Jerguson® External Cage Level Switches

Jerguson® products are also available under the Magne-Sonics® brand as required based on approved vendor specifications.

Jerguson offers a wide array of mechanical switch and transmitter products to provide reliable level measurement for your application. Our caged level switch products feature a unique, tri-magnet mechanism that offers high current, snap-action switching without the use of cams or springs. Products are available with ASME B31.1/B31.3, FM, UL, CSA, ATEX, & PED approvals.

Jerguson® External Cage Float Operated Magnetic Level Switch

Features

  • Tri-Magnet Switching

  • Vibration Resistant

  • Weatherproof

  • Flameproof

  • Sealed (shown) or Flanged Cage Body

  • 316 SS Trim

  • ASME B31.1/B31.3 Design

Operation

The float drives a stainless steel sheathed permanent magnet attached to the float rod in the glandless pressure tube.  As the float rises and falls with a changing liquid level the float assembly moves upwards inside the pressure tube.

A switch mechanism is mounted inside the enclosure adjacent to the pressure tube, and is activated by the rising or falling magnet.

The vertical movement of the float magnet in the pressure tube simultaneously actuates the secondary and switch magnets within the switch mechanism, to operate the contacts.  This “three-magnet” system enables the float magnet to pass the switch and actuate switch mechanisms at other levels.  Switch mechanisms which are actuated will not reset until the float magnet actuates the switch mechanism on a falling level.

Switching is achieved with the unique tri-magnet snap-action switch system.

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External Cage Float Operated Magnetic Le

Jerguson® External Cage Displacer Operated Level Switch

Features

  • Tri-Magnet Switching

  • Vibration Resistant

  • Weatherproof

  • Flameproof

  • Sealed (shown) or Flanged Cage Body

  • 316 SS Trim

  • ASME B31.1/B31.3 Design

Operation

The displacer element is made of either 316 Stainless Steel or Ceramic, is suspended on a Stainless Steel Rod from a spring.  The displacer element is always heavier than its equivalent volume of the liquid in which it is to operate, so it will extend the tension sprint at all times.  In free air, the spring will be extended to a known length, controlled by a mechanical stop to prevent overstressing.  Attached to the spring is a rod and magnet assembly, free to move up and down as the spring extends or contracts within the pressure tube.

A switch mechanism is mounted inside the enclosure adjacent to the pressure tube.

As liquid rises to cover the displacer element, a buoyancy force is created equal to the weight of the liquid displaced.  This force in effect is seen by the spring as a reduction in weight, causing the spring to contract, hence moving the magnet upwards inside the pressure tube and actuating the switch mechanism.  On a falling liquid level, the displacer element is uncovered and the spring sees an increasing effective weight, causing the spring to extend and move the magnet to re-set the switch mechanism.

Switching is achieved with the unique “tri-magnet” system, giving the snap-action “latch-on” switching.

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Jerguson® Horizontal External Cage Float Operated Switch

Features

  • Tri-Magnet Switching

  • Vibration Resistant

  • Sealed Cage

  • ANSI B31.1 Design

  • ANSI B31.3 Design

Operation

 A unique counter-balance design allows for a much heavier float than those used in a traditional external caged level switch in order to withstand extreme pressure and temperature.  As the float rises and falls with liquid level, it moves a pivot arm which is attached to the end of the float rod.  On the end of the float rod is a sheathed permanent magnet, just like all other external caged switch products.  A switch mechanism is mounted inside the enclosure adjacent to the pressure tube, and is activated by the rising or falling magnet.  The vertical movement of the float magnet in the pressure tube simultaneously actuates the secondary and switch magnets within the switch mechanism, to operate the contacts.  Switching is achieved with the unique tri-magnet system providing positive snap-action anti-vibration switching.

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