- Every boiler is to be fitted with at least two independent means of indicating the water level in it. One of which is to be a glass gauge. The other means is to be either an additional glass gauge or an approved equivalent device. (A set of not less than two test cocks will be accepted as the approved equivalent device mentioned above, for boilers having a design pressure less than 8 Bar or internal diameter less than 1.83m.) For water-tube boilers the approved equivalent device is to be other than the test cocks, but where a steam and water drum exceeding 3.96 m in length is fitted two glass gauges are to be fitted in suitable position.
- The water level gauges are to be readily accessible and placed so that the water level is clearly visible.
- The lowest visible part of the water level gauge and the lowest test cock (if fitted), are to be situated at the lowest safe w6rkirg water level.
- The cocks of all gauges are to be accessible from positions free from danger in the event of the glass breaking.
- Each of fired boiler is to be fitted with a system of water level detection which is to be independent of any other mounting and which will operate audible and visible alarms and shut of automatically the oil supply to the burners when the water level falls to a predetermined low level.
- Water-tube boilers are to be fitted with two system of water level detection, which are to be independent of any other mounting on the boiler. Both systems are to operate audible and visible alarms and automatic shut-off device.
1. High cost: Manganese bronze is a costly alloy, making it less economical for large propellers. 2. Low strength-to-weight ratio: Compared to other propeller materials like nickel-aluminum bronze or stainless steel, manganese bronze has a lower strength-to-weight ratio. 3. Susceptible to corrosion: Manganese bronze can corrode in seawater, especially when exposed to high velocities and turbulence. 4. Poor cavitation resistance: Manganese bronze is more prone to cavitation damage than other materials. 5. Difficult to cast and machine: Manganese bronze is challenging to cast and machine, making it less desirable for complex propeller geometries. 6. Limited weldability: Manganese bronze has poor weldability, making repairs and modifications difficult. Nickel-aluminum bronze or stainless steel are commonly used for propellers due to their: - High strength and durability - Excellent corrosion resistance - Good cavitation resistance - Ease of casting and machining - Weldability
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