View Full Version : Anyone familiar with pneumatic excavators?

04-23-2006, 05:07 AM
In particular the nozzles?
In the literature I found with google, it mentions "Divergent Convergent geometry" yada yada yada to produce an air stream at mach 2 speed to fracture soil etc.

Is this just a DeLaval nozzle? or something else entirely?

I couldn't find any close ups of the nozzles or even drawings of them in the patent filing.

The chief appeal of this, is the ability to dig near utilities or tree roots or anything you don't want to damage, at a reasonable rate and without causing damage.

Most of the google hits seemed to be about excavating around tree roots and tree care.

Any info related is appreciated.

04-23-2006, 12:36 PM
In the last few years around the west coast here, I've noticed lots of vacume trucks used for excavating. In soil you can dig round holes for poles, dig near utilities, in confined spaces, etc.
Cities, utility co's etc. seem to use them. Often seem to use a water stream to break up the soil. (Pressure washer ?)
I have a customer who bought a small vacume-excavating co. and added it to his septic sucking business. Makes great gobs of money working for cities & the regional gov't.

Mad Scientist
04-23-2006, 12:45 PM
I am not familiar with the name “DeLaval” but the "Divergent Convergent geometry” refers to a basic venturi shape.

A cross section view would look like a large radius “converging” into the neck of the venturi from there it “diverges” as a straight cone to the end of the nozzle. To achieve maximum force from the nozzle, the pressure drop across it is important and also the size of the radius of the converging inlet and the angle of the diverging outlet. These dimensions will also change depending on what is flowing thought the nozzle, gas or liquid.