Abstract: A system and method of safely discharging hydraulic fluid from a compressed gas cylinder, comprises filling first and second compressed gas cylinders with compressed gas. A compressed gas dispensing system has a pump that pumps hydraulic oil into the compressed gas cylinders to maintain a desired pressure while gas is dispensed. Gas is dispensed from the first cylinder while hydraulic fluid is pumped into the cylinder to maintain the desired pressure. Once the first cylinder is depleted, the hydraulic oil is discharged from the first cylinder. The process is repeated for the second cylinder. However, the hydraulic oil must be discharged from the second cylinder before the substantial depletion of the gas. To safely discharge the hydraulic oil, compressed gas from the second cylinder is distributed into the first cylinder. Once the second cylinder has reached a safe discharge pressure or volume, the hydraulic fluid is discharged.

Abstract: A fixed and/or stationary modular unit consists of a hydraulic fluid tank and a pressurization pump. A compressed gas transportation system consists of a set of cylinders. Each cylinder has a charging port and a dispensing port. A valve is connected at the dispensing port of each cylinder. Each of the valves at the dispensing ports of the cylinders are connected to one another. After an idle period of dispensing activity, the valves on the dispensing ports of the cylinders are opened and compressed gas is bled from one of the cylinders into at least one of the other cylinders in the set until the at least one of the other cylinders reaches a desired dispensing pressure. Hydraulic fluid is pumped from the tank into the cylinder being bled from to maintain a substantially constant pressure within the cylinder.

Abstract: A fixed and/or stationary modular unit consists of a hydraulic fluid tank, a pressurization pump, and a compressed gas transportation system consisting of a cylinder or set of cylinders. Each cylinder has two ends, a charging end and a dispensing end, with actuated valves positioned at each end. A pair of valves are located at each charging end of each cylinder, with one valve connected to an incoming hydraulic fluid line and the other valve connected to a hydraulic fluid return line. A valve is connected at the dispensing end of each cylinder. Adapters at each end of the cylinder have curved J-tubes that extend into the cylinder. The J-tube on the charging end curves downward and the J-tube on the dispensing end curves upward. The cylinder or sets of cylinders are inclined to a desired level for the dispensing process.

Abstract: A fixed and/or stationary modular unit consists of a hydraulic fluid tank, a variable frequency drive consisting of a variable frequency controller, a variable frequency motor, and a pressurization pump. A compressed gas transportation system consists of a cylinder or set of cylinders. Each cylinder has a charging port and a dispensing port. A pair of valves are located at each charging port of each cylinder, with one valve connected to an incoming hydraulic fluid line and the other valve connected to a hydraulic fluid return line. A valve is connected at the dispensing port of each cylinder. As gas is dispensed from cylinders, hydraulic fluid is pumped from the tank by the variable frequency drive into the cylinder at a rate substantially equal to the dispensing rate of the compressed gas to maintain a constant pressure within the cylinder.

Abstract: A storage vessel is filled with compressed gas by filling a first tank with gas from a low pressure gas source. Hydraulic fluid is drawn from a reservoir and pumped into the first tank in contact with the gas. This causes the gas in the first tank to flow into the storage vessel as it fills with hydraulic fluid. At the same time, gas is supplied from the gas source to a second tank. Hydraulic fluid previously introduced into the second tank flows out to the reservoir as the second tank fills with gas. When the first tank is full of hydraulic fluid, a valve switches the cycle so that the hydraulic pump begins pumping hydraulic fluid back into the second tank while the first tank drains. The cycle is repeated until the storage vessel is filled with gas to a desired pressure.

Abstract: A compressed natural gas (CNG) refueling system has banks of cylinders containing CNG, a hydraulic fluid reservoir containing a hydraulic fluid which does not readily mix with CNG, and reversible flow valves. Each cylinder has a fitting installed in an opening at one end. The fitting contains a hydraulic fluid port and a gas port. The other end of each cylinder is closed. Hydraulic fluid is pumped from the reservoir into each cylinder through the hydraulic fluid port. Inside each cylinder, the hydraulic fluid directly contacts the CNG, forcing the CNG out through the gas port. When a sensor detects that the cylinders are substantially drained of CNG, the reversible flow valves will reverse orientation, allowing the hydraulic fluid to flow back into the reservoir.