A vent valve apparatus (10) for use with a system for supplying breathable gas pressurised above atmospheric pressure to a human or animal. The apparatus (10) includes a gas washout vent (15), a vent valve (18) adapted to progressively restrict the flow area of the washout vent (15), and a pressure sensitive vent valve control means (20,22,23). The control means is adapted to progressively cause the vent valve (18) to restrict the flow area of the gas washout vent (15) in response to increases in the pressure of the gas supply, thereby substantially regulating the volumetric flow of gas and/or CO.sub.2 gas through the washout vent (15) over a range of gas supply pressures.

A method of stimulating a subterranean formation using a tubular member with one or more burst disks therein.

A valve body with an integral bypass includes a primary valve body portion defining a primary bore extending through the primary valve body portion from a primary upstream end to a primary downstream end, the primary bore defining an axis, the primary bore including a primary upstream bore extending through the primary upstream end and a primary downstream bore extending through the primary downstream end, the primary valve body portion configured to house a valve member between the primary upstream bore and the primary downstream bore; and the bypass seamlessly integrated with the primary valve body portion, the bypass defining a bypass bore, the bypass bore including a bypass upstream bore and a bypass downstream bore, the bypass including a bypass valve body disposed between the bypass upstream bore and the bypass downstream bore.

A valve body includes a flange; and an identification tab disposed on the flange, the identification tab defining indicia. A pipe system includes a first flange; a second flange fastened to the first flange by a plurality of fasteners; and an identification tab disposed on the first flange, the identification tab defining indicia.

There is provided a system separator having a backflow preventer including a housing enclosing a main flow conduit, a valve seat inside the housing on the main flow conduit, and a valve body movable relative to the valve seat to close off the main flow conduit together with the valve seat in a closed position and to release the main flow conduit in an open position. The valve body is alternately movable between the closed position and the open position by at least one of a pressure difference in the main flow conduit or a force of a spring element, and the main flow conduit is divided in the area of the valve body into at least one outer flow conduit and one inner flow conduit, and the valve body encloses the inner flow conduit and forms at least one valve-body valve seat on the inner flow conduit.

There is provided a system separator having a backflow preventer including a housing enclosing a main flow conduit, a valve seat inside the housing on the main flow conduit, and a valve body movable relative to the valve seat to close off the main flow conduit together with the valve seat in a closed position and to release the main flow conduit in an open position. The valve body is alternately movable between the closed position and the open position by at least one of a pressure difference in the main flow conduit or a force of a spring element, and the main flow conduit is divided in the area of the valve body into at least one outer flow conduit and one inner flow conduit, and the valve body encloses the inner flow conduit and forms at least one valve-body valve seat on the inner flow conduit.

A valve body with an integral bypass includes a primary valve body portion defining a primary bore extending through the primary valve body portion from a primary upstream end to a primary downstream end, the primary bore defining an axis, the primary bore including a primary upstream bore extending through the primary upstream end and a primary downstream bore extending through the primary downstream end, the primary valve body portion configured to house a valve member between the primary upstream bore and the primary downstream bore; and the bypass seamlessly integrated with the primary valve body portion, the bypass defining a bypass bore, the bypass bore including a bypass upstream bore and a bypass downstream bore, the bypass including a bypass valve body disposed between the bypass upstream bore and the bypass downstream bore.

A valve body includes a flange; and an identification tab disposed on the flange, the identification tab defining indicia. A pipe system includes a first flange; a second flange fastened to the first flange by a plurality of fasteners; and an identification tab disposed on the first flange, the identification tab defining indicia.

A valve body with an integral bypass includes a primary valve body portion defining a primary internal surface, the primary internal surface defining a primary bore extending through the primary valve body portion from a primary upstream end to a primary downstream end; and the bypass seamlessly integrated with the primary valve body portion, the bypass defining a bypass internal surface, the bypass internal surface defining a bypass bore, the bypass bore comprising a bypass upstream bore and a bypass downstream bore, the bypass upstream bore extending through the primary upstream end of the primary valve body portion, the bypass downstream bore extending through the primary downstream end of the primary valve body portion, the bypass internal surface seamlessly intersecting the primary internal surface at the primary upstream end and the primary downstream end.

A valve body with an integral bypass includes a primary valve body portion defining a primary internal surface, the primary internal surface defining a primary bore extending through the primary valve body portion from a primary upstream end to a primary downstream end; and the bypass seamlessly integrated with the primary valve body portion, the bypass defining a bypass internal surface, the bypass internal surface defining a bypass bore, the bypass bore comprising a bypass upstream bore and a bypass downstream bore, the bypass upstream bore extending through the primary upstream end of the primary valve body portion, the bypass downstream bore extending through the primary downstream end of the primary valve body portion, the bypass internal surface seamlessly intersecting the primary internal surface at the primary upstream end and the primary downstream end.