Thursday, November 30, 2017

What Are Industrial Ball Valves?

Internal view of a ball valve
Internal view of a ball valve
(MOGAS)
Ball valves are defined by their body style, the five major styles being: Uni-body; 3-piece; split-body; top-entry; and welded body. They are further defined by the machined hole in their ball (also known as the port); the categories being "standard port" or "full port".

On a full port valve, the port is the same size as the pipeline, resulting in a better flow profile and no restriction or pressure drop. A full ported ball valve, with better flow coefficients, comes at a higher price. In many application they are necessary because a reduction in diameter, or the resulting change in flow, can be detrimental.

The reduction in a standard port valve is one pipe size smaller than the pipe connected to the valve, resulting in restricted flow and increased velocity through the valve.

2-piece and unibody ball valves
2-piece and unibody ball valves (Flo-Tite)
Standard port and full port valves are not usually recommended for throttling service due the a very
non-linear flow characteristic. Characterizing the port with a special shaped orifice can improve the valve linearity and provide good control. V-port ball valves incorporate a machined "V" in the seat around the outlet side of the valve. The "V" provides a more controllable flow pattern and is desirable when ball valves are used as control valves.

A cavity filled ball valve is used in applications where cleanliness or sanitary conditions exist. Any voids, gaps or spaces between the ball, seat and stem that allow bacteria or contaminates to accumulate are filled.  The proper cavity filler material is selected consistent with the process media, application and level of cleanliness required. Cavity fillers eliminate the spaces and voids where contaminants accumulate and provides easy "flushing" (cleaning) of the valve.

In a trunnion mounted ball valve, the valve stem is mechanically attached to the ball. Trunnion mounted valves are mostly used in applications on large diameter gas and oil pipelines and at high pressures.

Most ball valves however, are designed with a “floating ball” and not held mechanically in place by a trunnion. This allows the ball to be "pushed" slightly downstream and seal itself better against the seat. One advantage to this design is that a valve using a floating ball, and fitted with metal seats, can be used for "fire-safe" applications. This means that if the valve is subject to high temperatures, such as those presented in a fire, the "soft" part of the seat will melt away, and allow the ball to secure itself against the metal seat, and thus not allow material to pass and potentially feed the fire.

For best service life and optimum safety, please review your application with a qualified ball valve applications consultant prior to specifying an industrial ball valve.

Tuesday, November 28, 2017

Understanding Rack & Pinion Pneumatic Valve Actuators

Internal view of rack and pinion actuator.
Internal view of rack and pinion actuator (UniTorq)
Rack & Pinion actuators are designed for operating quarter-turn valves such as butterfly, plug, and ball valves or for actuating industrial or commercial dampers.

The rotational movement of a rack and pinion actuator is accomplished via linear motion and two gears. A circular gear, referred to a “pinion” engages the teeth of a linear gear “bar” referred to as the “rack”.

In a pneumatic actuator, pistons are attached to the rack. As air or spring power is applied the to piston, the rack is “pushed” inward or “pulled” outward. This dual direction linear movement is transferred to the rotary pinion gear providing bi-directional rotation.

Rack and Pinion Animation
Rack and Pinion Animation
Pneumatic actuators have cylinders with pistons and springs that provide the linear movement. When one side of the piston is pressurized with air, gas or oil, the pinion bearing turns in one direction. When the air, gas or oil from the pressure side is vented, a spring (spring-return actuators) may be used to rotate the pinion gear in the opposite direction. A “double acting” actuator does not use springs, instead using the air, gas or oil supply on the opposing side of the piston to turn the pinion gear in the opposite direction.

Pneumatic pneumatic rack and pinion actuators are compact and save space. They are reliable, durable and provide a good life cycle. Mechanical wear of the heads and seals are their primary disadvantage.

Most actuators are designed for 100-degree travel with clockwise and counterclockwise travel adjustment for open and closed positions. World standard ISO mounting pad are commonly available to provide ease and flexibility in direct valve installation.
Rack and Pinion Actuator
Rack and Pinion Actuator (UniTorq)
NAMUR mounting dimensions on actuator pneumatic port connections and on actuator accessory holes and drive shaft are also common design features to make adding pilot valves and accessories more convenient.

Feel free to contact Piping Specialties, Inc. at www.psi-team.com or 800-223-1468 with any questions you may have about valve actuation.

Sunday, November 12, 2017

Instructional Video: Inserting K-Patents Generation 2.1 SAFE-DRIVE™ Process Refractometer PR-23-SD

This video is intended for individuals installing, commissioning, operating, and/ or servicing the K-Patents Safe-DriveTM Process Refractometer PR-23-SD, generation 2 model. The purpose of this video is to provide a quick guide for the above mentioned tasks in the form of K-Patents recommended best practices.

K-Patents SAFE-DRIVE™ design allows for safe and easy insertion and retraction of the sensor under full operating pressure without having to shut down the process.

Below the video is the document "Best Practices for the Safe-DriveTM Process Refractometer PR-23-SD Generation 2" for your convenience.

For more information, visit http://www.psi-team.com or call 800-223-1468.

VIDEO



DOCUMENT