Pisonics PS7000 Acoustic-Impedance vs Clamp-on Ultrasonic Density Meter
The Pisonics PS7000 (ultrasonic acoustic-impedance, sapphire window in direct contact with the slurry) and a clamp-on ultrasonic density meter (transducers strapped on the pipe exterior, through-transmission) both measure slurry, FGD-slurry and tailings density / concentration online. Three differences matter most: (1) lined pipe — the clamp-on must transmit through the pipe wall and liner, and strongly absorbing liners (rubber, ceramic, thick PTFE) often cannot be measured, whereas the PS7000 window sits inside the pipe and the measurement bypasses the liner; (2) bubbly slurry — the clamp-on long transmission path is disturbed by bubble scattering and tends to drift or lose lock, while the PS7000 uses a short reflection plus Chirp bubble rejection and stays stable; (3) couplant — the clamp-on needs acoustic couplant that dries / migrates over time, temperature and vibration and must be re-applied periodically, while the PS7000 couples through the slurry itself and needs none. The PS7000 is also independent of the pipe wall, needs no full pipe, holds ±1% FS and is maintenance-free for 5+ years; the clamp-on advantage is being non-invasive and movable without shutdown.
Feature comparison
| Feature | 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 | Window contacts slurry (transducer protected behind window; zero wear / no clogging) | 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 | Short interface reflection + Chirp sub-band consistency check + multi-shot statistics; active bubble rejection | Long transmission path; bubble scattering lowers SNR; readings drift or lose lock |
| High solids / attenuation | Handles 0–80% mass concentration (0–3000 kg/m³) | 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 (full range) | 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 (high-temp up to 120°C) | Limited by couplant temperature rating and hardware |
| Long-term maintenance | ≥ 5 years maintenance-free; non-volatile data (2000 live + 400 log records) | 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 maintenance-free high-accuracy 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 has no couplant and is maintenance-free for 5+ years;
- 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 | Chirp bubble rejection, stable |
Long continuous operation | periodic couplant re-apply, re-cal | 5+ yr maintenance-free, no couplant |
No shutdown / temporary · mobile | non-invasive, flexible (advantage) | one-time flange install |