Abstract: The mixing apparatus comprises a pressure vessel having a chamber and a first opening that communicates with the chamber. The mixing apparatus also comprises a first cap which fits over the first opening to engage the vessel and close the first opening. Additionally, the mixing apparatus comprises a stirrer having a shaft. The shaft extends through the first cap into the chamber. There is a motor connected to the shaft to turn the shaft. The motor is disposed adjacent to the vessel and external to the chamber. Moreover, there is a first self-sealing spring-loaded seal disposed between and preferably in contact with the first cap and the vessel to seal the first cap with the vessel as pressure increases in the vessel. The mixing apparatus comprises a shaft self-sealing spring-loaded seal which seals the shaft to the first cap as pressure increases in the vessel. The shaft is rotatable in the shaft self-sealing spring-loaded seal.

Abstract: A variable restrictor. The variable restrictor is comprised of a housing having a high pressure inlet. The housing also has a channel connected to the high pressure inlet. The housing also has a low pressure outlet connected to the channel with the channel disposed between the high pressure inlet and the low pressure outlet. The variable restrictor is also comprised of a mechanism for reducing supercritical fluid at a pressure between 100-12,000 psi from the high pressure inlet to a pressure between 0-800 psi from the low pressure outlet. The reducing mechanism is disposed in the housing and is in contact with the low pressure outlet. Additionally, the variable restrictor is comprised of a pressure transducer disposed in the housing and in contact with the channel to sense the pressure in the channel. A method for restricting fluid comprising the steps of introducing high pressure fluid at a pressure between 100-12,000 psi into a high pressure port of a housing.