Chapter 9 Alarm, Safety, and Warning Systems

CHAPTER 9

ALARM, SAFETY, AND WARNING SYSTEMS

LEARNING OBJECTIVES

Upon completion of this chapter you will be able to do the following:

Explain the purpose of alarm, safety, and warning systems installed on Navy

ships.

ldentify the various sensing devices used with alarm, safety, and warning

systems.

Identify the various audible and visual devices used with alarm, safety, and

warning systems.

Describe the components and operation of a B-51 alarm panel.

Describe the components and operation of an IC/SM alarm panel.

Briefly describe some of the common troubles of alarm, safety, and warning

systems and their effects on the systems.

SENSING DEVICES

INTRODUCTION

Devices are used with alarm, safety, and warning

Alarm, safety, and warning systems are installed

systems to initiate alarms when there is a deviation in

in Navy ships for certain equipment and compart-

normal operation. A sensing device senses the

ments. These systems provide audible and visual

deviation and, in turn, causes a switch or relay contact

signals when abnormal or dangerous conditions

to close and energize the alarm signaling device.

occur. The principal components of the alarm, safety,

Sensing devices include switches, detectors, and

and warning systems are sensing devices, audible and

relays.

visual signals, alarm panels, and alarm switchboards.

Circuit designations and classifications of some of the

SWITCHES

more common systems are listed in table 9-1.

Switches used with the alarm, safety, and warning

Sources of possible trouble areas in many of the

systems include lever-operated, pressure-operated,

interior communication circuits are components that

mechanical, water, liquid-level, and thermostatic

transmit information and the components that warn of

switches. These switches were discussed in chapter 3

malfunctions. Often, even though the detector and

of this training manual. In addition, the alarm, safety,

repeater parts of a system are aligned, an error is

and warning systems use flow switches, relay

introduced by components that transmit or retransmit

switches, and mercury thermostats.

information.

Flow Switches

This chapter discusses some of the devices that

transmit information and warn of malfunctions. When

Flow switches are installed in fluid lines to sense

you complete this chapter, you should have a basic

fluid flow. As the fluid flow rate increases or

understanding of transmission, alarm, and indicating

decreases, the contacts in the flow switch will close

systems, and be prepared to deal with malfunctions in

and initiate an alarm. Flow switches are available in

various sizes to sense a variety of flow rates.

such equipment.

9-1