Abstract: Valve seat rings are provided having sediment guard recesses formed in the back face portions thereof, which recesses are in the form of annular grooves having restricted annular openings and defining an internal stop shoulder. A sediment guard is movably positioned within the receptacle and includes an annular sediment blocking portion that protrudes through the restricted groove for sediment blocking engagement with a radial surface defining a portion of the seat recess. The sediment guard also defines a stop portion that is engageable with the stop shoulder to prevent separation of the sediment guard from its receptacle. The sediment guard is urged toward the radial surface of the seat recess by compression springs located within the receptacle.

Abstract: Apparatus comprising an interchange which receives a sphere from a meter prover loop after a meter prover run and which launches the sphere into the loop to commence a run. An assembly within the body of the interchange is movable between sphere receiving and sphere launching positions. When in sphere launching position it provides a seal which prevents flow through the interchange. Means is incorporated which prevents hydraulic shock when the assembly is moved from sphere receiving to sphere launching position. Also the apparatus has improved means for detecting leakage.