Page 20 - EngineerIT December 2022

MEASUREMENT

Hydrostatic measurements

Monitoring the fill level is a key factor for many applications and industries. This article focusses on

hydrostatic level measurement technology.

onitoring the fill level in tanks or sealed containers of oil or DATA LOGGERS
similar liquids is very important, especially on cost grounds, A variety of data logger designs for recording pressure and
Mand theft protection. Determining the exact fill level down temperature profiles: depending on the system, the data is read
to the centimetre is important in many industries, both in terms of out via a plug connection or remote transfer.
monitoring usage and when to replenish stock.
Using an additional radio module, a purchase order can be MULTI-PARAMETER DATA LOGGERS
triggered automatically using various applications as soon as the The DCX-22-CTD measures conductivity and temperature as well as
level falls below a certain threshold. pressure, along with the depth of bodies of water. The integrated
Pt1000 achieves an accuracy of ±0,1 °C, and the conductivity
Hydrostatic pressure can be measured at ± 2,5% of the selected range (0,2 / 2 / 20 /
Hydrostatic pressure is the pressure that forms within a liquid or 200 mS/cm). Thanks to its long-life battery, it can keep recording
gas at rest due to the influence of the force of gravity. The fluid at measurement results for years (up to ten years at a rate of one
rest exerts a dead weight on the layers below as a result of its mass. measurement per hour). The logger can be configured using the
Neither the type of medium nor whether or not the fluid is in motion supplied software (measurement interval, incident management,
plays a role here. Dynamic pressure due to flow is not recorded. delayed measurement start etc.) and data that has been read
Hydrostatic pressure can be measured in either an open or can be displayed in a graph or chart, corrected using air pressure
freely accessible container or body of water, as well as in a sealed values, converted into fill levels or other units, and exported.
tank with positive or negative pressure. In all cases, the actual fill
level is determined in consideration of the ambient pressure. The KOLIBRI CLOUD
pressure of the gas trapped above the liquid must also be factored Web app for collecting and displaying measured values that are
in if the container is sealed. This is done by taking another pressure recorded by KELLER IoT devices and transmitted via mobile radio or
measurement on a second transmitter, which is usually mounted into LoRaWAN. KOLIBRI cloud offers a wide variety of options for device
the side of the tank. configuration and displays current measured values and logger
recordings in graph form. Thanks to the search and filter options,
Hydrostatic pressure factoring in ambient pressure saved measurement data can be organised with ease and can also
This formula can be used to calculate the hydrostatic pressure while be exported as an image, as an Excel or Word report, or in additional
factoring in ambient pressure: formats. Existing software solutions can be used to access data in
KOLIBRI cloud via JSON API. All products in the KOLIBRI suite are
inter-compatible and can exchange data with one another. The
p(h, p 0 ) = ρ * g * h + p 0
functions are continually being further expanded and optimised. n
This 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 For more details visit https://bit.ly/3UxXkcR
pressure) is used for sealed containers. To factor ambient pressure
into open scenarios, measurements are taken using relative pressure
probes or AA (absolute-absolute) technology.

Remote transmission via the internet
When monitoring fill levels in open bodies of water or outdoors, the
measuring points may be relatively far away and difficult to reach.
For these applications, KELLER Pressure has solutions involving level
loggers via short-range radio interfaces as well as level loggers with a
remote data transmission unit via GSM or the internet. Kolibri cloud /
desktop is used to process and analyse/prepare the collected data.

Products for hydrostatic measurements
LEVEL PROBES
Submersible probes for level and fill measurement: with a special
design and cable and housing materials that have been chosen for
compatibility with their surroundings, these probes can be used in a
wide range of liquids.

EngineerIT | December 2022 | 20