DQ LEARNING CENTER
With over 60 years of design innovations and manufacturing excellence, we’d like to share with you some of the concepts and product knowledge we’ve gained along the way. We hope you will find these short articles helpful and insightful.
Why Use Automated Ball and Butterfly Valves?
Any piping system with valves which are subject to the following conditions or concerns will be excellent candidates for automated valves.
- Valves that are in elevated areas and difficult to reach, such as a piping galley or on the side of a tank are concerns for safety. Not just because they may require crawling out on a pipe or some other structure, but climbing outdoor ladders in winter during icy conditions can create hazards and be dangerous.
- Valves that are operated on the other side of busy or hazardous thoroughfares from the main plant can have safety concerns. Railroad tracks that divide a plant from the main operations can be a hazard to maintenance personnel.
- Hazardous gases that could leak, or any valve that is better operated from a distance due to heat, explosives, or other hazards in the general area are potential applications. Fail-safe spring return actuated valves may help meet safety standards required by law.
- Valves that must be cycled regardless of weather conditions such as lightning storms, hail, or high winds.
- Valves that can feed combustible materials to a fire or could be used to contain a fire and need to be cycled quickly.
- Valves installed underground in manways where hazardous gases can gather unexpectedly.
- Any application that could cause harm to personnel simply because of location or hazardous material in the line or area.
Cost of Manpower:
- Valves that require frequent or rapid opening and closing are excellent candidates for automation. Often it is difficult to do a manual operation in a timely manner. Due to the difficulty in turning some valves it becomes impossible to keep up with frequent manual operation. These valves should be automated valves.
- Valves that must cycle before or after another event has occurred are strong possibilities for automation. These types of systems can easily be automated so that the sequence happens with little or no manual input. Using limit switches or relays allows a whole series of events to occur based on a preceding event.
Valves which are some distance away from the operator who must cycle the valve should be automated. Today, automated ball and butterfly valves can be operated hundreds and even thousands of miles away from the control room. Using telephone, radio frequency and other hard wire and wireless control signals a plant can now get an almost instant response from their remote valves.
DynaQuip has many platform style manual valves that could be automated following instillation at a later date. Given the cost and downtime associated with piping control valves into a live system, a little foresight now will help to future proof your application.
Replacing a solenoid valve with a DynaMatic electric ball valve…Why and how?
Solenoid valves are typically easy to install and are used in applications utilizing pressure, flow, temperature and level switches. They can also be controlled by PLC units that only output a single control signal.
Unfortunately, solenoid valves have highly restricted media flow compared to other valves and have a tendency to clog, causing inconsistent operation. The most common solenoid valves use a diaphragm to obtain a shut-off. The seating area for the diaphragm inside the solenoid valve is restricted and causes low flows. Additionally, the diaphragm generally has within it a very small pilot hole to allow pressure to equalize on both sides of the diaphragm. The pilot hole easily clogs causing the solenoid valve to function erratically. Small and high-pressure solenoid valves use an internal spool arrangement that has a number of small orifices to control flow. These valves can suffer both reduced flow due to the spool obstructing the fluid’s flow path and erratic operation when the orifices clog.
Electrically actuated ball valves have replaced solenoid valves in many applications to provide vastly improved flow characteristics and consistent performance. Electric actuators consist of a motor, a gear train, cams and limit switches. The electric actuator requires two electrical input signals; one to open and another to close the valve. DynaQuip actuators are available in multiple voltages and options and are sized to provide the correct amount of torque required for the ball valve and application.
Make the switch. To convert from a solenoid valve (single input signal) to an electrically actuated ball valve (two input signals) requires the addition of a simple control relay. The single signal output from the control device is wired to the control relay coil, along with a constant neutral to the other side of the coil. A constant hot is wired into the common terminal for the control relay. A normally closed contact in the control relay is wired to a terminal in the electric actuator and a normally open contact in the control relay is wired to the opposing terminal in the electric actuator. The selection of which actuator terminal is used with the normally closed or normally open contacts of the control relay will depend upon the required action of the electric actuator. The choice of actuator terminals used will determine if the valve is to open or close and if this is to occur on a signal energizing the coil of the relay, or de-energizing the coil.
DynaQuip has several styles of ball valves with direct mount electric actuators to fit a wide range of applications.
Factors to consider when deciding between electric and pneumatic actuators.
Once the choice to automate has been made, it’s time to look a bit closer at the application to determine which type of actuator. The two most common types of actuators are pneumatic and electric. Both have a wide range of torque output and can be electronically controlled in many environments providing feedback and precise control. Both offer years of dependable operation and can represent a cost savings over manually operated valves. Certainly, availability of electric power or plant air is a major factor in selection, but beyond this, the choice should be made dependent upon application.
DynaQuip Pneumatic actuators are available in double acting or spring return (fail-close or fail-open) configurations. Torques range from 100 to 46,540 in lbs. Actuators are available with accessories such as solenoid pilot valves, positioners, valve position limit switches, speed control, dribble control and manual overrides.
Suggested Applications or environments:
- Rapid cycling is required
- Plant air is available
- Hazardous locations
- Submerged locations
- Fail-safe applications
- High ambient temperatures
DynaQuip Electric actuators are available in a wide range of voltages and torques. Accessories common to electric actuators include auxiliary limit switches, NEMA ratings for specific environmental requirements, heaters, timers, modulating controls, continuous position indication, and limited fail-safe options.
Suggested Applications or environments:
- Electric current is available (AC or DC)
- Where providing plant air or compressor air is not practical
- Corrosive environments
- Mobile environments (truck mounted)
- Cold ambient temperatures (heater option)
- Environments where water hammer is a concern
- Distributed control systems tied back to computer control
Full, Standard, Reduced…what does this mean and which porting should I use?
First, a little history…Did you know early mass production of ball valves used a methodology of boring out a solid metal bar or rod and machining the internals to accept the seats, ball and retaining rings? Manufacturers were limited to the physical dimensions of the diameter of the bar and had to maintain sufficient wall thickness to withstand the pressures inside the body of the valve. The overall diameter of the ball could not be larger than the inside diameter of the machined bar. Additionally, the ball orifice (the opening in the ball which sees media flow) was also restricted in size because it had to maintain sufficient wall thickness as well. The result was an innovative 90 degree shut-off solution with less than ideal flow characteristics.
As valve markets expanded and technology developed, other methods, such as forging and casting, became cost effective in the manufacture of ball valves. These methods allowed the valve body to take on configurations other than just the outside diameter of a metal bar or rod. Adding one or two more pieces to the valve body permitted the center portion to grow in size and accept larger internal components. For many years, valve manufacturers produced ball valves with an orifice through the ball that was approximately one pipe size smaller than the corresponding pipe inside diameter. This is known as a standard port valve.
Now enter the full port ball valve. As companies demand greater productivity from all aspects of their operations, full port valves are developed to ensure a restriction-free media flow. Full port valves have zero pressure drop (no loss of pressure) for the most demanding and critical applications. With one exception (VYHG 3-way), all of DynaQuip’s automated valves are fully ported for maximum performance.
Porting Summary Glossary:
- Reduced port ball valves are still commonly used today where cost savings outweigh the need for greater flow capacity. By definition, the orifice of the ball measures more than one pipe size smaller than the nominal size of the valve. For instance, a two-inch (2”) pipe size reduced port ball valve would have a 1 1/4" or smaller orifice in the ball. DynaQuip’s VME3 carbon steel and VNH brass mini valves are perfect examples of reduced port valves which offer significant value.
- Standard port ball valves are valves with a reduced bore through the ball no more than one pipe size smaller than the inside diameter of the pipe it is matched with. A two-inch (2”) pipe size standard port ball valve has an orifice in the ball no smaller than 1 1/2". Standard port valves offer a great balance between cost and flow. Look for DynaQuip’s VME1 carbon steel, VMB stainless steel or VMA bronze valves for examples.
- Full port ball valves are unrestricted valves with a bore through the ball that is larger or nearly matching the inside diameter of the pipe it is matched with. A 2” pipe size full port ball valve would be the same 2” nominal orifice inside the valve. Full port ball valves were developed to respond to a demand in the market for greater flow. Nearly all of DynaQuip’s current product offerings are fully ported.