Importance

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Abstract

A marine air gun is advantageously converted into a hydro gun by substitution of two clamp rings and by convenient addition of various parts, allowing normal air gun firing by triggering with usual solenoid valve. In a presently preferred embodiment, a novel firing chamber is also substituted, providing outwardly-facing piston rings and cylinder encircling this chamber. A special clamp is substituted for that which normally secures operating chamber to firing chamber. An outer-cylinder-defining housing is concentric around the firing chamber, with an annular piston sliding in the annular cylinder space defined intermediate the firing chamber and the new outer housing. This annular piston is propelled by the air blast, suddenly ejecting water slugs from ports in the new outer housing. Also added is a pressure-controlled air-vent valve, responsive to air pressure coupled through passages in an adapter mounted between solenoid valve and air gun. This vent, held closed by pressurized air during firing, afterwards vents to atmosphere. Advantageously it conserves firing-chamber air; it now enables ambient water pressure automatically to return the annular piston to initial position. By virtue that the air gun can be fired in usual manner and by virtue of automatic return of the annular piston after each firing, the usual firing and control systems and usual air compressors are used on shipboard, thereby creating large economies and time savings resulting from convenient conversion to hydro gun action or convenient conversion back to air gun action, whenever desired. In a modified embodiment of the invention, the air vent valve can be totally eliminated. The inertia of the water in an air vent line in communication with the upper end of the outer annular cylinder space has been found to be sufficient for momentarily preventing significant escape of pressurized air up into the air vent line during firing, thereby advantageously maintaining the desired high air pressure within the hydro gun structure during firing, without the need to provide a pressure-controlled air vent valve. The lower portion of the air vent line is preferably made of metal and may have exterior fins for readily conducting heat from the ambient water into the interior of the vent line for preventing internal ice build-up resulting from chilling due to rapid air expansion in the vent line near the exit from the upper end of the outer annular cylinder space.

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First Claim