CSA 3.19:2015 pdf download.Direct gas-fired process air heaters
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 of a 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 % in (6.4 mm) rod.
4.1.8 Enclosures for gas trains shall be adequately ventilated.
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, ANSI/NFPA 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 Method of Surface Burning Characteristics of Building Materials, NFPA 255, or with the Standard for Surface Burning Characteristics of Building Materials, ULC S102.
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.
4.1.11 When the heater is operated as a process air heater in a paint booth application or other applications with airborne particulate matter that could be detrimental to the operation of the heater in the recirculating mode, the recirculated air must be filtered to remove particulates from the air. If the filters and filter sections are not supplied with the heater, instructions shall be provided to require that particulate removal filters that are approved by the Authority Having Jurisdiction be installed in the return air duct system. (See Clause 4.21.14.)
4.1.12 When the heater is operated as a process air heater in a paint booth application or other applications with airborne particulate matter that could accumulate in the duct system in the recirculation mode,the duct system shall be provided with doors, panels, or other means to facilitate inspection,maintenance, cleaning, and access to fire protection devices. If the return air duct system is not supplied with the heater, instructions shall be provided that require the return air duct system be installed with the proper access means to meet this requirement. (See Clause 4.21.15.)CSA 3.19 pdf download.