Jamesbury™ Quadra-Powr™ Spring Diaphragm Quarter Turn Actuators for Use in Both Modulating Control and On-Off Service

Valves provide pressure reduction and flow control through piping systems and are critical to industries that form the backbone of the modern world. The valve actuator is crucial for valve operation. Actuators are powered devices that move valves between open and closed states. The valves can open or close depending on the movement it receives from an actuator; this motion is responsible for controlling the flow and pressure within an industrial system or process.

Jamesbury™ Quadra-Powr™ spring diaphragm QPX series quarter turn actuators are applicable for modulating control and on-off service. These actuators offer an exceptionally long cycle life and are well-suited to operate almost any type of rotary valve. The QPX actuator provides smooth and efficient quarter-turn valve operation and safe and reliable operation even when minimal supply pressure is available.

Exclusively developed for quarter-turn valve service, Quadra-Powr™ X spring-diaphragm actuators provide safe and reliable operation even when minimal supply pressures are available. Yet they can operate at pressures as high as 7 bar (100 psi).

These units operate by air, gas, water, oil, or other supply media compatible with the actuator's ductile iron/carbon steel casing and the Buna-N diaphragm reinforced with polyamide fabric. This unique spring-diaphragm actuator for rotary valves provides safe, smooth, and reliable valve actuation at minimal pressures and up to 100 psi (6.9 BAR). Quadra-Powr X torque outputs range from 15 to 796 Nm (11 to 587 ft-lbs), depending on actuator selection and available supply pressure.

Jamesbury™ Quadra-Powr™ Features:

• Rolling diaphragm for minimum friction
• Low friction bearings – factory lubricated for lifetime
• Field reversible for spring to open or close simply by flipping actuator over
• Safety contained springs prevent hazards of inadvertent ejection during maintenance
• Corrosion resistant – two layer epoxy and polyurethane paint with stainless steel fasteners
• Adjustable stops for both open and closed positions
• Wide input pressure range – up to 7 bar (100 psi)

For more information, contact Mead O'Brien. Call (800) 874-9655 or visit https://meadobrien.com.

Industrial Actuators, Valves, and Positioners

Valves regulate fluid flow to provide accurate control and safety in any given process system, and methods of adjusting valve position are always required.

Commonly, valves are operated with handwheels or levers, although some must be regularly opened, closed, or throttled. In certain conditions, it is not always practical to position valves manually; hence actuators are employed instead of hand wheels or levers. 

An actuator is a mechanism that moves or regulates a device, such as a valve. Actuators decrease the requirement for people to operate each valve manually. Valves using actuators can remotely control valve position, particularly crucial in applications where valves open and close or modulate fast and precisely. 

Pneumatic, hydraulic, and electrical actuators are the three fundamental types. 

1. Pneumatic actuators employ air pressure to generate motion and are probably the most prevalent type of actuator utilized in process systems. 
2. Actuators powered by a pressurized fluid, such as hydraulic fluid, are called hydraulic actuators. Typically, hydraulic actuators of the same size produce more torque than pneumatic actuators. 
3. Electric actuators generate motion using electricity. Actuators usually belong to two broad categories: solenoid or motor-driven actuators. 

Actuators position valves in response to controller signals and can be positioned rapidly and precisely to accommodate frequent flow variations. The instrumentation systems that monitor and respond to fluctuations in plant processes include controllers. Controllers receive input from other instrumentation system components, compare that input to a setpoint, and provide a corrective signal to bring the process variable (such as temperature, pressure, level, or flow). 

You have a control valve when actuators pair with flow-limiting or flow-regulating valves. Generally speaking, control valves automatically restrict flow to provide accurate flow to a process to maintain product quality and safety. 

Control valves can be linear, where the stem moves the valve disk up and down like globe valves, or rotational. Rotary control valves include butterfly valves, which open or close with a 90-degree rotation. The pneumatic diaphragm and electric actuators are the most prevalent on linear and rotational control valves.

Some valves require long stem travel or substantial force to change position. A piston actuator's higher torque is preferable to diaphragm actuators in these situations. Examples of piston actuators are rack and pinion and scotch-yoke designs. 

Single-acting piston actuators control the air pressure on one side of a piston, and with higher air pressure, the piston moves within the cylinder and turns the valve. The air on the opposite side of the piston exits the cylinder via an air vent. With decreased air pressure, the spring expands, causing the piston to move in the opposite direction. 

If air pressure falls below a predetermined threshold or is lost, the spring will push the piston to the desired position, referred to as the "fail" position (open or closed). 

A double-acting piston actuator lacks a spring and has air supply ports on both ends of the cylinder. Increasing air pressure to the supply port moves the valve in one direction. Higher pressure air entering from the opposite supply port pushes the valve in the opposite direction. Filling the cylinder with air and releasing air from the cylinder is regulated by a device known as a positioner. 

Typically, the control of pneumatic actuators occurs from air signals from a controller. Some actuators react directly from a controller, for instance, a pneumatic 3-15 PSI controller output. Sometimes, a controller signal alone cannot counteract a valve's friction or the process media's fluid pressure. This situation requires a separate, high pressure air supply and modulating it with a pneumatic or electro-pneumatic positioner. These devices regulate a high pressure air supply to ensure that an actuator has enough torque to position a valve accurately. The positioner responds to a change in the controller's air, voltage, or current signal and proportions the high pressure air to the actuator. Connecting the actuator stem to the positioner is a mechanical linkage. This mechanical connection is also known as a feedback connection. The link moves as the actuator stem moves up, down, or rotationally. The location of the connection informs the positioner when sufficient movement coincides with the controller's air signal. The controller's signal transmits to the positioner instead directly to the actuator, and the positioner regulates the air supply provided to the actuator.

Like other process components, actuators are prone to mechanical issues. Since actuator issues can negatively impact the operation of a process, it is essential to be able to recognize actuator issues when they occur. Frequently, an operator can notice an actuator fault by comparing the valve position indication to the position specified by the controller. For instance, if the position indicator shows the valve closed, but the flow indicator on the controller indicates that flow is still passing through the valve, the valve seat and disc are likely worn, enabling leakage through the valve.

Because there are so many different styles and designs of actuators, positioners, and valves and so many industrial applications, the combination possibility matrix is vast. You must discuss your application with a knowledgeable, experienced valve expert. The success of your project in terms of product quality, system cost, maintenance, and safety depends upon it.

Mead O'Brien
(800) 874-9655

What is a Ball Valve?

Cutaway of specialized ball valve with characterized
ball for control valve applications. (Neles)

A ball valve is a 90 degree rotational motion valve that uses a metal or ceramic ball with a hole through its center to stop or start fluid flow. The ball, shown below in Figure 1, opens and closes to allow fluid flow through the ball valve. When the valve handle or stem is turned to open the valve, the ball rotates to a point where the hole in the ball is parallel with the valve body inlet and outlet. When the valve is shut, the ball is rotated so that the ball's hole is perpendicular to the inlet and outlet of the valve body and the flow is stopped.

Most ball valve actuators are of the quick-acting type, which require a 90° turn of the valve handle or stem to operate the valve. Other ball valve actuators are planetary gear-operated manual,  electrically operated motors, or pneumatic piston type. All actuators provide the necessary operating force to open and close valves.

Figure 1 

Ball Valve Advantages

A ball valve is often the least expensive of any industrial valve configuration and has low maintenance costs. In addition to quick, quarter turn on-off operation, ball valves are compact, require no lubrication, and give tight sealing with low torque.

Ball Valve  Disadvantages

Conventional industrial ball valves have relatively poor throttling characteristics (except when using a characterized ball, as shown above). A standard ball valve when in throttling position will fail because of because of the impingement of high velocity flow and the erosive effect on the partially exposed seat.

Ball Valve Port Patterns

Ball valves are available in the venturi, reduced, and full port pattern. The full port pattern has a ball with a bore equal to the inside diameter of the pipe.

Ball Valve Materials

Balls are usually metallic in metallic bodies with trim (seats) produced from "soft" seats referring to the elastomeric materials used such as PTFE (100% Virgin Polytetrafluoroethylene), RTFE (Reinforced Teflon®), TFM, CTFE, Polychlorotrifluoroethene, Polyether Ether Ketone, and UHMWPE. Care must be used in the selection of the seat material to ensure that it is compatible with the materials being handled by the valve.Ball valve bodies may also be made of various plastic materials for corrosive applications.

Ball Valve Stem Design

The stem in a ball valve is not fastened to the ball. It normally has a rectangular portion at the ball end which fits into a slot cut into the ball. The enlargement permits rotation of the ball as the stem is turned.

Ball Valve Bonnet Design

A bonnet cap fastens to the body, which holds the stem assembly and ball in place. Adjustment of the bonnet cap permits compression of the packing, which supplies the stem seal. Packing for ball valve stems is usually in the configuration of die-formed packing rings normally of TFE, TFE-filled, or TFE-impregnated material. Some ball valve stems are sealed by means of O-rings rather than packing.

Ball Valve Position

Some ball valves are equipped with stops that permit only 90° rotation. Others do not have stops and may be rotated 360°. With or without stops, a 90° rotation is all that is required for closing or opening a ball valve.

The handle indicates valve ball position. When the handle lies along the axis of the valve, the valve is open. When the handle lies 90° across the axis of the valve, the valve is closed. Some ball valve stems have a groove cut in the top face of the stem that shows the flowpath through the ball. Observation of the groove position indicates the position of the port through the ball. This feature is particularly advantageous on multiport ball valves.

For more infomration about industrial ball valves, contact Mead O'Brien by calling (800) 892-2769 or visit their website at https://meadobrien.com.

Valves Designed for Severe Service. Not Just Heavy Duty

High performance butterfly
valve (Jamesbury)

From time to time, industrial process control applications involve very stringent and challenging performance requirements for the valves, process piping, and instruments that are part of the control loop. Control valves are a significant example where the impact of extreme fluid conditions require careful design and selection consideration to assure proper performance and safety levels are maintained in a predictable way.

Severe service is a term that describes valves used in application at the extremes of pressure, temperature, cycling, and material compatibility. While there are plenty of published and accepted standards for industrial valves, one does not exist to precisely define a severe service valve.


So, what then defines the selection of severe service valves, as opposed to general purpose valves?

There are a number of basic selection criteria that might point you in that direction, but in general they are:

• Very extreme media or environmental temperature
• High pressure drop operation that may cause cavitation
• Rapid and extreme changes to inlet pressure
• Certain types or amounts of solids contained in the fluid
• Highly corrosive, or erosive process media.

Certainly, any of these criteria might be found in an application serviceable by a general purpose valve, but their presence should be an indicator that a more involved assessment of the fluid conditions and commensurate valve requirements is needed. The key element for a specifier is to recognize when conditions are apparent that might exceed the capabilities of a general purpose valve, leading to premature failure in control performance or catastrophic failure that produces an unsafe condition. Once the possibility of a severe service condition is identified, a careful analysis of the possible operating conditions will reveal the performance requirements for the valve.

When in doubt, its critical to discuss your special requirements with an experienced product application specialist. They have access to technical resources that can help with selecting the right valve components to meet your severe service applications.

For more information contact:

Mead O'Brien
(800) 892-2769

www.meadobrien.com