Figure 10-39.--Ships' water system diagram.

speed and distance information to various equipment

VALVE POSITION INDICATOR SYSTEMS

and remote indicators throughout the ship.

Valve position indicator systems (circuit VS) pro-

The main internal components of the indicator-

vide personnel at remote stations of the positions (open

transmitter are the speed servo, the integrator, and the

or closed) of certain valves.

distance servo. The main external components of the

Sensitive switches, mounted on the valve housing

indicator-transmitter are a distance motor, a speed dial,

and actuated by the valve, energize the indicators. On

a distance counter, an electronic trim pot assembly, and

most installations, you will find two switches. One

a dummy signal unit used for calibration.

switch indicates that the valve is open and the other

The ac signal voltage produced by the rodmeter is

indicates that the valve is closed. They normally have a

fed to the speed servo. The speed servo drives the

make contact arrangement. There are usually two lamps

synchro output transmitters, the dual-pointer dial, and

in each indicator; one lamp for the open position of a

the integrator. The integrator converts the speed input

valve and the other for the closed position. The remote

to a distance-traveled output, which drives a synchro

indicators may be found singly, but they are normally

output transmitter and a six-drum counter to display

grouped into valve position indicator boards of from 5

distance traveled.

to 15 indicators to indicate the positions of valves

located in the same engineering space.

Remote Control Unit

SALINITY INDICATOR SYSTEM

The remote control unit, or dummy log as it is

commonly called, is used in place of the rodmeter

The salinity indicator system, described in this

when the ship is operating in shallow water, where

chapter, is a representative system. When working on

lowering the rodmeter is impractical. The unit is

the salinity system on your ship, you should consult the

normally located in the main propulsion control

technical manual pertaining to your equipment for spe-

station. The unit has a spring-loaded, center-off,

cific settings.

increase-decrease switch and is operated by the

The salinity indicator system (circuit SB) measures

throttleman. The shaft rpm is used to determine

the electrolytic impurities present in fresh water in

approximate ship's speed.

equivalent parts per million (epm) or parts per million

Figure 10-39.--Ships' water system diagram.

10-24