• The upper connection is as close to the tank top as possible and is to be above the maximum liquid level in the tank.
• The gauge glass is so located or protected that any leakage therefrom will be contained.
11.5.2(d) Fresh water tanks. Structural tanks whose boundaries do not extend to the vessel's shell, and independent tanks for fresh water may all be fitted with tubular gauge glasses with a valve at each end or a valve at the bottom end of the glass.
11.7 Level Indicating Device
Where a level-indicating device is provided for determining the level in a tank containing flammable or combustible liquid, the failure of the device is not to result in the release of the contents of the tank through the device. Level switches, which penetrate below the tank top, may be used, provided they are contained in a steel enclosure or other enclosures not being capable of being destroyed by fire. Where the device is located, such that it is subjected to a head of oil, a valve is to be fitted to allow for its removal, see 4-6-2/9.11.3. If an overflow is not fitted, means are also to be provided to prevent overfilling of the tank in the event of malfunction of the indicating device/system.
11.9 Remote Level Indicating Systems
Where fitted, plans showing the arrangements and details of the system, along with particulars of the sensing and transmitting devices, are to be submitted for review in each case.