Magnesonics Level Equipment 

Jerguson Top Mount Displacer Level Switch

The displacer element is suspended on a stainless steel cable attached to a spring. The displacer is always heavier than its equivalent volume of the liquid in which it is to operate, and therefore will always extend the tension spring. Hanging freely in air, the spring extends to a predetermined length, limited by a mechanical stop to prevent overstressing. Attached to the spring is the magnet assembly which is free to move up and down as the spring . extends or contracts.

As rising liquid submerges the displacer, a buoyant force is created equal to the weight of the displaced liquid volume. This buoyancy force reduces the apparent displacer weight, contracting the spring, and moves the magnet up\yards inside the pressure tube actuating 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 simply resetting the displacers on the cable at the desired switch actuation point.

Features:

  • Tri-Magnet Switching
  • Vibration Resistant
  • Pump Control
  • Multi-Point Alarm
  • T316 SST Trim
 
Application:

Jerguson displacer operated switches are ideal for sump and other top mounted applications such as low level alarm in deep tanks. Their principle of operation also makes them suitable, in a modified form, for very high pressure or low S.G. applications.

The four typical displacer arrangements shown in the model selection guide cover the most common applications. However should you have a special configuration requirement, please consult the factory.

 
Internal Mount Displacer Types:

CODE

Function-Differential

Displacer

SPDT*

DPDT*

Tolerance

JDCID

Single Switch-Narrow

316-SST

.50- 1.2

.50- 1.2

N/A

JDC4D

Single Switch-Narrow

Porcelain

.50- 1.2

.50- 1.2

N/A

JDC2D

Single Switch-Wide

316-SST

.50- 1.2

.50- 1.2

±10%

JDC5D

Single Switch-Wide

Porcelain

.50- 1.2

.50- 1.2

±10%

JD3D

Dual Switch-Wide

316-SST

.60- 1.2

.80- 1.2

±5%

JDC6D

Dual Switch-Wide

Porcelain

.60- 1.2

.80-1.2

±5%

JDC8D

Dual Switch-Narrow

316-SST

.60- 1.2

.80- 1.2

±10%

JDC9D

Dual Switch-Narrow

Porcelain

.60- 1.2

.80- 1.2

±10%

 
Enclosure Types:

 

Duty

Mat'l of cover

Mat'l of base

Mat'l of press. tube

Mat'l of screwed union

Max no. of switches

SA7

Explosion-proof

Aluminum Alloy

316 Stainless Steel

To match chamber material

2 x four contact or 2 x eight contact

S17

Cast Iron

SA4

Weather-proof

Drawn Steel

Aluminum Alloy

 
International Approvals:

U

Underwriters Laboratories

Cl. I, Div. 1, Grp. C & D

C

Canadian Standards Association

Cl. 1, Div. 1, Grp. C & D

B

BASEEFA/CENELEC

E Exd ITC T6: BS5501: Pts 1 & 5

H Underwriters Laboratories Cl. I, Div. 1, Grp. B,C&D

N

Weatherproof to NEMA 4X/IP66

U.L. CSA EANSW 71

 
Number of Switch Mechanisms:
  Temp. Wet-Side AC max. values DC max. values
  °F VA Volts Amps Watts Volts Res. Amps Ind. Amps
D4 750 2000 440 5 50 250 5 0.5
X4 480 2000 440 10 50 250 10 0.5
H4 480 2000 440 10 50 250 10 0.5
P4 750 6 250 0.25 3.6 250 0.25 0.1
D8 750 2000 440 5 50 250 5 0.5
X8 480 2000 440 10 50 250 10 0.5
H8 480 2000 440 10 50 250 10 0.5
P8 750 6 250 0.25 3.6 250 0.25 0.1
 
Mounting Connection:

Code

Size

Carbon Steel Rating SST Rating

60

3" 150# R.F. ANSI

285 PSIG @ 100°F 275 PSIG @ 100°F

61

3" 300# R.F. ANSI

740 PSIG @ 100°F 720 PSIG @ 100°F

62

3" 600# R.F. ANSI

1480 PSIG @ 100°F 1440 PSIG @ 100°F

65

4" 150# R.F. ANSI

285 PSIG @ 100°F 275 PSIG @ 100°F

66

4" 300# R.F. ANSI

740 PSIG @ 100°F 720 PSIG @ 100°F

67

4" 600# R.F. ANSI

1480 PSIG @ 100°F 1440 PSIG @ 100°F

69

6" 150# R.F. ANSI

285 PSIG @ 100°F 275 PSIG @ 100°F

80

2-1/2" NPT

1000 PSIG @ 100°F 1000 PSIG @ 100°F

90

3" NPT

1000 PSIG @ 100°F 1000 PSIG @ 100°F
 
Enclosure Dimensional Data:

Type

Duty

Height

Conduit Thread

Weatherproof Rating

SA7, S17

Explosionproof

13-3/4"

1 " NPT

NEMA 4x & 7

SA4

Weatherproof

12"

1 " NPT

NEMA 4x

 
Materials of Construction:

Technical Specification

Model DC

Model DS

Material of Construction

Carbon Steel Connection

Stainless Steel Connection

Pressure Tube

ASTM A312 T316

ASTM A312 T3I6

Pressure Tube Fittine

1018 C.S.

T316 LSST

Flange

ASTM A105

ASTM A182 F316

Displacer

As Specified

As Specified

Spring

lnconel 625

lnconel 625

Trim T316 SST T316 SST
 
Options: Low temperature carbon steel materials - Controls to meet N.A.C.E. requirements - A comprehensive N.D.T. package.
 
The Switch Mechanism:
Switch Mechanism - Principle of Operation:
The switch mechanism is based on a unique Jerguson three-dimensional magnet design where the snap action is accomplished by the utilization of magnetic repulsion. The magnet mounted on the float rod causes the secondary magnet to rotate as it passes up and down. The switch magnet is repelled by the secondary and snaps to the opposite side. This causes the cradle to pivot, moving the push rods which operate the switch contacts. The result is positive snap action interlock switching ... no springs ... no spring problems.
Choice of Switch Mechanisms
Type Application
X4, X8 General Purpose - 10 amp mechanisms for general purpose duties up to 480° F
D4, D8 High temperature - 750° F mechanisms for high temperature applications up to 5 amps.
H4, H8 Hermetically sealed - Suitable for low temperature duties, contaminated atmosphere environments and intrinsically safe circuits.  All moving parts and contacts enclosed in an inert gas filled stainless steel enclosure.
P4, P8 Low current - Gold plated contact switch mechanisms for use in intrinsically safe or low power circuits up to 750° F
 
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