DMTF transit time flow meter utilizes two transducers that function as both ultrasonic transmitters and receivers. The transducers are clamped on the outside of a closed pipe at a specific distance from each other. The transducers can be mounted in V-method in which case the ultra sound transverses the pipe twice, or W-method in which case the ultra sound transverses the pipe four times, or in Z-method in which case the transducers are mounted on opposite sides of the pipe and the ultra sound transverses the pipe only once. The selection of mounting method depends on pipe and liquid characteristics. When the flow meter works, the two transducers transmits and receives ultrasonic signal amplified by multibeam that travels firstly downstream and then upstream (Figure 1). Because  ultra sound travels faster downstream than upstream, there will be a difference of time of flight(¡÷£ô). When the flow is still, the time difference(¡÷£ô) is zero. Therefore, as long as we know the time of flight both downstream and upstream, we can work out the time difference, and then the flow velocity (V) and flow volume (Q) via the following formula.

    

 

 

V= K*D* dt            
  Where:  V: Liquid velocity
  K: Constant
  D: Distance between the two transducers
  dt: difference in time of flight

 

 

1. Calibrated in manufacture's lab, field setup is unnecessary.

2. Measurement is independent of fluid nature with wider applications than magnetic meters.

3. Available including up to 8GB event data logger, can search the¡¡event of totalizer flow, flow rate, velocity etc.¡¡

4. Parallel operation of positive, negative and net flow totalizer, while the output of totalizer pulse and frequency output are transmitted via open collector.

5. Re-calibration or maintenance is easy, no processing interruption (just plug out the inserted transducers from pipe line, when re-calibration or maintenance is finished), can be hot-tapped.

 

 

Transmitter	Power Supply	(Std) 10-28 VDC @ 2.5VA max.115/230VAC 50/60Hz ¡À15%@ 5VA max. Solar energy
	Velocity	0 ~ ¡À40 ft/s (0 ~ ¡À12m/s), bi-directional
	Display	4 line¡Á16 English letters LCD back lit, can display total flow, flow rate, velocity and meter running status etc.
	Units Rate Totalized	User Configured (English and Metric); Rate and Velocity Display; (FWD, NET, REV or BATCH) gallons, ft³, barrels, lbs, litters, m³,kg
	Output	4~20mA, Pulse, Relay, RS232C or RS485, options: up to 8 GB Data logger, Hart +(4~20mA), Modbus
	Accuracy	¡À1.0% of reading at rates >0.5 m/s);
		¡À0.005 m/s of reading at rates<0.5 m/s
	Sensitivity	Flow Rate: 0.001f/s (0.0003m/s)
	Repeatability	0.2% of reading
	Security	Keypad lockout, access code enable
	Dimensions	Std.:242*190*115 Weight: <2.5kg
		Exp: 255*220*110 Weight: <5.0kg
Transducer	Liquid Types Supported	Virtually most any liquid containing less than 2% total suspended solids (TSS) or aeration
	Suited Liquid Temperature	Std. Temp. Transducer: -40¡æ~121¡æ High Temp. Transducer : -40¡æ~150¡æ
	Cable Length	Std: 20 feet (6m); Opt: Maximum: 990 feet (300m)
	Pipe Size	ND65~ND3000; select S type flange transducers if pipe

 

   Model        DMTFF   ¨C X   ¨C X  X  X   X *£¨Transducers£©                                        

 

 

Parts Number Construction example:
For example: DMTFF¨CN-B1NN-N/DF-0-B-0-0400-030
Note: DMTF Flanged ultrasonic flow meter, 220VAC power supply, 4-20mA output, non-multiple output selection; common pipeline Flange mounting transducer, pressure is 1.0Pa, pipeline is ND400, transducer cable length is 30m.