𝐌𝐄𝐓𝐑𝐎 — 3D printed Level Indicator

All the lime producers know the importance of the limestone level measurement in a PFR kiln. It is a critical and key parameter, which give precious information regarding the condition of the lime kiln and the calcination process that is taking place inside it.

Apr 22 · 4 min read

METRO: The new limestone level indicator!

METRO is the new limestone level indicator, especially developed for lime vertical kilns.

A tool that can physically and continuously touch the material bed to be measured, remains the preferred and most reliable solution, to properly control the discharging system for a consistent retention time of the material within the kiln shaft.

Moreover it is fundamental that the level device has a wide operating range to allow a flexible change of the working band, first of all to regulate the waste gas temperatures, and to improve limestone preheating as well.

The level instruments available on the market are not able to fully satisfy the needs and problems dictated by this process. Bulk stones, dust, high temperature and other factors prevent many electronic devices from working properly and reliably.

Why METRO level indicator?

Capacitive level sensor is principally developed to provide point value signal, with installation and mechanical limitations.Radar level instruments, tested on many occasion by some our clients, are not so accurate and cannot guarantee the reliability of the measurement.Gamma Ray devices, are regulated by safety and environmental legislation.

METRO embeds various innovating technologies and features, wich will definitely provide advantages from the installation to the operating activities.

METRO has been severely and successfully tested on many PFR lime kilns, QualiCal and not only, confirming accuracy and reliability.

Highest measurement Accuracy

  • The fundamental characteristic of METRO is the seamless measure of the material bed level.
  • This is guaranteed by the “always in touch” counterweight that is driven in continuous torque control by the motor reducer. The result is an extremely reliable measurement.
  • The measurement accuracy is guaranteed in any operating range and does not require continuous adjustment whenever the working condition is changed.

Easy & Fast Installation

  • The device requires only two electrical connections i.e. power and signal.
  • Furthermore METRO is configured, programmed & tested before delivery.
  • The package will be supplied with simple installation instruction with sample applications for easy integration with most PLCs eg SIEMENS, GE, ROCKWELL and others.

Easy Handling & Maintenance

  • METRO is very simple in construction.
  • Small and lightweight, transfer and installation is a breeze.
  • No special gears and screw shaft.
  • No moving parts installed, other than the motor.
  • Not pneumatically and/or hydraulically operated.
  • As a result thereof, maintenance is drastically minimized to almost nil!

METRO Components

METRO motorization

Each METRO is provided with one single brushless DC motor, heart of the machine.

An absolute encoder, embedded in the brushless motor, provides the level position signal on. continuous basis.

Rope & Plumb

The rope & its plumb, made of stainless steel, are directly connected to the geared motor and laid down deftly on the material bed.

A safety brake is integrated to prevent the plumb from free falling.


Metro Box: it is the electrical panel which contains the controller and all the electrical devices (such as switches, 230VAC/24VDC transformer, connectors, etc).

NEW production technique

3D additive manufacturing casing & drum

“METRO is the first 3D printed equipment in the lime industry!”

New production techniques like additive manufacturing, or 3D printing, allowed us to create completely new parts with the following properties:

  • new geometrically complex structures that could not be obtained with traditional manufacturing techniques.
  • Lighter & optimized parts compared to the traditional production way.

Additive manufacturing is fundamentally different from traditional “subtractive” techniques, which rely on casting, cutting, drilling, milling and joining materials. While subtractive manufacturing “wastes” up to 90 percent of the raw material, with additive manufacturing, almost all printed material is part of the final product.


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