Dwyer SF User Manual

BULLETIN F-41-SF

Series SF Sight Flow Transmitter

Specifications - Installation and Operating Instructions

700462-00

GENERAL

Series SF Sight Flow Transmitter integrates tangential turbine
technology with hermetically sealed circuitry to provide accu­rate flow measurement and control in the harshest environ­ments. The 2-wire loop-powered design transmits a 4 to 20
mA signal proportional to flow rate. Models can accurately
measure flow in both directions and can be mounted in any
orientation. Series SF Transmitters are ideal for measuring
flow rates in cooling and lubrication circuits, HVAC systems,
aggressive chemical metering, and batching systems.

MECHANICAL INSTALLATION

The Series SF Sight Flow Transmitter has a 1/2 NPT(F)
plumbing connections. It is recommended to use a paste
type pipe sealant on the threads. Teflon tape sealant can
also be used as long as it is applied so the tape does not
enter the flow stream (pieces of tape can wrap around the
turbine and impeded rotation).

The recommended mounting orientation would be any
plane that will place the axis of the turbine vertical or hori­zontal with respect to ground. The unit will operate satis­factory with the axis at other angles, but side loading of the
bearing surfaces will lead to premature wear of the rotating
parts.

For the best flow measurement results, place the inlet (ref­erences to “inlet” and “outlet” refer to unidirectional sys­tems) of the flow sensor at least 10 straight pipe diameters
downstream from any fitting, valve, elbow, reducer, etc. that
causes nonstable flow conditions. Ideally, 5 straight pipe
diameters should be placed at the outlet of the sensor. If
the sensor must be placed closer to a source of nonstable
flow than the recommended distances, some instability of
the output signal may result. The average signal will be
accurate.

Place the sensor in such a position that the round access
cover can be removed for cleaning and turbine servicing. A
union placed near the sensor is recommended to allow
easy removal.

[50.80]

1/2⬙ NPT (F)

2

2-7/16

[61.91]

PHYSICAL DATA

Flow Range: 0.5 to 15 GPM (2

to 60 LPM).
Accuracy: 30 Watts: 0.14A @
220VAC, 0.28A @ 110VAC,

0.07A @ 120VDC, 0.28A @
24VDC.
Temperature Range: 20 to
225°F (-7 to 107°C).
Maximum Pressure: 500 psig
(34 bar) Model SF10, 200 psig
(14 bar) Model SF11.
Repeatability: 0.5% Full Scale.

2-5/8

[66.68]

1-1/8

[28.58]

3-11/16

[93.66]

Supply Voltage: 12 to 35 VDC.
Output: 4 to 20 mA.
Loop Resistance: 1150Ω max.
Response Time: 2 seconds to

90% (step change in flow rate).
Wetted Parts: 316 SS shaft and
case, iglide
seal and acetal copolymer, (poly­carbonate cover on Model
SF11).

Connections: 2″ NPT(F).
Wire Leads: 22 AWG ⫻ 9′

(2.7m).

®

bearings, Buna-N

MODELS

Model

Number

SF10 316 Stainless Steel
SF11 Clear Polycarbonate

Cover Material

ELECTRICAL INSTALLATION

The Series SF Sight Flow Transmitter is a two-wire loop­powered device desined to transmit a 4-20mA signal
proportional to flow rate. The noise-immune current trans­mission from the sensor can be routed with low cost two
conductor twisted-pair cable. The current operates on 12­35VDC and requires a source capable of supplying at least
20mA of current. The circuit has built-in polarity protection
and over-current limiting to protect both the sensor and
what the sensor is connected to.

To connect the sensor:

1. Connect the red wire from the sensor to the positive 12­35VDC power supply output.

2. Connect the black wire from the sensor to the positive
side of the loop load (resistor, chart recorder, data aquisi­tion board, meter, etc.). This connection may be labeled “4­20mAInput” on some devices.

3. If applicable, connect the negative side of the loop load
to the negative side of the power supply.

®

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361 U.S.A.

Phone: [phone] www.dwyer-inst.com
Fax: [phone] e-mail: [e-mail]
Lit-by-Fax: [phone]

4. Apply power to the system.

5.If everything ois operating correctly, the green LED on the
sensor will dimly illuminate and 4mA will be flowing in the
loop. If fluid is flowing through the sensor, the current will
be higher than 4mA.

Troubleshooting

If the LED does not illuminate:

• Check wiring terminations for good connections.

• Check wiring polarity.

• Verify correct supply voltage.

• Insure the load impedance is within allowable
limits.

• Apply the DC supply voltage directly across the

sensor wires. If the LED does illuminate, the load is
either: too great of impedance or an open circuit. If
the LED does not illuminate, the sensor’s lead
wires or circuit are defective.

SERVICE and MAINTENANCE

The Series SF Flow Transmitter is designed to provide
years of low maintenance service in industrial environ­ments. As with all mechanical rotating devices, the bearing
surfaces will wear with use. The life of the parts will depend
on factors such as cleanliness of fluid, media, mounting
orientation, temperature, fluid velocity and frquency of
operation. The sensor was designed with simple field­replacement of the rotating parts.

To inspect or replace the rotating components:

1. Relieve pressure in the piping system.

3. Remove the access cover with pliers, taking care not to
damage the o-ring seal.

4. Pull out turbine assembly and shaft.

5. Inspect the shaft for things that may have wrapped
around it.

6. Inspect the turbine bearing surface for wear and elonga­tion. replace as necessary.

7. Clean any rust off of the magnets that may have accu­mulated.

8. Reassemble the unit by placing the turbine into the body
cavity with the two magnet pockets facing inward. Place
the shaft into the turbine hole and guide it into the retaining
hole in the body cavity. Lubricate the o-ring with glycerine
or other lubricant and press it into the pocket of the body.
Replace the retaining ring securely before applying pres­sure to the system.

Circuit Recalibration:

1. Place a milliamp meter into the current loop.

2. Turn off the flow going through the sensor. Adjust the
OFFSET control for a reading of 4mA on the milliamp meter.

3. Adjust the flow rate through the sensor to full flow rate.
Adjust the SPAN control for a reading of 20mA on the mil­liamp meter. The zero and span adjustment are not interac­tive and should require additional adjustments.

2. Remove the retainer ring that secures the turbine access
cover.

©Copyright 1998 Dwyer Instruments, Inc.

Printed in U.S.A. 3/98

FR R1-443038-00

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361 U.S.A.

Phone: [phone] www.dwyer-inst.com
Fax: [phone] e-mail: [e-mail]
Lit-by-Fax: [phone]