Dwyer VF Manual

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Series VF Visi-Float® Flowmeters

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Specications - Installation and Operating Instructions

Bulletin F-33

Model VFB Model VFA-SSV

The Series VF Visi-Float® Flowmeters are furnished in two models (see drawing

above) each available in a broad choice of ow 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 owmeter 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 certied accuracy. DO NOT

attempt to check the Visi-Float® Flowmeter with a similar owmeter as seemingly unimportant variations in piping and back pressure may cause noticeable differences

in the indicated reading. If in doubt, return your owmeter to the factory. Before

proceeding with the installation of your Visi-Float® Flowmeter, check to be sure you

have the model and ow 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 owmeter 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 owmeter i.e. 1/8˝ Iron Pipe Size. Length of inlet piping makes little difference for normal pressure fed owmeters.

For ow 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 ow control valve if any, should be on the discharge side of the owmeter. 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

owmeter connection. In addition, for pressure fed owmeters on air or gas service the

discharge piping should be as short and open as possible. This will allow operation

of the ow tube at near atmospheric pressure and insure the accuracy of the device. This is of less importance on water or liquid owmeters since the owing medium is

generally incompressible and moderate back pressure will not affect the accuracy of the instrument as calibrated.

SPECIFICATIONS Service: Compatible gases and liquids. Wetted Materials: Body: Acrylic plastic; O-ring: Buna-N (uoroelastomer 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 Model VFB

4 [101.6]

3 [76.20]; 1/8 NPT conn.

1-5/8 [41.28]; 10-32 thd

1/2 [12.70]

1-3/16 [30.16]

1-1/4 [31.75]

2-1/16 [52.39]; Open

4-3/32 [104.0]

1 [25.40]

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 owmeter 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 rst 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.

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]

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.

Phone: 219/879-8000

Fax: 219/872-9057

www.dwyer-inst.com

e-mail: info@dwyermail.com

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RANGE CHART - VFA 2˝ SCALE - POPULAR RANGES Range No. SCFH Air Range No. LPM Air

1 2 3

5 6 7

8 9

Range No. CC/Min. Water Range No. GPH Water

32 33

RANGE CHART - VFB 4˝ SCALE - POPULAR RANGES Range No. SCFH Air Range No. LPM Air

51 52 53

Range No. SCFM Air Range No. GPH Water

90 .3 to 3 80

Range No. CC/Min. Air

60 100 to 1000

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.

Mounting on Piping Only Without Panel: For the temporary or laboratory type

installation, the panel may be omitted altogether and the owmeter installed directly in rigid piping. Its light weight permits this without difculty.

OPERATION

To start system, open the valve slowly to avoid possible damage. Control valves on BV and SSV models are turned clockwise to reduce ow, counter clockwise to increase ow (valve is designed for ow 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 rm 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 oat 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 oat, and then align that with the theoretical center of the scale graduation. In the event that the oat is not aligned with a grad, an extrapolation of the oat location must be made by the operator as to its location between the two closest grads. The following are some sample oats shown with reference to the proper location to read the oat.

.1 to 1 .2 to 2 .6 to 5 1 to 10 2 to 20

4 to 30

5 to 50 10 to 100 20 to 200

6 to 50 10 to 100 20 to 200

.3 to 3 1 to 10 2 to 20

4 to 40

10 to 100 15 to 150 20 to 200

21 22 23

25 26 27

41 42 43 44

65 66 67

68 69

Range No. CC/Min. Water

82 2 to 30

83 81

Range No. GPM Water

85 86

.06 to 0.5 .15 to 1 .6 to 5 1 to 10 3 to 25 6 to 50 10 to 100

.6 to 5 2 to 10 3 to 20

8 to 40

.2 to 4

1 to 10 1 to 20 3 to 30

4 to 40

.5 to 12 1 to 20 6 to 60

.2 to 2 .5 to 5

CAUTION

will allow gas or liquid to ow out front of valve body and could result in serious personal injury. For applications involving high pressure and/or toxic gases or uids, special

non-removable valves are available on special order. Contact factory for details.

Variable Area Flowmeters used for gases are typically labeled with the prex “S” or “N”, which represents “Standard” for English units or “Normal” for metric units. Use of this prex designates that the owmeter is calibrated to operate at a specic 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 owmeter 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 owmeter, except under vacuum applications where they should be measured at the owmeter inlet. The equation to correct for nonstandard operating conditions is as follows:

Q2 = Q1 x

Where: Q1 = Actual or observed owmeter reading

Q2 = Standard ow 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 owmeter with a scale of 10-100 SCFH Air. The oat is sitting at the 60 grad on the owmeter 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

Q2 = 68.5 SCFH Air

MAINTENANCE

The only maintenance normally required is occasional cleaning to assure reliable operation and good oat visibility.

Disassembly: The owmeter 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 oat by inverting the body and allowing the oat

to fall into your hand. (Note: It is best to cover the discharge port to avoid losing the

oat through that opening.) When removing the oat 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 oat stops.

Cleaning: The ow tube and owmeter 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 oat, 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, rst install the lower tting, next the oat guide and oat and nally the upper tting and plug. Be certain that both ends of the oat guide are properly engaged and the oat is correctly oriented.

ADDITIONAL INFORMATION

For additional owmeter application information, conversion curves, factors and other data covering the entire line of Dwyer Instruments, Inc. full-line catalog.

Do not completely unscrew valve stem unless owmeter is unpressurized and drained of any liquid. Removal while in service

P1 x T2

P2 x T1

(14.7 + 5) x 530

14.7 x (460 + 85)