SDM: Slurry Density Meter

Rhosonics introduces the latest generation non-nuclear density meter, the SDM Slurry Density Meter. This instrument is suitable for real-time density measurement in all kinds of slurries. The product uses sustainable ultrasonic technology and is specifically designed for dredging and mineral processing applications.

Dredging and mining companies are increasingly looking for non-nuclear measuring instruments. A growing demand is seen for non-nuclear alternatives, because of stricter government regulations, safety related costs and the need to reduce nuclear waste. The SDM uses non-intrusive ultrasonic sensors to measure the real-time density of mineral slurries. Like nuclear density gauges, the SDM is able to measure under high density levels and at very large pipes.

By measuring the acoustic impedance of a slurry, the SDM calculates the density of the slurry in-line during the process. The sensor is made of stainless steel and ceramic material. Because of the new sensor material, the sensor has lots of better properties. By making use of ceramics material, the ultrasonic signal is more brightful and powerful than before. Also, the sensor is at least as wear resistant as its predecessor, model 9690. By means of wafer cells, spool pieces or even a weld-on piece, installation is easy and possible at very large pipe sizes like 32” and even higher.

Get in touch with Rhosonics for further information about the Slurry Density Meter (SDM).

Download the SDM Brochure: English - Portuguese - Spanish

Download the SDM Case Study: Dredging - Mining - Comparison test

Features and benefits

  • Non-Nuclear density meter, ultrasonic technology
  • Real-time density measurement
  • Durable probe system
  • Lowest possible maintenance needs
  • High accuracy and reproducibility
  • Suitable for all types of slurries
  • Compact integrated system
  • Process connection via HART and 4-20mA
  • Continuous data & system logging

Performance specifications


Ultrasonic Spectral Power /

Acoustic impedance

Density Range:

700 … 3.000 g/l


0.2 g/l


S.G., Density g/l


Up to 0.005 S.G … +/- 0.5%

Decay time:

1 to 99 s (adjustable)


Monochrome display with RGB backlight, visible through glass cover.


Push-buttons, HART, Computer

General specifications

Process conditions


1 … 16 bar


0 °C … 110 °C (32 °F … 230 °F)

Wetted materials:

Ceramics and Duplex Stainless steel 1.4462

Electrical specifications

Power supply:

18 … 32 VDC, 8 Watt

Optional: Power supply/converter for 90 … 240 VAC


4 … 20 mA / HART


2-way through HART protocol

Data logging & fault reporting:

Internal memory,

via USB memory stick

Cable entries:

3X M16X1.5, cable OD Ø 3-10 mm

Ambient conditions

Ambient temperature:

-20 °C … +65 °C (-4 °F … 149 °F)


< 95% at 40 °C (noncondensing)




Resistant to moderate / high vibration of pumps

Dimensions and weights


Approx. 6.4 – 6.8 kg

Housing materials:

Coated stainless steel

Housing dimensions:

218–402* (L) x 208 (W) x 170 mm (H)

* Various depths, depending on probe type

Process connection:

Spool (sensor depth: 16 mm)

Weldolet (sensor depth: 34 or 52mm)

Wafer (sensor depth: 146 or 200 mm)


DIN/ANSI/JIS (others on request)

Nominal pipe size:

Up to 60”

RCU Remote Control Unit / Communication Protocol Converter

The newest Rhosonics instruments, such as the SDM, are supplied with sensor, display and operation panel integrated in a compact all-in-one system. The user interfaces of these instruments can sometimes be hard to reach, for example because of installation in a difficult position of the process pipe. Yet, in these cases, the Rhosonics RCU Remote Control Unit will be the perfect solution.

This multifunctional device is connected to the instrument by cable and can be used to monitor measurement results and change settings real-time at a safe and convenient location near the process. Another feature of the RCU is the communication protocol converter. For example, one of the RCU models is equipped with a HART/4...20 mA signal to Modbus RTU signal converter which can be very useful in case a Modbus RTU output is required. Click here to learn more about the RCU models.

Contact us for more information »