Fig 5 fusible plugs are used to provide protection to internally fired steam boilers.

If overheating occurs due to low water conditions, the plugs are designed to operate and thereby allow pressure to reduce, provide a visual and audible warning and help prevent the collapse of a boiler.

The Fig 5 fusible plugs are of gunmetal construction with a certain portion held in position by a suitable low melting point alloy.

In the Fig 5 fusible plug the centre plug is moulded directly into the body. When the allow fuses, the plug is ejected by steam pressure.

The Fig 5 fusible plug is intended for loco boilers, where fitting is from the fire side. Plugs should be checked every twelve months, and cleaned and replaced as necessary every two years.

Installation instructions are provided.

They MUST NOT be used as the only or main safety device in any pressure system.

	Size DN	R (BSPT)	A (mm)	B (mm)	C (mm)
	15	1/2"	29	40	28
	20	3/4"	30	47	33
	25	1"	30	47	38
	32	1 1/4"	45	59	47