The RVL series meter uses vortex-shedding technology for repeatable flow measurement accurate to ±1 percent of full
scale. The meter has no moving parts, and any potential for fluid contamination is eliminated by the corrosion-resistant all
plastic construction. The meter includes a compact two-wire (4…20 mA) or three-wire (pulse) transmitter, contained within a
conveniently replaceable plug-in electronics module. All electronics are housed in a corrosion-resistant enclosure.
Unlike meters containing metal or moving parts, the RVL is perfect for aggressive or easily contaminated fluids. Applications
range from ultra-pure water to highly corrosive chemicals and slurries. Units can be recalibrated and the meter output span
can be reprogrammed in the field.
OPERATING PRINCIPLE
Operation of the RVL vortex flow meter is based on the vortex shedding principle. As fluid moves around a body, vortices
(eddies) are formed and move downstream. They form alternately, from one side to the other, causing pressure fluctuations.
The pressure fluctuations are sensed by a piezoelectric crystal in the sensor tube, and are converted to a 4…20 mA or pulse
signal. The frequency of the vortices is directly proportional to the flow rate. The results are extremely accurate and repeatable
measurements using no moving parts.
Counter
Blu
Body
Detector
Detector
Figure 1: Operating principle
FLUIDS
Use any clean liquid compatible with the plastic material of construction that does not contain significant amounts of fibers
or abrasive materials.
DO NOT USE WITH EXPLOSIVE OR FLAMMABLE MATERIALS, FOOD OR BEVERAGES, OR GASEOUS FLUIDS.
Viscosities above 1 cSt raise the minimum usable flow rate and reduce the flow range. This effect is linear to viscosity. No
adjustments are required for viscosities up to 2.0 cSt. Liquids with higher viscosities adversely affect the permissible amount
and duration of over range flow. See Table 1.
ViscosityMinimumMaximumFlow Range
1 cSt11212:1
2 cSt2126:1
3 cSt3124:1
4 cSt4123:1
5 cSt5122.4:1
6 cSt6122:1
Table 1: Viscosity and flow range
Page 5 April 2017VRX-UM-00371-EN-03
General Installation Information
GENERAL INSTALLATION INFORMATION
Before installing the meter:
• Find an area for installation away from large electrical motors, transformers or other devices that can produce high
electromagnetic or electrostatic fields. The vortex transmitter contains electric circuitry that can be affected by
these interferences.
• Proper grounding is required to eliminate electrical noise which may be present within the fluid and piping system or in
the near vicinity of the vortex transmitter. Use exterior grounding strap for non-conductive piping systems to provide a
path to earth ground. Properly ground pipes in conductive piping systems.
Flow Rate and Range Requirements
Most manufacturers state flow range capabilities by publishing the maximum allowed flow rates. Then they provide a
turndown ratio to determine minimum flow rate. To use the turndown ratio, simply divide the maximum rate by the ratio
to determine the minimum rate. Vortex flow meters have a 12:1 turndown ratio at a viscosity of 1 cSt. Higher viscosities will
reduce the turndown.
OTE:NThe 1/4 in. NPT and 1/2 in. flare end meters have a standard turndown ratio of 8:1.
Piping Requirements
Turbulence in the pipeline can affect the accuracy of flow meters. Typical sources of turbulence are pumps, valves, change
in pipe diameter or changes-in-direction in the line. Install the meter away from the turbulence source to avoid turbulence
issues. These distances are indicated in Pipe Diameters (PD). For example, 10 PD is ten times the inside pipe diameter away
from the source of turbulence. Follow upstream and downstream distances for all sources of turbulence. See Figure 2 on page
7, Figure 3 on page 8, Figure 4 on page 9 and Figure 5 on page 9 for proper piping distance requirements.
Figure 2: Horizontal flow with sensing element in vertical orientation
10 Dia
Minimum
Page 7 April 2017VRX-UM-00371-EN-03
General Installation Information
Configuration
1 plane change
1 plane change w/outlet valve10 PD
2 plane changes
2 plane changes w/outlet valve10 PD
Two Plane
Changes
Piping Requirements
InletOutlet
20 PD
27 PD
20 Dia
Minimum
Flow
20 Dia
Minimum
Flow
27 Dia
Minimum
Flow
5 PD
5 PD
5 Dia
Minimum
10 Dia
Minimum
5 Dia
Minimum
Accuracy
(full scale)
Repeatability
(of point)
±1.50%0.25%
Two Plane
Changes
27 Dia
Minimum
Flow
Figure 3: Horizontal flow with sensing element in horizontal position
10 Dia
Minimum
Page 8 April 2017VRX-UM-00371-EN-03
General Installation Information
Configuration
1 plane change
1 plane change w/outlet valve10 PD
2 plane changes
2 plane changes w/outlet valve10 PD
Two Plane
Changes
Flow
27 Dia
Minimum
10 Dia
Minimum
Piping Requirements
InletOutlet
20 PD
27 PD
Two Plane
Changes
Flow
Minimum
Minimum
27 Dia
5 Dia
5 PD
5 PD
Flow
20 Dia
Minimum
10 Dia
Minimum
Accuracy
(full scale)
Repeatability
(of point)
±1.00%0.25%
Flow
20 Dia
Minimum
5 Dia
Minimum
Figure 4: Vertical flow with a change in direction or valve
25 Dia
Minimum
Minimum
Flow
5 Dia
Minimum
20 Dia
Minimum
25 Dia
Minimum
Minimum
5 Dia
Minimum
Flow
Changes
20 Dia
Minimum
30 Dia
Minimum
Minimum
5 Dia
Minimum
5 Dia
Minimum
Two Plane
Flow
5 Dia
Minimum
25 Dia
Minimum
Minimum
Figure 5: Horizontal flow with a change in pipe diameter
10 Dia
2 Dia
2 Dia
2 Dia
Page 9 April 2017VRX-UM-00371-EN-03
General Installation Information
1
Back Pressure
Back pressure, the pressure immediately downstream of the meter, must be maintained above a minimum level to avoid
cavitation. For most applications this may be ignored if the flow rate is less than 75% of maximum. For other applications, use
the following formula to calculate the minimum back pressure.
Back Pressure = 2.75 ∆P + 1.25 PV - 14.7
Where:
∆P = Pressure drop in psi at max flow
PV = Vapor pressure in psia of the liquid at operating temp.
(For example, the PV of water at 100° F is 0.42.)
BP = Back pressure (downstream of meter) in psig.
Example
For water, at 100° F (37° C) in a 1/2 in. (12.7 mm) meter, where the maximum pressure drop is 8 psi minimum back pressure is
7.8 psig.
BP = (2.75 × 8) + (1.25 × 0.42) - 14.7
BP = 22 + 0.525 - 14.7
BP = 7.825
Outputs
The RVL series meters can be ordered with a current output or a rate frequency output. The current output can be re-scaled in
the field using a PC communications cable and programming software, which are both available as PN RVS220-954.
OTE:NThe two outputs use unique circuit boards and cannot be changed in the field.
The rate frequency output produces pulses whose frequency is proportional to the flow going through the meter. Each meter
has a slightly different output frequency which is listed on the calibration sheet that accompanies the meter. See Table 2 for
the long term average full scale output frequency for standard size meters.
Meter SizeAverage Full Scale FrequencyPulse Width
1/4 in. (6.35 mm)1055 Hz0.47 msec
1/2 in. (12.7 mm)820 Hz0.61 msec
1/2 in. (12.7 mm)570 Hz0.88 msec
3/4 in. (19.05 mm)284 Hz1.76 msec
1 in. (25.4 mm)292 Hz1.71 msec
1-1/2 in. (38.1 mm)144 Hz3.47 msec
2 in. (50.8 mm)148 Hz3.38 msec
3 in. (76.2 mm)61 Hz8.20 msec
Table 2: Full scale output frequency
The frequency output option generates a square wave with an amplitude that matches the input power level. The pulse width
varies with frequency and is found by using the following formula.
PW in sec. =
2 x Ma ximum Frequency (Hz)
K-Factors
The K-factor is the number of pulses that must be accumulated to equal a particular volume of fluid. Think of each pulse as
representing a small fraction of the totalizing unit.
Calibration reports that accompany RVL series meters include a nominal K-factor in both gallons and liters. See “Calibration
Certificate Sample” on page 23.
Page 10 April 2017VRX-UM-00371-EN-03
Electrical Installation
ELECTRICAL INSTALLATION
Power
Use the following guidelines when selecting a power source:
• Use an 8…28V DC power supply. The specific connection depends on which output is option is used.
• Use clean electrical line power.
• Do not operate this unit on circuits with noisy components such as fluorescent lights, relays, compressors or variable
frequency drives.
• Use linear power supplies.
OTE:NThe power and output connections share a common ground.
Wiring
4…20 mA Loop
Connect a twisted pair wire (not provided) to the terminals of the transmitter marked 8…28V DC and Output. Do not connect
the shield to the transmitter if the twisted pair wire is shielded. The shield should be grounded at the receiver only.
See Figure 6. The transmitter is reverse-polarity protected.
+8-28 VDC
Programming
+8-28 VDC
Output
Output
Gnd
Gnd
4…20 mA
RECEIVER
POWER
SUPPLY
8…28V DC
8…28V DC
Output
Load
Figure 6: Loop connection with single load
The receiving equipment must accept industry standard true two-wire or loop powered 4…20 mA process transmitter inputs.
The power can either be supplied by the receiving equipment or an external power supply that supplies 24V DC an 30 mA.
See Figure 6 for the wiring setup using an external power source and Figure 7 using the receiver as the power source. Several
receivers may be connected in a series as shown in Figure 7, but only one should provide power, and all should have
isolated inputs.
+8-28 VDC
Programming
+8-28 VDC
Output
Output
Gnd
Gnd
4...20 mA
RECEIVERRECEIVER
Additional Loads
RECEIVER/POWER SUPPLY
8…28V DC
Output
Figure 7: Loop connection with multiple loads
Page 11 April 2017VRX-UM-00371-EN-03
Electrical Installation
Loop Load (Ohm's)
Loop Load (Ohm's)
The voltage provided by the receiver must be within the limits shown in Figure 8.
1100
1000
900
800
700
600
500
400
300
200
100
Supply Voltage – 8V DC
0.02
= Maximum Loop Resistance
Operate in the
Shaded Region
10
1281416182022242628
Supply Voltage (V DC)
Figure 8: Supply voltage chart
To use this figure:
1. Add the resistance of all the receivers, indicators and the wire in the loop. If the wire resistance is unknown, use a value of
50 ohm for a twisted wire of 1000 feet or less with a gauge of #22 awg or heavier.
2. Find the total load (in ohms) on the left side of the chart in Figure 8 and follow that value horizontally until it intersects
with the shaded area.
3. From the intersection point look straight down to where a vertical line would intersect the voltage scale. This is the
minimum voltage needed for the transmitter to operate properly under the specic load conditions.
Example
After checking the specification for all the loads in an application the total amounted to 800 ohms. Following the 800 ohm
line to the right, the intersection point is about 3/4 of the way across the chart in Figure 9.
A vertical line through the intersection point crosses the voltage axis at about 24V DC, so with a load of 800 ohms a standard
24 volt power supply would be used.
1100
1000
900
800
700
600
500
400
300
200
100
Supply Voltage - 8V DC
0.02
= Maximum Loop Resistance
Operate in the
Shaded Region
10
1281416182022242628
Supply Voltage (V DC)
Figure 9: Supply voltage example
Pulse Output
Counter
Pulse
Output
8…28V DC
POWER
SUPPLY
Programming
+8-28 VDC
Output
Gnd
8…28V DC
Output
Ground
Figure 10: Pulse output wiring
Page 12 April 2017VRX-UM-00371-EN-03
Electrical Installation
White
Three-Pin Connection Option
An optional three-pin connection is available for when the transmitter/meter combination is mounted remotely from the
power source/receiver. The mating connector is PN RF8687000.
4…20 mA Input
8…28V DC
Output
4…20 mA Input
– 4…20 mA Input
+8-28 VDC
Output
Gnd
Meter
Electronics
P.N. RF8687000 Connector
Figure 11: Remote connection loop power
ON
12345678
2
CW
13
SPANZERO
– 4…20 mA Input
-+
8…28V DC
Power Supply
mA
Ammeter
White
4…20 mA Input
Black
– 4…20 mA Input
Black
-+
Figure 12: Integral configuration for rate indicator
Page 13 April 2017VRX-UM-00371-EN-03
Mechanical Installation
MECHANICAL INSTALLATION
RVL Inline Installation
For proper installation, follow these guidelines:
• Install the meter where pipe vibration is minimal.
• Use the upstream and downstream piping requirements shown in “Piping Requirements” on page 6.
• Do not use upstream valves to control flow rate. Always keep upstream valves fully open.
• Connect good quality ball valves with integral unions directly to the flow meter if the valves are fully open during
operation for easy isolation and removal of the flow meter. Cavitation and flow rate pulsation adversely affects the flow
meter performance.
• Do not use diaphragm or piston pumps.
• Do not use Teflon tape or any kind of pipe dope when piping.
• Handle the meter with care.
• Do not use excessive force. Screw mating fittings (FNPT) and flanges into the meter hand-tight; then tighten an additional
1/2…3/4 turn.
• Always use two wrenches when turning the flow meter into a fitting; one across the flats on the flow meter end, close to
the fitting, and one on the fitting.
• Do not use tools inside the flow meter, as this may damage the vortex sensor, and void the warranty.
The flow meter may be mounted in any orientation. Three holes, tapped 1/4-20 UNC-2B, 0.375 in.-deep, on 3/4 in. centers are
provided on the 3/4 in. and smaller flow meters. Use these holes to provide support for the flow meter if pipe supports are
not practical.
Page 14 April 2017VRX-UM-00371-EN-03
Mechanical Installation
RVL Wafer Installation
The RVL Wafer series transmitters are designed with wafer style flow bodies, that mount easily between standard ANSI style
pipe flanges.
For proper installation, follow these guidelines:
• Install the meter where pipe vibration is minimal.
• Use the upstream and downstream piping requirements shown in “Piping Requirements” on page 6.
• Do not use upstream valves to control flow rate. Always keep upstream valves fully open.
• Connect good quality ball valves with integral unions directly to the flow meter if the valves are fully open during
operation for easy isolation and removal of the flow meter. Cavitation and flow rate pulsation adversely affects the flow
meter performance.
• Do not use diaphragm or piston pumps.
• Do not use Teflon tape or any kind of pipe dope when piping.
• Do not allow gaskets to protrude into the flow stream on flanged meters.
Flange SizeRecommended Torque
1/2…1-1/2 in.10…15 ft Ibs
2…3 in. 20…30 ft Ibs
Table 3: Torque rating
Follow these steps for proper installation and operation:
1. Space anges to accommodate the width of the ow body. See “RVL Wafer” on page 21 for dimensions.
2. Align the ow body centered with respect to anges and gaskets, insert threaded rods, retaining nuts and lock washers.
3. Install all retaining nuts hand-tight, and then uniformly tighten the nuts in an alternating sequence, diametrically opposed
to each other. Uniform stress across the ange prevents leakage at the gasket. Torque ratings are listed in Table 3.
4. Use grounding rings when metal pipes are used in conjunction with this meter. See Figure 13.
Grounding
Rings
Figure 13: Grounding ring installation
Page 15 April 2017VRX-UM-00371-EN-03
Maintenance
CAUTION
RVL Tube Installation
For proper installation, follow these guidelines:
• Install the meter where pipe vibration is minimal.
• Use the upstream and downstream piping requirements shown in “Piping Requirements” on page 6.
• Do not use upstream valves to control flow rate. Always keep upstream valves fully open.
• Connect good quality ball valves with integral unions directly to the flow meter if the valves are fully open during
operation for easy isolation and removal of the flow meter. Cavitation and flow rate pulsation adversely affects the flow
meter performance.
• Do not use diaphragm or piston pumps.
• Do not use Teflon tape or any kind of pipe dope when piping.
• Handle the meter with care.
To install the meter:
1. Remove any burrs from the pipe ends.
2. Slide the are nut onto the pipe.
3. Push the are nut back far enough so that it will be out of the way when you use the aring tool.
4. Clip the pipe in the aring tool, keeping the end ush with the face of the tool.
5. Slowly turn the handle on the tool until it bottoms out.
6. Unscrew the handle and remove the tool to check the quality of the are.
a. If the flare is not smooth or even the first time, cut off the end with your pipe cutter, and repeat steps 4…6.
7. Line up and tighten the nut and ared pipe to the tting body. Make the connection tight, but not so tight that the ow
meter body is distorted.
• Always use two wrenches when turning a fitting onto the flow meter; one across the flats on the flow meter end close to
the fitting, and one on the fitting.
• Do not use tools inside the flow meter, as this may damage the vortex sensor, and invalidate the warranty.
MAINTENANCE
RVL flow meters do not require maintenance in normal service if they are properly installed. Remove the meter from service
for cleaning if the flow tube becomes clogged with debris. Significant clogging often results in high (up to 20%) and/or erratic
output. Do not stick tools into the tube, as this may permanently damage the vortex sensor. The vortex sensor cannot be
repaired in the field. To clean the flow tube, run hot, up to 160° F (71.1° C), soapy water into the downstream end of the flow
tube. Dislodge large objects jammed against the bluff body by lightly tapping the upstream end of the flow tube against a
firm surface.
DO NOT REMOVE VORTEX METER DURING OPERATION. ALWAYS DISCONNECT THE PRIMARY POWER SOURCE
BEFORE INSPECTION OF SERVICE. DO NOT TAP THE FLOW TUBE SO HARD THAT THE THREADS, ON THREADED UNITS,
BECOME DAMAGED.
A schedule of maintenance checks should be determined based upon environmental conditions and frequency of use.
Inspect the meter at least once a year.
• Visually check for evidence of overheating by noting discoloration of wires or other components.
• Check for damaged or worn parts, especially the bluff body, or indications of corrosion.
• Check for tight, clean electrical connections and that the device is operating properly.
1/2 in. (12.7 mm)1.31 (33.3)6.25 (158.8)4.87 (123.7)
3/4 in. (19.05 mm)1.31 (33.3)6.25 (158.8)4.66 (118.4)
1 in. (25.4 mm)1.44 (36.6)6.59 (167.4)5.42 (137.7)
C
in. (mm)
Page 21 April 2017VRX-UM-00371-EN-03
Troubleshooting
TROUBLESHOOTING
If difficulty is encountered, locate the symptom most likely present and follow the appropriate instructions.
Current Loop
No Current Output
• Place a DC voltmeter across the two terminal block screws. With the electronics module powered there must be at least
8V DC present. If there is less than 8V DC, but more than 0V DC, check the power source for sufficient voltage to drive the
loop, as shown in Figure 8 on page 12.
◊ If there is 0V DC present, check for a broken wire or connector in the loop.
• Check for the proper polarity of the current loop connections.
• Make sure the receiving device is configured to provide source current to the electronics module.
Zero Flow Indication (4 mA in Loop)
• Check that the flow is greater than the minimum specified for the particular size flow meter in use.
◊ If the flow rate is too low, replace the flow meter with the proper size flow meter.
◊ If the flow rate is sufficient, partially remove the electronic module. Check that the three pin connector that connects
the electronics module to the flow transducers is positively connected. See Figure 20. Align and insert the connector on
to the bottom of the electronics module if it is disconnected.
Terminal Strip
Electronics Module
Three-Pin Connector
Flow Sensor Body
Figure 20: Electrical connection
Erratic Flow Indication
• Check that there is at least 8V DC present across the two terminal block screws.
• Check for material clogging the flow meter and in the upstream piping.
• Check for erosion of the bluff body by sighting down the meters bore. Erosion or damage to the bluff body causes erratic
readings and compromise accuracy. If the erosion continues, the flow meter will need to be periodically replaced.
• Check upstream piping distance. See “Piping Requirements” on page 6.
• Check for excessive pipe vibration. Normal amounts of pipe vibration are easily tolerated. The transmitter module contains
a highly effective active filter that rejects false signals caused by pipe vibration. This filter is most effective under flowing
conditions. If vibration is causing the meter to indicate flow when the flow is stopped it will most likely not cause error
under flowing conditions. The false flow indication may be ignored, or the pipe may be restrained by firm clamps.
• Check for electrical noise. Under some conditions there can be high common mode AC noise present between the fluid
and the power supply ground. The flow meter is designed to reject up to 50 volts of AC common mode noise without loss
of accuracy. If noise adjustment is used, accuracy is effected at low flow rates. Place a ground strap on the pipe on both
sides of the flow meter (the flow meter is made of non-conductive plastic) and connect them both to the one point where
the loop is grounded if metal piping is used. See “Wiring” on page 11. Use a grounding orifice if plastic piping is used. The
transmitter module contains a highly effective active filter that will reject false signals due to high common mode voltage.
This filter is most effective under flowing conditions. If a false indication of flow is encountered at zero flow, it will probably
not cause error under flowing conditions.
Over-Stressed Sensor
The sensor can be over-stressed if the maximum permitted flow rate of 125% of recommended capacity (100% of HT meters)
is exceeded.
Page 22 April 2017VRX-UM-00371-EN-03
CALIBRATION CERTIFICATE SAMPLE
Calibration Report
Unit Under Test (UUT) Information: Master Meter:
Description: ¾ in. In-Line NPT End Flow Meter Std uncertainty: ±0.25%
Model Number: RVL075-N 1 VNN Traceability No: 30400/31801
Serial Number: 99999 Model No: FT8-8N EXW-LEG-5/FT-16 NEXW-LEG-1
Sensor Type: Vortex Shedding Serial No: 806890/16011903
Output type: 0-5V
Minimum Flow: 2.1 GPM 7.9 LPM Customer Information:
Maximum Flow: 25 GPM 94.6 LPM Customer Name:
Calibration Date: October 24, 2007 Customer No.:
Calibration Interval: 12 Months Order No.:
Cal. Liquid: Water
Ambient Temperature: 71.74 °F
Ambient Humidity: 31.39 %RH
Linear Points: 5