Dwyer Series VF Instruction Manual

Dwyer Series VF Instruction Manual
Bulletin F-33
Series VF Visi-Float® Flowmeters
®
Specifications - Installation and Operating Instructions
F
L
M
A
B
K
C
E
D
M
Model VFB
I
FULL OPEN
Model VFA-SSV
The Series VF Visi-Float® Flowmeters are furnished in two models (see drawing
above) 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 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 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 flowmeter to the factory. Before
proceeding with the installation of your 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, INDIANA 46360, U.S.A.
N
SPECIFICATIONS
Service: Compatible gases and liquids.
Wetted Materials: Body: Acrylic plastic; O-ring: Buna-N (fluoroelastomer available);
Metal parts: brass standard, SS optional; Float: SS, black glass, aluminum, K monel
depending on range.
Temperature and 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% FS; VFB= 3% FS.
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).
DIMENSIONS - FLOWMETER
Model VFA
A 4 [101.6]
B 3 [76.20]; 1/8 NPT conn.
C 1-5/8 [41.28]; 10-32 thd
D 1/2 [12.70]
E 1-3/16 [30.16]
F 1-1/4 [31.75]
I
2-1/16 [52.39]; Open
K 4-3/32 [104.0]
L 1 [25.40]
M 7/8 [22.23] ; 1/8 NPT
N 3/32 [2.381]
Model VFB
6-1/2 [165.1]
5-1/2 [139.7]; 1/8 NPT conn.
3-1/2 [88.90]; 10-32 thd
1/2 [12.70]
1-1/2 [38.10]
1-1/4 [31.75]
2-1/16 [52.39] ; Open
6-11/16 [169.9]
1-3/8 [34.93]
7/8 [22.23]; 1/8 NPT
3/32 [2.381]
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
the drawing above. 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 collapsed 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 pipe thread sealant tape or pipe thread sealant to insure against leakage.
Phone: 219/879-8000
www.dwyer-inst.com
Fax: 219/872-9057
e-mail: [email protected]
RANGE CHART - VFA 2˝ SCALE - POPULAR RANGES
Range No. SCFH Air
Range No. LPM Air
1
.1 to 1
21
.06 to 0.5
2
.2 to 2
22
.15 to 1
3
.6 to 5
23
.6 to 5
4
1 to 10
24
1 to 10
5
2 to 20
25
3 to 25
6
4 to 30
26
6 to 50
7
5 to 50
27
10 to 100
8
10 to 100
9
20 to 200
Range No.
32
33
34
CC/Min. Water
6 to 50
10 to 100
20 to 200
Range No.
41
42
43
44
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.
CAUTION
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:
GPH Water
.6 to 5
2 to 10
3 to 20
8 to 40
Q2 = Q1 x
RANGE CHART - VFB 4˝ SCALE - POPULAR RANGES
Range No. SCFH Air
Range No. LPM Air
50
.3 to 3
65
.2 to 4
91
1 to 10
66
1 to 10
51
2 to 20
67
1 to 20
52
4 to 40
68
3 to 30
53
10 to 100
69
4 to 40
54
15 to 150
Range No. CC/Min. Water
55
20 to 200
82
2 to 30
Range No. SCFM Air
Range No. GPH Water
90
.3 to 3
80
.5 to 12
83
1 to 20
Range No. CC/Min. Air
81
6 to 60
60
100 to 1000
Range No. GPM Water
85
.2 to 2
86
.5 to 5
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
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. Control valves on BV
and SSV models are turned clockwise to reduce flow, counter clockwise to increase
flow (valve is designed for flow adjustment only, not intended to be used as an open/
shut-off valve). 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 performance of low range units used in air or gas applications may be affected by
static electricity. Excessive static charge may cause the ball float to behave erratically
or provide a false reading. To ensure the proper function of the unit, the application
should be designed to minimize or dispel static electricity.
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.
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.
(14.7 + 5) x 530
14.7 x (460 + 85)
Q2 = 68.5 SCFH Air
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 the drawing on the previous page, but omit the small holes.
©Copyright 2019 Dwyer Instruments, Inc.
P1 x T2
P2 x T1
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 topplug-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 Instruments, Inc. full-line catalog.
Printed in U.S.A. 2/19
FR# 440241-00 Rev. 7
Phone: 219/879-8000
www.dwyer-inst.com
Fax: 219/872-9057
e-mail: [email protected]
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