Dwyer CPF User Manual

FEMALE NPT

FLANGE VERSION

A1

A

NPT

F
E

B

HEX
CONNEC­TION

2-1/2

[63.5]

5-23/32

[145.26]

G

REMOVAL CLEARANCE

NPT

C

D

ØK

ØL

IN

OUT

J

I

5-23/32

[145.26]

2-1/2

[63.5]

H

NPT

HEX
CONNECTION

A1

B

E

F

FEMALE NPT

C

REMOVAL CLEARANCE

NPT

C

D

OUT

IN

J

I

H

ØL

ØK

FLANGE VERSION

A

Range
00/10
29/40
11/17
41/51
18/22
52/56
23/28
57/62

CPF

NPT

3/4˝

1-1/2˝

3˝

4˝

A
11-1/32
[280.19]
16-15/16
[430.21]
24-11/32
[618.27]
26-43/64
[728.20]

B
3-25/64
[86.12]
4-1/4
[107.95]
7-29/32
[200.66]
9-13/16
[248.66]

C
2-53/64
[71.83]
4
[101.6]
7-29/32
[200.66]
9-13/16
[248.66]

Series PVF and CPF Industrial Body PVC and CPVC Flowmeters

Specifications - Installation and Operating Instructions

D
4-43/64
[118.67]
6-29/64
[163.91]
11-19/32
[294.63]
14-9/32
[362.96]

E
3-39/64
[91.68]
5-1/32
[127.79]
5-1/32
[127.79]
5-7/16
[138.17]

F
2-35/64
[64.69]
3-29/64
[87.71]
4-5/16
[109.22]
5-7/16
[138.17]

G
3
[76.2]
5
[127]
5
[127]
5
[127]

Option

F1

F2

F3

F4

Range
00/10
29/40
11/17
41/51
18/22
52/56
23/28
57/62

Flange

3/4˝

1-1/2˝

3˝

4˝

H
12-1/4
[311.65]
18-5/8
[473.19]
22-35/64
[572.64]
26-3/8
[669.86]

I
4-5/8
[117.6]
5-15/16
[151.13]
6-7/64
[155.18]
7-1/2
[190.5]

J
4-1/16
[103.38]
5-11/16
[144.78]
6-7/64
[155.18]
7-1/2
[190.5]

K
2-3/4
[69.85]
3-7/8
[98.55]
6
[152.4]
7-1/2
[190.5]

L
3-7/8
[98.55]
5
[127]
7-1/2
[190.5]
9
[228.6]

# of Bolt
Holes

4

4

4

8

Bulletin F-23

Flange Opening
Diameter

(1-1/8˝)

(2˝)

(3-1/2˝)

(4-1/2˝)

A
11-1/32
[280.19]
16-15/16
[430.21]
24-11/32
[618.27]
26-43/64
[728.20]

Standard (NPT)

B
3-25/64
[86.12]
4-1/4
[107.95]
7-29/32
[200.66]
9-13/16
[248.66]

C
2-53/64
[71.83]
4
[101.6]
7-29/32
[200.66]
9-13/16
[248.66]

D
4-43/64
[118.67]
6-29/64
[163.91]
11-19/32
[294.63]
14-9/32
[362.96]

E
3-39/64
[91.68]
5-1/32
[127.79]
5-1/32
[127.79]
5-7/16
[138.17]

G

F
2-35/64
[64.69]
3-29/64
[87.71]
4-5/16
[109.22]
5-7/16
[138.17]

3
[76.2]
5
[127]
5
[127]
5
[127]

Flange

3/4˝

1-1/2˝

3˝

4˝

H
12-1/4
[311.65]
18-5/8
[473.19]
22-35/64
[572.64]
26-3/8
[669.86]

Range

Option

00/10

F1

29/40
11/17

F2

41/51
18/22

F3

52/56
23/28

F4

57/62

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

Optional Flange

I
4-5/8
[117.6]
5-15/16
[151.13]
6-7/64
[155.18]
7-1/2
[190.5]

J
4-1/16
[103.38]
5-11/16
[144.78]
6-7/64
[155.18]
7-1/2
[190.5]

K
2-3/4
[69.85]
3-7/8
[98.55]
6
[152.4]
7-1/2
[190.5]

L
3-7/8
[98.55]
5
[127]
7-1/2
[190.5]
9
[228.6]

# of Bolt
Holes

4

4

4

8

Range
00/10
29/40
11/17
41/51
18/22
52/56
23/28
57/62

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: [phone] e-mail: [e-mail]

PVF

NPT

3/4˝

1-1/2˝

3˝

4˝

Flange Opening
Diameter

(1-1/8˝)

(2˝)

(3-1/2˝)

(4-1/2˝)

The Series PVF and CPF Flowmeters are heavy bodied meters
for corrosives and high purity fluids. They are economically priced
meters ideal for acids or de-ionized water, making them suited for
water & wastewater treatment facilities. The flowmeters are com­prised of all plastic wetted components for maximum corrosion re­sistance. They have a full-scale accuracy of ±2% and can be
disassembled quickly without the meter being removed from the
pipeline for easy cleaning. The Series CPF flowmeters are avail­able with standard 3/4˝, 1-1/2˝, 3˝ and 4˝ female NPT. Optional
flange connections also available.

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, it is recommended
that safety shielding be used with the meter along with safety
glasses. Another protective measure is to use a sheet of
transparent, high-impact material in a broad area in front of the
meter. If hazardous, toxic, or flammable fluids are being
metered, recommended safeguards should include methods to
protect personnel from splash or rebound. A method of quick,
safe removal of dangerous fluids should also be included.

SPECIFICATIONS
Service: Compatible gases or liquids.
Wetted Materials: Series PVF: PVC, fluoroelastomer O-rings;

Series CPF: CPVC, fluoroelastomer O-rings.

Temperature Limits: See operating limits (Next page).
Pressure Limits: See operating limits (Next page).
Accuracy: ±2% of full scale.
Repeatability: ±1/2% of indicated flow rate.
Process Connections: 3/4˝, 1-1/2˝, 3˝ and 4˝ female NPT with

optional flange connection available.
Weight: 3 lbs (1.4 kg) for 3/4˝, 9 lbs (4.1 kg) for 1-1/2˝, 14 lbs
(6.4 kg) for 3˝, and 18 lbs (8.2) for 4˝.

RECOMMENDED PIPING: Series PVF and CPF 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 below. 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.

INSTALLATION

PREPARATION: Series PVF and CPF flowmeters are ready to
install as-is, although the sight tube may need repositioning so
the scale is visible after installation. First, remove the protective
caps from the connection ports. ALSO, REMOVE THE PLASTIC
SHIPPING TUBING ABOVE THE INLET CAP IN THE METER
CORE TUBE! Check that the float moves freely within the core

tube, and that no packing materials are in the meter.
Control valves should be mounted on the outlet side of the
meter. The use of a three valve manifold around the meter is
suggested (per Figures 2 & 3) as it allows uninterrupted process
flow while the meter is being cleaned.

MAXIMUM FLOWS (WITHOUT EFFECTING ACCURACY)
FOR UNDERSIZED PIPES CONNECTED DIRECTLY TO FLOWMETER INLETS

PIPE NPS

1/4
3/8
1/2
3/4
1
1-1/4
1-1/2
2
2-1/2
3
4
6

* Data per Cameron Hydraulic Data. Based on 5 FPS max. liquid velocity having no effect on Series
PVF and CPF flowmeters accuracy if the inlet pipe is smaller than the meter connections.
† SCFM = 0.445 x (psig + 14.7) x (ID)2. Based on 20 FPS max. air velocity having no effect on Series
PVF and CPF flowmeters accuracy if the inlet pipe is smaller than the meter connections.

DATA

2

(ID)

0.132

0.243

0.387

0.679

1.100

1.904

2.592

4.272

6.096

9.413

16.209

36.784

MAX. *
GPM LIQ.

1.72

2.98

4.74

8.31

13.47

23.32

31.74

52.29

74.56

115.2

198.4

450.0

MAX. SCFM AIR @ †
ATMOS

0.864

1.59

2.53

4.44

7.20

12.5

17.0

28.0

39.9

61.6
106
241

50 PSIG

3.80

7.00

11.1

19.5

31.7

58.8

74.6
123
176
271
467
1059

100 PSIG

6.74

12.4

19.8

34.7

56.1

97.2
132
218
311
480
827
1878

200 PSIG

12.6

23.2

37.2

64.9
105
182
248
408
582
804
1549
3514

FLOWMETER

MAIN

PROCESS

LINE

BY-PASS

VALVE

FLOW

FIGURE 2: TYPICAL INSTALLATION-

VERTICAL LINE FOR LIQUID, GAS, OR VAPOR

SHUT-OFF

VALVES (2)

FIGURE 3: TYPICAL INSTALLATION-

HORIZONTAL LINE FOR LIQUID, GAS, OR VAPOR

SHUT-OFF

VALVES (2)

FLOWMETER

BY-PASS VALVE

FLOW

MAIN PROCESS LINE

OPERATING LIMITS FOR SERIES PVF and CPF FLOWMETERS

Maximum Non-Shock Working Pressure, PSIG @ °F (bar @ °C)

Body Size and Description
3/4˝ PVC-NPT connection
1-1/2˝ PVC-NPT connection
3˝ and 4˝ PVC-NPT connection
3/4˝ PVC-Flange connection
1-1/2˝ PVC-Flange connection
3˝ and 4˝ PVC-Flange connection

70°F (21°C)
250 (17)
170 (11)
160 (11)
150 (10)
150 (10)
150 (10)

80°F (26°C)
255 (15)
150 (10)
150 (10)
150 (10)
150 (10)
150 (10)

100°F (37°C)
150 (10)
105 (7)
105 (7)
150 (10)
105 (7)
105 (7)

120°F (48°C)
90 (6)
65 (4)
65 (4)
65 (4)
65 (4)
65 (4)

140°F (60°C)
50 (3)
40 (2)
40 (2)
50 (3)
40 (2)
40 (2)

160°F (71°C)
N.R.
N.R.
N.R.
N.R.
N.R.
N.R.

180°F (82°C)
N.R.
N.R.
N.R.
N.R.
N.R.
N.R.

210°F (98°C)
N.R.
N.R.
N.R.
N.R.
N.R.
N.R.

Body Size and Description
3/4˝ CPVC-NPT connection
1-1/2˝ CPVC-NPT connection
3˝ and 4˝ CPVC-NPT connection
3/4˝ CPVC-Flange connection
1-1/2˝ CPVC-Flange connection
3˝ and 4˝ CPVC-Flange connection

Note: N.R. = Not Recommended

70°F (21°C)
270 (19)
180 (12)
160 (11)
150 (10)
150 (10)
150 (10)

80°F (26°C)
270 (19)
180 (12)
160 (11)
150 (10)
150 (10)
150 (10)

100°F (37°C)
250 (17)
170 (11)
140 (10)
150 (10)
150 (10)
150 (10)

120°F (48°C)
200 (10)
145 (10)
125 (9)
135 (9)
135 (9)
135 (9)

140°F (60°C)
150 (10)
115 (8)
105 (7)
110 (8)
110 (8)
110 (8)

160°F
(71°C)
130 (9)
85 (6)
75 (5)
90 (6)
90 (6)
90 (6)

180°F (82°C)
80 (6)
50 (3)
50 (3)
70 (5)
70 (5)
70 (5)

210°F (98°C)
50 (3)
30 (2)
30 (2)
40 (2)
40 (2)
40 (2)

Figure 1

Apply wrenches only on the flats or outer rims of the connection
ports. Avoid over-tightening (particularly with PVC or CPVC
models – no more than one turn after hand tight), and do not use
wrenches on other portions of the body or sight tube. When

solvent cementing in the vicinity of a meter with a
polysulfone sight tube, the tube should be removed until
the cement dries and fumes clear.

SURGE CHAMBERS & ACCUMULATORS: Flow meters 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 or compressors causing pulsation are
used, surge chambers or accumulators are strongly suggested
to damp the shock wave.

Figure 2

SIGHT TUBE ROTATION: On visual (the float disk is seen)

indication models with PLASTIC sight tubes, grasp the tube

firmly BY HAND near the body and twist until the scale faces the

desired direction. USE NO TOOLS!

On PLASTIC (PVC, CPVC) flow meters, the magnet is

encapsulated in the top of the float assembly to seal it from the

wetted system.

STARTUP

System flow should be started with the by-pass 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 SIGHT TUBE!

Although not essential, the meter sight tube 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.

Material

PVC/CPVC

* “Average” for these floats is f = 3.50, df = 217.8.

pf

VARIES*

df

VARIES*

EXAMPLE: Using a standard brass meter scaled for water (s =

1.00), what is the conversation factor for an oil with a specific

gravity of 0.85?

Qa= 1.00 x = 1.096

1.00 (8.30 - 0.85)

0.85 (8.30 - 1.00)

CORRECTING READINGS FOR NEW GAS CONDITIONS

READING FLOW

On transparent sight tube models, read flow directly from the
scale as the number nearest the top edge of the float indicator
disk. For magnetically-linked models, flow is read at 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 data below. The most practical method of applying
the formulae is to calculate a conversion factor for the new
system conditions, multiplying the scale reading by that factor. In
the problems below, “Qs” has been assigned a value of “1” to
determine the conversion factor. (The factory 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 per table.

s

Pgx Tsx ps)

Qg= Q

Psx Tgx pg)
Where:
Qg= SCFM, corrected to new conditions.
Qs= SCFM read on meter scale.
Pg= Operating pressure, psia (psig + 14.7).
Ps= Pressure stated on scale, psia (psig + 14.7).
Tg= Operating temperature, absolute (°F + 460).
Ts= Temperature stated on scale, absolute (°F + 460).
pg= Specific gravity of metered gas.
ps= Specific gravity stated on scale.

EXAMPLE: If using a standard meter scale for SCFM Dry Air @
100 psig, 70°F on argon (SP. GR. = 1.378) at 50 psig, 100°F.,
what would the conversion factor be?

Qa= 1.00 x = 0.522

64.7 x 1.00 x 530

114.7 x 1.378 x 560

Thus, actual flow of argon would be observed scale reading
times 0.622.

STEAM
Series PVF and CPF flowmeters may be used for vapors such
as steam. The conversion factor may be determined with the
following formula:

M

fh =Qm

5.879

S

v

Where:
M

= Actual flow, lbs/hr.

fh

Qm= Meter scale reading, standard.

(SCFM Dry Air @ 100 psig, 70°F.)

Sv= Specific volume of media (from steam tables)

EXAMPLE: When using a standard Series PVF and CPF gas
meter scaled for SCFM Dry Air @ 100 psig, 70°F., what is the
conversion factor for lbs/hr. steam at 50 psig, 300°F.?

M

=1 x

fh

5.879

6.727

Thus, actual flow of steam in lbs/hr. would be the observed scale
reading times 2.267.

VISCOSITY CONSIDERATIONS:

Each Series PVF and CPF liquid flowmeters has a so-called
“Viscosity Immunity Ceiling” (V.I.C.). Usually, if the viscosity of
the metered liquid is less than the V.I.C. of the meter, the
accuracy will not be influenced by changes in viscosity. When
greater than the V.I.C., the meter will be influenced significantly,
and must be calibrated for that viscosity. Effects of viscosity on
a given flowmeter are not always predictable. Two apparently
similar liquids with comparable densities and viscosities may
impact meter calibrations quite differently. The table below
provides general guidelines for the typical maximum viscosity for
meter models without affecting accuracy.

DISASSEMBLY: The spare parts sheet included for each
flowmeter model type ordered includes cutaway drawings.
Please refer to the appropriate sheet during the disassembly
and assembly procedures.

CAUTION:

BE SURE PRESSURE IS FULLY VENTED AND FLUIDS
COMPLETELY DRAINED BEFORE DISASSEMBLING THE
FLOWMETER. WEAR SAFETY GLASSES AND PROTECTIVE
CLOTHING IF THERE IS ANY CHANCE OF EXPOSURE TO
HAZARDOUS CHEMICALS.

AVERAGE V.I.C., CENTISTROKES, FOR STANDARD
SERIES PVF AND CPF FLOWMETERS

100% GPM,
SIZE 6

0.54 - 0.80

1.20 - 2.60

3.80 -7.00

10.0 - 23.0

MAINTENANCE:

Occasional cleaning of the sight tube and internal sensing
elements to assure float visibility and continued accuracy is the
only maintenance necessary for Series PVF and CPF
Flowmeters. Frequency will depend on the application — in
most cases, and annual cleaning is adequate. It is not necessary
to remove the Series PVF and CPF flowmeters from the pipeline
for cleaning or replacing parts. The body remains plumbed into
the pipe, allowing easy service and even installation of different
sensing elements to accommodate new flow rates or fluids.

Upon final installation of the Series PVF and CPF Flowmeters,
no routine maintenance is required. A periodic check of the
system calibration is recommended. Occasional cleaning of the
sight tub and internal sensing elements us assure float visibility
and continued accuracy is the only maintenance necessary for
the Series PVF and CPF Flowmeters. Frequency will depend on
the application - in most cases, an annual cleaning is adequate.
It is not necessary to remove the flowmeter from the pipeline for
cleaning. Please follow the instructions in the manual under
“Inspection and Cleaning.” The Series PVF and CPF
Flowmeters are not field serviceable and should be returned if
repair is needed (field repair should not be attempted and may
void warranty). Be sure to contact customer service to receive a
return goods authorization number before shipping.

CTS

3
7
15
25

100% GPM,
1-1/2˝ SIZE

11.0 - 15.0

21.0 - 35.0

50.0

70.0 - 120

CTS

50
100
250
500

The sight tubes of all standard Series PVF and CPF flowmeters
may be removed by, depending on model type: (a) removing the
cotter pins and pulling the lock rings out horizontally; (b)
removing the bolts from the body/sight tube flange; or (c)
removing the internal snap ring with retaining ring pliers. Using
hands only, pull the sight tube straight up out of the body with a
slight twisting motion, lifting it clear of the body and snorkel or
guide rod. Remove the float assembly by lifting it up and away
from the snorkel/guide rod (On PVC and CPVC the
snorkel/guide rod transition assembly must be lifted out with the
float). The core tube assembly may then be lifted out — if stuck,
CAREFULLY pry up at the top of the slot with a brass rod, taking
care not to damage the body or core tube.

INSPECTION & CLEANING

Inspect parts for nicks, scratches, chips, wear, and contaminant
build-up. The edges of the core tube slot, ID of the core tube,
and OD of the piston (largest section at the float assembly
bottom) are precision machined. Damage to these areas can
destroy the meter's accuracy. Also inspect the O-ring, the
bottom section of the sight tube, and the inside of the upper body
section. Damage to these areas may result in leaking. Clean,
rinse, and dry all parts carefully, including the O-ring, preferably
with a mild detergent and water and a soft cloth or soft tube
brush. If solvents are used, make sure they are compatible with
all meter parts (plastic sight tubes may be attacked by chemical
vapors or solvents —consult the factory).

CAUTION:

DO NOT SCRAPE OR USE ABRASIVE MATERIALS FOR
CLEANING.

ASSEMBLY

Replace all parts in reverse order of disassembly. Note the small
key on the core tube that must be aligned with a corresponding
keyway in the meter body. Seat the O-ring on the sight tube
before assembly (put the metal back-up ring on first for glass
sight tube models). Lubricate the O-ring with a small amount of
service compatible silicone grease or petroleum jelly to facilitate
replacement.

After replacing the internals, using hands only, press the sight
tube firmly down into the meter body with a twisting motion. Be
careful not to rock the sight tube side to side and bend the
snorkel tube/guide inward where it might interfere with float
movement. Rotate sight tube as necessary for scale visibility
and/or alignment of slots for lock ring tabs. Reinsert lock rings
and cotter pins, lower flange and snap ring (be sure snap ring
engages groove in body), or flange bolts (do not over tighten).

If reassembled correctly, the top edge of the indicator disk or
center of the ball should line up with the scale “zero” (either
dotted black or scribed line). If it does not, disassemble the
meter completely and carefully reassemble it, making sure core
tube is completely seated in the body.

If new flow internals are used, the scale may have to be
remounted on the sight tube. Depending on the model type, this
can be done either by loosening the mounting screw, or
reattaching the scale with double sided adhesive (new flow
internals are shipped with a new scale).

REPLACEMENT PARTS

Under proper care, there should be no need to stock
replacement parts.

Otherwise, parts only need to be replaced if damaged. Any
visible damage to the entire surface of the O-ring or sight tube
(particularly from the bottom edge) indicates need for
replacement. To insure accuracy, the inside surface of the meter
core tube, slot edges, and OD of the float piston should be free
of nicks, chips, with no visible erosion of any surfaces.

STORAGE REQUIREMENTS

There are no special requirements for Series PVF and CPF
flowmeters and parts. They should be kept in a reasonably clean
location away from excessive heat (over 120°F, 48ºC.) or
chemical or solvent fumes and vapors.

MAINTENANCE

Upon final installation of the Series PVF and CPF Flowmeters,
no routine maintenance is required. A periodic check of system
calibration is recommended. The Series PVF and CPF is not
field serviceable and should be returned if repair is needed (field
repair should not be attempted and may void warranty). Be sure
to include a brief description of the problem plus any relevant
application notes. Contact customer service to receive a return
goods authorization number before shipping.

TROUBLESHOOTING

SYMPTOM
FLOAT HANG-UP

FLOAT BOUNCE

USUAL CAUSE

Caused by particles, sludge, etc. (including
failure to remove the plastic tubing used to block
meter float during shipment) inside the core tube
and/or sight tube holding float. A bent snorkel
tube/guide rod (usually caused by careless
disassembly or violent surges) may also be
causing float to stick. Violent surges may also
unseat the internals in extreme cases.

Caused by pumping/compressor surges or
other pulsation sources, loose valve disks or
similar mechanical components, extreme
violation of inlet piping recommendations, or for
gas applications, harmonics commonly found in
systems with low pressure, low density gas.

SUGGESTED REMEDY

Remedies include tapping the meter gently to
temporarily dislodge the float, but if problem
reoccurs, meter should be disassembled &
cleaned, and/or snorkel/guide rod straightened. If
hang-up caused by sludge or pipe scale, clean
lines & install a filter or other form of cleaner in
supply line. If surges have caused the internals to
unseat, install a de-surger, accumulator, etc. You
may also wish to order a buffer kit — the buffer
serves as a resilient cushion for the float, and
prevents unseating.
Modification of piping, such as addition of a de­surger, receiver, accumulator, vibration
eliminators, loops, hoses, etc. between the source
and meter should remedy the problem. Severe
vibration may ultimately damage the meter, and
should be avoided. If "bounce" seems to be from
some other source, or shocks such as "water
hammer" (a potentially dangerous condition),
discontinue using the meter and contact factory.

APPARENT FALSE
READINGS, GAS
METERS

APPARENT FALSE
READINGS,
LIQUID METERS

Gas density not according to calibration data
(different pressure, temperature, gas, etc.), high
water vapor content, saturated gas going into
vapor or condensation phases, partially clogged
core tube slot or foreign matter interfering with
float movement, and/or violation of piping
recommendations at high flow velocities.

Liquid density not according to calibration data
(different temperature or new liquid or liquid
mixture), excessive dissolved or suspended
solids or gases, partial clogging of core tube slot
or foreign matter interfering with float
movement, or viscosity levels above the meter's
immunity index (V.I.C.). NOTE: If the meter is
suspected of giving false readings, and none of
the causes mentioned is found, please advise
as to the method used in determining the
suspected flow “error.” Each flowmeter is
individually calibrated by traceable methods,
and carefully inspected. There may be some
error in checking the meter against another
standard.

Remedies include checking meter pressure &
temperature, determining actual gas mixture
density & correcting with appropriate formulae in
this bulletin. Modifying inlet piping, relocating meter
to point of higher temperature and/or lower
pressure to eliminate vapor or condensation phase
effects, and/or cleaning the meter (install filter or
other form of cleaner if dirt repetitive problem) may
also be required. If accuracy still questioned, return
core tube/float assembly for calibration check.

By determining the actual density (due to changes
in mixture, temperature, etc.), the correction
formulae may be applied. If dissolved gases are in
the liquid, some elimination means should be
provided on the supply side (also recheck all
piping, as improper seals at connection points are
common sources of air in the liquid). If the metered
liquid is near the boiling point producing partial
"flash gas" at the meter, relocate the meter to point
of lower temperature and/or higher pressure, or
cool lines and/or increase system pressure. Note: It
is potentially dangerous to meter near the "flash
point" of any fluid, and this practice should be
avoided. Consult the factory for recommendations.
The previous recommendations regarding cleaning
the meter and/or filtration will also solve problems
due to dirt. If metering liquids with high viscosities,
consult the factory (may require special
calibration). If none of these causes seem to be
present, return meter core tube/float assembly
along with application data.

APPARENT
METER READING
MIGRATION
(reading changes
but flow appears
constant)

Frequently caused by use of soft disc type
valves, which may need to be replaced with a
valve more suited to flow control.
Can also be indicative of changing fluid
conditions (density, viscosity, etc.). Problems
with other elements of the flow system, including
leaks, clogged filters, pump/compressor wear,
etc. may first appear as a change in meter
reading — one of the functions of a flowmeter.

Verifying the proper fluid conditions are known and
applying correction formulae as needed will
remedy problems associated with changing fluids.
Cleaning, servicing, and replacement and/or repair
of other system components may be required.

LEAKAGE

If at the junction of the body and sight tube, it is
indicative of either (a) damaged O-ring (most
common); (b) damaged sight tube; or (c)
damage to the gland section of the body. It may
also be caused by improper reassembly of the
flowmeter in the field. If there is leakage at the
pipe connections to the meter, it is probably

Replace any damaged parts immediately; using
the proper assembly procedures indicated in this
instruction and the assembly detail drawings.
Remove the body and inspect for damage — if
none is visible, check pipe threads, reapply proper
thread lubricant/sealant, and reinstall.

If leak persists, replace meter body.
caused from over-tightening pipes on a prior
installation (or the initial installation, particularly
with PVC or CPVC flowmeters).

NOTE: All Series PVF and CPF flowmeters are hydrostatically pressure tested before they are shipped. Dwyer Instruments, Inc. encourages you to
contact the factory with any questions regarding proper installation and operation of Series PVF and CPF flowmeters.

©Copyright 2009 Dwyer Instruments, Inc. Printed in U.S.A. 10/09 FR# R1-443618-00 Rev.1

DWYER INSTRUMENTS, INC.

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

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: [phone] e-mail: [e-mail]