Abstract: A marine seismic array wherein each air gun in the array is provided with an air supply valve that can be closed remotely to inactivate a particular air gun and then reopened upon command to reactivate the gun without retrieving the array. The valve is comprised of a housing having a ball valve therein which is rotated between an open and closed position by a reversible, electric motor in the housing upon the flowing of current to the motor in either a first direction or in an opposite direction. Limit means are provided in the housing to stop the motor when the ball valve rotates to either a full open or a full closed position.

Abstract: A dual chamber seismic air gun which discharges both chambers simultaneously to counterbalance the reactive forces generated by the discharges. The chambers are symmetrical within the housing of the gun so that the movement of the internal parts during operation also counterbalance each other. The gun is mounted coaxially on the air supply of a seismic array to provide a good profile for towing.

Abstract: A dual chamber seismic air gun which discharges both chambers simultaneously to counterbalance the reactive forces generated by the discharges. The chambers are symmetrical within the housing of the gun so that the movement of the internal parts during operation also counterbalance each other. The gun is mounted coaxially on the air supply of a seismic array to provide a good profile for towing.

Abstract: A hydraulic interlock system is disclosed wherein several pumps may be used to activate a plurality of hydraulic circuits while preventing activation of a single hydraulic circuit by more than one pump simultaneously.

Abstract: An apparatus and method are provided for measuring hematocrit. A diluted blood sample is passed through a well-known conductivity sensor providing a sensor pulse for each sensed blood cell. Each pulse has a peak amplitude corresponding to the size of a blood cell passing through the sensor. During a first time period initiated by passing of the sensor pulse above a threshold level, the sensor pulse is coupled to peak detecting means, and a signal indicative of the level of the peak is generated and stored. The value of each stored signal is added to an integrator for a fixed period of time. The value stored by the integrator is thus indicative of hematocrit level for a known sample volume.