Figure 2-19.--Liquid-level float switch.

switch. The entire assembly can be mounted at any

switch casting is dry. The switch is mounted in the

magazine flooding system, and a sprinkling control

predetermined level, and the switch can be made

valve is installed between the switch and the firemain.

normally open or closed by reversal of the core. Level

When the sprinkling control valve is opened, water

conditions are indicated as normal, above normal, or

floods the switch casting and shorts out the 5-watt

below normal.

resistor. With the supervisory resistor shorted, a

current of sufficient value to operate the alarm will

MAINTENANCE OF SWITCHES

flow in the circuit.

Switches should be checked periodically to ensure

A water switch is used principally in sprinkling

alarm systems (circuit FH).

that all electrical connections and mechanical

fastenings are tight. Lockwashers must be in place.

Liquid-Level Float Switch

Avoid overtightening the packing and nut on

watertight rotary switches, as excessive pressure on

A relatively new development in indicating alarm

the switch shaft will cause improper positioning of the

and control functions, the liquid-level float switch

switch.

(fig. 2-19), is replacing the float-and-switch

Remove dirt and grease from switch and relay

combination found in tank- and bilge-level alarms.

contacts with a cloth moistened with an approved

This float switch has a doughnut-shaped, floatable

solvent. No lubricants of any kind should be applied

magnetic core operating over an encapsulated reed

Figure 2-19.--Liquid-level float switch.

2-12