Chapter: Aquaculture Engineering : Instrumentation and Monitoring
Construction of measuring instruments
Construction of measuring instruments
The
construction of measuring instruments depends on the measuring principles used
and the signal transfer. One classification is mechanical, hydraulic,
pneumatic, electrical and electronic, where the last is being increasingly
used.
A measuring
instrument often comprises three major parts (Fig. 19.1):
A sensor or probe
A transmitter to transfer the
signal
A display or another type of
indicator (connected to the transmitter).
In some
instruments the three major parts are connected within the same unit, while in
other instruments the parts are separate and connected via cables for electric
signals or another principle for transfer of the measured values. Measuring
equipment can either give continuous signals (analogues), or on/off signals
(digital). An example of the first case is an oxygen meter that shows the concentration
of oxygen. Flow indicators that register if there is water flow or not (on/off)
are an example of the latter case.
The sensor in
the unit is used to record the phys-ical conditions in the medium, such as the
probe in an oxygen meter. The transmitter can either be electrical or
mechanical and translates the signal coming from the sensor to a scaled signal
that as is further transported to the display or indicator where the results
are shown in an understandable way. In the display the physical conditions of
the medium are shown. Signals may also go directly to a recording unit such as
a computer for
A short
description of the measuring instruments most used in aquaculture facilities is
given below. Equipment is separated into that used for measuring water quality
and that used to measure physical conditions.
Related Topics