Dwyer Visi-Float Flowmeter Installation & Operating Instructions

Dwyer Visi-Float Flowmeter Installation & Operating Instructions
F-33
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8:14 AM
Page 1
Bulletin F-33
Series VF Visi-Float® Flowmeter
Specifications - Installation and Operating Instructions
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FULL OPEN
Dwyer Visi-Float® Series Flowmeters are furnished in two models (see
Figure 1) each available in a broad choice of flow ranges with direct reading scales for air, gas or water. Installation, operation and maintenance are
very simple and only a few common sense precautions must be observed
to assure long, trouble-free service.
CALIBRATION
Each Dwyer flowmeter is calibrated at the factory. If at any time during the
meter’s life, you wish to recheck its calibration, do so only with devices of
certified accuracy. DO NOT attempt to check the Dwyer Visi-Float®
Flowmeter with a similar flowmeter as seemingly unimportant variations in
piping and back pressure may cause noticeable differences in the indicated reading. If in doubt, return your Dwyer flowmeter to the factory. It will
be checked for conformance at no charge. Before proceeding with the
installation of your Dwyer Visi-Float® Flowmeter, check to be sure you have
the model and flow range you require.
LOCATION
Temperature, Pressure, Atmosphere, and Vibration:
Visi-Float® Acrylic Flowmeters are exceptionally tough and strong. They are
designed for use at pressures up to 100 psi
(7 bar) and temperatures up to 150°F (66°C). DO NOT EXCEED THESE
LIMITS! The installation should not be exposed to strong chlorine atmospheres or solvents such as benzene, acetone, carbon tetrachloride, etc.
The mounting panel should be free of excessive vibration since it may prevent the unit from operating properly.
Inlet Piping Run: It is good practice to approach the flowmeter inlet with
as few elbows and restrictions as possible. In every case the inlet piping
should be at least as large as the connection to the flowmeter i.e. 1/8˝ Iron
Pipe Size. Length of inlet piping makes little difference for normal pressure
fed flowmeters.
For flow meters on vacuum air service the inlet piping should be as short
and open as possible. This will allow operation near atmospheric pressure
and thereby insure the accuracy of the device. (Note that for vacuum air
service the flow control valve if any, should be on the discharge side of the
flowmeter. Either the TMV unit or a separate in line valve may be applied.)
Discharge Piping: As on the inlet, discharge piping should be at least as
large as the flowmeter connection. In addition, for pressure fed flowmeters
on air or gas service the discharge piping should be as short and open as
possible. This will allow operation of the flow tube at near atmospheric
pressure and insure the accuracy of the device. This is of less importance
on water or liquid flowmeters since the flowing medium is generally incompressible and moderate back pressure will not affect the accuracy of the
instrument as calibrated.
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, IN 46361, U.S.A.
Fig. 1
DIMENSION-IN INCHES
Model VFA
Model VFB
4
61⁄2
3 (1⁄8 female NPT)
51⁄2 (1⁄8 female NPT)*
15⁄8 (10-32 Thread)
31⁄2 (10-32 thread)
1
1
⁄2
⁄2
13⁄16
11⁄2
11⁄4
11⁄4
21⁄16 (BV or SSV)
21⁄16 (BV or SSV)
43⁄32
619⁄32
1
13⁄8
3
3
⁄4 (EC)
⁄4 (EC)
3
3
⁄32 (EC)
⁄32 (EC)
*VFB ranges 85 and 86 have 1⁄4" NPT back connections or 3⁄8" NPT end connections.
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SPECIFICATIONS
Service: Compatible gases & liquids.
Wetted Materials:
Body: Acrylic plastic.
O-ring: Buna-N (Viton® available).
Metal Parts: Brass standard, stainless steel optional.
Float: Stainless steel, black glass, aluminum, K Monel
depending on range.
Temperature & Pressure Limits:
Without Valve: 100 psig (6.9 bar) @ 150°F (65°C);
150 psig (10 bar) @ 100°F (38°C).
With Valve: 100 psig (6.9 bar) @ 120°F (48°C).
Accuracy: VFA = 5% of full scale; VFB= 3% of full scale.
Process Connection: 1/8˝ female NPT. VFB ranges 85 and 86 have 1/4˝
NPT back connections or 3/8˝ NPT end connections. These ranges not
available with brass valves.
Scale Length: VFA 2˝ typical length; VFB 4˝ typical length.
Mounting Orientation: Mount in Vertical Position.
Weight: VFA: 4.0-4.8 oz (.11-.14 kg). VFB: 7.2-8.8 oz (.20-.25 kg).
POSITION AND MOUNTING
All Visi-Float® Flowmeters must be mounted in a vertical position with the
inlet connection at the bottom and outlet at the top.
Surface Mounting: Drill appropriate holes in panel using the dimensions
shown in Figure 1. Hold the flowmeter in position in front of the panel and
install the mounting screws through the panel from the rear. Mounting
screws must not be longer than the panel thickness plus 1/4˝, or the screw
will hit the plastic and may damage the meter. The screws will require additional force during the initial installation, since the insert boots are of a col-
Phone: 219/879-8000
Fax: 219/872-9057
www.dwyer-inst.com
e-mail: [email protected]
F-33
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Page 2
POPULAR RANGES
CAUTION
Model VFA — 2" Scale
Range
No.
1
2
3
4
5
6
7
8
9
32
33
34
Range
SCFH Air
.1-1
.2-2
.6-5
1-10
2-20
4-30
5-50
10-100
20-200
CC Water
per min.
6-50
10-100
20-200
Range
No.
21
22
23
24
25
26
27
Range
LPM Air
.06-0.5
.15-1
.6-5
1-10
3-25
6-50
10-100
41
42
43
44
Gal. Water
per hour
.6-5
1.2-10
3-20
8-40
Model VFB — 4" Scale
Range
No.
50
91
51
52
53
54
55
90
60
Range
SCFH Air
.3-3
1-10
2-20
4-40
10-100
15-150
20-200
SCFM Air
.3-3
CC/Min. Air
100-1000
Range
No.
65
66
67
68
69
82
80
83
81
85
86
LPM Air
.2-4
1-10
1-20
3-30
4-40
CC/Min. Water
2-30
GPH Water
.5-12
1-20
6-60
GPM Water
.2-2
.5-5
Do not completely unscrew valve stem unless flowmeter is
unpressurized and drained of any liquid. Removal while in service
will allow gas or liquid to flow out front of valve body and could
result in serious personal injury. For applications involving high
pressure and/or toxic gases or fluids, special non-removable
valves are available on special order. Contact factory for details.
Variable Area Flowmeters used for gases are typically labeled with the prefix “S” or “N”, which represents “Standard” for English units or “Normal” for
metric units. Use of this prefix designates that the flowmeter is calibrated
to operate at a specific set of conditions, and deviation from those standard conditions will require correction for the calibration to be valid. In practice, the reading taken from the flowmeter scale must be corrected back to
standard conditions to be used with the scale units. The correct location to
measure the actual pressure and temperature is at the exit of the flowmeter, except under vacuum applications where they should be measured at
the flowmeter inlet. The equation to correct for nonstandard operating conditions is as follows:
Q2 = Q1 x
Where:
Q1 = Actual or Observed Flowmeter Reading
Q2 = Standard Flow Corrected for Pressure and
Temperature
P1 = Actual Pressure (14.7 psia + Gage Pressure)
P2 = Standard Pressure (14.7 psia, which is 0 psig)
T1 = Actual Temperature (460 R + Temp °F)
T2 = Standard Temperature (530 R, which is 70°F)
Example: A flowmeter with a scale of 10-100 SCFH Air. The float is sitting
at the 60 grad on the flowmeter scale. Actual Pressure is measured at the
exit of the meter as 5 psig. Actual Temperature is measured at the exit of
the meter as 85°F.
Q2 = 60.0 x
lapsed thread type and must be expanded into the plastic for the knurled
surface to take hold. Insert boots will not have the proper 10-32 threads
until the first screw has been inserted to expand the boot. Pipe up inlet and
discharge using RTV silicone sealant or Teflon® tape on pipe threads to
insure against leakage.
Surface Mounting on Piping Only: An alternate method of surface
mounting is by omitting the mounting screws and supporting the Visi-Float®
Flowmeter on the connecting piping only. For this method extra long or
straight pipe threads should be used so that nuts may be run onto the pipe
and later tightened against the back of the panel to retain the unit in proper position. Use the appropriate hole layout information from Figure 1, but
omit the small holes.
Mounting on Piping Only Without Panel: For the temporary or laboratory type installation, the panel may be omitted altogether and the flowmeter installed directly in rigid piping. Its light weight permits this without difficulty.
OPERATION
To start system, open the valve slowly to avoid possible damage. Rate of
flow is read at the point of maximum horizontal width for spherical floats or
at the top of the largest diameter for non-spherical floats. Control valves on
BV and SSV models are turned clockwise to reduce flow, counter clockwise to increase flow. A nylon insert is provided in the threaded section of
the valve stem to give a firm touch to the valve and to prevent change of
setting due to vibration.
The standard technique for reading a Variable Area Flowmeter is to locate
the highest point of greatest diameter on the float, and then align that with
the theoretical center of the scale graduation. In the event that the float is
not aligned with a grad, an extrapolation of the float location must be made
by the operator as to its location between the two closest grads. The following are some sample floats shown with reference to the proper location
to read the float.
©Copyright 2004 Dwyer Instruments, Inc.
P1 x T2
P2 x T1
(14.7 + 5) x 530
14.7 x (460 + 85)
Q2 = 68.5 SCFH Air
MAINTENANCE
The only maintenance normally required is occasional cleaning to assure
reliable operation and good float visibility.
Disassembly: The flowmeter can be disassembled for cleaning by simply
disconnecting the piping, dismounting the unit from the panel and removing the top-plug-ball stop. Take out the ball or float by inverting the body
and allowing the float to fall into your hand. (Note: It is best to cover the discharge port to avoid losing the float through that opening.) When removing
the float guide assembly on VFB models 85 and 86, be careful not to lose
the short pieces of plastic tubing on both ends of the guide which serve as
float stops.
Cleaning: The flow tube and flowmeter body can best be cleaned with a
little pure soap and water. Use of a bottle brush or other soft brush will aid
the cleaning. Avoid benzene, acetone, carbon tetrachloride, alkaline detergents, caustic soda, liquid soaps (which may contain chlorinated solvents),
etc. and avoid prolonged immersion.
Reassembly: Reinstall the float, remount, connect and place the unit back
in service. A little stop cock grease or petroleum jelly on the “O”rings will
help maintain a good seal as well as facilitate assembly. No other special
care is required.
For VFB models 85 and 86, first install the lower fitting, next the float guide
and float and finally the upper fitting and plug. Be certain that both ends of
the float guide are properly engaged and the float is correctly oriented.
ADDITIONAL INFORMATION
For additional flowmeter application information, conversion curves, factors
and other data covering the entire line of Dwyer full-line catalog.
Printed in U.S.A. 3/04
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, IN 46361, U.S.A.
Phone: 219/879-8000
Fax: 219/872-9057
FR# 52-440241-00 Rev.2
www.dwyer-inst.com
e-mail: [email protected]
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