These requirements cover constant-level oil valves for use as factory-assembled components of oil-burning heating appliances. Constant-level oil valves may include manually or automatically operated metering valves to regulate the flow of oil to an appliance and may include thermostatic and electrical control features. Requirements for the installation and use of constant-level oil valves are included in the Standard for the Installation of Oil-Burning Equipment@ NFPA 31. A product that contains features@ characteristics@ components@ materials@ or systems new or different from those covered by the requirements in this standard@ and that involve a risk of fire@ electric shock@ or injury to persons shall be evaluated using the appropriate additional component and end-product requirements as determined necessary to maintain the acceptable level of safety as originally anticipated by the intent of this standard. A product whose features@ characteristics@ components@ materials@ or systems conflict with specific requirements or provisions of this standard cannot be judged to comply with this standard. Where considered appropriate@ revision of requirements shall be proposed and adopted in conformance with the methods employed for development@ revision@ and implementation of this standard.