A fluid-flow measuring ball valve (20, 120), comprising: a housing (22, 122) having inlet (24, 124) and outlet (26, 126) openings and a valve chamber (28, 128); a ball (40, 140) contained within the valve chamber, said ball having an orifice (42, 142); an actuator (44, 144) supported by said housing and connected to said ball for turning the ball within said housing between an open position allowing fluid flow through the orifice and a closed position preventing fluid flow; a first ultrasonic transducer (66, 166) positioned in said housing (22, 122) upstream of said ball; a second ultrasonic transducer (68, 168) positioned in said housing (22, 122) downstream of said ball; first (84, 184) and second acoustic reflectors (86, 186) positioned within the housing; a controller (70, 170) connected to said first and second ultrasonic transducers, wherein said first and second ultrasonic transducers and first and second acoustic reflectors are aligned to transmit and reflect ultrasonic signals in at least one direction through the orifice of the ball when the ball is in an open position and said controller is configured to determine the fluid velocity based on measured speed of sound and calculate the volume of fluid passing through the orifice based on the measured fluid velocity and cross-sectional area of the orifice, characterised in that the housing (22, 122) comprises a valve body (30, 130) and an end adapter (32, 132) connected together and configured to form the inlet opening and the outlet opening and the valve chamber, and wherein said body and end adapter each include gauged threads for assembling the end adapter onto the body and alignment marks on the body and end adapter that when aligned indicate the ultrasonic transducers and acoustic reflectors are aligned. a housing (22, 122) having inlet (24, 124) and outlet (26, 126) openings and a valve chamber (28, 128); a ball (40, 140) contained within the valve chamber, said ball having an orifice (42, 142); an actuator (44, 144) supported by said housing and connected to said ball for turning the ball within said housing between an open position allowing fluid flow through the orifice and a closed position preventing fluid flow; a first ultrasonic transducer (66, 166) positioned in said housing (22, 122) upstream of said ball; a second ultrasonic transducer (68, 168) positioned in said housing (22, 122) downstream of said ball; first (84, 184) and second acoustic reflectors (86, 186) positioned within the housing; a controller (70, 170) connected to said first and second ultrasonic transducers, wherein said first and second ultrasonic transducers and first and second acoustic reflectors are aligned to transmit and reflect ultrasonic signals in at least one direction through the orifice of the ball when the ball is in an open position and said controller is configured to determine the fluid velocity based on measured speed of sound and calculate the volume of fluid passing through the orifice based on the measured fluid velocity and cross-sectional area of the orifice, characterised in that the housing (22, 122) comprises a valve body (30, 130) and an end adapter (32, 132) connected together and configured to form the inlet opening and the outlet opening and the valve chamber, and wherein said body and end adapter each include gauged threads for assembling the end adapter onto the body and alignment marks on the body and end adapter that when aligned indicate the ultrasonic transducers and acoustic reflectors are aligned.