Pisonics PS7000 Acoustic-Impedance vs Clamp-on Ultrasonic Density Meter
The PS7000 reads acoustic impedance at a wetted probe flush with the pipe bore; a clamp-on ultrasonic density meter transmits through the pipe wall from outside. Three differences decide most projects: lined pipe, entrained air, and whether you are willing to maintain acoustic couplant.
Feature comparison
| Feature | Ultrasonic Slurry Density Meter | 行业通用 Clamp-on Ultrasonic Density Meter |
|---|---|---|
| Measurement principle | Single-probe acoustic-impedance reflection: sapphire window contacts slurry, Chirp (linear-FM) wideband, non-nuclear | Externally-clamped through-transmission: ultrasound crosses pipe wall + liner + slurry; density from sound speed / attenuation |
| Mounting | Flanged measuring spool on a straight run (integral / remote) | Transducers clamp on the pipe exterior; non-invasive, movable, no pipe cutting or shutdown |
| Sensing contact | Sapphire window wetted, flush with the bore; the transducer sits behind it and does not protrude into the flow | Fully external; no contact with the medium |
| Pipe lining | Measurement bypasses pipe wall and liner; unaffected by liner material; spool can be specified with PTFE / rubber / ceramic liner | Must penetrate pipe wall and liner; strongly absorbing liners (rubber, thick PTFE, ceramic, cement) attenuate heavily and often cannot be measured |
| Bubbly slurry | Keeps measuring in bubbly slurry — a stable reading in the presence of gas, not accurate density at any gas fraction; outputs a 0–100 aeration index and a bubble flag | Long transmission path; bubble scattering lowers SNR; readings drift or lose lock |
| High solids / attenuation | 0–80 % mass concentration | Tends to be un-penetrable under high-solids, strongly attenuating conditions |
| Acoustic coupling | Slurry is the coupling medium; no external couplant; smooth sapphire window resists scaling | Couplant required between transducer and pipe; dries / migrates with time, temperature and vibration; periodic check or re-apply |
| Accuracy | ±1 % FS; datasheet publishes ±1 % mass concentration | Affected by pipe material / wall thickness / liner / coupling; typically ±5–10% on lined pipe or worse |
| Pipe-wall dependence | Independent of pipe material and wall thickness | Depends on pipe material, wall thickness, scale and uniformity; re-calibration needed after pipe change or corrosion |
| Full-pipe requirement | No full-pipe requirement; can measure small flows | Transmission usually needs a full pipe and avoidance of top-of-pipe gas |
| Medium temperature | 0–80 °C standard; 120 °C high-temperature version to order | Limited by couplant temperature rating and hardware |
| Long-term maintenance | No moving parts and no consumables; 360 local history records retained in Flash | Periodic couplant check / re-application and re-calibration |
| Output / comms | 4-20 mA ×2 + RS485 Modbus-RTU (optional 4G) | Model-dependent |
| Ex / certification | Optional Ex d IIC T6 Gb; CE | Model-dependent |
| Mounting flexibility | One-time shutdown to flange in the measuring spool | Non-invasive; can be installed and relocated without shutdown (its structural advantage) |
| Best-fit conditions | Lined / bubbly / high-solids lines, long-term stable continuous measurement, DCS / hazardous area | Pipe cannot be cut or shut down, temporary or mobile measurement, clean full pipe without a (thick) liner |
Takeaway
When the pipe is clean and full with no (thick) liner, or the site cannot be drilled or shut down and a temporary / mobile reading is needed, a clamp-on ultrasonic meter is flexible and non-invasive and remains a useful option. The PS7000 is the better choice when:
- the pipe is lined — the clamp-on must cross the wall and liner and strongly absorbing liners often cannot be measured, whereas the PS7000 window is inside the pipe and is unaffected by the liner;
- the slurry is bubbly or high-solids — the clamp-on long path drifts or loses lock, while the PS7000 short reflection plus Chirp wideband rejects bubbles and stays stable;
- operation is long and continuous — the clamp-on needs periodic couplant checks / re-application and re-calibration, while the PS7000 needs no couplant at all;
- accuracy and stability matter — the PS7000 is independent of the pipe wall and holds ±1 % FS, whereas clamp-on accuracy is affected by wall / liner / coupling;
- DCS integration or a hazardous-area rating is needed — the PS7000 offers 4-20 mA ×2 + RS485, with optional Ex d IIC T6 Gb and CE.
In short: the clamp-on wins on fast, movable mounting; the PS7000 wins on accurate, durable measurement. For lined, bubbly or long-running high-accuracy duty, evaluate the PS7000 first.
Where each fits
Condition | Clamp-on (transmission) | PS7000 (acoustic impedance) |
|---|---|---|
Lined pipe (rubber / PTFE / ceramic / cement) | often not measurable | unaffected (window inside pipe) |
Bubbly / high-solids slurry | drifts / loses lock | Keeps measuring, reports aeration index |
Long continuous operation | periodic couplant re-apply, re-cal | No couplant to maintain |
No shutdown / temporary · mobile | non-invasive, flexible (advantage) | one-time flange install |