Abstract: Improved techniques are provided for separating mixtures of materials having different densities. The apparatus of the present invention is well suited for separating oil from water, and includes a separation tank defining a cylindrical water storage chamber and a frustroconical separation chamber spaced above an adjoining the water storage chamber. Fluid is input to the separation tank at the level of the oil/water interface. An oil leg is spaced above the separation chamber, and an adjustable oil overflow unit is provided adjacent the oil outlet for selectively varying the head pressure of oil in the oil leg. A water leg is provided in parallel with the separation tank, and an adjustable water overflow unit is provided adjacent the water outlet for selectively varying the head pressure of water in the water leg. The adjustable overflow units allow the head pressure in the oil leg relative to the head pressure in the water leg to maintain the interface within the upper portion of the separation chamber.

Abstract: A piston-type portable sample cylinder is provided suitable for obtaining and transporting a liquified petroleum gas sample taken from a flow line. A piston slidable in a cylinder creates an increasing volume for the sample, and displaces an opposing inert gas maintained in the sample cylinder at a present pressure. A toroidal mixing element has an outer diameter approximating the inner diameter of the cylinder, and slides over a cylinder projection on the piston to minimize voids when the sample cylinder is empty. The piston may be provided with a selectively adjustable seal for maintaining sealing integrity over a long life, with or without the use of lubricants. Magnets on the piston for activating external magnetic trip flags may be contained in a nylon protector ring. Precision fill measurements may be obtained from a sight gauge including a biased coiled tape mounted within the pressurized inert gas cavity of the sample cylinder and secured to one end of the piston.