Markland's S.S. Meters use the attenuation of ultrasound to measure the concentration of sludges and slurries that are too thick for optical methods. Markland's Meters operate in the region between TURBIDIMETERS and NUCLEAR GAUGES.

The sonic pulse passing through clear water returns a strong echo and the Meter reads zero.

Suspended Solids absorb some of the sonic energy making the echo weaker and the Meter then reads the %S.S. of the slurry.