Tank Level Indicator Systems

maintains power relay K1-1, operated so that its

the size of the tank and its shape, as well as the desired

contacts are closed. (For simplicity, only one

type of level indication.

solenoid-operated valve is shown.)

The electrical signals generated by the level links

and transmitters are converted at the receivers and

TANK LEVEL INDICATOR SYSTEMS

indicated on meters in gallons. Each meter is

calibrated for a specific tank, and each tank is different

Tank level indicator systems provide an accurate

in size and shape. The size and shape of the tank also

measure of the fluid level within a tank, as well as

accounts for the nonlinearity of the meter forces.

sound an alarm, audible and/or visual, to indicate

either a high or low fluid level. The fluid levels can be

MAINTENANCE

c o n t i n u o u s l y indicated or in predetermined

increments, depending on the type of equipment

Preventive maintenance for the ship's order

installed in the tank. This can be accomplished using

indicating and metering systems consists of routine

various types of detection equipment, the most

tests, inspections, cleaning, and lubrication. All

common of which is the magnetically operated reed

preventive maintenance should be accomplished

switch. For the purposes of our discussion, we will talk

according to current applicable MRCs.

about the magnetically operated reed switch.

Corrective maintenance for the systems consists

The system consists of a level detector, which is

mainly of replacing burned out illumination lamps and

installed in the tank, a receiver mounted outside the

z e r o i n g synchros. For detailed information

tank, and an alarm device. The types of alarm devices

concerning the maintenance of synchro systems and

used varies depending on the system; however, they

the zeroing of synchros, refer to Navy Electricity and

perform the same function.

Electronics Training Series (NEETS), NAVEDTRA

The level detectors used in a tank level indicating

172-15-00-85, Module 15.

system fall into two categories: level links and

transmitters. Level links indicate the fluid level in

SUMMARY

increments. Transmitters provide continuous fluid

level indications and are used in systems requiring

In this chapter, we have described the purpose of

greater accuracy.

the ship's order indicating and metering systems. We

The method of indication for level links and

have identified and discussed the operation of the

transmitters are the same. A permanent magnet, which

ship's control order and indicating systems and the

moves with the fluid level, is enclosed in the float.

various control consoles used with the systems. We

When the permanent magnet becomes parallel to a

have identified and discussed the operation of some of

switch, the switch closes. As it moves further on the

the various metering and indicating systems installed

stem, it will make the next switch before opening the

on Navy ships. We have briefly discussed some of the

former switch (make-before-break).

preventive and corrective maintenance measures

Transmitters and level links are sometimes used

associated with the ship's order indicating and

together. The actual combinations are determined by

metering systems.

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