Section 20 Level Indicators

2001. Application

1. In accordance with the requirements in Pt 5, Ch 6, 203. 4, Pt 7, Ch 1, 1002. 8 and Pt 7, Ch 5 and Ch 6 of the Rules, the requirements in this Section apply to tests and inspection for the approval of pneumatic, electric and/or electronic type level indicators installed in tanks, cofferdams, etc.

2. The level indicators include all parts of the device from the detector to the display.

2002. Construction

The construction of the level indicator is to satisfy the following requirements.

(1) To be able to adequately withstand ship vibration, ship motions, trim and heel.

(2) For devices which are used in tanks carrying flammable liquid, special consideration is to be given against prevention of generation and charge of static electricity.

(3) To be able to withstand the most severe pressure and temperature expected during working con-

ditions and, for parts in contact with the liquid, to have adequate compatibility between the de- vice and the liquid considered.

(4) The construction in addition of the above is also to be as follows:

(A) To be such that maintenance and inspection can be carried out easily and safely

(B) To have appropriate devices installed to prevent metal fittings from coming loose.

(5) To be provided with a mechanism to correct specific gravity where necessary.

(6) Electrical parts of the level indicator which is installed within the dangerous zones are to be of explosion protective construction as specified in each of the relevant Parts of the Rules.

2003. Type tests

1. The type tests are to include the following (1) through (5) depending on application and type of level indicators.

(1) In addition to conformity with the requirements in 2002., confirmation of whether the test sam- ple agrees with the established specifications for completion, construction, dimensions and used parts.

(2) Confirmation of whether the test sample performs as specified where the configuration is in the regular installed direction and in 22.5° inclined direction under the working condition given in the following.

(A) Parts located out of the tank: normal temperature and maximum working pressure.

(B) Parts located inside the tank and on the tank walls: maximum and/or minimum working temperature (However, where this temperature is within the range of 0°C and 60°C, normal

temperature may be used instead.) and maximum working pressure.

(3) For devices in which the liquid level is measured by use of floats and where the float is not fixed during navigation, confirmation of whether specified performance can be realized after a

drop test in which the float is dropped from a height of 3 m onto a steel plate in 10

thickness. (However, where a damping device such as springs are provided at the top and bot- tom edge of the guide, tests may be carried out with such devices installed, although the tests

are to be repeated at least ten times.)

(4) For devices in which the liquid level is measured by use of floats, confirmation of whether any damage occurs to the rubbing parts where the same equipped pipes and wires are set up hori-

zontally and the float and guide are made to contact each other at the same places much as

practicable. Then, for devices which the float is not fixed during navigation, which the float is slided 5,000 times between 5 m span are to be carried out.

(5) For the electrical parts of the devices, testing as given in the following (A)

However the type tests are to comply with the requirements in 2304. 2 and, in

rubbing tests

through (E). case the ex-

plosion-protected construction is required, type tests also are to comply with the requirements in

2107. of the Guidance.

(A) Dry heat test

(B) Damp heat test

(C) Vibration test

(D) Inclination test

(E) Electrical power supply variation test

2. Additional tests other than those of the preceding 1. may be requested, where deemed necessary by the Society.

126 Guidance for Approval of Manufacturing Process and Type Approval, Etc. 2015