Dynasonics TFXL Clamp-On Ultrasonic Flow User Manual download pdf (Page 10)

10 06-TTM-UM-00158 8/2012

NOTE: The transducer cable carries low level, high frequency

signals. In general, it is not recommended to add additional

length to the cable supplied with the transducers. If additional

cable is required, contact the factory to arrange an exchange

for a transducer with the appropriate length of cable. Cables

100 to 990 feet (30 to 300 meters) are available with RG59 75

Ohm coaxial cable. If additional cable is added, ensure that it is

the same type as utilized on the transducer. Twinaxial (blue and

white conductor) cables can be lengthened with like cable to

a maximum overall length of 100 feet (30 meters). Coaxial

cables can be lengthened with RG59 75 Ohm cable and BNC

connectors to 990 feet (300 meters).

DC POWER CONNECTIONS

The TFXL should be operated from an 11 to 28 VDC Class 2

power source capable of supplying a minimum of 250 mA

of current.

Connect power to the screw terminal block in the TFXL trans-

mitter. See Figure 1.4. Utilize the conduit hole on the right

side of the enclosure for this purpose. Use wiring practices

that conform to local and national codes (e.g., The National

Electrical Code® Handbook in the U.S.)

Connect the DC power to 11 to 28 VDC In, and DC Gnd., as

in Figure 1.4.

DC Ground

11 - 28 VDC

DC Ground

11 - 28 VDC

FIGURE 1.4  DC POWER CONNECTIONS

1) Connect an 11-28 VDC Class 2 power source as illus-

trated in the schematic in Figure 1.4. Wire up to 14

AWG can be accommodated in the TFXL terminal blocks

a) A switch or circuit breaker is required in the

installation.

b) The switch or circuit breaker must be in close

proximity of the TFXL and within easy reach of

the operator.

c) The switch or circuit breaker must be marked as

the disconnect device for the TFXL.

PART 2  TRANSDUCER

INSTALLATION

GENERAL

The transducers that are utilized by the TFXL contain piezo-

electric crystals for transmitting and receiving ultrasonic

signals through walls of liquid piping systems. DTTN and

DTTH transducers are relatively simple and straightforward

to install, but spacing and alignment of the transducers is

critical to the system’s accuracy and performance. Extra care

should be taken to ensure that these instructions are care-

fully executed. DTTS and DTTC, small pipe transducers, have

integrated transmitter and receiver elements that eliminate

the requirement for spacing measurement and alignment.

Mounting of the DTTN and DTTH clamp-on ultrasonic transit

time transducers is comprised of three steps:

1) Selection of the optimum location on a piping system.

2) Entering the pipe and liquid parameters into the soft-

ware utility. The software utility will calculate proper

transducer spacing based on these entries.

3) Pipe preparation and transducer mounting.

STEP 1  MOUNTING LOCATION

The  rst step in the installation process is the selection of an

optimum location for the  ow measurement to be made. For

this to be done e ectively, a basic knowledge of the piping

system and its plumbing are required.

An optimum location is de ned as:

~ A piping system that is completely full of liquid when

measurements are being taken. The pipe may become

completely empty during a process cycle – which will

result in the error code 0010 (Low Signal Strength)

being displayed on the  ow meter while the pipe is

empty. This error code will clear automatically once the

pipe re lls with liquid. It is not recommended to mount

the transducers in an area where the pipe may become

partially  lled. Partially  lled pipes will cause erroneous

and unpredictable operation of the meter.

~ A piping system that contains lengths of straight pipe

such as those described in Table 2.1. The optimum

straight pipe diameter recommendations apply to pipes

in both horizontal and vertical orientation. The straight

runs in Table 2.1 apply to liquid velocities that are

nominally 7 FPS (2.2 MPS). As liquid velocity increases

above this nominal rate, the requirement for straight

pipe increases proportionally.

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Dynasonics TFXL Clamp-On Ultrasonic Flow User Manual Page 10

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