Jerguson® Mercury-Free Level Switch™

Jerguson Mercury-Free Level Switches feature a unique, snap-action tri-magnet switch that withstands heavy vibration and high cycle, high current applications. This mechanism has been tested to over 850,000 cycles without a failure.

 

Jerguson® External Cage Float Operated Magnetic Level Switch

The following video depicts the benefits of the Tri-Magnet level switch system compared to a standard micro-switch or mercury-switch mechanism in external cage level switches:

 

Picture1Features

• Tri-Magnet Switching
• Vibration Resistant
• Weatherproof
• Flameproof
• Sealed (shown) or Flanged Cage Body 
• 316 SS Trim
• ASME B31.1/B31.3 Design
 
 
 
 
 
 
 
 
 
 
 

Picture2Operation

 
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.

 

 

 

 

Jerguson® External Cage Displacer Operated Level Switch

Picture3

 

 

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 and 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 which is 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 is seen by the spring as a reduction in weight causing the spring to contract 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 reset the switch mechanism.

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

 

Jerguson® Top Mount Displacer Operated Level Switch

 

Picture4

 

Features

• Tri-Magnet Switching
• Vibration Resistant
• Weatherproof
• Flameproof
• 316 SS Trim
• ASME B31.1/B31.3 Design
• Pump Control
• Multi-Point Alarm
 

 

 

 

  

 

 

Operation

The displacer element(s) is made of either 316 Stainless Steel or Ceramic and is suspended on a Stainless Steel Rod from a spring.  The displacer element(s) 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 which is 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(s) a buoyancy force is created equal to the weight of the liquid displaced.  This force is seen by the spring as a reduction in weight causing the spring to contract moving the magnet upwards inside the pressure tube and actuating the switch mechanism.  On a falling liquid level, the displacer element(s) is uncovered and the spring sees an increasing effective weight causing the spring to extend and move the magnet to reset the switch mechanism.  This simple principle also operates a single switch over a very wide differential by simply providing the buoyancy force from two displacers instead of a single displacer.

Two switch models are available for either two alarm applications, two narrow differentials, or for pump control with appropriate wide differentials.  All models are fully field adjustable by simple re-setting the displacers on the cable at the desired switch actuation point.
 
 

Resources

 
 
 
                    Top Mount Displacer Operated Magnetic Level Switch Brochure