Product Overview

When standard polished stainless steel or PTFE-coated tuning fork density sensors fail prematurely in abrasive slurry service — pitting, grooving, and erosion of the fork tines within weeks of installation — the LONN-700C ceramic tuning fork density meter changes the equation entirely. Unlike conventional tuning fork density meters where the fork tines are bare 316L stainless steel or coated with soft polymer, the LONN-700C features fork tines made from ceramic material — a hard, dense oxide ceramic with Vickers hardness exceeding 1200 HV, roughly six times harder than 316L stainless steel. In mining slurry pipelines, sand and gravel processing circuits, mineral concentrate launders, and dredging transfer lines, the LONN-700C keeps measuring accurately where other instruments surrender to erosion.

The ceramic tuning fork density meter operates on the same proven vibration frequency principle as the standard LONN-700CM — a pair of fork prongs vibrate at their natural resonant frequency, which shifts in direct proportion to the density of the surrounding liquid. The ceramic fork tines add zero interference to the acoustic signal: the fork still vibrates freely, the frequency still responds precisely to fluid density changes, and the measurement still achieves ±0.002 g/cm³ accuracy across the full 0~2 g/cm³ range. What changes is the service life — measured not in months but in years, even in the most aggressive sand-laden and mineral-laden slurry streams found in hard rock mining, coal preparation, and offshore dredging operations.

This ceramic fork density meter is available with 316L stainless steel, Hastelloy C-276, Titanium, or Zirconium wetted materials for the sensor body and process connection, each paired with ceramic fork tines for the actively vibrating element. The result is an inline density measurement solution that survives where competitive instruments require constant replacement — reducing unplanned downtime, eliminating measurement gaps during critical concentration control loops, and delivering a genuine total cost of ownership advantage that more than justifies the modest premium over standard configurations.

Why Ceramic Fork Tines Outperform Other Surface Treatments in Slurry Service

The Abrasion Problem in Slurry Density Measurement

Any slurry pipeline carrying solid particles — whether iron ore concentrate, copper tailings, coal slurry, sand-water mixtures, or mineral precipitate — subjects instrument sensor surfaces to continuous particle impact. Particles suspended in turbulent flow strike exposed surfaces at velocities determined by flow regime, particle specific gravity, and pipeline geometry. Over time, this solid-particle erosion removes material from sensor surfaces, fundamentally altering their geometry and destroying measurement accuracy.

Standard polished 316L stainless steel fork tines in most tuning fork density sensors begin showing measurable erosion marks within 2-4 weeks in typical mining slurry service. By three months, fork tine geometry has shifted enough to invalidate factory calibration. PTFE-coated forks — while excellent for sticky media like polymer solutions or adhesive chemical slurries — wear through the polymer layer even faster in abrasive service, exposing the bare metal beneath and defeating the purpose of the coating entirely.

How Ceramic Fork Tines Solve the Erosion Challenge

The LONN-700C addresses this failure mode at its root. The fork tines themselves are made from ceramic material — a hard, dense, inert oxide ceramic with Vickers hardness exceeding 1200 HV, roughly six times harder than 316L stainless steel (~200 HV) and significantly harder than PTFE polymer (~100 Shore D). This extreme hardness means mineral particles in the slurry — quartz, feldspar, magnetite, pyrite, and other silicates and sulfides common in mining streams — simply cannot penetrate or scratch the ceramic surface at normal pipeline flow velocities.

The characteristic orange color of the ceramic fork tines reflects the specific iron-oxide-based ceramic formulation (equivalent to alumina-toughened zirconia or similar oxide ceramic systems) that provides the optimal balance of hardness, fracture toughness, thermal expansion matching to the stainless steel substrate, and long-term adhesion under cyclic vibration loading. The ceramic tines are manufactured using a thermal spray process that creates a metallurgically bonded, dense, uniform ceramic layer typically 150-300 microns thick — enough to provide years of erosion protection even in high-velocity slurry pipelines.

Direct Comparison: Fork Surface Treatments for Slurry Applications

Key Benefits — Ceramic Tuning Fork Density Meter

• ✅ Superior Abrasion Resistance: Ceramic fork tines (1200+ HV) withstand sand, mineral ore, and tailings particles that destroy standard metal fork surfaces — extending sensor service life by 5-10× in slurry service
• ✅ Proven ±0.002 g/cm³ Accuracy: Ceramic fork tines add zero interference to vibration frequency — accuracy identical to standard polished fork configuration
• ✅ Wide Slurry Compatibility: Handles particles up to 50μm diameter, suspended solids up to 40%, and gas content up to 20% — suitable for most mineral processing and mining slurry circuits
• ✅ High Temperature Performance: Process temperature range from -25°C to +150°C handles steam-blended pipelines, hot leachates, and thermal slurry heating systems
• ✅ Non-Nuclear Technology: Zero radioactive source — eliminates licensing, safety inspections, decommissioning costs, and regulatory compliance burden that radiometric density gauges impose
• ✅ Multiple Sensor Body Materials: Sensor body in 316L SS (standard), Hastelloy C-276 (acid service), Titanium Grade 2 (seawater/chloride), or Zirconium 702 (highly oxidizing acids) — paired with ceramic fork tines for complete chemical + abrasion resistance
• ✅ Flexible Output Options: Dual 4-20mA analog outputs (density + temperature simultaneously) plus RS485 Modbus RTU for full digital integration with any DCS, PLC, or SCADA system
• ✅ IP65 Weatherproof Enclosure: Die-cast aluminum transmitter housing with epoxy powder coating withstands harsh plant environments — outdoor and coastal installations covered
• ✅ Explosion Proof Available: ATEX/IECEx Zone 1 certified configurations for hazardous area deployment in oil & gas slurry handling, coal processing, and petrochemical facilities

Technical Specifications — LONN-700C Ceramic Tuning Fork Density Meter

Particle & Slurry Suitability — Why the Ceramic Fork Excels in Mining and Dredging

How Particle Size and Concentration Affect Measurement Performance

The LONN-700C ceramic tuning fork density meter is engineered for continuous liquid density measurement in particle-laden process streams. The vibrating fork measures the density of the continuous liquid phase plus the contribution of suspended solids — provided the particles remain in suspension and do not settle between the fork tines. Understanding the relationship between particle characteristics and measurement quality is essential for optimal instrument selection.

For particles below 10μm in diameter — fine mineral suspensions such as flotation concentrates, colloidal silica, and sub-sieve process streams — the particles behave essentially as part of the fluid medium and do not introduce significant measurement noise. The tuning fork vibrates through the suspension uniformly, and the density reading accurately represents the total mass per unit volume of the fluid-particle mixture.

For particles between 10μm and 50μm — typical of hydrocyclone overflow, classifier overflow, and conventional flotation tailings streams — some measurement noise appears due to intermittent particle impingement on the fork surfaces. The ceramic fork tines absorb this impact without damage or geometry change, ensuring that measurement drift does not occur even as particles continuously strike the tines. The ceramic surface maintains its smooth, precisely calibrated geometry indefinitely, unlike unprotected metal surfaces that erode progressively.

For particles above 50μm — coarse sand, gravel, or grinding circuit product — the LONN-700C is not recommended. Large particles can become lodged between fork tines or generate impact forces sufficient to crack even ceramic surfaces at very high velocities. For coarse particle slurry service, the LONN-7000 ultrasonic slurry density meter using acoustic impedance technology is the recommended alternative.

Erosion Comparison: 316L Stainless vs. PTFE vs. Ceramic Fork Tines in Identical Slurry Test

In standardized erosion testing using 30μm silica sand slurry at 3 m/s flow velocity over 1,000 operating hours:

The ceramic fork tines demonstrated essentially no measurable wear or accuracy degradation over the full 1,000-hour test — confirming their suitability for multi-year continuous service in abrasive slurry pipelines without recalibration or replacement.

Applications by Industry — Where the Ceramic Fork Makes the Difference

Mining & Mineral Processing — The Primary Application

Hard rock mining operations — copper, gold, iron ore, nickel, lead, zinc, and polymetallic sulfide ores — generate enormous volumes of slurry at every stage of the process: grinding circuit classification, flotation concentration, tailings disposal, and concentrate dewatering. Pipeline densities in these circuits typically range from 1.05 to 1.60 g/cm³, and accurate density measurement is critical for:

• Grinding circuit load monitoring: Density measurement controls water addition to the SAG or ball mill — too high a density reduces grinding efficiency; too low increases steel media wear. The LONN-700C with ceramic fork tines survives the high slurry density and abrasive media (ore particles + grinding ball chips) that destroy standard sensors.
• Flotation feed density control: Maintaining consistent flotation feed density within ±0.01 g/cm³ directly affects concentrate grade and recovery rate. The ceramic fork density sensor provides stable, drift-free measurement throughout the operating shift.
• Tailings pipeline monitoring: Long-distance tailings disposal pipelines require density monitoring for pipeline integrity (density indicates settling tendency) and water recovery optimization. The LONN-700C handles the high solids concentration and particle loads in tailings streams.
• Concentrate thickener control: Underflow density measurement controls the thickener underflow solids content — critical for downstream filter press or pressure filter performance. Ceramic fork tines survive the abrasive mineral concentrate slurry.

Dredging & Marine Sediment Handling

Offshore and river dredging operations move enormous quantities of sand, gravel, and sediment slurries through floating pipeline systems. The LONN-700C ceramic tuning fork density meter provides:

• Dredge cut density monitoring: Measuring the density of the slurry mixture being pumped allows the operator to optimize the cutting head water injection — maximizing solids content in the discharge while preventing pipeline blockages from too-thick a mixture.
• Hopper dredger fill monitoring: Density measurement in the hopper overflow weirs indicates when the hopper is full of solids versus water — allowing efficient filling to target density rather than relying on time-based discharge cycles.
• Offshore discharge monitoring: For beach nourishment and nearshore placement operations, density monitoring at the discharge point confirms successful solids delivery versus seawater dilution.
• Sand washing circuit density control: Washed sand processing circuits use hydraulic classification — density measurement controls the water flow rate that separates fine particles from coarse product. The ceramic fork survives the abrasive sand slurry continuously.

Sand & Gravel Processing

Construction aggregate washing and classification plants process sand, gravel, and crushed rock into sized products for concrete, asphalt, and construction fill. The LONN-700C ceramic fork density meter monitors:

• Hydrocyclone feed density: Controlling the feed density to classification cyclones determines the cut point (particle size separation) — accurate density control directly affects product gradation quality.
• Sand washer effluent density: Monitoring wash water clarity and solids content in the washing circuit — higher density indicates dirty water requiring further settling or clarification.
• Aggregate slurry transfer lines: Density measurement on long slurry pipelines between processing stages provides early warning of pipeline blockages (density drops when water channel forms at pipe wall) and confirms continuous solids transport.

Chemical & Petrochemical Slurry Processing

Chemical processes involving catalyst slurries, mineral acid slurries, lime slurry, gypsum slurry, and other solid-laden chemical streams benefit from the ceramic fork’s combined chemical and abrasion resistance:

• Limestone (CaCO₃) slurry for flue gas desulfurization (FGD): Scrubbing slurry in power plant FGD systems contains limestone particles that erode standard sensors — the ceramic fork tines handle this abrasive slurry continuously.
• Catalyst slurry in refineries: Fluid catalytic cracking (FCC) units use catalyst slurry as a heat transfer medium — the LONN-700C ceramic fork density sensor measures catalyst concentration in the slurry return line.
• Kaolin and mineral pigment slurries: Paper coating and paint pigment slurries contain abrasive mineral particles — ceramic fork tines extend service life in these challenging process streams.

Installation Guidelines — Getting Accurate Density Measurement from Day One

Optimal Pipeline Location Selection

The single most important factor in achieving stable, accurate, long-term density measurement is correct instrument location in the pipeline. Follow these placement guidelines for slurry service:

1. Avoid low-velocity sections: Install the LONN-700C ceramic tuning fork density meter in pipeline sections where slurry velocity exceeds 0.5 m/s — below this velocity, particles begin to settle and may accumulate around the fork tines, creating measurement bias.
2. Orientation matters: Mount the fork sensor with tines oriented vertically (tines pointing up or down) for vertical pipeline runs, or with tines perpendicular to flow for horizontal runs. Never mount with tines parallel to flow direction — this creates dead zones where particles accumulate.
3. Minimum straight run: Provide minimum 5 pipe diameters (5D) of unobstructed straight pipe upstream of the density meter location and 3D downstream. Avoid locations immediately downstream of pumps, elbows, reducers, or valves — turbulence and flow asymmetry introduce measurement noise.
4. Avoid air entrainment: Do not install at the top of a vertical pipeline run where air or gas can accumulate at the instrument. For pipelines prone to gas breakout (carbonated process streams, anaerobic digesters), select a location on the lower section of the pipe.
5. Flange gasket clearance: Ensure the ANSI or DIN flange gaskets do not intrude into the flow path and create turbulence that impinges directly on the fork tines — use flat-face gaskets for ring-type joint (RTJ) flanges.

Electrical Connection and Signal Integration

1. Power: Connect 24V DC to the transmitter terminal block (observe polarity markings). The 4-20mA output is loop-powered — both power and signal travel on the same two wires from the DCS/PLC.
2. 4-20mA scaling: Default density span is 0 ~ 2 g/cm³ corresponding to 4 ~ 20 mA. Scale your DCS analog input card to match: 4mA = 0 g/cm³, 20mA = 2 g/cm³ (or your site-specific density range if narrower).
3. RS485 Modbus wiring: Connect A/B terminals to your Modbus RTU network. Default settings: address 01, 9600 baud, 8 data bits, 1 stop bit, no parity. Full register map is provided in the instrument manual.
4. Grounding: Connect the instrument earth ground terminal to a clean plant ground — this prevents common-mode voltage noise on the 4-20mA loop in electrically noisy environments such as variable frequency drive (VFD) motor circuits running near the instrument cable path.
5. Signal cable routing: Route the instrument signal cable at least 300mm away from VFD power cables and motor starters to prevent induced electrical noise. Use shielded twisted pair cable for the RS485 digital signal.

LONN-700C vs. LONN-700CM vs. LONN-7000 — Model Selection Guide

Selection Rule:

• Abrasive slurry with particles <50μm and solids <40% → LONN-700C Ceramic Fork (this product)
• Clean liquid or sticky/polymer media → LONN-700CM Standard or PTFE
• Heavy coarse slurry (>100μm particles, >40% solids) → LONN-7000 Ultrasonic Slurry Density Meter

Frequently Asked Questions — Ceramic Tuning Fork Density Meter

Q: Do the ceramic fork tines affect the tuning fork vibration frequency or measurement accuracy?
A: No. The ceramic fork tines are manufactured with precise geometry accounted for during factory calibration. The LONN-700C achieves identical ±0.002 g/cm³ accuracy as the standard LONN-700CM with polished metal fork. Third-party laboratory verification using certified reference density liquids (water, glycerol solutions, and calcium chloride solutions) confirms measurement uncertainty well within specification across the full 0~2 g/cm³ range.

Q: How long do the ceramic fork tines last before they need replacement?
A: The ceramic fork tines are designed for the operational lifetime of the instrument — typically 8-15 years under normal slurry service conditions. Unlike PTFE coatings that can tear or delaminate, the ceramic material is metallurgically bonded to the fork substrate and cannot peel off during normal operation. The ceramic hardness exceeds that of common slurry particles (quartz ~700 HV, magnetite ~600 HV, pyrite ~1000 HV) — under normal pipeline velocities, particle impact does not remove ceramic material at a measurable rate. The only scenario that would damage the ceramic tines is severe cavitation or direct impact by a large foreign object — which would damage any sensor surface.

Q: Can I use the LONN-700C in seawater or chloride-containing slurry?
A: Yes — select the Hastelloy C-276 or Titanium Grade 2 sensor body material for seawater or chloride slurry applications. Both Hastelloy and Titanium provide excellent chloride stress corrosion cracking resistance. The ceramic fork tines themselves are chemically inert to seawater and chloride solutions. Standard 316L stainless steel sensor body is suitable for seawater applications below +30°C, but for elevated temperature seawater or concentrated chloride brines, specify Hastelloy or Titanium wetted material.

Q: What is the minimum flow velocity required to prevent particle settling around the fork tines?
A: The LONN-700C requires minimum slurry flow velocity of 0.5 m/s at the instrument location to ensure particles remain in suspension and do not accumulate on or between the fork tines. For static or very low-velocity process conditions, particle settling between the fork tines can create a protective particle layer that biases the density reading high. If your application cannot guarantee 0.5 m/s minimum velocity, consider the LONN-7000 ultrasonic density meter, which has no obstruction in the flow path and is unaffected by particle settling.

Q: How does the LONN-700C compare to nuclear/radiometric density gauges used in mining?
A: The LONN-700C delivers comparable or superior accuracy (±0.002 g/cm³) compared to nuclear density gauges (±0.005~0.01 g/cm³ depending on geometry) while eliminating every radioactive source management requirement: no source import/export licenses, no annual radiation safety inspections, no sealed source leak testing, no emergency response planning, no specialized transport documentation, and no decommissioning cost for radioactive material disposal. For sites operating radiometric gauges, the LONN-700C provides a clear path to source removal — particularly relevant as radioactive source security regulations tighten globally and disposal costs escalate.

Q: Is field calibration required after installation, and how is it performed?
A: The LONN-700C arrives factory-calibrated using certified reference density standards traceable to national measurement institutes. For most applications, no field calibration is required — install the instrument, enter the process fluid calibration parameters (slope and intercept for your specific liquid), and begin measuring. For custody transfer or regulatory measurement applications requiring ISO/IEC 17025 traceable calibration certificates, LONNMETER provides factory calibration services with certified reference liquid measurements. Field calibration is performed by entering known-density reference samples (provided calibration kit) through the LCD menu — the two-point calibration corrects for any minor offset between factory calibration and specific installation conditions.

Q: What maintenance does the ceramic fork density sensor require?
A: Minimal maintenance. The ceramic fork tines do not corrode, pit, erode, or delaminate under normal operating conditions. The only regular maintenance task is periodic cleaning of any accumulated deposits on the fork tines — use clean process liquid or water flush only. Never use hard tools, brushes, or scrapers on the ceramic surfaces. Inspect the process connection flange gasket periodically for leakage and replace if compressed set is observed. For remote transmitter versions, verify cable connector sealing and tighten if any moisture ingress is suspected. Annual verification against a reference density measurement (portable density meter or lab sample) is recommended for quality assurance programs.

Request a Quote — Ceramic Tuning Fork Density Meter

Configure your LONN-700C ceramic tuning fork density meter: Email anna@xalonn.com or complete our RFQ form. Please include:

1. Process slurry description — solid type, approximate particle size distribution, solids concentration range
2. Density range of interest — e.g., 1.00 ~ 1.60 g/cm³ (for scale optimization)
3. Temperature and pressure — maximum process temperature and operating pressure at instrument location
4. Pipeline details — pipe size, flange standard (ANSI/DIN/JIS), preferred orientation
5. Sensor body material — 316L SS (standard), Hastelloy C-276 (acid), Titanium (seawater), Zirconium (oxidizing acid)
6. Output requirement — 4-20mA only, or 4-20mA + RS485 Modbus RTU
7. Hazardous area certification — ATEX/IECEx Zone 1 required (specify zone classification)
8. Quantity and timeline — single unit or project volume; target delivery date

What you receive with every quote: Full technical datasheet, dimensional drawing (PDF), Modbus register map, installation manual, and application engineering review — at no charge. LONNMETER’s application team reviews every inquiry to confirm instrument suitability for your specific process conditions before proposing a solution.

As a direct-from-manufacturer density measurement specialist, LONNMETER supplies the ceramic tuning fork density meter with factory pricing, global technical support .