PS7000 Acoustic Impedance vs PS7010 Acoustic Attenuation: Ultrasonic Density Meter Comparison

Steps

1. Measurement principle

   PS7000 uses acoustic impedance: a single sensor transmits and receives, with linear frequency-modulated (chirp) excitation, and the density follows from the reflection at the sensor-to-slurry boundary together with the measured sound speed. PS7010 uses acoustic attenuation: two sensors face each other across the pipe, one transmitting and one receiving, and concentration follows from how much energy the medium absorbs and scatters along that path. The consequence that matters commercially is that impedance is a single-face measurement while attenuation is a through-path measurement — almost every difference below traces back to that one distinction. Background: acoustic impedance and the attenuation coefficient.

2. Installation

   PS7000 mounts either as a spool piece with flanges spliced into the line, or by welding a base onto an existing pipe through a bored hole — so it needs a tapping and therefore a shutdown window. In both arrangements the sensor face finishes flush with the bore, so nothing protrudes into the stream. PS7010 clamps onto the outside of the pipe with steel bands and needs no penetration at all, or can be supplied as a spool piece if preferred. The clamp-on option is often decisive on lines that cannot be shut down, and it carries a second advantage that is easy to undervalue: if the first position proves wrong, the instrument can be moved. Installation position causes more disappointing first weeks than any other factor.

3. Bubble tolerance

   This is the most important practical difference and the one most often discovered late. Gas bubbles scatter strongly and resonate, presenting an acoustic cross-section far larger than their physical size, so a void fraction well under one percent can absorb a transmission path and drive the PS7010's received signal toward zero. PS7000's single-face measurement does not depend on energy surviving a crossing, so it tolerates entrained air and additionally outputs a gas index (0–100) with a bubble flag alongside the density value. Where a process deliberately aerates — flotation, FGD oxidation air, agitated tanks — that diagnostic is not a convenience but the thing that lets an operator separate more solids from more bubbles, since both move a naive density reading the same way.

4. Pipe wall and material

   PS7010 in clamp-on form sends its signal through the pipe wall twice, so wall material, wall thickness and the condition of the outside surface all matter. Heavily scaled, coated, lined or non-metallic pipe can attenuate or scatter enough to make the arrangement unworkable, and this needs confirming before ordering rather than at commissioning. PS7000 places the sensor face at the bore, so the pipe wall is not in the acoustic path at all and its material is irrelevant to the measurement — the trade being that a penetration is required. Where a spool piece is acceptable for either instrument, both avoid the wall question, and the choice returns to bore size and gas content.

5. Bore size range

   PS7000 covers DN50–DN1000, with larger bores available as a custom build. PS7010 covers DN50–DN500. The reason is physics rather than product policy: received energy falls exponentially with path length, so a through-transmission arrangement runs out of signal as the path grows, particularly at high concentration where attenuation is already high. This single line eliminates PS7010 from most FGD absorber recirculation mains, large tailings lines and dredge discharge lines, which routinely run DN500 and above.

6. Typical applications

   PS7000 suits mining slurry and cyclone circuits, FGD limestone and gypsum slurry, coal-washing heavy media, tailings, and dredge discharge — abrasive, large-bore, often aerated duties where a radiometric gauge used to be the default. PS7010 suits retrofits where tapping is impossible, low-bubble solutions and syrups, black liquor, trial installations where the measuring point is not yet settled, and temporary surveys. A practical note that applies to both: prefer a vertical rising section over a horizontal run, and interlock the reading to a pump-running signal, since a stopped line settles and the resulting steady climb in indicated density is a stagnation artefact rather than a process event.