A method for protecting a pressure transducer from fluid pressure damage using a pressure isolation mechanism is disclosed. The method includes associating the pressure transducer with an isolation port of the pressure isolation mechanism, placing a pressurizing device for delivering fluid under pressure in fluid connection with an inlet port of the pressure isolation mechanism, and actuating the pressurizing device to cause fluid flow in the inlet port such that a free floating, fluid flow responsive valve member positioned in an internal cavity of the pressure isolation mechanism engages a seal seat therein to attain a closed position, preventing fluid flow between the inlet port and the isolation port and thus prevent overpressure in the isolation port. Hemodynamic pressure signals read with the pressure transducer may be transmitted at least in part through a body of the valve member, or a portion thereof, when in the closed position.

A gas pressure regulator is disclosed that includes a reciprocating piston that engages and disengages from a seat to open the higher pressure and lower pressure sides of the regulator to one another. The regulator includes an elastomer seal between the seat and the piston that has an ignition rating sufficient to avoid combustion in the presence of oxygen at pressure differentials that are a factor of between 5 and 10 between the higher pressure and lower pressure sides of the regulator.

The fluid delivery system includes a pressurizing device for delivering a pressurized injection fluid, a low pressure fluid delivery system, and a pressure isolation mechanism adapted for fluid communication with the pressurizing device and low pressure fluid delivery system. The pressure isolation mechanism includes a housing defining an inlet port, an isolation port, and an internal cavity. The housing defines a seal seat in the internal cavity between the inlet port and isolation port. A valve member is disposed in the internal cavity. The valve member is free floating in the internal cavity and is adapted to engage the seal seat. The valve member has an open position permitting fluid communication between the inlet port and isolation port, and is fluid flow responsive to fluid flow in the inlet port to engage the seal seat and attain a closed position preventing fluid flow between the inlet port and isolation port.