Dynasonics TFXL Clamp-On Ultrasonic Flow Manuel d'utilisateur télécharger pdf (Page 11)

06-TTM-UM-00158 8/2012 11

Flow

***

Upstream

Pipe

Diameters

Downstream

Pipe

Diameters

Piping Configuration

and Transducer Positioning

TABLE 2.1  PIPING CONFIGURATION AND

TRANSDUCER POSITIONING

~ Mount the transducers in an area where they will not

be inadvertently bumped or disturbed during normal

operation.

~ Avoid installations on downward  owing pipes unless

adequate downstream head pressure is present to over-

come partial  lling of or cavitation in the pipe.

The  ow meter system will provide repeatable measure-

ments on piping systems that do not meet these require-

ments, but accuracy of these readings may be in uenced to

various degrees.

STEP 2  TRANSDUCER SPACING

TFXL remote mount transit time  ow meters can be used

with four di erent transducer types: DTTN, DTTH, DTTS

and DTTC. Meters that utilize the DTTN or DTTH transducer

sets consist of two separate sensors that function as both

ultrasonic transmitters and receivers. DTTS and DTTC trans-

ducers integrate both the transmitter and receiver into one

assembly that  xes the separation of the piezoelectric crys-

tals. DTTN and DTTH transducers are clamped on the outside

of a closed pipe at a speci c distance from each other.

Transducer

Mount

Mode

Pipe Material Pipe Size

Liquid

Composition

W-Mount

Plastic (all types)

2-4 in.

(50-100 mm)

Low TSS;

non-aerated

Carbon Steel

Stainless Steel

Copper

Ductile Iron

Not

recommended

Cast Iron

V-Mount

Plastic (all types)

4-12 in.

(100-300 mm)

Carbon Steel

Stainless Steel

Copper

4-30 in.

(100-750 mm)

Ductile Iron

2-12 in.

(50-300 mm)

Cast Iron

Z-Mount

Plastic (all types)

> 30 in.

(> 750 mm)

Carbon Steel

> 12 in.

(> 300 mm)

Stainless Steel

Copper

> 30 in.

(> 750 mm)

Ductile Iron

> 12 in.

(> 300 mm)

Cast Iron

TSS = Total Suspended Solids

TABLE 2.2  TRANSDUCER MOUNTING MODES

 DTTN AND DTTH

The DTTN and DTTH transducers can be mounted in:

W-Mount where the sound traverses the pipe four

times. This mounting method produces the best relative

travel time values but the weakest signal strength.

V-Mount where the sound traverses the pipe twice.

V-Mount is a compromise between travel time and

signal strength.

Z-Mount where the transducers are mounted on oppo-

site sides of the pipe and the sound crosses the pipe

once. Z-Mount will yield the best signal strength but

the smallest relative travel time.

For further details, reference Figure 2.1. The appropriate

mounting con guration is based on pipe and liquid char-

acteristics. Selection of the proper transducer mounting

method is not entirely predictable and many times is an

TOP VIEW

OF PIPE

W-Mount V-Mount Z-Mount

TOP VIEW

OF PIPE

TOP VIEW

OF PIPE

FIGURE 2.1 TRANSDUCER MOUNTING MODES 

DTTN AND DTTH

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 43 44

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Dynasonics TFXL Clamp-On Ultrasonic Flow Manuel d'utilisateur Page 11

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