Omega FSW-50 User Manual

FSW-50 Series

Industrial Flow Switches

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The information contained in this document is believed to be correct, but OMEGA Engineering, Inc. accepts
no liability for any errors it contains, and reserves the right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for, patient-connected applications.

WARRANTY/DISCLAIMER

OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and
workmanship for a period of 13 months from date of purchase. OMEGA’s Warranty adds an
additional one (1) month grace period to the normal one (1) year product warranty to cover
handling and shipping time. This ensures that OMEGA’s customers receive maximum
coverage on each product.

If the unit malfunctions, it must be returned to the factory for evaluation. OMEGA’s Customer
Service Department will issue an Authorized Return (AR) number immediately upon phone or
written request. Upon examination by OMEGA, if the unit is found to be defective, it will be
repaired or replaced at no charge. OMEGA’s WARRANTY does not apply to defects resulting
from any action of the purchaser, including but not limited to mishandling, improper interfacing,
operation outside of design limits, improper repair, or unauthorized modification. This
WARRANTY is VOID if the unit shows evidence of having been tampered with or shows evidence
of having been damaged as a result of excessive corrosion; or current, heat, moisture or vibra­tion; improper specification; misapplication; misuse or other operating conditions outside of
OMEGA’s control. Components which wear are not warranted, including but not limited to
contact points, fuses, and triacs.

OMEGA is pleased to offer suggestions on the use of its various products. However,
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RETURN REQUESTS/INQUIRIES

Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department.
BEFORE RETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN
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(IN ORDER TO AVOID PROCESSING DELAYS). The assigned AR number should then be
marked on the outside of the return package and on any correspondence.

The purchaser is responsible for shipping charges, freight, insurance and proper packaging to
prevent breakage in transit.

FOR WARRANTY

RETURNS, please have
the following information available BEFORE
contacting OMEGA:

1. Purchase Order number under which

the product was PURCHASED,

2. Model and serial number of the product

under warranty, and

3. Repair instructions and/or specific

problems relative to the product.

FOR NON-WARRANTY REPAIRS,

consult
OMEGA for current repair charges. Have the
following information available BEFORE
contacting OMEGA:

1. Purchase Order number to cover the

COST of the repair,

2. Model and serial number of the

product, and

3. Repair instructions and/or specific problems

relative to the product.

OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible.
This affords our customers the latest in technology and engineering.

OMEGA is a registered trademark of OMEGA ENGINEERING, INC.
© Copyright 2002 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied,

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the prior written consent of OMEGA ENGINEERING, INC.

12

General Description

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 non­magnetic 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.

1

Notes

2

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 .5" dia.

#2 .83" dia.

#3 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 Nominal Pipe Nominal High Flow % Increase

Model Low Flow Size High Flow Model of Listed

Number Cont. Adj. (Ins.) Cont. Adj. Number Flows via

Range Range Moment
(GPM) (GPM) Arm Adj.

FSW-50 w/drag * ** * ** FSW-50 w/drag

disk #2 8-13 1 18-28 disk #1 None

Shortest drag Shortest drag

disk arm. disk arm.

Mid. size 3.3-5.3 7.4-11.5 Smallest drag

drag disk ft/sec ft/sec disk

FSW-51 w/drag 15-30 1

1

/

2

30-60 FSW-51 w/drag

disk #3 25-50 2 50-105 disk #1 None

40-80 2

1

/

2

80-155

Mid. size Mid. size

drag disk drag disk

arm. Largest 2.7-5.4 5.4-10.8 arm. Smallest

drag disk ft/sec ft/sec drag disk

FSW-52 w/drag 40-90 3 90-180 FSW-52 w/drag

disk #3 60-120 3

1

/

2

120-240 disk #1 +25%

75-155 4 155-310

Longest drag 120-245 5 245-480 Longest drag

disk arm. 180-350 6 350-700 disk arm.

Largest 300-600 8 600-1200 Smallest

drag disk 500-950 10 950-1900 drag disk

2.4-4.0 4.0-8.0
ft/sec ft/sec

**Force/Balance spring relaxed.
**Force/Balance spring fully extended.

Notes

11

Relay Switch: SPDT 15A @ 125 or 250 Vac, 10,000,000

operations median

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: Water resistant for cable diameters .250"

±0.25"

Weight: 0.25 lb.

PPS* = polyphenylene sulfide plastic

Installation Dimensions

3

INSTALLATION WARNING

THE 1

1

/

2

" X 1

1

/

4

" 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

Notes

4 9

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.

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.

Installation

The FSW-50 Series Fluid Flow Switch is supplied with a 11/4" x 1" PVC TT
bushing (standard construction model) or 1

1

/4" x 1" PPS* bushing (special
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.

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

10402-6. GROMMET

10402-27. LEADSCREW

10402-29. LEADSCREW NUT

10402-28. LEADSCREW RETAINING

SLEEVE

10402-26. ADJUSTING SPRING

10402-1. BODY

10402-35. 11/4" x 1" BUSHING

SUPPLIED

DIAPHRAGM CLAMPING
(SONICALLY WELDED)

3 RETAINING SCREWS

10402-18. DRAG DISK #1 (SMALL)

19. DRAG DISK #2 (MEDIUM)

20. DRAG DISK #3 (LARGE)

10402-15. DRAG DISK ARM MODEL FSW-50

16. DRAG DISK ARM MODEL FSW-51

17. DRAG DISK ARM MODEL FSW-52

10402-21. SEAL SHAFT ASSEMBLY

SUPPLIED ONLY COMPLETE WITH
A) SEAL SHAFT
B) DIAPHRAGM
C) DIAPHRAGM WASHER
D) FEED THRU SHAFT

10402-24. 2 SCREWS

25. 2 SPLIT LOCKWASHERS

10402-4. O-RING

10402-31. 2 SCREWS

32. 2 NUTS

33. 2 SPLIT LOCKWASHERS

34. 1 PLAIN WASHER

10402-23. MICROSWITCH BRACKET

COMPLETE WITH SPRING LEVER

10402-30. MICROSWITCH COMPLETE

WITH 3 SLIP-ON TERMINALS

10402-2. COVER

3. 4 RETAINING SCREWS
(NOT SHOWN)

10402-5. STRAIN RELIEF NUT

WARNING
DO NOT APPLY TORQUE TO DRAG DISK
ARM SINCE IT MAY BE UNTHREADED
FROM SEAL SHAFT (A).

8 5

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.

NOTE

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.

Electrical Wiring

1. Remove gland nut, grommet and switch cover.

2. Strip outer jacket of electrical cord back approximately 1

1

/4inches.

Strip insulation from individual conductors back approximately

1

/4inch.

3. Slip on terminals are supplied with each switch. Remove from switch
terminals and crimp on or solder to electrical leads.

4. Feed electrical cable through gland nut, grommet and switch cover as
shown.

5. Apply slip on terminals to appropriate contacts of microswitch.

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.

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.

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).

FSW-50 Series w/Standard Construction Parts Diagram

10398-6. GROMMET

10398-28. LEADSCREW

10398-30. LEADSCREW NUT

10398-29. LEADSCREW RETAINING

SLEEVE

10398-27. ADJUSTING SPRING

10398-1. BODY

10398-36. 11/4" x 1" BUSHING

SUPPLIED

10398-10. DIAPHRAGM CLAMP RING

(SONICALLY WELDED)

3 RETAINING SCREWS

FLEXIBLE DRAG STRIP ASSEMBLY
IS AVAILABLE TO REPLACE DRAG
DISK AND DRAG DISK ARM. NO
FILTER BOOT IS USED.

10398-37. DRAG STRIP

38. CLAMP WASHER

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).

10398-16. DRAG DISK ARM MODEL FSW-50

17. DRAG DISK ARM MODEL FSW-51

18. DRAG DISK ARM MODEL FSW-52

10398-22. SEAL SHAFT ASSEMBLY

SUPPLIED ONLY COMPLETE WITH
A) SEAL SHAFT
B) DIAPHRAGM
C) DIAPHRAGM WASHER
D) FEED THRU SHAFT

10398-25. 2 SCREWS

26. 2 SPLIT LOCKWASHERS

10398-4. O-RING

10398-32. 2 SCREWS

33. 2 NUTS

34. 2 SPLIT LOCKWASHERS

35. 1 PLAIN WASHER

10398-24. MICROSWITCH BRACKET

COMPLETE WITH SPRING LEVER

10398-31. MICROSWITCH COMPLETE

WITH 3 SLIP-ON TERMINALS

10398-2. COVER

3. 4 RETAINING SCREWS
(NOT SHOWN)

10398-5. STRAIN RELIEF NUT

6 7

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.

NOTE

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).

Switch Point Adjustment

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.

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.

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. 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.

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.

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.

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.

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 through­out its complete fore and aft travel.

NOTE