Level Measurement of Viscous Powders

For a simplified introduction, contact measurement devices must navigate the object/part point-to-point, where non-contact systems measure with absolutely no contact or direct touch probing whatsoever. Contact measurement is an ideal choice for viscous powders, such as Rotary Paddle Level Switches, RF Admittance Level Switches and Vibrating Level Switches.

Rotary Paddle Level Switch

The advantage of the Paddle Level Switch is that an electric motor drives the shaft connected to the rotating paddle and the paddle is non-sensitive to material hanging. However, when measuring powders with strong moisture absorption, the sealing of the shaft becomes a problem. Especially in high temperature pressure bins, the powders stuck on the blade affects the operation, and the high temperature powders are easy to penetrate into the housing and cause motor burning.

RF Admittance Level Switches are developed on the basis of capacitive type, the design of anti-hanging circuit is added for a better anti-hanging effect. However, when measuring viscous materials, the big change of dielectric constant makes the powders tend to scar on the probe, which results in frequent false alarms. Obviously, RF Admittance Level Switches are better for the level measurement of dry powders/ashes with stable dielectric constant.

RF Admittance Level Switch

Vibrating Rod Level Switches uses piezoelectric devices to drive and detect the vibration, which is independent of the medium dielectric constant. Different from the Vibrating Rod Level Switches with single rod structure in the market, double rods Vibrating Rod Level Switches are designed with double vibrating tubes, that is, the inner vibrating tube nests with the outer vibrating tube, which can reach resonance state after precise tuning, and maximize the anti-hanging performance. But for single rod Vibrating Rod Level Switches, the probe resonance state cannot be reached, and even if the material is slightly hung, it triggers the false alarms.

double rods Vibrating Rod Level Switch

Double rods Vibrating Rod Level Switch is an ideal choice for measuring the level of viscous powders, but it has limitations on powders that are easily caking and scarring, especially in extremely low or high temperature ambient. For above cases, we generally recommend adding auxiliary steps to reduce the material hanging, such as regular purging.