C74 External Cage Liquid Level Switches

C74 External Cage
Liquid Level Switches
Instruction Manual and Parts List
Description
C74 external cage liquid level switches are displacer
actuated units, utilizing a single switch mechanism for level
alarm or control functions. These units are designed
to provide high pressure/temperature capability with low
specific gravity.
Operating principle
The design of displacer operated level switches is based
upon the principle that a magnetic field will see through
non-magnetic materials such as 316 stainless steel. In this
case, the displacer moves a magnetic attraction sleeve
within a non-magnetic enclosing tube and actuates a switch
mechanism. The enclosing tube provides a pressure seal to
the chamber and therefore to the process.
3
4
5
3
6
2
1
5
4
5
Figure 1
Operating cycle
As the liquid level rises in the chamber, refer to Figure 1, the
displacer (5) moves the magnetic attraction sleeve (1) up
within the enclosing tube (4), and into the field of the switch
mechanism magnet (2). As a result, the magnet is drawn in
tightly to the enclosing tube causing the switch (3) to trip,
making or breaking an electrical circuit. As the liquid level
falls, the displacer drops and moves the attraction sleeve
out of the magnetic field, releasing the switch at a predetermined low level. Refer to Figure 2.
6
5
6
2
1
4
6
4
Figure 2
Unpacking
Unpack the instrument carefully. Inspect all units for
damage. Report any concealed damage to carrier within 24
hours. Check the contents of the packing slip and purchase
order. Check and record the serial number for future reference when ordering parts.
GENERAL INFORMATION
Part number construction
Model identification
C74 level controls are identified by a ten digit alphanumeric
part numbering system. The part number provides exact
specifications of unit configuration, materials of construction and other options vital to the performance of the
instrument.
C74-
-
Model number code and
materials of construction
Tank connection type and size
Switch mechanism and enclosure
MODEL number code & materials
of construction
Model Number
Code
Electric switch mechanism and enclosure Œ
Displacer Cage
Attraction
Sleeve
C74-1
Carbon Steel
400 SST
C74-2
Carbon Steel
316 SST
Trim
Inconel
and
316 SST
Tank connection type & size
Connection
Type
Threaded
Socket Weld
Flanged Upper
Side/Bottom
Flanged
Side/Side
Connection Size
1"
11⁄2"
2"
300 lb. 600 lb. 300 lb. 600 lb. 300 lb. 600 lb.
B70
B90
C70
C90
D70
D90
B80
B01
C80
C01
D80
D01
N40
N50
P40
P50
Q40
Q50
S40
S50
T40
T50
V40
V50
Note: Flanges are ANSI raised face.
Pneumatic switch mechanism & enclosure
NEMA 1
Max.
Max.
Bleed
Switch
C74-2
Supply Process Orifice
Description Pressure Temp. Diameter C74-1
300 lb. 600 lb.
100 PSIG
.063
JDE
JDE
JKE
(7 Bar)
(1.6 mm)
Series J
Bleed Type 60 PSIG 400° F
.094
JEE
JEE
JLE
(4 Bar) (204° C) (2.4 mm)
Series K
100 PSIG
—
KOE
KPE
Non-Bleed (7 Bar)
2
Switch 
Description
Max. Ž
Process One
Set
Temp.
Point
° F (° C)
Series A
Mercury Switch
500
(260)
Series B
Snap Switch
250
(121)
Series C
Snap Switch
450
(232)
Series D
Snap Switch
for DC Current
Application
Series E
Vibration
Resistant
Mercury Switch
Series F
Hermetically
Sealed
Snap Switch
Series HS
Hermetically
Sealed
Snap Switch
w/Wiring Leads
Series HS
Hermetically
Sealed
Snap Switch w/
Terminal Block
250
(121)
500
(260)
500
(260)
500 
(260)
500 
(260)
NEMA 4X/7/9
SPDT
DPDT
SPDT
DPDT
SPDT
DPDT
Alum.,
Polymer
Coated
AKQ
ANQ
BKQ
BNQ
CKQ
CNQ
Alum.,
Cl I Div. 1
Group B
AKS
ANS
BKS
BNS
CKS
CNS
SPDT
DKQ
DKS
DPDT
DNQ
DNS
SPDT
EKQ
EKS
DPDT
ENQ
ENS
SPDT
FKQ
FKS
DPDT
FNQ
FNS
SPDT
HMC
HEK
DPDT
HMF
HET
SPDT
HM3
HM4
DPDT
HM7
HM8
Œ Consult factory for NEMA 4X/7/9 cast iron housings.
 Uncontrolled housing heater; drain available in NEMA 4X/7/9
enclosures. Consult factory for switch codes.
Ž Process temperature based on +100° F (+38° C) ambient.
 On condensing applications, temperature down-rated to +400° F
(+204° C) process at +100° F (+38° C) ambient.
INSTALLATION
Critical alarm function
Mounting
It is recommended that for critical alarm functions, an additional level switch be installed as a high–high or low–low
level alarm for maximum protection.
Adjust piping as required to bring control to a vertical position. Magnetrol controls must be mounted within three
degrees (3°) of vertical. A three degree slant is noticeable by
eye, but installation should be checked with a spirit level on
top and/or sides of float chamber.
Piping
Figure 3 shows a typical piping installation of a C74 control
to a pressure vessel. An instruction tag secured to the control gives dimensional data on switch actuating levels
referenced from center line of upper side tank connection.
Position control so that actuating levels correspond with the
desired liquid level trip points in process vessel.
Controls should be mounted as close to the vessel as possible. This will result in a more responsive and accurate level
change in the control. Liquid in a long line may be cooler
and more dense than liquid in the vessel causing lower level
indication in the control than actual level in the vessel.
Use pipe of sufficient strength to support the control. If necessary, provide a stand or hanger to help support its weight.
All piping should be straight and free of “low spots” or
“pockets” so that lower liquid line will drain towards the vessel and upper vapor line will drain toward the control.
Shut-off valves are recommended for installation between
the vessel and the control. If control is to be used with a low
temperature liquid (one which will “boil” in the float chamber
if outside heat is absorbed), the chamber and piping should
be insulated. Such boiling in the chamber will cause
false level indications.
Wiring
DO NOT INSULATE SWITCH MECHANISM HOUSING.
On controls equipped with pneumatic switch assemblies,
consult bulletin on mechanism furnished for air (or gas) piping instructions. Refer to chart on Page 4 for bulletin
numbers for pneumatic switches.
CAUTION: All Series C74 units are shipped from the
factory with the enclosing tube tightened and the
switch housing set screw locked to the enclosing tube.
Failure to loosen the set screw prior to repositioning the
supply and output connections my cause the enclosing
to loosen, resulting in possible leakage if the process
liquid or vapor.
C74 controls are shipped with the conduit entry of the
switch housing placed 180° opposite to the tank configurations to simplify installation in most cases. If this
configuration is appropriate to the installation, proceed to
Step 4 to begin wiring the unit. If another configuration is
desired, the switch housing can be easily rotated by first following Steps 1, 2, and 3.
Conduit Outlet
LL
Pressure
Vessel
HL
Screw
Set
Screw
Screw
Figure 4
Shut-Off
Valve
Drain Valve
1. Loosen set screw(s) at base of switch housing. Refer to
Figure 4.
2. Switch housing may be rotated 360° to allow correct
positioning of conduit outlet.
3. Tighten set screw(s) at base of switch housing.
Max. 12"
Figure 3
Typical Piping Arrangement
4. Unscrew and remove switch housing cover. The threads
have been lubricated to facilitate removal.
NOTE: On high temperature applications (above 250° F
[121° C] in float chamber), high temperature wire should be
used between control and first junction box located in a
cooler area.
5. The switch terminals are located next to the conduit outlet to facilitate wiring. Bring supply wires through conduit
outlet. Route extra wire around enclosing tube under the
baffle plate, and connect them to the proper terminals.
Refer to the wiring diagram in your switch bulletin for this
information.
3
INSTALLATION cont.
Wiring cont.
Switch Series
Letter
A
B, C, D
E
F
HS
J
K
Wiring cont.
Bulletin
No.
Description
Standard Mercury Switch
Dry Contact Switch
Vibration Resistant Mercury Switch
High Temperature Hermetically
Sealed Snap Switch
Hermetically Sealed Snap Switch
Bleed Type Pneumatic Switch
Non-Bleed Type Pneumatic Switch
42-683
7. Replace housing cover.
8. If control has been furnished with an explosion proof or
moisture proof (gasketed) switch housing, it must be
sealed at the conduit outlet with a suitable compound
or non-hardening sealant to prevent entrance of air.
9. Test switch action by varying liquid level in float chamber.
42-694
42-685
42-686
NOTE: For models with a Series HS switch with high temperature lead wire, the leads are routed out through the
conduit opening by the factory. A suitable conduit box
should be provided for the connection of the leads to the
control wiring.
NOTE: If switch mechanism fails to function properly, check
vertical alignment of control housing and consult installation
bulletin on switch mechanism furnished.
10. Check cover to base fit to be certain gasketed joint is
tight. A positive seal is necessary to prevent infiltration
of moisture laden air or corrosive gasses into switch
housing.
Internal Circuit
(Left) Switch
OBSERVE ALL APPLICABLE ELECTRICAL CODES
AND PROPER WIRING PROCEDURES.
CAUTION: In hazardous areas, do not power the unit
until the conduit is sealed and the enclosure cover is
screwed down securely.
1
6
3
5
6. Dress wiring to ensure no interference or contact with tilt
of switch, or replacement of switch housing cover.
Prevent moisture seepage into the enclosure by
installing approved seal-drain fittings in the conduit run
leading into the unit.
4
Close on high level
Common
Line
Close on low level
Load
Load
Internal Circuit
(Right) Switch
2
Load
Load
Close on high level
Common
Close on low level
Line
Terminal Connections
DPDT Switch Mechanism
Series A, B, C, D, E, and F
PREVENTIVE MAINTENANCE
Periodic inspections are a necessary means to keep your level control in good working order. This control is a safety
device to protect the valuable equipment it serves. Therefore, a systematic program of “preventive maintenance”
must be implemented when the control is placed into service. If the following sections on “what to do” and “what to
avoid” are observed, your control will provide reliable protection of your capital equipment for many years.
What to do
1. KEEP CONTROL CLEAN.
Be sure the switch housing cover is always in place on
the control. This cover is designed to keep dust and dirt
from interfering with switch mechanism operation. In
addition, it protects against damaging moisture and acts
as a safety feature by keeping bare wires and terminals
from being exposed. Should the housing cover or any
seals become damaged or misplaced, obtain a replacement immediately.
2. INSPECT SWITCH MECHANISMS, TERMINALS AND
CONNECTIONS MONTHLY.
a. Mercury switches may be visually inspected for short
circuit damage. Check for small cracks in the glass
tube containing the mercury. Such cracks can allow
entrance of air into the tube causing the mercury to
“oxidize”. This is noticeable as the mercury will
appear dirty or dull, and will not break into clean,
round pools. If these conditions exist, replace the
mercury switch immediately.
4
What to do cont.
b. Dry contact switches should be inspected for
excessive wear on actuating lever or misalignment of
adjustment screw at point of contact between screw
and lever. Such wear can cause false switch actuating
levels. Adjust switch mechanism to compensate (if
possible) or replace switch.
c. DO NOT operate your control with defective or
maladjusted switch mechanisms (refer to bulletin on
switch mechanisms furnished for service instructions.)
d. Level controls may sometimes be exposed to
excessive heat or moisture. Under such conditions,
insulation on electrical wiring may become brittle,
eventually breaking or pealing away. The resulting
“bare” wires can cause short circuits.
Check wiring carefully and replace at the first sign of
brittle insulation.
e. Vibration may sometimes cause terminal screws to
work loose. Check all terminal connections to be
certain that screws are tight.
INSTALLATION cont.
What to do cont.
What to avoid
2. INSPECT SWITCH MECHANISMS, TERMINALS AND
CONNECTIONS MONTHLY. CONT.
1. NEVER leave switch housing cover off the control longer
than necessary to make routine inspections.
f. On units with pneumatic switches, air (or gas)
operating medium lines subjected to vibration, may
eventually crack or become loose at connections
causing leakage. Check lines and connections
carefully and repair or replace, if necessary.
2. NEVER place a jumper wire across terminals to “cut-out”
the control. If a “jumper” is necessary for test purposes,
be certain it is removed before placing control into
service.
NOTE: As a matter of good practice, spare switches should
be kept on hand at all times.
3. INSPECT ENTIRE UNIT PERIODICALLY.
Isolate control from vessel. Raise and lower liquid level to
check for switch contact and reset.
3. NEVER attempt to make adjustments or replace
switches without reading instructions carefully. Certain
adjustments provided for in level controls should not be
attempted in the field. When in doubt, consult the factory
or your local representative.
4. NEVER use lubricants on pivots of switch mechanisms.
A sufficient amount of lubricant has been applied at the
factory to ensure a lifetime of service. Further oiling is
unnecessary and will only tend to attract dust and dirt
which can interfere with mechanism operation.
TROUBLESHOOTING
Usually the first indication of improper operation is failure of
the controlled equipment to function, i.e.: pump will not start
(or stop), signal lamps fail to light, etc. When these
symptoms occur, whether at time of installation or during
routine service thereafter, check the following potential
external causes first.
—Fuses may be blown
—Reset button(s) may need resetting.
—Power switch may be open.
—Controlled equipment may be faulty.
—Wiring leading to control may be defective.
If a thorough inspection of these possible conditions fails to
locate the trouble, proceed next to a check of the control's
switch mechanism.
Check switch mechanism
1. Pull disconnect switch or otherwise disconnect power to
the control.
2. Remove switch housing cover.
CAUTION: Unit must be normalized to atmospheric
pressure before removing switch housing assembly.
3. Disconnect power wiring from switch assembly.
4. Swing magnet assembly in and out by hand to check
carefully for any sign of binding. Assembly should require
minimal force to move it through its full swing.
5. If binding exists, magnet may be rubbing enclosing tube.
If magnet is rubbing, loosen magnet clamp screw and
shift magnet position. Retighten magnet clamp screw.
6. If switch magnet assembly swings freely and mechanism
still fails to actuate, check installation of control to be
certain it is within the specified three (3°) degrees of
vertical. (Use spirit level on side of enclosing tube in two
places, 90° apart. Refer to Figure 3.
7. If mechanism is equipped with a mercury switch,
examine glass mercury tube closely as previously
described in “Preventive Maintenance” section. If switch
is damaged, replace it immediately. If microswitch, check
continuity with ohmmeter.
8. If switch mechanism is operating satisfactorily, proceed
to check sensing unit.
Check sensing unit
1. Check to be certain liquid is entering float chamber. A
valve may be closed or piping plugged.
2. With liquid in chamber, proceed to check level sensing
action by removing switch housing assembly and
enclosing tube.
3. Inspect attraction sleeve and inside of enclosing tube for
excessive corrosion or solids build-up which could restrict
movement, preventing sleeve from reaching field of
magnet.
4. Never change the settings of the jam nuts which position
the magnet attractor.
5. Remove parting flange. Check spring and displacer
assembly for freedom of movement. Check for collapsed
or liquid filled displacer. If displacer is determined to be
filled or collapsed, contact the factory.
Check complete unit
Reassemble unit. Reconnect power supply and carefully
actuate switch mechanism manually (using a non-conductive tool) to determine whether controlled equipment will
operate.
CAUTION: With electrical power “on”, care should be
taken to avoid contact with switch leads and
connections at terminal block.
If all components in the control are in operating condition,
the trouble must be (and should be) located external to the
control. Repeat inspection of external conditions previously
described.
NOTE: If difficulties are encountered which cannot be
identified, consult the factory or your local representative for
assistance. A complete description of the trouble should be
provided along with information concerning your piping and
mounting arrangement, plus a description of your operating
sequence. Sketches or photographs showing the installation
are also beneficial.
When communicating about your control, be certain always
to specify the complete Model and Serial numbers.
5
SPECIFICATIONS
5.93
(150)
5.93
(150)
5.93
(150)
6.25 Œ
(158)
D
7.94 Œ
(201)
7.94
Œ
(201)
6.25
Œ
(158)
D
7.94
(201) Œ
6.25
Œ
(158)
D
D
D
D
Plugged
Plugged
Plugged
HL
HL
HL
C
3.78 (96)
3.78 (96)
3.78 (96)
C
LL
LL
C
LL
A
A
A
B
B
B
Vertical Flanges
Upper Side/Bottom
Threaded and Socket Weld
Upper Side/Bottom
Conn. Flange
Size Rating
1"
11⁄2"
2"
NPT Threaded
& Socket Weld
A
B
C
300 lb. 15.65 2.77 22.69 (601)
600 lb. (397) (70) 23.06 (585)
Upper Side/
Bottom Flanges
A
B
C
5.45 25.38 (644)
(138) 25.75 (653)
Horizontal Flanges
Side/Side
Side/Side
Flanges
A
B
C
5.45 26.0 (270)
(138) 26.38 (670)
300 lb. 15.77 3.19 22.81 (579) 18.33 6.19 25.38 (644) 18.97 6.19 26.0 (270)
600 lb. (400) (81) 23.19 (589) (465) (157) 25.75 (653) (481) (157) 26.38 (670)
300 lb. 15.90 3.31 22.94 (582)
600 lb. (403) (84) 23.31 (592)
6.25 25.38 (644)
(158) 25.75 (653)
6.25 26.0 (270)
(158) 26.38 (670)
Œ These dimensions increase by 2.19 when used with series HS Switch w/ Terminal Block.
6
Conduit Connections D
Electric Switches:
NEMA 4X/7/9: 1" NPT
Group B:
1" NPT
Pneumatic Switches:
1
NEMA 1:
⁄4" NPT
SPECIFICATIONS cont.
Actuating Levels In Inches
Liquid Specific Gravity
Process
Temperature
°F (°C)
0.40
HL
LL
0.50
HL
LL
0.60
HL
LL
HL
0.70
LL
HL
0.80
LL
HL
0.90
LL
HL
1.00
LL
100 (38)
4.38
8.24
5.56
8.74
6.35
9.07
6.92
9.31
7.34
9.49
7.67
9.63
7.94
200 (93)
4.01
7.83
5.27
8.41
6.11
8.80
6.71
9.08
7.16
9.28
7.51
9.44
7.79
9.74
9.57
300 (149)
3.59
7.36
4.94
8.04
5.83
8.49
6.47
8.81
6.95
9.05
7.32
9.24
7.62
9.39
400 (205)
3.13
6.84
4.56
7.62
5.52
8.14
6.20
8.51
6.72
8.79
7.12
9.00
7.44
9.18
500 (260)
2.61
6.26
4.15
7.15
5.18
7.75
5.91
8.18
6.46
8.50
6.89
8.75
7.23
8.94
Actuating Levels In Millimeters
Liquid Specific Gravity
Process
Temperature
°F (°C)
HL
LL
HL
LL
HL
LL
HL
LL
0.80
HL
LL
0.90
HL
LL
1.00
HL
LL
100 (38)
111
009
141
222
161
230
176
236
186
195
202
0.40
0.50
0.60
0.70
241
245
247
200 (93)
102
199
134
214
155
224
170
231
182
236
191
240
198
243
300 (149)
91
187
125
204
148
216
164
224
177
230
186
235
194
239
400 (205)
80
174
116
194
140
207
157
216
171
223
181
229
189
233
500 (260)
66
159
105
182
132
197
150
208
164
216
175
222
184
227
3
REPLACEMENT PARTS
Item
Description
1
2
Housing Cover
Housing Base
3
Switch Mechanism
4
Enclosing Tube
5
E-Tube Gasket
Head Flange
Gasket
6
7
Bolts and Nuts
8
Spring and
Stem Assy.
9
Displacer Assy.
10
Chamber and
Flange Assy
Replacement Part Number
Housing Kit
Refer to bulletin on switch
mechanism and housing
furnished (listed on page 4).
300 lb.
600 lb.
032-6325-002
032-6325-003
012-1204-001
1
4
2
7
5
6
012-1204-019
300 lb.
600 lb.
C74-1 (300 lb.)
C74-1 (600 lb.)
C74-2 (300 lb.)
C74-2 (600 lb.)
300 lb.
600 lb.
089-3101-001
089-3102-001
089-5321-001
089-5322-001
089-5323-001
089-5324-001
089-6137-001
089-6138-001
Chamber and head flange
assemblies are available by
contacting the factory.When
ordering specify model and
serial number of control.
8
10
9
7
PRODUCT WARRANTY
QUALITY ASSURANCE
All Magnetrol mechanical level and flow controls are warranted free of defects in materials or workmanship for five
full years from the date of original shipment. Repair parts
are warranted free of defects in materials and workmanship
for one year from the date of shipment. Materials, specifications, and contents are subject to change without prior
written notice.
The quality assurance system in place at Magnetrol guarantees the highest level of quality
throughout the company. Magnetrol is
committed to providing full customer
satisfaction both in quality products
and quality service.
If returned within the warranty period; and, upon factory
inspection of the control, the cause of the claim is determined to be covered under the warranty; then, Magnetrol
will repair or replace the control at no cost to the purchaser
(or owner) other than transportation.
Magnetrol’s quality assurance system
is registered to ISO affirming its commitment to known international quality
standards providing the strongest
assurance of product/service quality available.
Magnetrol shall not be liable for misapplication, labor
claims, direct or consequential damage or expense arising
from the installation or use of equipment. There are no other
warranties expressed or implied, except special written warranties covering some Magnetrol products.
ASSURED QUALITY & SERVICE COST LESS
SERVICE POLICY
RETURN MATERIAL PROCEDURE
Owners of Magnetrol may request the return of a control or
any part of a control for complete rebuilding or replacement. They will be rebuilt or replaced promptly. Controls
returned under our service policy must be returned by
Prepaid transportation. Magnetrol will repair or replace the
control at no cost to the purchaser (or owner) other than
transportation if:
So that we may efficiently process any materials that are
returned, it is essential that a “Return Material
Authorization” (RMA) number be obtained from the factory,
prior to the material’s return. This is available through
Magnetrol local representative or by contacting the factory.
Please supply the following information:
1. Returned within the warranty period; and
2. The factory inspection finds the cause of the claim to
be covered under the warranty.
If the trouble is the result of conditions beyond our control;
or, is NOT covered by the warranty, there will be charges for
labor and the parts required to rebuild or replace the equipment.
In some cases it may be expedient to ship replacement
parts; or, in extreme cases a complete new control, to
replace the original equipment before it is returned. If this is
desired, notify the factory of both the model and serial numbers of the control to be replaced. In such cases, credit for
the materials returned will be determined on the basis of the
applicability of our warranty.
1.
2.
3.
4.
5.
Company Name
Description of Material
Serial Number
Reason for Return
Application
Any unit that was used in a process must be properly
cleaned in accordance with OSHA standards, before it is
returned to the factory.
A Material Safety Data Sheet (MSDS) must accompany
material that was used in any media.
All shipments returned to the factory must be by prepaid
transportation.
All replacements will be shipped F.O.B. factory.
No claims for misapplication, labor, direct or consequential
damage will be allowed.
LOW VOLTAGE DIRECTIVE
For use in Category II installations. If equipment is used in a
manner not specified by ,manufacturer, protection provided
by equipment may be impaired.
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Regent Business Ctr., Jubilee Rd. • Burgess Hill, Sussex RH15 9TL U.K. • 01444-871313 • Fax 01444-871317
Copyright © 2009 Magnetrol International, Incorporated. All rights reserved. Printed in the USA.
BULLETIN: 46-609.3
EFFECTIVE: January 2000
SUPERSEDES: June 1996