What is Boiler Mountings? – Types and its Workings
The devices used for the efficient operation, proper maintenance, safe operation, etc are called Boiler mountings.
The different boiler mountings are given below
1. Water Gauge or Water Level Indicator: It indicates the level of the water inside the boiler. It is a glass tube covered with a special glass cover. It is fitted in front of the boiler. It is used to maintain the quantity of water at safe level.
2. Pressure Gauge or Steam Gauge: It is the device used to indicate the pressure inside the boiler. It is mounted in the front end, at the top of the steam drum.
3. Safety valves: It is used to maintain safe pressure inside the boiler. When the pressure exceeds the limit, the excess steam will be allowed to escape through the safety valves to the atmosphere to reduce the pressure inside the boiler. It is mounted on the top of the steam drum. Different types of safety valve are given below:
(a) Dead Weight safety valve: It is just like the dead weight in the household cookers. Since the heavy weight is required to balance the steam pressure, it is not suitable for high pressure boilers.
(b) Spring loaded (Rams bottom) safety valve: The valve is loaded with spring instead of weights; Here heavy spring force is needed to balance the steam pressure.
(c) Lever safety valve: The heavy dead weight is replaced by a lever with a smaller weight.
(d) Excess steam – Low water level safety valve: The excess steam is allowed to escape when the steam pressure exceeds the limit. And when the level of water in the boiler falls below a certain minimum value, this safety valve open to prevent bursting.
4. Fusible Plug: It is fitted just above the grate in the furnace. It is used to extinguish the fire in the furnace when the water level falls below safe level to avoid bursting.
5. Stop valve: It is used to control the amount of the steam passing through the steam pipe. It is hand operated. It is fitted with the steam pipe.
6. Blow off cock: It is fitted at the bottom of the boiler. When it is opened during the running of the boiler, the high pressure steam pushes out the impurities like mud, sand, etc. in the water collected at the bottom.
7. Feed check valve: The feed check valve is used to allow the supply of water to the boiler at high pressure continuously. It prevents the back flow of water from the boiler, when the pump pressure is less than the boiler pressure. It is fitted to the shell slightly below the normal water level of the boiler.