INDUSTRY 07

Dredge Slurry Density Meter

07 / DREDGING

Inline slurry density monitoring for cutter suction (CSD), trailing suction hopper (TSHD) and sand dredgers — non-nuclear ultrasonic measurement that prevents pump blockages and optimizes discharge.

1 applicable products 3 application cases
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Onboard slurry density for cutter-suction, hopper & sand dredgers

Dredgers (CSD, TSHD and sand dredgers) remove sediment and pump slurry via floating pipelines to discharge zones. Slurry density — solids content in the discharge line — is the key parameter for production monitoring, pump-speed control and blockage prevention. Operators such as Royal IHC, Jan De Nul and CCCC dredging fleets rely on inline density for real-time discharge monitoring. Pisonics ultrasonic density meters measure non-intrusively, non-nuclear.

Measurement points

Process pointPrincipleModel
CSD / TSHD discharge mainUltrasonic acoustic impedance (clamp-on)PS7000
Sand dredger dischargeUltrasonic acoustic impedancePS7000
Reclamation inlet manifoldUltrasonic acoustic impedancePS7000

Related field case: CSD · hopper · sand-dredger slurry density monitoring solution.

Why dredging slurry is hard

  • Highly abrasive, variable grain size — wears out intrusive sensors; the flush PS7000 window has no protruding parts.
  • Large pipelines (DN500–DN1000) need non-intrusive measurement to avoid pressure drop.
  • Vessel motion, temperature swings and entrained air demand robust signal stability — Chirp wideband rejects bubble scatter.
  • Pump-blockage risk needs fast density-gradient alarms feeding the DCS for pump-speed interlock (4-20 mA / RS485 / HART).

Non-nuclear, by design

A direct substitute for Cs-137 / Co-60 dredge gauges — eliminates shipboard radiation licensing, cross-border port inspection delays and dedicated radiation-safety officers. Compare: PS7000 vs Cs-137 · PS7000 vs Rhosonics SDM ECO.

Selection help

Tell us your pipe size and dredger type for a recommendation.

Production monitoring & guides

Beyond density, see live dredge production monitoring (dry-solids t/h), the production-calculation guide, non-nuclear density for dredgers, and an overseas CSD case study.

RECOMMENDED PRODUCTS

Products that fit this industry

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PS7000

Ultrasonic Slurry Density Meter

The PS7000 series ultrasonic slurry density meter uses no gamma-ray source, and therefore involves no radiation protection and none of the associated environmental approval, registration and decommissioning procedures. It runs an in-house linear frequency-modulated (chirp) acoustic impedance algorithm, delivering continuous inline measurement to ±1 % over a 0–80 % mass concentration range, with the complete signal chain engineered against bubble interference.
APPLICATION CASES

Cases in this industry

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Ultrasonic Slurry Density Meter · PS7000

Cutter Suction Dredger · Hopper Dredger · Sand Dredging Vessel Slurry Density Online Monitoring Solution

During dredging operations, the density of the slurry discharged by cutter suction dredgers fluctuates significantly. Conventional nuclear‑based or contact‑type density meters suffer from difficulties in obtaining radiation permits, rapid wear and tear, and slow response times, leading to frequent pump blockages that are hard to predict. The PS7000 ultrasonic acoustic impedance concentration meter is installed non‑contact on the discharge pipeline, withstands erosion by coarse sand, and boasts a response time of less than one second, enabling real‑time density monitoring and early warning to prevent pump blockages.

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Ultrasonic Slurry Density Meter · PS7000

Dredge Production Monitoring — Real-Time Dry-Solids Output from Density + Flow

Turn inline slurry density and pipe flow into live dredge production: dry-solids tonnes/hour, Cv, Cw, specific gravity and line velocity — non-nuclear, with a dashboard, shift totals and history.

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Ultrasonic Slurry Density Meter · PS7000

Case Study: Non-Nuclear Density & Production Monitoring on an Overseas Cutter-Suction Dredger

How an overseas reclamation contractor replaced a nuclear gauge with a non-nuclear PS7000 + flow + production-monitor system on a CSD discharge line — real-time dry-solids output, no radiation licence.

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Selection support for this industry

Guides

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Comparisons

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Industry FAQ

How is dredge production (dry solids per hour) measured?
You cannot get it from density alone. Dry-solids production P_dry (t/h) = Q x Cv x rho_s, where Q is the volumetric flow (from a flow meter), Cv = (rho_m - rho_w)/(rho_s - rho_w) is the volumetric concentration from the mixture density rho_m (from an inline density meter such as the PS7000), and rho_s is the dry-solids density. The Pisonics Dredge Production Monitor reads the density and flow meters over Modbus and computes this every second, with dashboard and shift totals. See /guides/dredge-production-calculation-density-flow.

Can I measure dredge slurry density without a radioactive source?
Yes. An ultrasonic acoustic-impedance meter (PS7000) reads discharge-line slurry density to +/-0.005 g/cm3 with no radioactive source, so there is no shipboard radiation licence, no port-inspection delay and no radiation-safety officer. A clamp-on option (PS7010) allows no-hot-work retrofit. See /guides/non-nuclear-density-meter-for-dredgers.

What density meter should go on a cutter-suction dredger discharge line?
A PS7000 ultrasonic acoustic-impedance meter suits CSD discharge lines (DN50-DN1000): flush sapphire window for abrasion, Chirp wideband to reject entrained air, non-nuclear. For no-cut retrofit use the clamp-on PS7010. Pair with a flow meter and the Dredge Production Monitor to also get dry-solids t/h. See /industries/dredging.

How do density meters on dredging vessels cope with ship vibration and salt spray?

Challenges posed by the environment of dredging vessels (cutter suction dredgers, trailing suction hopper dredgers, and sand‑suction vessels) to instrumentation:

  1. Continuous vibration—vibration from the main engine, mud pump, and cutter ranges from 0.5 to 5 g;
  2. Salt‑mist corrosion—seawater aerosols severely corrode the enclosures of electronic instruments;
  3. Coarse‑sand abrasion—the slurry contains coarse sand with particle sizes ≤ 50 mm;
  4. Cross‑border operations—nuclear‑source density meters are subject to cumbersome approval procedures for international transport licenses.

Recommended: PS7000 ultrasonic acoustic impedance concentration meter—

  1. Flange‑mounted direct‑insertion design with a non‑contact probe, eliminating wear;
  2. The ceramic probe withstands continuous erosion by sand and gravel, with a service life ≥ 5 years;
  3. IP65 rating; explosion‑proof ExdⅡCT6Gb optional;
  4. Completely non‑nuclear;
  5. 4G module optional, enabling the fleet headquarters to monitor all operating vessels in real time.

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