user manual

Page 9
MSL600
Installation, Operation & Maintenance Manual
IP262/Z0, Rev. AB
February 2012
2. Application planning
The following section discusses a few practical considerations when planning an installation.
2.1 Circular clarifiers
Circular clarifiers are very common and can come with rotating or static bridges over them.
2.1.1 Rotating bridge
If the transducer is mounted on a rotating bridge then it should be positioned on the leading edge of the bridge,
see Figure (2). This places it ahead of any bow wave in the sludge blanket which may be created by trailing sub
surface scrappers that would otherwise give rise to a false indication of the blanket level.
Ideally the transducer should be mounted between 1/3 and 2/3 of the way along from the outer (wall) edge of the
settlement tank (i.e. 1/3 to 2/3 of the radius from the inside of the tank wall).
Care should be taken to ensure that the transducer is mounted over an undisturbed section of the tank, i.e. not
too close to the tank inlet or tank wall, and away from columns of rising gas bubbles. All of these factors can
result in false sonar echoes being received. It is recommended that the transducer be mounted at least
1m (3.3 feet) from any such structures.
If a scum removing skimmer is present then the transducer should be mounted behind this.
When locating the transducer the user must ensure that there are no permanent underwater obstructions below
the transducer, as these will give false sonar echoes and disrupt the signal. It is recommended that the
transducer be mounted at least 1m (3.3 feet) from any such structures.
Ensure that the transducer does not come into contact or collide with any scum boards, weirs or other surface
obstructions as the bridge rotates.
Figure (2): Circular clarifiers – Rotating bridge
Approximate
MSL600
mounting
position