GOLD Hand Dredges and Dry Vac's

M625 HD     M625 HD P

  Model 2125 HD/HDPC Gold Hand Dredge's

  With a single elongation stroke of the bellows, these hand powered suction separator dredges are capable of creating enormous suction at the nozzle end due to their sealed no leaks construction. Pulling the handle can  more than double the mechanical force of the water compared to siphoning thereby improving gold recovery from cracks and crevices. A standard in/hg vacuum gauge was used to test the Model 625 HD assembled to be used as each of the available models.

  In the hands of an adult person of above average strength a constant sealed suction vacuum rating of greater than  minus -10 inches/hg was achieved and held consistently, that's over 1/3 of an atmosphere. For all of the models: standard HD Dredge, Dry Vac, Crevice Dredge, the Bilge dredge and the Aquarium Gravel Vacuum. 

   The per stroke capacity of the Model 625 HD is over 57 cubic inches per stroke.  For the test of the Model 625 HD, as the full size dredge, it was equipped with 24" of class 200 1 1/2 in. PVC pipe. Each 12 inch section of 1 1/2 inch class 200 PVC pipe is around 27 cubic inches or 15 fluid oz., each 12 inch section of 1 1/2 in ABS schedule 40 pipe holds 24 cubic inches. 
   Formulas:

   1 atmosphere (29.92 inches mercury) = 14.695948775 pounds per square inch 

  1/3 of 14.695948775 = 4.898  

   1.71 I.D. /2 = .855r

   (.855r x .855r) x 3.14159 (pi) = 2.29658 

   4.898 psi x 2.29658 sq. in.  =  11.24866lbs.

If this calculation is right that 11.25 lbs.would be a lot of weight that could be held to the end of the 1.71 I.D. nozzle. Compare that to the world famous TV vacuum cleaner commercial that used a 16 pound bowling to prove their product and that was with a 6" cone so that created a larger area to apply vacuum over.
Of course, the larger the volume of space that the vacuum is being created in, the shorter the duration of the vacuum effect once suctioning dredge material begins. So apply this formula when trying to determine how fast you need to work any hand pump: 1 US fluid ounce = 1.8046875 cubic inches. 

If anything keep the Model 625 in the first aid kit should anyone need emergency care for a snake bite! With -10 in/hg and over 57 cubic inches of sucking power, you might be able to get the venom before it gets you!