CSA 3.7:2015 pdf download.Non-recirculating direct gas-fired industrial air heaters
4.1.1 The heater shall be constructed entirely of new, unused parts and material. The construction of the heater shall be such that it will not show signs of becoming warped, bent, broken, or otherwise damaged during the initial test installation or during any of the tests specified herein, so as to prevent its compliance with any of these provisions and whether specifically covered by the various provisions of the Standard or not, shall be in accordance with reasonable concepts of safety, substantiality, and durability.
All provisions as to construction set forth herein may be satisfied by the construction actually prescribed or such other construction as will provide at least equivalent performance.
4.1.7 A heater shall have means provided to prevent leaves, papers, or other objects from being picked up from the outside, ignited, and discharged into the heated space. The upper limit of the size of the openings of this means shall be such as to prevent the entrance ofa 1% in (28.6 mm) diameter rod. The lower limit of the size of the openings in this means shall not prevent the entrance of 14 in (6.4 mm) rod.
4.1.9 Thermal or acoustic insulation, that may allow smoke to be discharged to the circulating air in the event of a malfunction either shall comply with the requirements for duct coverings and duct linings in the Standard for the Installation of Air Conditioning and Ventilation Systems, ANSIINFPA 90A, or shall have a flame-spread rating less than 25 and a smoke-developed rating less than 50 when tested in accordance with the Safety Standard for Tests for Surface Burning Characteristics of Building Materials, ANSI/UL 723 or with the Method of Surface Burning Characteristics of Building Materials, NFPA 255 or with Standard ULC S102, Surface Burning Characteristics of Building Materials and Assemblies.
4.1.10 Insulating materials shall be mechanically or adhesively retained in place. Insulating materials and their internal bonding or adhesive means shall withstand temperatures and air velocities to which subjected in normal operation. If the insulation is such that air impingement on the edges might cause displacement or damage, such edges shall be protected.
4.3.1 All controls shall be accessible for normal servicing and functional adjustment in position and shall be replaceable during normal servicing. Manifold assemblies that permit removal of a control(s) intact shall be considered as complying with this provision. Removal of an access panel or door to provide access to a control compartment is acceptable.
4.3.2 Provisions shall be made to permit ready observation of the igniter or pilot and a major portion of the flames of each burner with the heater operating during service or start-up activity. An unsealed observation means with a movable cover shall be acceptable provided it does not exceed 4 in 2(25.8 cm2). The cover shall be designed and installed with a corrosion-resistant mechanism so as to insure that it closes automatially when the inspection port is not in use (i.e., positive gravity or spring).CSA 3.7 pdf download.