The 1/8″ NPT brass fusible plug is used in air or hydraulic systems as a thermal protection device.  It can be installed in emergency valves, air actuators, or tied in with any air or hydraulic  system.  If the fusible plug is subjected to temperatures in the range of 212°F to 250°F, the solder will melt and relieve line pressure to facilitate closing of emergency valves and vapor recovery valves.  When this fusible plug is installed properly and used in a correctly designed air or hydraulic system, it fulfills the requirements of, but not limited to, US DOT 49CFR§178.345-11(b)(1)(iii) and 49CFR§178.341-5(a), CSA B620-09 clause 5.6.12.3(e). Minimum Melt Temperature 212°F (100°C),  Maximum Melt Temperature 250°F (121°C),  Typical Melt Temperature 220 to 225°F. **  Do not paint the face of the fusible plug.  Replace if solder is extruding past the face of the plug.