The B40 external cage type level switch is a float-actuated control specifically designed and constructed for high pressure, high temperature service conditions such as boilers. It is available in rugged industrial or ASME B31.1 construction.
A permanent magnet is attached to a pivoted switch actuator. As the float/displacer rises following the liquid level, it raises the attraction sleeve into the field of the magnet, which then snaps against the non-magnetic enclosing tube, actuating the switch. The enclosing tube provides a static pressure boundary between the switch mechanism and the process. On a falling level, the float/displacer deactivates the switch.
Choices of chamber materials include carbon steel, stainless steel and chrome-moly
300 series stainless steel float
Choice of switch mechanism: ◦ Dry contact ◦ Hermetically sealed
Minimum specific gravity 0.65
Choice of switch mechanism enclosure: ◦ TYPE 4X polymer coated steel ◦ TYPE 4X/7/9 Class I, Div. 1, Groups B, C & D, polymer coated aluminum or cast iron
Choice of tank connection: ◦ 1" welding nipples ◦ 1" or 1½" socket welds
Low specific gravity
As the counter weighted float follows liquid level changes, a magnetic sleeve is moved into or out of the field of a switch-actuating magnet causing switch operation. A non-magnetic barrier tube isolates the switch mechanism from the controlled liquid.