UL SUBJECT 4300

Abstract

Scope: These requirements cover electrically heated insulated covers for compressed gas cylinders for use in Class I, Hazardous (Classified) Locations. The use is limited to high pressure cylinders containing only mixtures of non-toxic flammable materials for laboratory or analyzer use in which some of the constituents in the high pressure cylinder require heating above room temperature to ensure a uniform gas mixture. These products are intended for use in specialized commercial and industrial facilities, where safe operations are addressed by responsible parties at the installation. These considerations include ambient temperature control, assessment of the suitability of the tank and its contents to be used with the heaters, safety coordination associated with any releases due to elevated pressure, and similar aspects of safe usage. Refer to the US Code of Federal Regulations, Title 29, Subtitle B, Chapter XVII, Part 1910, Subpart H, Section 1910.101, Compressed Gases (general requirements), regarding the control and use of compressed gas cylinders. These requirements cover electrically heated insulated covers intended for use in accordance with the National Electrical Code, NFPA 70 and the Canadian Electrical Code, C22.1. They are also intended for use with Compressed Gas Association CGA P-1 by having a maximum limiting temperature of 125º F Covers are made in a variety of shapes and sizes for direct application to a cylinder. A cover of unusual size or odd shape is to be judged on its compliance with the requirements in this outline and on further examination and tests to determine its acceptability for the intended use and possible misuses. These requirements do not apply to units intended to be installed outdoors.