UL Standards & Engagement Pressure-Indicating Gauges for Compressed Gas Service UL 404

1.1 This Standard covers minimum requirements for indicating pressure gauges of the elastic element type.

1.2 Indicating pressure gauges include:

1. a) High pressure gauges employed in the high-pressure side of regulators or reducing valves used on compressed gas containers or cylinders of oxygen, hydrogen, nitrogen, and other gases usually have pressure ranges of 0 - 500, 0 - 1 000, 0 - 1 500, 0 - 2 000, 0 - 3 000, 0 - 4 000, 0 - 5 000, or 0 - 6 000 pounds per square inch (psi) (The related metric gauge ranges are approximately 0 - 3.4, 0 - 6.89, 0 - 10.34, 0 - 13.78, 0 - 20.68, 0 - 27.56, 0 - 34.47, or 0 - 41.36 MPa); and
2. b) Differential pressure gauges employed to measure the difference between two pressures with a maximum inlet pressure of 1 000 psig (6.89 MPa).

1.3 For requirements for gauges employed in the low side of regulators with ranges of 1 000 psig (6.89 MPa) or less, refer to the Standard for Compressed Gas Regulator Accessories, ANSI/CAN/UL/ULC 252A.

1.1 This Standard covers minimum requirements for indicating pressure gauges of the elastic element type.

1.2 Indicating pressure gauges include:

1. a) High pressure gauges employed in the high-pressure side of regulators or reducing valves used on compressed gas containers or cylinders of oxygen, hydrogen, nitrogen, and other gases usually have pressure ranges of 0 - 500, 0 - 1 000, 0 - 1 500, 0 - 2 000, 0 - 3 000, 0 - 4 000, 0 - 5 000, or 0 - 6 000 pounds per square inch (psi) (The related metric gauge ranges are approximately 0 - 3.4, 0 - 6.89, 0 - 10.34, 0 - 13.78, 0 - 20.68, 0 - 27.56, 0 - 34.47, or 0 - 41.36 MPa); and
2. b) Differential pressure gauges employed to measure the difference between two pressures with a maximum inlet pressure of 1 000 psig (6.89 MPa).

1.3 For requirements for gauges employed in the low side of regulators with ranges of 1 000 psig (6.89 MPa) or less, refer to the Standard for Compressed Gas Regulator Accessories, ANSI/CAN/UL/ULC 252A.

1.1 This Standard covers minimum requirements for indicating pressure gauges of the elastic element type.

1.2 Indicating pressure gauges include:

1. a) High pressure gauges employed in the high-pressure side of regulators or reducing valves used on compressed gas containers or cylinders of oxygen, hydrogen, nitrogen, and other gases usually have pressure ranges of 0 - 500, 0 - 1 000, 0 - 1 500, 0 - 2 000, 0 - 3 000, 0 - 4 000, 0 - 5 000, or 0 - 6 000 pounds per square inch (psi) (The related metric gauge ranges are approximately 0 - 3.4, 0 - 6.89, 0 - 10.34, 0 - 13.78, 0 - 20.68, 0 - 27.56, 0 - 34.47, or 0 - 41.36 MPa); and
2. b) Differential pressure gauges employed to measure the difference between two pressures with a maximum inlet pressure of 1 000 psig (6.89 MPa).

1.3 For requirements for gauges employed in the low side of regulators with ranges of 1 000 psig (6.89 MPa) or less, refer to the Standard for Compressed Gas Regulator Accessories, ANSI/CAN/UL/ULC 252A.