Jerguson Top Mount Displacer Level Switch
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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
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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.
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Internal Mount Displacer Types: |
CODE
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Function-Differential
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Displacer
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SPDT*
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DPDT*
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Tolerance
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JDCID
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Single Switch-Narrow
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316-SST
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.50- 1.2
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.50- 1.2
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N/A
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JDC4D
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Single Switch-Narrow
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Porcelain
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.50- 1.2
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.50- 1.2
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N/A
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JDC2D
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Single Switch-Wide
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316-SST
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.50- 1.2
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.50- 1.2
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±10%
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JDC5D
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Single Switch-Wide
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Porcelain
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.50- 1.2
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.50- 1.2
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±10%
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JD3D
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Dual Switch-Wide
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316-SST
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.60- 1.2
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.80- 1.2
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±5%
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JDC6D
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Dual Switch-Wide
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Porcelain
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.60- 1.2
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.80-1.2
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±5%
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JDC8D
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Dual Switch-Narrow
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316-SST
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.60- 1.2
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.80- 1.2
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±10%
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JDC9D
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Dual Switch-Narrow
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Porcelain
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.60- 1.2
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.80- 1.2
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±10%
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Enclosure Types: |
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Duty
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Mat'l of cover
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Mat'l of base
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Mat'l of press.
tube
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Mat'l of screwed
union
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Max no. of switches
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SA7
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Explosion-proof
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Aluminum
Alloy
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316 Stainless
Steel
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To match
chamber material
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2 x four
contact or 2 x eight
contact
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S17
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Cast
Iron
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SA4
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Weather-proof
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Drawn
Steel
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Aluminum
Alloy
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International Approvals: |
U
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Underwriters Laboratories
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Cl. I, Div. 1, Grp.
C & D
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C
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Canadian Standards Association
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Cl. 1, Div. 1, Grp.
C & D
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B
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BASEEFA/CENELEC
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E Exd ITC T6: BS5501:
Pts 1 & 5
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H |
Underwriters Laboratories |
Cl. I, Div. 1, Grp. B,C&D |
N
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Weatherproof to NEMA
4X/IP66
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U.L. CSA EANSW 71
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Number of Switch Mechanisms: |
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Temp. Wet-Side |
AC max. values |
DC max. values |
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°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 |
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Mounting Connection: |
Code
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Size
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Carbon Steel Rating |
SST Rating |
60
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3" 150# R.F. ANSI
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285 PSIG @ 100°F |
275 PSIG @ 100°F |
61
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3" 300# R.F. ANSI
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740 PSIG @ 100°F |
720 PSIG @ 100°F |
62
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3" 600# R.F. ANSI
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1480 PSIG @ 100°F |
1440 PSIG @ 100°F |
65
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4" 150# R.F. ANSI
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285 PSIG @ 100°F |
275 PSIG @ 100°F |
66
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4" 300# R.F. ANSI
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740 PSIG @ 100°F |
720 PSIG @ 100°F |
67
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4" 600# R.F. ANSI
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1480 PSIG @ 100°F |
1440 PSIG @ 100°F |
69
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6" 150# R.F. ANSI
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285 PSIG @ 100°F |
275 PSIG @ 100°F |
80
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2-1/2" NPT
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1000 PSIG @ 100°F |
1000 PSIG @ 100°F |
90
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3" NPT
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1000 PSIG @ 100°F |
1000 PSIG @ 100°F |
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Enclosure Dimensional Data: |
Type
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Duty
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Height
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Conduit Thread
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Weatherproof Rating
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SA7, S17
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Explosionproof
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13-3/4"
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1 " NPT
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NEMA 4x & 7
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SA4
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Weatherproof
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12"
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1 " NPT
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NEMA 4x
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Materials of Construction: |
Technical Specification
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Model DC
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Model DS
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Material of Construction
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Carbon Steel Connection
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Stainless Steel Connection
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Pressure Tube
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ASTM A312 T316
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ASTM A312 T3I6
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Pressure Tube Fittine
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1018 C.S.
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T316 LSST
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Flange
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ASTM A105
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ASTM A182 F316
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Displacer
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As Specified
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As Specified
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Spring
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lnconel 625
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lnconel 625
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Trim |
T316 SST |
T316 SST |
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Options: Low temperature carbon steel materials -
Controls to meet N.A.C.E. requirements - A comprehensive N.D.T.
package. |
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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. |
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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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