Moisture measurement in sand and aggregates

The Hydro-Probe was the first moisture sensor to use the digital microwave moisture measurement technique. The principle of operation lies on the microwave technology, which allows the moisture measurement over a great distance (~ 10cm) from the sensor’s surface. The measurements are not affected by salt contents of the aggregate, its color or its temperature (as it happens with many other moisture sensors) or even by a thin material layer that may be lies on the surface of the sensor. It is usually installed inside bins or chutes, belt conveyors or feeders. The sensor is positioned into the flow of material.

Quick Overview

Especially for the Ready-Mix Concrete and precast industry, Hydro-Probe is the ideal moisture meter with great futures and a high accuracy (0.2%) for sand and generally all aggregate materials. This ensures that the manufacturer can continually produce a consistent, quality product and reduce costs by limiting the amount of wasted or spoilt materials.

Using a Hydro-Probe moisture sensor connected with the plant’s automation, the correct aggregates and water weights that must be dosed in each batch can be compensated in real time, accordingly to the moisture value readings taken by the sensor. Measurements are taken 25 times per second as the material passes over or around the sensor face, meaning that the sensor can rapidly detect changes in moisture levels.


  • The sensor’s body is made of stainless steel while its measuring surface is made of ceramic faceplate material highly resistant to wearing out by the materials’ friction.
  • It incorporates all electronical circuits without the need of any outer device apart from the power supply.
  • It has powerful digital 32-bit micro controller with 2 analogue outputs (0-10 V or 4-20mA) and an RS485 serial output that is optically isolated and connects through protocol.
  • The sensor is equipped with two inputs in order to activate average calculation of the moisture’s value as well as switching its output between moisture and temperature value. . The 'averaging' mode continuously provides the 'average' reading of moisture from the start of reading to any time selected - normally the closing of the hopper door. Averaging, bin empty alarms and signal processing performed internally by sensor.
  • The Hydro-Probe can be remotely configured and calibrated using \Hydro-Com diagnostic software. All readings and sensor parameters are available including the type of output and filtering characteristics.


The Hydro-Probe microwave moisture sensor has been designed for a variety of mounting options. The most typical installation is in or underneath a bin (silo) or above a conveyor or belt feed. These different options provide the installer with flexibility in determining the most suitable location for the sensor to be installed.

The Hydro-Probe should be mounted in the flow of material which must pass across the ceramic faceplate of the sensor. To ensure that the material flow is not obstructed and to prevent build up on the sensor face, the moisture probe should be installed at an angle of approximately 60 degrees to the flow of material. For installations where the silo is wide an extension mounting sleeve can be used.

Below are listed certain installation examples of the Hydro-Probe:

hydro probe egkatastasi

Open to new challenges

Do you have any idea of cooperation, you believe that our know-how can be adapted to your own field?
Do you have a special project and are looking for suitable partners to implement it? We are open to new opportunities...

  • Connect with us
    Do you prefer live communication? So do we!
    We'd love to speak with you.
    Contact us

  • Get support
    Do you have any technical questions?
    Our experienced engineers will gladly discuss with you.
    Technical Support

  • Stay updated
    Are you interested in receiving updates
    about our new products and offers?

Protem Group S.A.

3, 35th Str., 133 41 Industrial Park
Ano Liossia / Athens, Greece
Τ. +30 210 5716500
F. +30 210 5710008
GCR No: 7633901000