Metal Seated Ball Valves

Linuo Metal Seated Ball Valve

The ball in metal seated ball valves has been hardened via plating or heat treatment so that it can sustain the friction imparted by the metal seat. The metal seat is machined to the profile of the ball to give tight shutoff. A metal seat spring, normally made of Inconel, keeps  positive contact between the seat and ball while operating. Precision machining ensures the ball and spring-loaded seats maintain a tight seal for superior shutoff.

Metal seated ball valves can handle much higher temperatures (and still provide tight shutoff) than soft seated valves. Typical working temperatures for metal seated valves are above 600 deg. F. while soft seated valves top out at around 400 deg. F.

A common metal seat material is Stellite, a cobalt-chromium alloy designed for high temperatures and wear resistance.

Metal seated ball valves stand up to high temperatures, pressures and abrasive materials encountered in the oil and gas, chemical, power generation, pulp & paper, food processing, and mining industries.

A variety of special ball and seat materials are available. These include stainless steel, stellite, hard chrome plated steel, tungsten carbide, and chrome carbide. These materials allow the valves to be used in highly abrasive fluids as well as steam.

Knifegate Control Valves

Knifegate with linear pnuematic actuator

A knife gate valve has a metal wedge or gate that "slices" through a process material. The valve is inserted in the piping system directly in the line of flow, or at the discharge end. The valve uses a a linear motion to open and close. In the closed position, the knifegate valve is designed to seat tightly and not allow leakage in either direction. They are designed to minimize pressure drop across the valve when fully open. They are great for slurries and thick, viscous fluids. Knifegate valves are operated via manual hand wheel or with pneumatic or electric actuators.

Although knifegate valves are designed primarily for for on-off service, there are situations and modifications available where they can be used for control (throttling). When used as control valves, the gate is precision machined with a notch or "V" to provide a specific flow characteristic that linearizes the flow through the valve. Without this modification, a standard knifegate disk demonstrates very non-linear flow characteristics and higher disk and seat wear.

Customer Confirms Linuo Top and Bottom Splined Shaft Controls Best

Linuo Segment Control Valve

A well respected, and experienced engineer working in the Ethanol production industry recently confirmed what Linuo knew all along - the Linuo Segment Control Valve has lower hysteresis and tighter control than competitive rotary control valves.

(courtesy of Wikipedia)

Any mechanical connection, no matter how well machined, has very small spaces where pieces fit together. These spaces can be minimized, but not eliminated. In a control valve shaft and disk assembly you have several of these mechanical connections where the tolerances add up and introduce a "deadband" in the movement of the control valve disk in relation to the valve actuator.  Its been "preached" for years, the best method for tight control and low hysteresis for rotary control valves is to eliminate these tolerances using splines machined on the shaft at the actuator connection.

Linuo Segment takes it one step further.  Linuo splines the shaft at the segment itself. Both, top and bottom shafts.  This leaves the top shaft available to match up to virtually any type of actuator.

The splines reduce "slop" or "drag" with the control signal.  Also, the shafts are then pinned to eliminate any excess movement.

Word seems to be getting out. Ethanol plants across the US are seeing better control results using the Linuo Segment and the valve is being specified for more critical applications each day.

The Linuo Segment Control Valve: Great Control and Suitable for Tough Applications

Linuo Segment Control Valve

The Linuo "Segment" Ball Valve combines globe valve control with the efficiency of a rotary ball valve. It provides excellent sealing capability with both metal and soft seats. Machined to a very precise contour, the V-notched ball provides excellent control characteristics for an extensive variety of flow applications.