CSA 2-6:2016 pdf pdf download.Gas unit heaters, gas packaged heaters,gas utility heaters, and gas-fired duct furnaces
4.1.5 Every part of the appliance shall be secure against displacement and constructed to maintain a fixed relationship between essential parts under normal and reasonable conditions of handling and usage.
Parts not permanently secured shall be designed so they cannot be incorrectly assembled and cannot be improperly located or misaligned when removed and replaced during cleaning or other servicing.
4.1.6 A panel shall be designed so as to prevent its being attached in an improper position or being interchanged with other panels on the same appliance in a manner that may interfere with proper operation of the appliance.
4.1.7 Valve trains for appliances with inlet pressures specified in excess of 14 in wc (3.48 kPa) must comply with the following:
a) Valve trains for appliances with inlet gas pressures of 2 psi (13.8 kPa) shall have all components rated at not less that the static supply pressure.
b) Valve trains for appliances with inlet gas pressures of 5.0 psi (34.5 kPa) shall have all components rated at not less than the static supply pressure. Where the gas pressure in the valve train downstream of the pressure regulator is limited (e.g., by full internal relief in the pressure regulator or by a separate relief valve) to a maximum static pressure of 2 psi (13.8 kPa), the components downstream of the regulators shall be rated as in Clause 4.1.7-a).
c) Valve trains operated at a static supply pressure in excess of 1/2 psi (3. 5 kPa) measured at the outlet of the gas pressure regulator shall supply a high pressure safety cut-out switch connected downstream of all controls. Where applicable, a listed high gas pressure safety cut-out switch shall be provided with the limit setting not to exceed 125 percent of the design manifold pressure. The switch should act to shut off the main burner gas in the event of an over pressure condition.Manual reset within the control system shall be required to resume burner operation. Power interruption is not an acceptable method of control reset.
d) Valve trains for unit heaters, packaged heaters, and duct furnaces with burners having input rates over 400,000 Btu/hr (117 228 W) with inlet gas pressures greater than 5.0 psi (34.5 kPa) shall have all components rated at not less than the static supply pressure. The gas pressure in the valve train downstream of the pressure regulator shall be limited (e.g., by full internal relief in the pressure regulator or by a separate relief valve) to the lowest rated static pressure of all components downstream of the regulator. A listed low pressure switch or operator shall be supplied and connected into the main burner manifold just downstream of the main gas pressure regulator just upstream of the safety shutoff valve and wired in series with the high pressure switch. The switch shall act to shut off the main burner gas in the event of a low pressure condition.CSA 2-6 pdf download.