CLARK SONIC HOME > Ultrasonic Flow Meters Model CSLFC

Ultrasonic Flow Meters Model CSLFC

4-20 mA Output, Frequency Output, Flows to 3000 GPM, 3" to 10" Pipe


Clark Sonic® Ultrasonic Flow Meters are ideal for measurement of flow rates of acoustically conductive liquids including most clean liquids and many liquids with entrained solids.

Main advantages include excellent long term stability, no pressure drop, broad fluid compatibility, high accuracy and low cost. Also, there are no moving parts.

At the heart of the CSLFC flow meter/flow transmitter is a proprietary mixed signal ASIC which allows sophisticated timing, control and transducer drive circuitry to be combined on a single integrated circuit. The ASIC uses a special algorithm that is an improvement upon the standard single-path measurement technique. Using the "sing around" method, the ultrasonic transducer alternates between transmitting and receiving to measure differences in flight time between upstream and downstream transmissions. A sound pulse is transmitted from an upstream transducer towards a downstream transducer like a traditional time-of-flight measurement. However, the received sound pulse then triggers a second downstream transmission that then triggers a third and so on for a specific number of cycles. This process is repeated in the upstream direction.

Because it takes an average flight time over multiple cycles to compute the difference in flight times, the approach yields a significant improvement in timing accuracy when compared with the time-of -flight difference of a single sound pulse in each direction. This algorithm, combined with the pico-second timing resolution of the ASIC, provides the precise time measurement capability necessary for compact, small diameter ultrasonic meters.

The output of the CSLFC ultrasonic flow meter is unaffected by changes in fluid temperature, density and viscosity as the flow calculation is independent of the speed of sound.

Wetted materials include ULTEM® encapsulated ultrasonic transducers with a choice of elastomer seals and epoxy coated carbon steel body material.


Flow Range: Bi-directional, field selectable per "Standard Models" table
Accuracy: ±0.75% of full scale
Operating Temperature: -40 to 190°F (-40 to 87.8°C)
Response Time: User selectable, 2 or 10 seconds
Viscosity Range: 0.2 to 150 cSt (0.2 to 150 mPas)
Liquid Density: 30.6 to 74.9 lb/cu.ft. (490 to 1200 kg/m3)
Max. Working Pressure: 200 PSI (13.8 bars)
Pipe Sizes: 3", 4", 6", 8", 10"
Pipe Connections: ASME class 150 flange
Electrical Enclosure: Integral to Body casting with gasketed cover; One 1/2" 
    NPT conduit connection (plugged when model ordered with metric threads) 
    and one M16 x 1.5 connection (plugged when model ordered with NPT threads)
Electrical Connections: Screw terminal connections on PC board
Enclosure Rating: NEMA 4 (IP 65)
Power: 18 to 36 VDC


Ultrasonic Transducers: ULTEM® Encapsulated
Seals: EPDM, Buna-N, Neoprene, FKM, or other
Body Material: Schedule 40, epoxy coated, carbon steel pipe


Analog: 2-wire, 4-20 mA output; Output is 4 mA from zero to min. flow 
    (see Standard Model table)
A second output is available in the form of an optically 
isolated NPN transistor. The second output is configured at the factory. 
The configuration choices are:
	Error Detection: An optically isolated sink output is activated under 
	certain detectable fault conditions, such as transducer failure or 
	overly noisy output due to flow stream anomalies, as might be seen 
	due to excessive bubble entrainment. The optional Fault output is 
	an optically isolated NPN transistor capable of sinking up to 25 mA 
	from a voltage source of no more than 48 VDC.
   	Frequency: Output is an optically isolated NPN transistor capable of 
	sinking up to 25 mA from a voltage source of no more than 48 VDC. 
	Frequency output is from 240 to 1200 pulses/gallon depending on range 
	(see Standard Model table). Lower frequency can be provided on request. 
	Direction of Flow: Optional output to indicate direction of flow is available. 
 	Activation or deactivation of an optically isolated 25 mA (max. 48V no load voltage) 
 	sink output indicates flow direction. Error detection is not available when this 
 	option is ordered.
Optional Temperature Sensor: 3 wire RTD, 100 Ohm, Platinum, Class A, IEC60751, built 
	in to transducer shell for monitoring process temperature; optional 4 or 8 pin electrical 
	connector recommended with this option.
Pipe Sizes
3" to 10" Schedule 40 Carbon Steel Pipe, ASME 150 Flange
Pipe Size Dimensions (Inches)
A B C D E F Bolt Circle Diameter Number of Holes
3" 11.00 7.50 3.50 6.54 2.62 0.75 6.00 4
4" 13.00 9.00 4.00 6.54 2.62 0.75 7.50 8
6" 16.00 11.00 5.09 6.54 2.62 0.88 9.50 8
8" 18.00 13.50 6.11 6.54 2.62 0.88 11.75 8
10" 22.00 16.00 7.18 6.54 2.62 1.00 14.25 12


Model Pipe Size   *Field Selectable Full Scale Ranges (GPM) *Field Selectable Full Scale Ranges (LPM) Frequency Output Option Flow Constant (Gallons) Frequency Output Option Flow Constant (Liters)
Min. Max. Min. Max. Pulses/Gallon Gal/Min=FC*Freq. Pulses/Liter L/Min=FC*Freq.
CSLFC3 3” L 3.0 200 11.0 750 72 0.833 18 3.33
H 6.0 400 23.0 1500
CSLFC4 4” L 4.5 300 17.0 1150 60 1 15 4
H 7.5 500 29.0 1900
CSLFC6 6” L 9.0 600 35.0 2300 30 2 6 10
H 18.0 1200 68.0 4500
CSLFC8 8” L 15.0 1000 57.0 3800 15 4 3 20
H 30.0 2000 114 7600
CSLFC10 10” L 22.5 1500 86.0 5700 12 5 3 20
H 45.0 3000 165 11000
*F.S. ranges can be user specified to 125% of each stated high (H) range with no change to specifications and to 25% of each low (L) range with some specification modification. Consult factory.


Digital panel meter installed on transmitter
Power Supply: Loop Powered
Display: 4-1/2 Digit LED, 0.6"
Case: NEMA 4X
Versions: DP Option: Displays 0-100% F.S
                  DS Option: Scaled to customer requirement

Panel Meter/Display option Four or eight pin receptacle
connector recommended.


Optional NEMA 4 four or eight-pin receptacles installed in
transmitter conduit connection and factory wired along
with mating simplify field installation.

connecter options

GSP 312 installed and wired at factory
GDM3012 J Kit installed in field
4H-Hirschmann Connector
4H-Hirschmann 1/2" NPTF Connector

Terminal Hirschmann Connector Wiring
(-) Vin Return, 4-20 mA
1 (+) Vin Supply, 18-36 VDC, 4-20 mA
2 C Alarm (Collector)
3 E Alarm (Emitter)

4R/8R installed and wired at factory
4C/8C installed in field

Transmitter Connection Terminal 8-Pin (8C) Connector *8-Pin Connector Cable 4-Pin (4C) Connector 4-Pin Connector Cable
+ 1 Brown 1 Red
- 2 White/Brown 2 Black
C (Collector) 3 Green 3 White
E (Emitter) 4 White/Green 4 Green
RTD Red 5 Orange
RTD Red 6 White/Blue
RTD White 7 Blue
*When factory supplies a length of connector cable pre-wired to 4C/8C



Wiring Diagram




Field Service
Two opposing CSLFC ultrasonic transducers are inserted into fixed ULTEM® drywells and held in place 
with light spring force. A locating keyway in the drywell aids insertion and positioning of the transducers. 
In the event of field failure of a transducer, replacement is straightforward and can be accomplished 
without removing the pipe spool and shutting down the process.

The electrical PC board can also be field replaced. Calibration factor and other specific information are 
maintained at the factory for all transmitters shipped.

Transducer Components
1 Spring Retainer
2 Spring
3 Clamp
4 Bushing
5 Drywell
6 Ultrasonic Transducer



Model Units of Measure Transducer Seal
CSLFC3 G= Gallons Per Minute (U.S.) E= EPDM
CSLFC4 L= Liters Per Minute B= Buna-N
CSLFC6   N= Neoprene®
D - Options
NPN Transistor Output - Select One
- = Error Detection (Default)
F = Frequency Output
DF = Direction of flow output option
Other Options
R = 100 Ohm Platinum RTD
DP = Display % F.S
DS = Display in Engineering Units- specify
F - Transmitter Connector Options
4H =Hirschmann 4-conductor Receptacle & 1/2" NPTF Conduit Connector Set (our default/standard connector)
4R = 4-Pin Male Circular Receptacle
8R = 8-Pin Male Circular Receptacle
4C = 4-Pin Female Circular Connector
8C = 8-Pin Female Circular Connector
*For non-listed ranges specify model followed by full span value.  Example: CSLFC4-150G = 150 GPM at 20 mA or CSLFC4-750L=750LPM @ 20 mA


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ULTEM® is a registered trademark of The General Electric Company
Neoprene® is a registered trademark of DuPont Dow
Clark reserves the right to make design changes without prior notice.
Ask about our remote mount Series DS1000 flow rate indicators and totalizers.
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