Sensit Company

Mass Catchers


Mass Catchers



The model H11-LIN eroding mass flux sensor is vertically mounted above the surface of the ground and is used for mass flux and movement monitoring. Calibration of its KE data relies on post processing of the Sensit high resolution data.

The more complex method is first calculating the driving energy of the wind often referred to as shear stress or U*. This calculation requires three wind speeds at three different heights. The anemometer heights are normally logarithmic to provide data that is most suited to the U* equation. U* is the slope of the line on a graph of wind speeds verses the log of the anemometer height vs. U* will be used to replace the velocity term in the standard kinetic energy equation ke = 1/2 m v2

                  U2 – U1                                                                         

U*  = k  ------------------    Where U = wind speed @ Z (anemometer height), k= 0.4 (Von Karman constant)

                ln( Z2 / Z1 )

k =

Theodore von Kármán was a Hungarian-American mathematician, aerospace engineer and physicist who was active primarily in the fields of aeronautics and astronautics. Wikipedia
BSNE Catcher
BSNE Catcher
Cox Sand Catcher
Big Spring Number Nine (BSNE) Mass Catcher

BSNE - Supplier: Dr. W. Fryrear, Big Spring, TX

BSNE Technical

Currently manufactured by Custom Products (Dr. W. Fryrear - formerly head of the USDA Wind Erosion Field Laboratory, Big Spring, TX).

Processing data from the Sensit eroding mass sensor requires the coincident use of a sand catcher as a total mass reference.

This catcher was designed for efficiency and verified by wind tunnel testing. The catcher is pointed into the wind by the rear vane. The wedge shaped sand capturing container creates a vacuum at the back of the container where a fine screen allows air to pass but traps particles. The wedge is designed such that the vacuum at the back exactly compensates for any pressure buildup at the entrance opening at the front. This causes air (with particles) to enter the catcher as if it were not there. The particles are trapped inside the cavity while the air passes out through the screen at the back.


Custom Soil Erosion Products also manufacturers and supplies custom remote tower setups like the ones in the banner picture located in China.

Custom Products
Dr. W. Fryrear & Brad Fryrear
7204 S Service Rd
Big Spring, TX 79720-0546
ph 432 393 5517 - fax 432 393 5519



Designed by Bill Cox of the Great Basin Air Pollution Control District (GBAPCD), Bishop, CA for their own use.


This is an omni-directional catcher made by GBAPCD for their massive erosion monitoring project at Owens' Dry Lake, Keeler, CA.  The design demonstrates an economical yet effective catcher.