1.0

Introduction

Magnetrol's B40 level switches are specifically designed for

extremely high pressure, high temperature service conditions

found principally in power plants, petroleum and petro-

chemical refineries, and nuclear power installations.

Caution: If equipment is used in a manner not specified by manufac-

turer, protection provided by equipment may be impaired.

1.1

Principle of Operation

The design of Magnetrol float-operated level switches is

based upon the principle that a magnetic field will “see

through” non-magnetic materials such as 316 stainless steel.

In this case, the float moves a magnetic attraction sleeve (1)

within a non-magnetic enclosing tube (2) and actuates

a switch mechanism (3). The enclosing tube provides a

pressure seal to the chamber and, therefore, to the process.

1.2

Operating Cycle

As the liquid level decreases in the chamber, refer to

Figure 1, the float moves the magnetic attraction sleeve up,

within the enclosing tube, and into the field of the switch

mechanism magnet. As a result, the magnet is drawn in

tightly to the enclosing tube causing the switch to trip,

“making” or “breaking” an electrical circuit. As the liquid

level rises, the float moves the attraction sleeve out of the

magnetic field, releasing the switch at a predetermined low

level (see Figure 2). The tension spring ensures the return of

the switch in a snap action.

2.0

Installation

2.1

Unpacking

Unpack the instrument carefully, inspecting for damage.

Report any concealed damage to the carrier within

24 hours. Check the contents listed on the packing slip

and purchase order. Check and record the serial number

for future reference when ordering parts.

4

46-602 B40 Liquid Level Switches

5

6

4

Mercury

Switch

Pivots

Tension

Spring

Swing-In

Position

Float

1

3

Pivot

2

5

6

4

Swing-Out

Position

Figure 1

Switch Tripped

Figure 2

Switch Released