Abstract: A control system for controlling the pressure and pressure balance in two separate fluid pressure circuits. A valve being employed which comprises a balance piston and a regulating piston. Each of the pistons controls a connection of the first and second fluid pressure circuits to a respective relief line. Fluid pressure is applied to the regulating piston to regulate the pressure in one circuit and the balance piston regulates the pressure in the other circuits in relation to that regulated by the regulating piston. A three position switch and two air pressure regulators or a three position switch, two potentiometers and a servo control valve control the pressure applied to the regulating piston to control the pressures required in the first and second circuits for the desired modes of operation. A further balance valve may be disposed between the first and second circuits.

Abstract: A composition for insulation which may be used for reducing thermal transmission, for absorbing sound waves and for providing a fire spread barrier, and which may be sprayed on surfaces in relatively thick coats. The composition includes a blended mixture of cellulose fiber, mineral wool, boric acid and expanded silicate glass. The blended fibers are mixed with an adhesive and sprayed on a surface to be insulated, and the adhesive preferably is a fire retardant, nontoxic adhesive which remains flexible after it has dried so that expansion or contraction of the insulation or the insulated surface will not result in cracks in the insulation.