CGA S-1.1-2026

Pressure Relief Device Standards-Part 1-Cylinders for Compressed Gases - 18th Edition

This standard applies to the selection of pressure relief devices (PRDs) for a single component compressed gas in cylinders. For selection of PRDs for compressed gas mixtures in cylinders, see CGA S-7, Standard Method for Selecting Pressure Relief Devices for Compressed Gas Mixtures in Cylinders. This standard represents the minimum requirements for PRDs considered to be appropriate and adequate for use on cylinders with a water capacity less than or equal to 1000 lb (454 kg). This standard also applies to composite overwrapped pressure vessels (COPVs), DOT-3AX, DOT-3AAX, and DOT-3T cylinders with a water capacity greater than 1000 lb (454 kg) as well as UN pressure receptacles with a water capacity up to 3000 kg, and which comply with the design specifications and charging (filling) and maintenance regulations of U.S. DOT or the corresponding specifications and regulations of Transport Canada. This standard does not cover PRD requirements for CTC/DOT-4L and TC-4LM insulated cylinders containing cryogenic liquids, see CGA S-1.2, Pressure Relief Device Standards—Part 2—Portable Containers for Compressed Gases. This standard does not cover PRD requirements for multi-unit tank car tanks (DOT106A/TC106A and DOT110A-W/TC110A), see 49 CFR 179.300-15 and CGSB 43.147, Construction, Modification, Qualification, Maintenance, and Selection and Use of Means of Containment for the Handling, Offering for Transport, or Transporting of Dangerous Goods by Rail, as appropriate. For PRD standards for bulk transport containers and stationary storage containers, see CGA S-1.2 and CGA S-1.3, Pressure Relief Device Standards—Part 3—Stationary Storage Containers for Compressed Gases.