9 Damping mats
UMFLUXUS_G8V4-6-1EN, 2018-10-10
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9
Damping mats
Before the transducer mounting fixture is mounted, damping mats are installed.
• Ultrasonic waves do not only propagate in the fluid but also in the pipe wall. Transducer damping mats are installed to
counteract the propagation of ultrasonic waves in the pipe wall.
• Ultrasonic waves are reflected at reflection points (e.g., flanges). Pipe damping mats are installed to reduce the ampli-
tude of the reflected ultrasonic waves.
Depending on the transducer type, it can be necessary to install more than one layer of damping mats (see Technical
Specification, section Damping Mats).
9.1
transducer Damping Mats
Transducer damping mats are installed on the pipe lengthwise.
The installation depends on the outer pipe diameter:
• < 900 mm: The transducer damping mats are installed on the entire pipe circumference.
• > 900 mm: The transducer damping mats are installed only on parts of the pipe circumference.
The transducer mounting fixture is mounted on the transducer damping mat (see Fig. 9.1).
9.2
Pipe Damping Mats
Pipe damping mats can be installed on the pipe lengthwise or crosswise. They are installed on the entire pipe circumfer-
ence.
Pipe damping mats can be installed to reduce the propagation of acoustic noise in the pipe wall if it is not possible to keep
the minimum distance to the reflection points (see section 5.3).
If the measured SCNR value is > 40 dB (see section 11.6.1), it is not necessary to install. the pipe damping mats.
9.3
Installation of the Self-Adhesive Damping Mats
• Select the measuring point according to the recommendations in chapter 3 and 5.
• Observe the operating temperature of the damping mat (see Technical Specification, section Damping mats).
• Determine the area on the pipe where the damping mats are to be installed:
– For outer pipe diameters < 900 mm, see section 9.3.1.
– For outer pipe diameters > 900 mm, see section 9.3.2.
• Clean the area on the pipe where the damping mats are to be installed:
– If present, the paint layer has to be smoothed by sanding. The paint does not need to be removed completely.
– Remove rust or loose paint.
– Remove any grease or dust. Clean the pipe surface with soap sud.
Fig. 9.1: Installed transducer damping mat in reflection arrangement
Fig. 9.2: Installed transducer and pipe damping mats in reflection arrangement
transducer damping mats
transducer mounting fixture
pipe damping mats
(installed lengthwise)
reflection point
(e.g., flange,
weld)
pipe damping mats
