A gasketed fireplace door needs to be specifically tested and labeled according to which standard?

The appropriate standard for testing and labeling a gasketed fireplace door is UL 127. This standard pertains specifically to the safety and performance requirements for factory-built fireplaces, which include testing for various factors such as flue performance, temperature, and overall structural integrity when in use. UL 127 ensures that the fireplace is designed and built to prevent hazards related to fire and heat, providing assurance to consumers that the product meets safety criteria defined by Underwriters Laboratories.

While the other options refer to relevant standards in the field, they do not specifically address gasketed fireplace doors in the same comprehensive manner as UL 127 does. NFPA 211 focuses on the installation of chimneys, fireplaces, and vents, without specifically addressing the testing of the fireplace doors themselves. ANSI Z21.50 pertains to vented gas appliances, which is outside the scope of fireplace doors. IG-0903 is not widely recognized in the context of fireplace door standards. Thus, UL 127 is the most applicable and specific standard for this type of product.