end of the tapered plug shall be recessed into the tapered plug cavity, and the small-diameter end shall protrude out of the tapered plug cavity, with sufficient clearance provided for the protruding part.

5.2.12 Sealing angle of manual gas ball valve

When the manual gas ball valve is in the fully closed position, the angle between the gas sealing surface port in the ball and the inlet/outlet on the valve body shall not be less than 8°. See Figure 1 for a schematic diagram of the sealing angle.

5.2.13 Rotation angle of cock assembly for manual gas valve

5.2.13.1 When a reduced flow rate position is provided, the reduced flow rate position

shall be located behind the fully open position or between the fully open position and the closed position.

5.2.13.2 When the reduced flow rate position is behind the fully open position, the

following provisions shall be met.

a) To change from the closed position to the fully open position, the rotation angle shall be (90+/-5) °, unless otherwise specified in the installation and operating instructions;

b) Except for multi-outlet valves, the rotation angle between the fully open position and the reduced flow rate position of the valve shall be greater than 70°, unless otherwise specified in the installation and operating instructions;

c) A limit switch shall be set at the minimum flow rate position.

5.2.13.3 When the reduced flow rate position is between the closed position and the

fully open position, the following requirements shall be met.

a) To change from the closed position to the fully open position, the rotation angle shall be greater than 90°, unless otherwise specified in the installation and operating instructions;

b) Except for multi-outlet valves, the rotation angle required for the valve to move from the reduced flow rate position to the fully open position shall be greater than 70°, unless otherwise specified in the installation and operating instructions;

c) When the valve is operated in the closing direction, a component shall be provided to position the closure member at the minimum flow rate position, thereby ensuring the minimum flow rate;

d) A limit switch shall be installed at the fully open position.

5.2.14 Single-outlet valve

When a single-outlet valve is not provided with a minimum flow rate position, the rotation angle from the closed position to the fully open position shall be (90+/-5) °, unless otherwise stated in the installation and operating instructions.

5.2.15 Lubricating grease

Where lubricating grease is used in the valve, the design shall ensure that it does not result in blockage of the gas passage.