Dwyer STFLO User Manual

Bulletin F-41-STFLO

4-1/32

[102.25]

2-11/16

[68.07]

IN

10-21/32
[270.78]

LABEL, SEE

DETAIL 1

3/4 NPT CONNECTION

O

UT

2

-13/16

[

71.37]

LABEL

SEE

DETAIL 2

2-3/4

[69.95]

Ø1-11/32

[34.29]

3/4 NPT

1

5-21/32

[

397.28]

LABEL SEE

DETAIL 1

LABEL, SEE

DETAIL 2

IN

OUT

4

-1/2

[

114.38]

3-23/32

[94.23]

5

-11/16

[

144.65]

1

-1/2 NPT

Ø2-15/32

[62.99]

Ø4

[101.85]

1-1/2 NPT CONNECTION

3

[76.20]

LABEL, SEE

DETAIL 1

L

ABEL, SEE
DETAIL 2

5

[127.00]

4-31/32

[125.98]

5

[127.00]

6

-13/16

[

172.97]

3

-1/2

[

88.91]

Ø3-7/8

[Ø98.55]

Ø2-3/4

[Ø69.85]

2-1/8

[53.59]

3

[76.20]

4-1/2

[114.30]

LABLE, SEE

DETAIL 1

LABEL, SEE

DETAIL 2

3-11/16

[93.73]

3-9/16

[90.43]

3-7/8

[98.55]

3/4 FLANGE CONNECTION

1-1/2 FLANGE CONNECTION

Series STFLO Stainless Steel Flowmeters

Specifications - Installation and Operating Instructions

Series STFLO Stainless Steel Flowmeters are ideal for dirty or

opaque fluids, high temperature and high pressure service and harsh
environments, specifically steam applications.The direct reading scale
provides ±2% accuracy. Flowmeters can quickly be disassembled
without removing the body from the pipeline for easy cleaning.

SAFETY PRECAUTIONS

Personnel safety should be considered before pressurizing and
operating the system. There are numerous possibilities for
error in system operation and maintenance as well as
component installation. Because human eyes must necessarily
come into close proximity with the flowmeter to read it, Dwyer

SPECIFICATIONS
Service: Compatible with liquids and gases.
Wetted Material: T316 SS, Alnico magnet, PTFE.
Temperature Limits: See chart on page 7.
Pressure Limits: See chart on page 7.
Accuracy: ±2% FS.
Repeatability: ±0.5% of indicated flow rate.
Process Connections: 3/4˝ or 1-1/2˝ female NPT, optional flange

connections.

Scale Length: 3/4˝ models: 3.2˝ (8 cm); 1-1/2˝ models: 5.2˝ (13 cm).
Weight: 3/4˝ NPT models: 5.75 lb (2.6 kg); 1-1/2˝ NPT models: 14 lb (6.4

kg). 3/4˝ Flange: 9.75 lb (4.4 kg); 1-1/2˝ Flange: 22 lb (10 kg).

Instruments, Inc. recommends that safety shielding such as a
sheet of transparent, high impact material be used in front of
the meter. If hazardous, toxic, or flammable fluids are being
metered, recommended safeguard should include methods to
protect personnel from splash or rebound. A method of quick,
safe removal of dangerous fluids should also be included.

INSTALLATION

PREPARATION: Series STFLO Stainless Steel Flowmeters are ready to
install as-is, although the reading scales may need repositioning so the
scale is visible after installation. First, remove the protective caps from
the connection ports. Also, remove the plastic tubing above the inlet cap
in the meter core tube! This tubing blocks the float assembly in place
during shipment. Check that the float moves freely within the core tube,
and that no packing materials are in the meter.

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A. Fax: [phone] e-mail: [e-mail]

Phone: [phone] www.dwyer-inst.com

RECOMMENDED PIPING

SEC A-A, TOP VIEW

METAL
PRESSURE
TUBE

PHENOLIC
RACEWAY

A

A

MAGNET

BALL
INDICATOR

SNORKEL­GUIDE

READING
SCALES

Series STFLO Stainless Steel Flowmeters generally have no special
straight run or other piping requirements. Inlet piping should be the same
size as the meter connection. Some effect on meter accuracy may occur
at high flow velocities if inlet piping guidelines are violated. Please refer
to the table on the next page. When installing on different size pipe, use
standard pipe adapters and come into the meter inlet with a nipple 8
diameters long of the same size for greatest accuracy. Control valves
should be mounted on the outlet side of the meter. The use of a three
valve manifold around the meter is suggested, as it allows uninterrupted
process flow while the meter is being cleaned.

STARTUP

System flow should be started with the bypass valve open and meter
inlet and outlet valves closed. After the system is operating, open the
meter inlet valve gradually to equalize internal pressure. Then slowly
crack meter outlet valve and wait for float to stabilize. Finally, slowly
open the meter outlet and/or flow regulating valve all the way and close
the system by-pass valve.

AVOID SUDDEN SURGES THAT CAUSE THE METER
FLOAT TO SLAM INTO THE TOP OF THE READING
SCALES!

PLUMBING-IN

While the flowmeters should be vertical, exact plumbness is not
necessary. A general rule is that if the meter appears plumb, it is close
enough (even if off by 10º, the predictable reading error is usually less
than 1%). Pipe should be cut to proper lengths to avoid stress on the
meter. Avoid over-tightening, and do no use wrenches on the body or
reading scales. If using solvents in the vicinity of reading scales, the
scales should be removed until fumes clear.

SURGE & WATER HAMMER PREVENTION

Operating Limits are for non-shock conditions only. Flowmeters are more
accurate and less likely to be damaged when the fluid flow is smooth.
Water hammer is a hazardous phenomenon and should be eliminated
from any fluid system. Water hammer is a series of pressure shocks
create by a sudden change in the flow velocity of liquid in a pipe. This
sudden change, often caused by a fast acting valve or starting, stopping,
or change in speed of a pump, generates an immediate rise in pressure
that sometimes makes a noise similar to striking the pipe with a hammer.
The pressure wave is transmitted from the source throughout the
system, subjecting every component to the sudden shock. Pressure
returns to normal only when a larger vessel or pipe section is reached,
the energy dissipated thru friction and pipe expansion, or some
component ruptures. Rupture of piping, valves, flowmeters, or other
components have obvious safety ramifications that must be addressed.

SURGE CHAMBERS & ACCUMULATORS

Flowmeters are more accurate and less likely to be damaged when the
fluid flow is smooth. If the meter must be installed on a line where
reciprocating pumps causing pulsation are used, surge chambers,
accumulators, or desurgers are strongly suggested to dampen the shock
wave. This is a good, general practice for all flowmeters.

READING SCALES ROTATION

Series STFLO Stainless Steel Flowmeters use magnetically-linked ball
indicators and the scale may be positioned over approximately a 300 ˚
range. However, the magnet position must also be changed accordingly,
requiring removal of the reading scales (see “Disassembly”). On
standard STFLO Stainless Steel Flowmeters as depicted in Figure 1, the
magnet slides out of the carrier at the top of the float assembly. The
screw holding the carrier to the float may be loosened to allow rotation
of the carrier toward the desired scale location. Re-tighten the screw
(thread sealant is recommended), replace magnet, and reassemble the
meter (see “Assembly”). Verify that the ball indicator has been “captured”
by the magnet. If not, rotate the reading scales until the ball is “grabbed”
by the float magnet.

Although not essential, the meter reading scales should be filled to a
level above the float on liquid systems. The snorkel tube (present in most
standard models) allows escape of entrapped gases except for a small
pocket in the upper end which helps cushion hydraulic shock. To assure
proper filling and to flush any foreign particles from the meter, operate
the system at full flow briefly at startup.

READING FLOW

Read flow directly from the scale as the number nearest to the center of
the ball indicator.

COMPENSATING FOR SYSTEM CHANGES

To find the correct flow reading for a system whose fluid conditions vary
from those for which the meter is scaled, use the conversion equations
provided. The most practical method of applying the formulae is to
calculate a conversion factor for the new system condition and
multiplying the scale reading by that factor. In the problems to the right,
“Q’s” has been assigned a value of “1” to determine the conversion
factor. (Dwyer Instruments, Inc. can provide special scales at additional
cost for other fluids and/or units.)

CAUTION: DO NOT OPERATE THE FLOWMETER ON A
SYSTEM EXCEEDING THE OPERATING LIMITS OF THE
UNIT. WHEN CHANGING OPERATING CONDITIONS, MAKE
SURE THAT THE NEW SYSTEM CONDITIONS ARE WITHIN
THE FLOWMETER OPERATING LIMITS, AND ALL WETTED
MATERIALS ARE COMPATIBLE WITH THE FLUID.

CORRECTING READINGS FOR NEW LIQUID CONDITIONS

Qa= Q

s

√

Ps(Pf-Pa)
Pa(Pf-Ps)

or Qa= Q

s

√

ds(df-da)
da(df-ds)

Where:
Qa=Actual flow, GPM (or same units as scale)
Qs=Meter reading from scale, (scale units)
ps=Specific gravity of calibration liquid related to water in std.
atmosphere at 70˚F being 1.00
pa=Specific gravity of metered liquid, same base
ds=Density of calibration liquid, lbs/ft3
da=Density of metered liquid, lbs/ft3
pf=Specific gravity of meter float
df=Density of the meter float as per Table below

FLOAT SPECIFIC GRAVITIES/DENSITIES

Material

Stainless Steel

pf

8.05

df

501.1

EXAMPLE: Using a standard stainless steel meter scaled for water (ps
= 1.00), what is the conversion factor for an oil with a specific gravity of

0.85?
Qa= 1.00

FIGURE 1

Thus, actual flow of the oil would be the observed scale reading times

1.00 (8.05 - 0.85)

x

√

0.85 (8.05 - 1.00)

=1.11