Notice bolt
The notice bolt is an independent component in a fall jacket hydrant and serves as a vent valve .
The notice bolt is built into the hydrant head and has the task of allowing the air displaced by the inflowing water to escape from the hydrant column when the hydrant is started up, in order to then close it automatically by the water pressure that builds up. As long as the hydrant is under pressure, the notice bolt prevents the fall jacket from being closed inadvertently before the pending water column has been reduced by the self-emptying. The hydrant is also ventilated when the water column is removed via the marker bolt, which then enables the drop jacket to be pushed up. This is to effectively prevent damage to the hydrant from frost. The designation notice bolt comes from the fact that the operator “notices” that the water supply to the hydrant has not yet been shut off again.
See also
Web links
- Fire Department History Handbook (accessed March 26, 2020)
- Extinguishing water supply (accessed on March 26, 2020)