A mud tank suction valve is a control valve installed within a drilling mud tank to regulate the flow of driling fluid during the solids control operation.These custom-fabricated valves are a critical component of the solids control system, which separates solid particles from the drilling fluid so it can be reused. 

Function and operation
The primary functions of a mud tank suction valve include: 

• Flow control: Controls the suction and discharge of drilling mud into and out of each tank compartment (bin).
• Compartment isolation: Prevents different types of fluids in different bins from mixing by providing a reliable seal at the bottom of the tank.
• Balance control: Allows for the balancing of fluid levels between bins when needed.
• Surface operation: Operates via a handwheel or lever located on the top of the tank, connected to a lifting rod that opens and closes a valve plate at the tank's bottom. 

• Screw-type operator (handwheel): A handwheel rotates a lead screw, moving the valve stem up and down to lift the valve plate. Early models often used this design.
• Lever handle operator: A simpler, more space-efficient design preferred by many users. 

• "Flow through" or elbow pattern: A straight-through design where fluid flows directly in line with the valve.
• T-port pattern: Features a T-shaped suction port for increased mud flow capacity.
• Cross-type pattern: Another design variant with a different suction port configuration. 

• Materials: Built to withstand abrasive drilling mud. Materials often include common carbon steel, seamless tube, or stainless steel.
• Seals: Made from high-performance materials such as Viton synthetic rubber to resist high temperatures and oil.
• Size: Common valve diameters include 6", 8", 10", and 12", with 8" and 10" being the most popular.
• Customization: Valves can be customized for tank depth, suction height, and other specific requirements.