Mud Hoppers The low-pressure mud hopper was produced in the 1940's. National Oilwell Varco's Jet-Venturi Mud Hopper was introduced in the early 1950's and continues to be the hopper of choice today. Properly engineered hoppers ensure the highest discharge pressures, solid addition rates and shear rates. NOV Mission manufactures four (4) inch and six (6) inch hoppers with standard flow rates from 130 GPM to 830 GPM as well as the TurboShear, primarily used for shearing hard to mix additives. Over 60 years of application experience, extensive engineering design, and rigorous testing have produced the best possible mud hopper assembly. NOV Mission can assist with properly sizing a hopper to fit your system. There is no reason to be forced to mount the hopper on top of the mud tanks since the jet-venturi allows for convenient location of the hopper. Sizing assistance should be requested when extensive piping or elevation is planned for the downstream side of the hopper.