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An industrial online density meter is an instrument that is directly installed on process pipelines or storage tanks and continuously outputs the density (or concentration) of the medium in real time. Its main differences from laboratory density meters (such as pycnometers and vibrating-tube benchtop models) lie in three aspects:

1. Online density meters perform continuous measurements without the need for sampling;
2. They output 4–20 mA / Modbus signals, allowing direct connection to DCS/PLC systems;
3. Their protection and explosion-proof ratings, as well as their wetted materials, are all designed in accordance with industrial-site standards.

Pisonics offers online density meters based on various principles, including ultrasonic, tuning fork, differential pressure, Coriolis, optical, microwave, and nuclear-source technologies, covering all operating conditions—from slurries to clean liquids.

Short answer: For high solids content and bubbly processes, choose an acoustic impedance density meter (PS7000).

• Acoustic impedance meters excel at resisting fouling and bubbles, with a typical range of 0.5–3.0 g/cm³; their simple mechanical design keeps maintenance costs low. However, for highly abrasive slurries, a wear-resistant tuning fork is recommended.
• Tuning fork concentration meters are highly wear-resistant but susceptible to bubbles; they are relatively expensive, have specific pipe‑diameter requirements, and are easily affected by gas entrainment.

In mining applications such as overflow/slurry from ore beneficiation—where solids content is 30–60% and the slurry is highly abrasive—acoustic impedance meters are by far the most common choice; in cleaner conditions like the downstream section of chemical reactor vessels, tuning fork meters offer a clear advantage.

Selection primarily hinges on four key factors:

1. Medium characteristics—slurry solids content, presence of bubbles, scaling propensity, and corrosiveness;
2. Installation conditions—whether tapping and hot work are permitted, available straight-run pipe lengths, and pipe diameter;
3. Accuracy requirements—trade metering calls for ±0.0005 g/cm³ accuracy (Coriolis), while process monitoring can suffice with ±0.005 g/cm³;
4. Compliance requirements—whether radioactive sources are to be avoided.

Common applications include: bubbly slurries → Pisonics PS7000 ultrasonic acoustic impedance; no‑tapping allowed → Pisonics PS7010 external‑mount; high‑accuracy pure liquids → Pisonics PS7200 Coriolis; severe scaling → Pisonics PS7400 tuning fork; large‑diameter main lines → Pisonics PS7300 differential pressure; waterborne suspensions → Pisonics PS7600 microwave; ultra‑high‑precision optics → Pisonics PS7100 spectroscopy / PS7110 refractometry. For details, refer to the “How to Select a Density Meter” guide.

Accuracy is deviation from the true value — ±0.002 g/cm³ means the reading may run 0.002 above or below actual density. Repeatability is the spread between successive measurements on identical material — ±0.0005 g/cm³ means the trace won't wander beyond that band. For selection: custody transfer and quantitative batching demand accuracy; trend monitoring, process control, and alarm thresholds depend on repeatability. Most sites need both, but repeatability has the bigger day-to-day impact — a noisy reading floods the DCS with false alarms even when long-term accuracy is fine.

Pisonics offers four types of non-nuclear online density meters that can replace traditional instruments using Cs-137/Co-60 radioactive sources:

1. PS7000 ultrasonic acoustic impedance—suitable for bubbly slurry and highly abrasive slurries;
2. PS7010 ultrasonic acoustic attenuation—ideal for conditions where opening the vessel is not permitted, with an external mounting that requires no hot work;
3. PS7400 tuning fork—appropriate for scaling-prone applications and chemical slurries;
4. PS7300 differential pressure—designed for large‑diameter main pipelines (DN200+).

If the project still requires the accuracy afforded by nuclear‑source principles (such as in heavy‑media coal washing), the PS7500 Na22 nuclear density meter employs a source at an exempt activity level (<1,000 KBq) and thus does not necessitate obtaining any radioactive‑source or transport permits.

Pisonics’ mainstream density meters all offer explosion-proof versions:

1. The ultrasonic series (PS7000, PS7010, PS7020) can be optionally equipped with ExdⅡCT6Gb;
2. The tuning fork model PS7400 can be optionally equipped with Ex d ⅡC T6 Gb;
3. The Coriolis model PS7200 can be optionally equipped with Ex d ⅡB T6 Gb;
4. The differential pressure model PS7300 is available in intrinsically safe ExiaIICT6 and flameproof ExdIIBT4 configurations;
5. The spectral model PS7100 and the refractive‑index model PS7110 can be optionally equipped with Ex db ib IIC T6 Gb;
6. The microwave model PS7600 can be custom‑configured for explosion protection.

All explosion‑proof models have passed CNEX explosion‑proof certification. When placing an order, please specify the applicable hazardous area classification (Zone 0/1/2) and the temperature class.