The coupling agent enables reliable transmission of ultrasonic waves between the transducer and the tube wall contact surface. Long-term (fixed) installation and short-term (mobile) installation should use different types of couplings. Long-term applications of couplings are basically Araldites and unfilled epoxy resins (fillers will scatter ultrasonic waves). Permanent fixed installation couplings need to be checked regularly, the inspection cycle is specified by the product manufacturer according to its type, and the diagnostic function of the ultrasonic flowmeter itself can be used to check when it should be replaced. Short-term application coupling agent includes: silicone grease, axle grease and so on. In order to ensure that they are not dry, it is recommended to extrude a coupling of 3 to 4mm thick and about 5mm in diameter each time, and apply it along the axis of the transducer, and then press it to the tube wall. The following pretreatment measures and precautions should also be made before the disposal of coupler:
1. The outer wall of the tube where the transducer is installed should always be clean and grease free. If there is a coating or other covering layer, it must be removed, especially for those covering layers containing fiber and metal mesh.
2. When dealing with the pipe wall, it is necessary to maintain the original circumference line outline of the pipe, and keep the surface of the transducer parallel to the axial direction of the pipe, because the error of 1 degree may change the length of the acoustic path of 1% to 2%.
3. Do not overapply coupler, must be very careful operation to prevent excessive spread, to avoid mixing coupler into the air.
4. In the environment of dust and flocculent, we should pay great attention to prevent the mixing of other impurities, because dust and flocculent will reduce the coupling effect, and it is easy to dry the coupling agent.
5. If there are pits in the tube wall, apply sufficient coupling agent to fill them and form a complete sound path. If the pipe is plastic, the surface is slightly brushed to ensure adequate adhesion of the coupling agent such as epoxy resin.
6. Pay attention to the selection and application of coupler under different temperature conditions, and consult the supplier of coupler under abnormal operating conditions.
7. Water-based coupler will be evaporated at high temperature, frozen at low temperature and change properties; Oil-based couplings will flow at high temperatures, and some couplings will change performance at low temperatures.
8. At low temperatures (such as liquid oxygen, liquid nitrogen, etc.), metal indium series coupling pieces can be selected.
9. At higher temperatures (130C~200C), metal lead series coupling sheets can be selected.
10. At high temperature (200C~400C), you can choose metal silver series coupling piece.
11. In wet environment or underwater environment, special synthetic rubber coupling pieces can be applied.
Post time: Nov-05-2024