Mix head for mixing reactive chemicals

A mix head for mixing at least two reactive chemicals under high pressure comprising

• (a) a mix head body defining within said body
• (1) an elongated mixing chamber for mixing said chemicals, said mixing chamber having first and second opposite ends and a longitudinal axis and being closed at the first end and having an opening at the second end;
• (2) at least two inlet ports in the wall of said chamber for separately introducing said chemicals into the chamber by injection therethrough, said inlet ports being located between said opposite ends and being axially spaced from said second end;
• and
• (3) at least one discharge outlet in direct communication with said opening at the second end and axially aligned with and axially spaced from said inlet ports for discharging said chemicals after mixing;
• (b) a plunger fitted and slidably positioned in the mixing chamber, mounted for reciprocal axial movement along the longitudinal axis of the mixing chamber between a retracted injection position, wherein the reactive chemicals are injected through the inlet ports into the chamber to form a mixture in said chamber, and an extended position, wherein the plunger is advanced to the discharge outlet to drive the mixture from the chamber and to prevent the mixing of additional chemicals until the plunger is returned to the retracted position;
• and
• (c) at least two nozzles assemblies replaceably mounted in the mix head body substantially normal to the mixing chamber and aligned with the respective inlet ports in the mixing chamber to separately inject the respective reactive chemicals through the respective inlet ports into the mixing chamber such that impingement mixing of the chemicals occurs, each of said assemblies having
• (1) a nozzle body defining a bore having a longitudinal axis and having an inlet for receiving one of the reactive chemicals at one end of the bore and a connecting device at the other end of the bore, said nozzle body being constructed of a structurally stable material,
• (2) a tubular support means replaceably connected to the connecting device of the body such that said means is in coaxial alignment with the axis of the nozzle body, and
• (3) an orifice member coaxially aligned with and replaceably and securely mounted in the support means and constructed of a non-adherent, chemically-inert, abrasion resistant material different from the material of the nozzle body, said support means being constructed of an essentially non-adherent, chemically inert material different from the material of the nozzle body and the abrasion resistant material and (i) being structurally sufficient to securely hold the orifice member in an aligned and spaced apart relationship to the nozzle body during operation of the mix head, and (ii) having a coefficient of thermal expansion greater than the corresponding coefficients of either of said orifice member and nozzle body such that said support means is effective by thermal expansion during normal operation of the mix head to prevent exudation of chemicals between said support means and said orifice member or between said support means and said nozzle body.