Thermo Scientific HB-S200, User Manual

Page: 41 / 77

Sarasota 200 Ultrasonic Multipath
Flowmeter
Section 7, MAINTENANCE Page 7-1 Thermo Fisher Scientific
MAINTENANCE
7 MAINTENANCE
There is little maintenance as such relating to the flowmeter itself. However, the river or
channel must be kept free of weed, silt and other obstructions to avoid interruption of the
ultrasonic paths or changing the cross section area which would affect the accuracy of flow
determination.
Periodic checks on the functioning of the flowmeter and verification of the flow as calculated
are recommended.
7.1 Channel maintenance
7.1.1 Weed
•
If weed tends to grow in the channel, it must be kept cut.
•
Weed must be kept clear from between the transducer arrays where it may stop the
passage of sound between the transducers.
•
Weed should also be controlled on the approach to the gauged section and immediately
downstream of it where its presence could distort the velocity profile.
The user must decide on the seasonal cutting regime to suit the channel.
7.1.2 Profile
Periodically the channel shape should be checked to determine whether it has changed since
the flowmeter was programmed. It is particularly important to check the bed where silt might
have been deposited or scouring could have occurred.
Changes may be required to the programmed channel shape or mean bed level.
In serious cases, it may be necessary to dredge the channel, taking care not to damage the
transducers.
The user must decide on the checking regime to suit the channel.
7.1.3 Debris
Under high flow conditions it is not uncommon for debris to be washed along the channel.
Whilst the design of the transducer supports should be such as to minimise the risk of
snagging this debris, separate deflectors or devices intended to capture it may be employed.
If the channel is prone to this phenomenon, the user must instigate an appropriate debris-
clearing regime.
7.2 Flowmeter maintenance
There are no parts requiring maintenance except that the transducers should be checked
occasionally for a build-up of surface coating, for example by grease, and for misalignment
caused by physical shocks. These checks may be carried out along with the channel
maintenance.
Normally it is possible to obtain advance warning of problems by checking the signal quality.
This may be done on site or remotely via GAFA (Appendix 1: GAFA Screens).