Page 22 - Energize December 2022

NEWS

TAKING AND USING HYDROSTATIC MEASUREMENTS
Water fill level monitoring and measurement

“These days, monitoring the fill level is a key factor for many applications and industries
and even for our basic requirements.”

ost drinking water comes from groundwater. taken using relative pressure probes or AA (absolute-absolute)
No longer confined to the Global South, general technology.
Mwater scarcity is now an ever-present issue in
technologically developed countries as well. Climate change, Remote transmission via the Internet
forest fires, glacier melting and the resulting rise in world sea When monitoring groundwater/fill levels in open bodies of water
levels are all arguments in favour of the proper, well-thought- or outdoors, the measuring points may be relatively far away and
through management of groundwater resources. difficult to reach. For these applications, KELLER Pressure has
Furthermore, monitoring the fill level in tanks or sealed solutions involving level loggers via short-range radio interfaces
containers of oil or similar liquids is very important, especially as well as level loggers with a remote data transmission unit via
on cost grounds, and can also double as theft protection. GSM or the Internet.
Determining the exact fill level right down to the centimetre Kolibri Cloud/desktop is used to process and analyse/prepare
can therefore save users a fair amount. Using an additional the collected data.
radio module, a purchase order can be triggered automatically
in various applications as soon as the fill level falls below a Product overview for hydrostatic measurements
certain threshold. • Level probes: Submersible probes for level and fill
The most common form of electronic fill level measurement measurement. With a special design and cable and housing
is hydrostatic pressure measurement. materials that have been chosen for compatibility with their
surroundings, these probes can be used in a wide range of
Hydrostatic pressure liquids.
Hydrostatic pressure is the pressure that forms within a liquid • Data loggers: A variety of data logger designs for recording
or gas at rest due to the influence of the force of gravity. The pressure and temperature profiles. Depending on the system,
fluid at rest exerts a dead weight on the layers below as a result the data is read out via a plug connection or remote transfer.
of its mass. Neither the type of medium nor whether or not the • Multi-parameter data loggers: The DCX-22-CTD measures
fluid is in motion plays a role here. Dynamic pressure due to conductivity and temperature as well as pressure, along with
flow is not recorded. the depth of bodies of water. The integrated Pt1000 achieves
Hydrostatic pressure can be measured in either an open an accuracy of ±0,1 °C, and the conductivity can be measured
or freely accessible, container or body of water as well as in a
sealed tank with positive or negative pressure. In all cases, the
actual fill level is determined in consideration of the ambient
pressure. The pressure of the gas trapped above the liquid must
also be factored in if the container is sealed. This is done by
taking another pressure measurement on a second transmitter,
which is usually screwed into the side of the tank.

Hydrostatic pressure factoring in ambient
pressure
This formula can be used to calculate the hydrostatic pressure
while factoring in ambient pressure:

p(h, p 0) = ρ * g * h + p 0

and can be applied to open bodies of water and fluids at rest
(static) in containers. A differential pressure measurement to
factor in p 0 (lid pressure) is used for sealed containers. To factor Graphic of Hydrostatic pressure formula for calculating hydrostatic
ambient pressure into open scenarios, measurements are pressure while factoring in ambient pressure.

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