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User’s Guide
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FSW-50 Series
Industrial Flow Switches
M0772/0802
General Description
Notes
®
The OMEGA FSW-50 Series Flow Switches feature a 15A SPDT switch
and an internal screw adjustment which provides continuous switch point
adjustment while in operation in-line. Multiple drag disks are supplied
with each unit to provide incremental switch point adjustment. Their non-
magnetic design makes them ideal for applications where rust is a problem.
The FSW-50 comes standard in a plastic/316SS construction. The FSW-50
Series is also available in a special PPS* Hastelloy C and Viton construction.
The FSW-50 Series are for use in highly particle-contaminated liquids
such as sewage, machine cutting oils and medium slurries. The standard
models can be used in mildly corrosive liquids such as low to medium
concentration acids and bases; sea water, sewage oils; rusty coolant water,
etc. The special PPS* Hastelloy C and Viton construction models are for
use in concentrated corrosive liquids such as sulfuric, nitric, hydrochloric
and acetic acids; ferric chloride; aqueous ammonia; benzene; magnesium
chloride, etc.
Particle contamination resistance is provided by a flexible filter boot
which prevents crystallization, caking, heavy dirt concentration, slurries,
scum, etc., from affecting the operation of the flow detector. The FSW-50
Series Switches respond to flow only, independent of line pressure,
temperature and environment.
During emergency conditions these switches signal catastrophic system
failures such as line breakage; pump failure; incorrect valve opening or
closing; pipe, valve or filter clogging, etc.
Specifications
FLOW RANGE (water calibrated @ 70˚F)
The maximum flow range flexibility is provided by three adjustment
options:
1. Continuous adjustment while operating via a calibrated
FORCE/BALANCE spring.
2. Step incremental adjustment via drag disk size change.
3. Continuous adjustment via moment arm change.
12
1
Notes
Available Drag Disks
The FSW-50 Series Switches come with three different drag disks. The
drag disks are sized as follows:
DRAG DISK
SIZE
#1
#2
#3
.5" dia.
.83" dia.
1.0" dia.
The following table lists flow adjustment limits for various pipe sizes
relative to Model No. and drag disk size. The moment arm (see Step 3 of
FLOW RANGE) is held constant at the maximum value. Decreasing the
moment arm, increases the adjustment range.
Low Flow
Model
Number
Nominal
Low Flow
Cont. Adj.
Range
Pipe
Size
(Ins.)
Nominal
High Flow
Cont. Adj.
Range
High Flow
Model
Number
% Increase
of Listed
Flows via
Moment
(GPM)
(GPM)
Arm Adj.
FSW-50 w/drag
disk #2
* **
8-13
* **
18-28
FSW-50 w/drag
disk #1
1
None
Shortest drag
disk arm.
Mid. size
Shortest drag
disk arm.
Smallest drag
disk
3.3-5.3
ft/sec
7.4-11.5
ft/sec
drag disk
1
/
2
FSW-51 w/drag
disk #3
15-30
25-50
40-80
1
30-60
50-105
80-155
FSW-51 w/drag
disk #1
2
None
1
/
2
2
Mid. size
drag disk
arm. Largest
drag disk
Mid. size
drag disk
arm. Smallest
drag disk
2.7-5.4
ft/sec
5.4-10.8
ft/sec
FSW-52 w/drag
disk #3
40-90
3
90-180
120-240
155-310
245-480
350-700
600-1200
950-1900
FSW-52 w/drag
disk #1
1
/
2
60-120
3
+25%
75-155
4
5
Longest drag
disk arm.
Largest
120-245
180-350
300-600
500-950
Longest drag
disk arm.
Smallest
6
8
drag disk
10
drag disk
2.4-4.0
ft/sec
4.0-8.0
ft/sec
**Force/Balance spring relaxed.
**Force/Balance spring fully extended.
2
11
Relay Switch:
SPDT 15A @ 125 or 250 Vac, 10,000,000
operations median
Notes
Nominal Sensitivity
(% Flow Change to
Activate Switch):
Approximately 10% @ upper end of
range; approximately 30% @ lower end of
range
Differential Pressure
Drop Across Unit:
(Under normal operating conditions)
1"-3" pipe, less than 0.5 PSI; 4"-10" pipe,
negligible
Working Line Pressure:
For standard construction model: 100
PSIG at 150˚F; for special PPS*, Hastelloy
C and Viton construction model: 100
PSIG at 200˚F
Maximum Continuous
Temperature:
Standard construction: 150˚F; special
construction: 200˚F
Wetted Parts:
Standard construction PPS*, 316 SS, Viton
PVC; Special construction: PPS*,
Hastelloy C and Viton
Electrical Cable Fitting:
Weight:
Water resistant for cable diameters .250"
0.25"
0.25 lb.
PPS* = polyphenylene sulfide plastic
Installation Dimensions
INSTALLATION WARNING
1
1
/
4
/
2
THE 1 " X 1 " PVC BUSHING (WHITE OR GRAY) SUPPLIED WITH THE FSW-50 SERIES CAN BE
CRACKED IF THE CENTER BODY IS FIRST TIGHTENED INTO THE BUSHING. CRACKING PROBABILITY
IS REDUCED IF THE BUSHING IS FIRST TIGHTENED INTO THE PIPE OR TANK FITTING AND THEN THE
CENTER BODY TIGHTENED INTO THE BUSHING. THUS:
STEP 1: THREAD AND TIGHTEN THE PVC BUSHING INTO THE PIPE OR TANK FITTING.
STEP 2: THREAD AND TIGHTEN THE CENTER BODY INTO THE PVC BUSHING.
10
3
ASSEMBLY WARNING
THE FSW-50 SERIES SWITCHES EMPLOY AN EXTERNAL SEAL SHAFT (A) A FLEXIBLE ELASTOMER
DIAPHRAGM SEAL (B) AND AN INTERNAL FEED THRU SHAFT OR SWITCH ACTUATING ARM (D). ALL
THREE ELEMENTS ARE ASSEMBLED AND LOCKED IN PLACE WITH LOCTITE ADHESIVE. TO PREVENT
RUPTURE OF SEAL AND LEAKAGE INTO SWITCH AREA, IT IS CRITICALLY IMPORTANT THAT TORQUE
NOT BE APPLIED TO SEAL SHAFT (A), FLOAT SHAFT (E) OR DRAG DISK ARM (E) DURING CHANGE
OF FLOAT OR DRAG DISK.
10402-6. GROMMET
10402-5. STRAIN RELIEF NUT
IF FLOAT SHAFT OR DRAG DISK ARM (E) REQUIRE REPLACEMENT IT IS NECESSARY TO REMOVE
FILTER BOOT (F). SEAL SHAFT (A) MUST THEN BE HELD FIRMLY IN A VISE OR WITH PLIERS WHILE (E)
IS UNTHREADED AND A NEW SHAFT IS ASSEMBLED.
10402-2. COVER
3. 4 RETAINING SCREWS
(NOT SHOWN)
10402-27. LEADSCREW
10402-30. MICROSWITCH COMPLETE
WITH 3 SLIP-ON TERMINALS
10402-29. LEADSCREW NUT
10402-28. LEADSCREW RETAINING
SLEEVE
10402-23. MICROSWITCH BRACKET
COMPLETE WITH SPRING LEVER
10402-26. ADJUSTING SPRING
10402-1. BODY
10402-31. 2 SCREWS
32. 2 NUTS
33. 2 SPLIT LOCKWASHERS
34. 1 PLAIN WASHER
1
4
10402-35. 1 / " x 1" BUSHING
10402-4. O-RING
SUPPLIED
10402-24. 2 SCREWS
25. 2 SPLIT LOCKWASHERS
DIAPHRAGM CLAMPING
(SONICALLY WELDED)
10402-21. SEAL SHAFT ASSEMBLY
SUPPLIED ONLY COMPLETE WITH
A) SEAL SHAFT
B) DIAPHRAGM
C) DIAPHRAGM WASHER
D) FEED THRU SHAFT
3 RETAINING SCREWS
Installation
The FSW-50 Series Fluid Flow Switch is supplied with a 11/ " x 1" PVC TT
4
bushing (standard construction model) or 11/ " x 1" PPS* bushing (special
10402-15. DRAG DISK ARM MODEL FSW-50
16. DRAG DISK ARM MODEL FSW-51
17. DRAG DISK ARM MODEL FSW-52
4
PPS* Hastelloy C and Viton construction model) threaded in place with 2
to 3 wraps of Teflon tape, which must be intact or renewed if bushing and
switch are separated before assembly in tank. Care must be exercised
when threading the bushing into plastic or metal fittings.
Apply a minimum of 2 to a maximum of 3 wraps of Teflon tape to
threads of bushing – this is especially important if unit is to be used in
metal fittings where coarse metal threads could gall plastic if not
lubricated.
WARNING
10402-18. DRAG DISK #1 (SMALL)
19. DRAG DISK #2 (MEDIUM)
20. DRAG DISK #3 (LARGE)
DO NOT APPLY TORQUE TO DRAG DISK
ARM SINCE IT MAY BE UNTHREADED
FROM SEAL SHAFT (A).
The plastic bushing CAN BE CRACKED if the main body of the flow
switch is tightened into it FIRST. Cracking will not occur if the bushing is
FIRST tightened into the pipe or tank fitting and THEN the body is
tightened into the bushing.
PPS* = polyphenylene sulfide plastic
FSW-50 Series w/Special Ryton R-4, Hastelloy C and Viton Construction
Parts Diagram
4
9
Thus: 1. Teflon tape thread and tighten the plastic bushing into the pipe
or tank fitting.
2. Teflon tape thread and tighten the switch into the PLASTIC
bushing by applying a wrench to the hexagon section. Repeat
steps 1 and 2 until the ARROW on the body points in the
DIRECTION OF FLOW and threads are leak tight.
10398-6. GROMMET
10398-5. STRAIN RELIEF NUT
NOTE
10398-2. COVER
3. 4 RETAINING SCREWS
(NOT SHOWN)
10398-28. LEADSCREW
Plumber’s tools such as pipe wrenches are not recommended. If possible, use a ‘Rigid’ type
wrench where the smooth jaws closely fit the hexagon section.
10398-31. MICROSWITCH COMPLETE
WITH 3 SLIP-ON TERMINALS
10398-30. LEADSCREW NUT
Electrical Wiring
1. Remove gland nut, grommet and switch cover.
2. Strip outer jacket of electrical cord back approximately 11/ inches.
10398-29. LEADSCREW RETAINING
SLEEVE
10398-24. MICROSWITCH BRACKET
COMPLETE WITH SPRING LEVER
4
Strip insulation from individual conductors back approximately
1
10398-27. ADJUSTING SPRING
10398-1. BODY
/ inch.
4
10398-32. 2 SCREWS
33. 2 NUTS
3. Slip on terminals are supplied with each switch. Remove from switch
terminals and crimp on or solder to electrical leads.
34. 2 SPLIT LOCKWASHERS
35. 1 PLAIN WASHER
4. Feed electrical cable through gland nut, grommet and switch cover as
shown.
1
4
10398-36. 1 / " x 1" BUSHING
10398-4. O-RING
SUPPLIED
10398-25. 2 SCREWS
26. 2 SPLIT LOCKWASHERS
10398-10. DIAPHRAGM CLAMP RING
(SONICALLY WELDED)
10398-22. SEAL SHAFT ASSEMBLY
SUPPLIED ONLY COMPLETE WITH
A) SEAL SHAFT
B) DIAPHRAGM
C) DIAPHRAGM WASHER
D) FEED THRU SHAFT
5. Apply slip on terminals to appropriate contacts of microswitch.
3 RETAINING SCREWS
6. Slide the cover down the cable and fasten to the body of the switch
with 4 screws provided.
7. Slide the grommet down the cable until the outer jacket is level with
the small end of the grommet.
10398-16. DRAG DISK ARM MODEL FSW-50
17. DRAG DISK ARM MODEL FSW-51
18. DRAG DISK ARM MODEL FSW-52
FLEXIBLE DRAG STRIP ASSEMBLY
IS AVAILABLE TO REPLACE DRAG
DISK AND DRAG DISK ARM. NO
FILTER BOOT IS USED.
8. Push the grommet into the tapered end of the cover. Hold the cable
jacket to prevent rotation and thread the gland nut firmly on to the
cover.
10398-37. DRAG STRIP
38. CLAMP WASHER
Figure 1: Wiring Schematic for power applied to the load when the flow level is
less than set point (power to load interrupted when flow increases to above set
point).
39. DAMPENER WASHER
40. SCREW x 3/8" LONG
41. 2 PLAIN WASHERS
42. SPLIT LOCK WASHER
10398-19. DRAG DISK #1 (SMALL)
20. DRAG DISK #2 (MEDIUM)
21. DRAG DISK #3 (LARGE)
WARNING
DO NOT APPLY TORQUE TO DRAG DISK
ARM SINCE IT MAY BE UNTHREADED
FROM SEAL SHAFT (A).
FSW-50 Series w/Standard Construction Parts Diagram
8
5
6. If the system flow rate is changed, the FSW-50 can be adjusted to
monitor the new flow rate by turning the adjusting screw in a
counterclockwise direction to the minimum flow position and then
proceeding as in Step 4 above.
Figure 2: Wiring Schematic for power applied to load when the flow is greater
than set point (power to load interrupted when flow decreases to below set
point).
7. In the event that the system flow is at the desired rate and the
adjustment mechanism runs out of travel, i.e., the leadscrew nut is at
either end of the support bracket before the microswitch is actuated,
then the drag disk must be changed to shift the flow range so that it
straddles the system flow rate.
EXAMPLE: If the FSW-50 is fitted with a No. 1 drag disk and the
procedure in Step 4 has been followed, the adjusting screw has been
turned counterclockwise until the leadscrew nut is at the extreme end of
the support bracket (spring fully relaxed) and the microswitch still has
not been actuated, then the flow is too low and a larger drag disk will
have to be substituted for the drag disk #1 and the procedure in Step 4
repeated. If the No. 2 disk will not allow switch actuation via the
procedure in Step 4, substitute disk No. 3.
Switch Point Adjustment
The opposite procedure is used if the flow is so high that full extension of
the spring cannot counterbalance the fluid forces on the drag disk and the
switch remains actuated. Proceed by using a smaller drag disk, e.g.,
replace No. 3 with a No. 2, or a No. 2 with a No. 1 until the procedure in
Step 4 can be accomplished.
1. Thread the unit into line while observing the following precautions:
a) Use appropriate adapters to keep the body of the switch from
projecting into the flow stream.
b) Inspect to make sure that the drag disk does not touch the opposite
wall of a small diameter pipe.
Adjusting the moment arm can be employed after adjustment by the
spring and changing drag disk sizes have been tried to no avail.
Adjusting the moment arm consists of moving the drag disk along the
arm thereby changing the force-balance moment arm. Moving a drag disk
to the far end of the arm lowers the flow rate required to activate the
switch. Moving a drag disk towards the filter boot increases the flow rate
required to activate the switch.
c) Use Teflon tape to seal the threads and lubricate to allow the arrow
on the body to be aligned with the flow.
2. After aligning the arrow with flow, adjust the flow in the system to the
desired rate without regard to the FSW-50 Series switch point setting.
3. The Switch Point Adjusting Mechanism consists of a leadscrew, a
leadscrew nut and a helical spring.
CLOCKWISE rotation of the adjusting screw changes the microswitch
actuation point toward HIGHER flow rates. COUNTERCLOCKWISE
rotation changes the microswitch actuation point toward LOWER flow
rates.
NOTE
NOTE
It is necessary throughout all installation and adjustment procedures to check to ensure that
the drag disk is perpendicular to the flow and does not touch any interior surface through-
out its complete fore and aft travel.
All FSW-50 Series Switches are factory set at the lower end of the flow range, i.e., the
adjusting screw is set at the low flow COUNTERCLOCKWISE position.
The leadscrew nut locks the adjusting screw in position, maintaining the
flow set point under all environmental conditions.
4. Turn the adjusting screw in a clockwise direction until the microswitch
is actuated while maintaining the desired fluid flow rate in the system.
Turn the adjusting screw two additional turns in the clockwise
direction and then slowly back off in a counterclockwise direction until
microswitch is again actuated. The FSW-50 Flow Switch is now set for
maximum sensitivity for detecting small flow changes.
5. Microswitch actuation point may be monitored during the adjustment
procedure detailed in Step 4 above by an audible click or with an OHM
meter before connecting line power or by monitoring the voltage
supplied to the load through the microswitch.
6
7
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