AQ M-Tech AB Level Switch Manual 8
7. Installing the Level Switch
How to install the Ultrasound Controller D72 or DP72 and connect the cables is described in the
Ultrasound Controller D72 or DP72 manual.
There must be a tight ultrasound-connection without any air-gap between the Level Switch and
the container. This is easy achieved by using glue. Alternatives for glue do also exist.
Silicone is heat-resistant and is the best glue at all temperatures, even above 80C. A Level
Switch glued with silicone is also very easy to remove. The silicone can be Loctite 5366 or a
similar transparent (1-component moisture curing) silicone. It takes a few days to cure. Put some
silicone on the container-facing side of the Level Switch and press it on to the container. The
silicone should cover any gap between the Level Switch and the container. During the first hours
the Level Switch must be held properly in place with something like a tape or so. The Level Switch
can be used even though the silicone is not completely cured (which takes a few days).
Transparent 1-component MS-polymer can also be used if temperature is not above 80C. It is
flexible like silicone and takes some days to cure.
Hard glues should be avoided since they can come loose by temperature variations.
For temporary testing and when the Level Switch is not glued, Sonotech SONO 600 is
recommended. An economic alternative is Electrolube Heat Transfer Compound which can also
be used for transferring sound. It does not cure so the Level Switch must be held in place by other
means. If the Level Switch is removed, the old SONO 600 or Heat Transfer Compound should be
wiped off and new used next time. Heat Transfer Compound is not recommended at temperatures
above 60C.
The measuring technique WR used in Level Switch mode is sensitive for small movements, which
may occur when gluing is not done, therefore if not glued a stable support is needed.
Stainless Steel and Glass Containers
When the Level Switch is mounted on a stainless steel or glass container and the echo-technique
is used, it is advisable to also attach a sound absorbing tape on the container. The tape will
supress unwanted sound travelling along the
container and thereby improve the measurements
(the Edata will be lower with air, making threshold
Ethd also lower, which is good). The 3M tape
8671 is suitable for this purpose. It withstands
high temperature 135°C. The tape is transparent
and can be removed without leaving any trace.
The picture shows the tape with the protective
paper still attached. It should be placed centered
over the Level Switch and go around the
container, starting and ending near the Level
Switch. The important area to cover is about 100mm on each side, close to the Level Switch. On a
big container, if the tape is too short, it can be cut in two pieces and placed on each side of the
Level Switch. The tape is 50,8mm wide and one tape should be used for each Level Switch.
Attaching tape above or below the Level Switch does not help. The tape is supplied with the Level
Switch in 500mm length and can also be ordered separately from AQ M-Tech, order number
101310. The material is polyurethane and acetone should not be used for cleaning the tape.
