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Controlling Moisture In Whole Maize

Controlling Moisture In Whole Maize
16 May 2023  |
Maize, also known as corn, is one of the world most cultivated crops. Maise can be used for human consumption, animal feed and fuel. It can be heavily processed to produce products such as flour and biodiesel or sold as whole grains.

The need to measure the moisture content of maize

Maize processing benefits from moisture control for several reasons:

  • Correct moisture levels for storage, increasing shelf life and inhibiting mold growth
  • Increasing the reliability of the milling process
  • Increased product control
  • Reduction in waste and spoilt product
  • Direct continuous, real-time, control of the drying process
  • Monitor the material during the entire process, from delivery to the final product

Therefore, the control of the moisture, during processing and for storage, is vital to produce a final product that is suitable for its intended market.

The benefits of installing microwave moisture measurement sensors

  • Dryers can be used more efficiently thereby reducing energy costs
  • Improved and consistent product
  • Reduction of spoilt/wasted material
  • Not affected by dust or color
  • Real-time automation of the drying process, reducing the need for manual intervention
  • Reduced process downtime

Recommended installation

Hydronix sensors can be installed at various stages during processing of maize:

  • Raw material delivery to site
  • Before and after storage
  • Before and after drying
Figure 1: Moisture Sensor Locations

In the following example, a sensor is installed at a storage site. The material is moved between silos ready for discharge for further processing. The material is also transferred to ensure the correct moisture levels are maintained in the silos. The material can also be transferred for drying if required. A Hydronix Hydro-Mix XT sensor is installed in the discharge chute that feeds a conveyor belt transport system. A Hydronix Ducting System has been utilized to control the material flow and to ensure the sensor is exposed to enough material to calculate the moisture of the maize. The sensor is connected directly to the PLC to enable the control system to direct the material to a suitable silo or to discharge it to a waiting lorry.

Figure 2: Hydro-Mix HT and Ducting System Installed

Result after installing the sensors

A well-implemented installation will measure the moisture levels of the materials to an accuracy of +/- 0.5%, enabling the production process to be controlled more precisely.

Real-time control of the silo storage moisture levels (as opposed to waiting for oven tests) ensures there is instantaneous control of the maize and adjustments can be made rapidly. When drying the maize, there is a reduction in the amount of substandard or wasted product caused by the time delay between periodic sampling and subsequent dryer adjustment.

Hydro-Mix XT sensors

Hydro-Mix XT sensors are constructed of stainless steel and have an abrasion-proof ceramic measuring faceplate. The sensor is designed to be installed flush-mounted with the surface of the mechanical material transport system allowing the material to flow freely over the measuring faceplate without causing any build-up.

The Hydro-Mix XT has configurable parameters such as signal filtering and smoothing designed to eliminate noise created by the metal screw and air voids. The sensor also features a choice of output options such as 0-20mA (0-10V), 4-20mA, USB, Ethernet and RS485/232 and may be configured to output a moisture percentage value directly from the sensor. The Hydronix Hydro-Com software enables simple set-up and configuration of the sensor using a PC or laptop and USB connection.


The inclusion of a microwave moisture measurement system into the existing process will help you to:

  • achieve consistent quality products
  • reduce the number of spoilt materials
  • provide instant savings
  • repay its capital expenditure in a very short time.

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Hydronix is the world’s leading manufacturer of digital microwave sensors for online moisture measurement. Hydronix was established in 1982 and pioneered the digital microwave moisture measurement technique. Hydronix has a global presence, selling to over...

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