NFPA 31 Section 8.6.4 states vent screen must be #4 (0.187") or coarser. This does not align with UL180:2019 which states the screen must be 2.0 mm (0.787") to 4.0 mm (0.157") - Section 8.4. These need to be aligned. Please comment, Thanks.
Not clear if you think they "don't align", or whether you think they need to be identical. A fire inspector generally isn't going to read every UL standard -- he or she is going to apply the appropriate fire code to the facts and go from there.
NFPA 31 (2016) section 1.5 allows an AHJ to approve suitable equivalents. As a general rule, if the installation is done in accordance with the manufacturers' instructions, for a "listed and labeled" device, that should satisfy the inspector.
Also, "4.2.1 Oil-burning appliances and equipment shall be listed or approved for their intended use."
In theory, if the equipment is required to be listed and it doesn't meet the current standard for listing, then it may still be "approved" by the AHJ, and certainly if it provides some demonstrable "equivalency".
Looks to me like the UL listed vent cap complies with Section 8.6.4 of NFPA 101 so whats your thoughts on "These need to be aligned"
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