CSA ANSI Z21.11.3:2013 pdf download.Gas-fired room heaters, volume III,propane-fired portable emergency use heater systems
1.11 This standard contains SI (Metric) corresponding to the yard/pound quantities, the purpose being to allow the standard to be used in SI (Metric) units. (Standard for use of the International System of Units (SI): The Modern Metric System, lEEE/ASTM SI 10 or ISO 80000-1:2009 Quantities and units- Part 1:General are used as a guide in making metric conversion from yard/pound quantities.) If a value for a measurement and a corresponding value in other units are stated, the first stated value is to be regarded as the requirement. The given corresponding value may be approximate. If a value for a measurement and a corresponding value in other units are both specified as a quoted marking requirement, the first stated unit, or both shall be provided.
4.1.11 Slotted and recessed head screws used in the general assembly of the heater system shall conform to the Standard for Slotted Head Cap Screws, Square Head Set Screws and Slotted Headless Set Screws, ANSI B18.6.2, the Standard for Slotted and Recessed Head, Machine Screws and Machine Screw Nuts, ANSI B18.6.3, or the Standard for Thread Forming and Thread Cutting Tapping Screws and Metallic Drive Screws (Inch Series), ANSI B18.6.4.
4.1.12 Bolts, nuts and screws (except sheet-metal screws) used in the general assembly of the heater system,shall have threads conforming to the Standard for Unified Inch Screw Threads (UN and UNR Thread Form), ANSI/ASME B1.1.
4.1.13 All controls shall be accessible for servicing and functional adjustment in position and shall be replaceable during servicing. Manifold assemblies, which permit removal of a control(s) intact, shall be considered as complying with this provision for servicing. Removal of an access panel or door to provide access to a control compartment shall be considered acceptable.
4.1.14 The flexible hose connector (see Clause 3) to the heater shall be visible for inspection. The connection of the flexible hose connector to the heater shall not be readily accessible to the user.
4.3.1 The heating section and any part of the heating assembly (such as a radiant burner, and similar parts) shall be so guarded that flammable material as well as persons will be protected against contacting it.
4.3.2 Any heater projections such as guards or grilles that are intended to guard hot heater surfaces shall be positively secured to the heater such as by screws, rivets or welding or being engaged in slots so that they cannot be removed without the use of tools, breaking or permanent bending or distortion.CSA ANSI Z21.11.3 pdf download.