The fusible and frangible assembly offers two types of protection with both a thermally activated and a mechanically activated single-use emergency shut-down feature. With a properly plumbed system, breaking of the frangible device or melting of the fusible plug relieves pressure in the air or hydraulic line and allows the valves to close.
The frangible has 1/8″ male NPT mounting threads. When mounted and plumbed correctly it functions as a remotely actuated means of closure per US DOT 49CFR§178.345-11(b)(1)(i). The brass fusible plug (FP15003BR) is included in the end of the frangible. If the fusible plug is subjected to temperatures above 212 degrees F., the solder will melt and relieve line pressure to facilitate closing of the emergency valves and vapor recovery valves. When the 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).