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    Bernoulli’s theorem

    Daniel Bernoulli (1700-1782) was the first person to engage in the mathematical description of currents. His energy equation forms the basis for today's construction of wave solder baths. His theorem for incompressible fluids says:

    q22+pρ +g Z=const.

    where q is the flow rate, p is the pressure, ρ is the density, g is the gravitational acceleration, and Z is the height above an arbitrary horizontal plane. This means that if the force of gravity ( g ) and the amount Z ( friction effects ) are constant in an incompressible liquid, the sum of q 2 and p will always remain the same because the density does not change. Thus the higher the flow rate, the smaller the pressure p is. In wave solder baths, especially in hollow wave soldering, this insight can be put to good use. See also Hollow wave soldering.