Monday, July 31, 2017

A Very Unique "No Straight Run Required" Flowmeter

VERIS Accelabar
VERIS Accelabar Detail
The VERIS Accelabar® is a unique flow meter that combines two differential pressure technologies to produce performance never before attainable in a single flow meter.

The VERIS Accelabar® is capable of measuring gases, liquids, and steam at previously unattainable flow rate turndowns—with no straight run requirements.

No Straight Run Required

The VERIS Accelabar® can be used in extremely limited straight run piping configurations. All necessary straight run is integral to the meter. The stabilization and linearization of the velocity profile within the throat of the nozzle eliminates the need for any upstream or downstream pipe runs.

Read the document below for more information or download the VERIS Accelabar® PDF from Mead O'Brien's website here.

Monday, July 24, 2017

Mead O'Brien: Experts in Valves, Valve Automation, Steam & Hot Water Systems, Process Instruments

Mead O’Brien specializes in valves & valve automation, steam & hot water products and systems, instrumentation products, skid designs, field services, surveys, assessments, and consulting.

Product Focus:
  • Valves, valve automation and control
  • Steam and hot water products and systems
  • Instrumentation and controls
For more information, visit http://www.meadobrien.com or call  (800) 892-2769.

Please pardon our little shameless self-promotion. Thanks for watching this short video highlighting Mead O'Brien products.

Sunday, July 16, 2017

Industrial Valve Actuator Basics

Electric actuator
Electric actuator (Limitorque)
Actuators are devices which supply the force and motion to open and close valves. They can be manually, pneumatically, hydraulically, or electrically operated. In common industrial usage, the term actuator generally refers to a device which employs a non-human power source and can respond to a controlling signal. Handles and wheels, technically manual actuators, are not usually referred to as actuators. They do not provide the automation component characteristic of powered units.

The primary function of a valve actuator is to set and hold the valve position in response to a process control signal. Actuator operation is related to the valve on which it is installed, not the process regulated by the valve. Thus a general purpose actuator may be used across a broad range of applications.
Pneumatic actuator
Pneumatic actuator (Metso Neles)

In a control loop, the controller has an input signal parameter, registered from the process, and compares it to a desired setpoint parameter. The controller adjusts its output to eliminate the difference between the process setpoint and process measured condition. The output signal then drives some control element, in this case the actuator, so that the error between setpoint and actual conditions is reduced. The output signal from the controller serves as the input signal to the actuator, resulting in a repositioning of the valve trim to increase or decrease the fluid flow through the valve.

An actuator must provide sufficient force to open and close its companion valve. The size or power of the actuator must match the operating and torque requirements of the companion valve. After an evaluation is done for the specific application, it may be found that other things must be accommodated by the actuator, such as dynamic fluid properties of the process or the seating and unseating properties of the valve. It is important that each specific application be evaluated to develop a carefully matched valve and actuator for the process.

Hydraulic and electric actuators are readily available in multi-turn and quarter-turn configurations. Pneumatic actuators are generally one of two types applied to quarter-turn valves: scotch-yoke and rack and pinion. A third type of pneumatic actuator, the vane actuator, is also available.

For converting input power into torque, electric actuators use motors and gear boxes while pneumatic actuators use air cylinders. Depending on torque and force required by the valve, the motor horsepower, gearing, and size of pneumatic cylinder may change.
Linear pneumatic actuator
Linear pneumatic actuator (Neles)

There are almost countless valve actuator variants available in the industrial marketplace. Many are tailored for very narrow application ranges, while others are more generally applied. Special designs can offer more complex operating characteristics. Ultimately, when applying actuators to any type of device, consultation with an application specialist is recommended to help establish and attain proper performance, safety and cost goals, as well as evaluation and matching of the proper actuator to the valve operation requirements. Share your fluid process control requirements with a specialist in valve automation, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Tuesday, July 11, 2017

Segmented or V Ported Ball Valves

Metso Neles segment ball valve
Metso Neles segment ball valve
Ball, plug and butterfly valves all belong to a class of valves commonly referred to as "quarter-turn" valves. This refers the 90 deg (angular) rotation required to go from full closed, to full open position.

In most cases standard ball, plug, or butterfly valves are not the best choice as control valves (where the process media has to be modulated or throttled). Standard ball, plug and butterfly valves usually introduce very non-linear, dynamic flow coefficients. Furthermore, they can introduce undesirable turbulence to your piping system.

As a means to linearize flow coefficients and reduce turbulent flow, the machining, or characterization, of the valve disk is done so that the machined shape allows for more optimized flow.

For ball valves in particular, machining the ball's flow port with a "V", or even by machining the ball more radically, can deliver excellent flow curves. A term for a more radically machined ball is the "segment ball" (sometimes called "segmented").  In the following video you can see how a Metso Neles segment ball valve is designed to provide excellent control.

For more information about Metso Neles valves, contact Mead O'Brien at  (800) 892-2769 or visit http://meadobrien.com.