Consulting

Manually Operated Valves, Pressure Regulators, and Relief Valves. Manual valves isolate, switch and control fluid flow in a piping system. These valves are operated by hand with levers and gear operators. Regulators are self-contained valves used to maintain a constant pressure, temperature, or level based on the applied setting. Relief valves prevent over pressure conditions by opening when the process pressure exceeds the applied setting. Click on the desired valve type to continue with your selection.

Ball Valves

Ball valves are reliable and simple to use as a shutoff valve or flow metering valve. Just a quarter turn of the handle opens or closes the valve. Handle position lets you "see" the valve's position.

Butterfly Valves

Butterfly valves are used where economical, high capacity valves are needed. Resilient liners provide bubble tight shutoff in general service applications. High-performance butterfly valves provide excellent flow control, and Triple offset metal seated butterfly valves are designed for high pressure and high temperature severe service applications.

Check Valves

Check valves have a disc, ball, or plates that open when forward flow starts in the pipeline. When pressure drops, either gravity, back pressure, or a mechanical spring forces the disc back against its seat to prevent reversal of flow (backflow).

Diaphragm Valves

Diaphragm valves have excellent shut-off and flow control characteristics. A flexible molded diaphragm regulates flow, provides tight shutoff, and isolates the fluid from the environment. The valve consists of the body, diaphragm, and handwheel assembly. Their simple design and wide choice of materials make them ideal for corrosive, abrasive, and sanitary services.

Float Valves

Float valves automatically control liquid level and prevent overfilling tanks. The valve is operated mechanically by a float which rests on top of the liquid. As the liquid level rises, it pushes the float up and closes the valve. As the level falls, the valve opens. The amount of liquid pressure the valve can shutoff against is determined by the length of the rod and size of the float.

Gate Valves

Gate valves have a sliding wedge or disc which reciprocates into and out of the valve port. These valves are ideal for isolation of general purpose as well as high pressure and high temperature applications where operation is infrequent. Manual operation is accomplished through a multi-turn handwheel assembly.

Globe Valves

Globe valves have a conical plug which reciprocates into and out of the valve port. These valves are ideal for metering fluid flow as well as shutoff in high pressure drop and high temperature applications. Available in globe, angle, and y-pattern designs. Manual operation is accomplished through a multi-turn handwheel assembly.

Needle Valves

Needle valves have a relatively small conical seat with matching needle-like tapered plug on the end of a finely threaded screw. The fine multi-turn action provides high resolution positioning of the plug relative to the seat making it ideal for regulating fluid flow. Needle valves are ideal for precise flow metering, process dampening, and shutoff applications. Also known as gauge valves, needle valves are commonly used to protect pressure gauges and instruments from pressure spikes by dampening the flow/pressure. Needle valves can be used with pneumatic actuators to control the rate of valve open and close times (speed control).

Plug Valves

Plug valves are similar to ball valves except instead of a spherical element, a cylindrical element is used as the internal restriction. Plug valves are typically more expensive than ball valves, but they are inherently more rugged as well. The plug is guided by a sleeve which acts as the sealing member. These valves are available in 2, 3, and 4-way configurations.

Pressure Regulators

Regulators are self-operated valves which use a spring and diaphragm to regulate the flow of fluids to maintain set pressure. Ideal where simple automatic control of pressure, level, and temperature is required. Settings are field adjustable within a specified range.

Relief Valves

Relief valves are normally closed and use a spring and diaphragm to monitor process pressure. The valve is designed to lift sufficiently to relieve fluid pressure build-up over setting. These valves help protect vessel and piping system damage from over pressurization.

Strainers

Strainers are placed in process piping lines to remove large solid contaminants from the flow stream. Stainers help protect valves, pumps, and other expensive equipment against dirt, scale, chips and other sediment. Strainers should always be installed upstream of solenoid valves to prevent clogging of internal passages.

 

Valve Selection

Isolation Valves

Ball Valves

Butterfly Valves

Diaphragm Valves

Float Valves

Gate Valves

Globe Valves

Plug Valves

Solenoid Valves

Switching (3-way) Valves

Control Valves

Proportional Solenoid Control Valves

Reciprocating Globe Valves

Rotary Globe Valves

Pressure/Temperature Rating

Body Materials

Seal Materials

End Connections

Actuator Selection

Pneumatic Double Acting

Pneumatic Spring Return

Electric

Accessories

Solenoid Valves

Limit Switches

Positioners

I/P Transducers

Filter Regulators

Speed Control Valves

Valve Selection

Valves isolate, switch and control fluid flow in a piping system. These valves can be operated manually with levers and gear operators or remotely with electric, pneumatic, electro-pneumatic, and electro-hydraulic powered actuators. Manually operated valves are typically used where operation is infrequent and/or a power source is not available. Powered actuators allow valves to be operated automatically by a control system and remotely with push button stations. Valve automation brings significant advantages to a plant in the areas of process quality, efficiency, safety, and productivity.

Valves must be properly selected to operate safely, efficiently, and reliably without excessive maintenance. First select the most cost effective valve type suitable for the given application. Then select the appropriate pressure/temperature rating, materials of construction, end connections, and actuation based on the service conditions and system requirements.

Isolation Valves are considered on/off because they typically operate in two positions; the fully open and fully closed position (thus on/off). Valves made specifically for on/off service are designed with tight reliable shutoff in the closed position and little restriction in the open position. Ball valves, gate valves, butterfly valves, diaphragm valves and plug valves are the most commonly used isolation valves.

Ball Valves were a welcomed relief to the process industry. They provide tight shutoff and high capacity with just a quarter-turn to operate. Ball valves are now more common in 1/4"-6" sizes. Ball valves can be easily actuated with pneumatic and electric actuators.

Butterfly Valves have come a long way from the old damper valve days. Today's butterfly valves are designed for general as well as severe service applications. Resilient liners provide tight shutoff in general service applications. Triple offset metal seated butterfly valves are designed for severe service applications. Butterfly valves are the most economical valves per comparable capacity and are easily automated with pneumatic and electric actuators.

Diaphragm Valves are by far the simplest valves. A resilient diaphragm provides tight shutoff and isolates the body from its operator. The operator consists of a plunger and handwheel assembly. Diaphragm valves are ideal for corrosive, slurry and sanitary services. They are easily and inexpensively actuated with pneumatic and electric actuators.

Float Valves automatically control liquid level and prevent overfilling tanks. The valve is operated mechanically by a float which rests on the top of the liquid. As the liquid level rises, it pushes the float up and closes the valve. As the level falls, the valve opens. The amount of liquid pressure the valve can shutoff against is determined by the length of the rod and size of the float for a given valve size.

Gate Valves have a sliding disc (gate) which reciprocates into and out of the valve port. Gate valves are an ideal isolation valve for high pressure drop and high temperature applications where operation is infrequent. Manual operation is accomplished through a multi turn handwheel gear shaft assembly. Multiturn electric actuators are typically required to automate gate valves, however long stroke pneumatic and electro-hydraulic actuators are also available.

Globe Valves have a conical plug which reciprocates into and out of the valve port. Globe valves are ideal for shutoff as well as throttling service in high pressure drop and high temperature applications. Availablle in globe, angle, and y-pattern designs. Manual operation is accomplished through a multi-turn handwheel assembly. Multiturn electric actuators are typically required to automate globe valves, however linear stroke pneumatic and electro-hydraulic actuators are also available.

Plug Valves are similar to ball valves except instead of a spherical element, a cylindrical element is used as the internal restriction. Plug valves are typically more expensive than ball valves, but they are inherently more rugged as well. The plug is guided by a sleeve which acts as the sealing member. Plug valves require more torque to operate than ball valves, but are easily automated with quarter turn actuators. Plug valves are also available in 3-way and 180º configurations.

Solenoid Valves are simple electrically operated devices. The valve plug is held in place by a spring. When electric power is applied to the solenoid (Energized), the current draw through the coil generates an electromagnetic force which opposes the spring, causing the plug to change position. When power is taken away (De-energized), the spring returns the plug to the normal position. Solenoid valves are ideal for fluid shutoff and switching in general service applications. Proportional solenoid control valves are available for modulating service.

Switching Valves converge and divert fluid flow in a piping system. 3-way valves are typically used because they can do the job of two, 2-way valves. 3-way valves are typically of ball, plug and globe design, however two butterfly valves mounted on a pipe tee and connected via a lever can be more cost effective in large pipe sizes. The port configuration is of prime importance when selecting a 3-way valve. Ports must be specified to meet piping installation and flow switching requirements. 3-way valves are quarter-turn operation and easily automated. 180º turn is also available, but requires special actuation.

Control Valves modulate the fluid flow in a piping system. All the valves listed above can be used for manual and automated flow control with certain limitations. Reciprocating and rotary globe control valves are recommended for automatic process control where precise (<2% accuracy) flow control is required. High performance versions of ball valves and butterfly valves are available, which under acceptable process conditions perform very well. Diaphragm valves, surprisingly enough, have excellent throttling characteristics. In order to automate a valve, it must be able to accept an actuator and control signal.

Proportional solenoid control valves are very economical solutions for general purpose applications. Variable flow is achieved by positioning the armature proportionally to a control signal. Internally, high frequency pulse-width modulation of the coil provides excellent near linear control characteristics. These miniature control valves are typically available in sizes from 1/4" up to 1".

Reciprocating globe valves are the most rugged, and usually the most expensive, particularly in the larger sizes. The torturous path through this type of valve, provides excellent energy conversion of the process fluid resulting in accurate, repeatable control. Severe service noise and cavitation control trims are available in this valve style.

Rotary Globe Valves consist of cammed plug and segmented "V" ball designs. They have similar control characteristics to reciprocating globe valves with the benefit of low friction from rotary motion. Rotary valves inherently have significantly more capacity and turndown than reciprocating globe valves. Their low cost and comparable installed accuracy performance make rotary globe valves preferred in general service applications.

Pressure/Temperature Rating: The process fluid's combined pressure and temperature must be within the manufacturers published rating for a given valve. The given rating will be unique to a given body shell, body and trim material combination, seal material, and end connections. Select a rating that insures these combinations are sufficient to handle the maximum possible process conditions.

Body Materials: Select body and trim materials based on their strength (pressure/temperature rating) and resistance to corrosion and erosion of a given process fluid. Plastic is used on very low pressure systems where corrosion is of primary concern. Brass/bronze is very economical and fairly corrosion resistant. Iron is very cost effective and can be economically coated or lined for compatibility with corrosive fluids. Select carbon steel where strength is needed. Stainless steel has very good strength and corrosion resistance. Other exotic alloys and molys can be supplied where needed.

Seal Materials: Further select elastomeric and plastic seals, liners and diaphragms based on their chemical compatibility to the process fluid. Elastomeric elements (natural and synthetic rubbers) have better sealing characteristics, however plastics (PTFE, PFA, etc.) are typically chosen for harsh chemicals. Refer to chemical resistance guides for proper selection.

End Connections: Valve body end connections are typically chosen based on initial cost, plant standard, and/or maintenance preference. Maintenance consideration is the preferred method of selection. Threaded ends (NPT/screwed) have a low initial cost, but are subject to leak paths and stripping. Use threaded ends where maintenance is not a concern. Welded ends provide for rigid, leak tight connections. They have low initial hardware cost, but high maintenance cost should they need to be cut out of the line for repair or replacement. Flanged ends have the highest initial cost, but are preferred from an installation and removal standpoint. Wafer bodies give the benefits of a flanged installation with very low initial cost. Use wafer bodies only where the pipe is rigid or fully supported. 3-Piece ball valve designs give the benefit of threaded or welded joints with integrally flanged wafer bodies.

Actuator Selection

As mentioned previously, actuators are used to operate valves automatically and/or remotely. Actuators typically use pneumatic, electric and hydraulic power to actuate a valve shaft. The force output of the actuator must be sufficient to overcome valve static friction and dynamic torque. Static friction is developed in the metal-to-metal surfaces, seats, and seals. Dynamic torque is that unbalanced force of the process acting on the plug, disc, or ball. Valve torque requirements are supplied by the manufacturer and based on pressure drop across the valve. A minimum of 10-20% safety factor should be added to insure reliable operation. The on/off actuator positions the valve in the open or closed position. Modulating actuators use controllers/positioners to maintain a valve position based on an input signal.

Pneumatic double acting actuators use gas, typically air or nitrogen to pressurize a double acting cylinder. An unbalance in the opposing cylinder areas drive the connected shaft in the required direction. A 4-way solenoid valve is used to switch pressure between the cylinders. The normal position is the position of the valve with the solenoid de-energized. Available output force is equal to the pressure times the area of the piston (F=PxA). Piston actuators are typically sized for 80 psi minimum. Double acting actuators do not have an inherent fail safe action. If only electrical power is lost, then the valve will go to or remain in its normal position. If pneumatic power is lost, and the friction in the valve and actuator is sufficient to overcome the dynamic unbalance in the valve, then the valve will remain in its last position. If the dynamic unbalance force is greater, then the valve will drift in the dominating direction. Accumulator systems with trip valves are available to provide pneumatic fail safe operation.

Pneumatic spring return actuators are spring opposed pneumatic cylinders. A 3-way solenoid valve is used to operate a spring return actuator. The normal position is the position of the valve with the spring extended and the solenoid de-energized. The available force is the pressure times the area of the piston less the spring force [F=(PxA)-Fs] in one direction and the available spring compression force in the opposite. Spring force is determined by the spring rate (K) times the compression, in inches (F=KxIn) at any given position of stroke. Spring and piston actuators are typically sized for 80 psi minimum. Spring and diaphragm actuators (for Control Valves) should be sized for 35 psi (6-30 psi signal). Spring return actuators are inherently fail safe. Trip valves are available for lock-in-last position fail action.

Electric actuators use a reversing electric motor and gear reduction to drive a valve shaft. A given motor size and gearbox are matched to provide the most effective force output. The output force is measured in inch or foot pounds of torque. Standard voltages are 220-480VAC/3-phase, although single phase and 120VAC options are available. Torque switches are used to position the valve open and closed. The normal position is the position of the valve with the solenoid de-energized. Electric actuators inherently fail in the last position. Battery back up is needed to drive the actuator to a specific fail safe position.

Accessories

Accessories are components within an actuation system. The components are required to operate, override, and support the actuation assembly. Select accessories based on the valve, actuator, and control system requirements.

Solenoid Valves use electromagnetic force to switch pressure ports. A spring holds the valve plug in position (usually closing a port). When electric current is applied to the coil of the solenoid valve, the spring opposed plug opens or switches ports within the valve. Pneumatic pressure is then allowed to load or exhaust the actuator cylinder. 3-way valves are used on spring-return actuators and 4-way valves are used on double acting actuators. Solenoid valves can be normally open (de-energized to load actuator) or normally closed (de-energized to vent actuator). Solenoid valves typically come in aluminum, brass and stainless steel. Select the appropriate coil voltage and area classification.

Limit Switches are activated by cams connected to the actuator shaft. When activated, they send discrete electrical signals to indicate actual valve position, usually confirming that a valve fully opened or closed operated remotely. In addition, these signals can be used as interlocks in a control system. For example, locking out a pump until its supply valve has been opened. Mechanical switches should be housed in an enclosure (Switchpak), which will also provide visual position indication. Proximity (magnetically latching switches) are hermetically sealed which makes them less susceptible to moisture intrusion. Select the appropriate switch type and area classification.

Positioners are used to position a valve based on a control signal. The signal can be pneumatic or electric. The positioner is mechanically attached to the valve stem. It compares the valve position to the input signal and sends the required output to the actuator to bring the valve to the correct position. The positioner can be analog or digital. Analog positioners use mechanical or electromechanical methods to position the valve. Digital (Smart) positioners use microprocessor technology. Smart positioners can operate on digital networks as well as traditional analog signals. They provide 2-way communication with the microprocessor which allows remote configuration and autocalibration, operating information such as actual valve position, and diagnostics information such as cycle count, deviation, friction band, and valve signature. Digital positioners should be used whenever possible.

I/P Transducers are used to convert a current signal to a pneumatic signal. Typically a 4-20mA control signal to an existing 3-15 psi pneumatic positioner. I/P's are very economical and can be used to directly control a valve, however an I/P positioner will usually provide much better performance.

Filter Regulators should be used whenever possible. They are used to filter and regulate the supply pressure for pneumatic instruments. Instruments have small orifices that can become restricted and plugged by dirty air, moisture can corrode and short electrical components, and pneumatic instrument performance is optimum with regulated supply pressures. Set regulators to 5 psi greater than the maximum supply pressure required by the actuator. Solenoid valves with built in timers are ideal for blowing off regulator drain cocks.

Speed Control Valves are used to control the rate at which automated pneumatic valves operate. Metering valves reduce valve speeds by restricting the flow in and/or out of the actuator. Volume boosters increase the actuator loading time and exhaust valves increase the actuator unloading time.

Fail Safe Accumulators are used to provide a fail safe means for double acting pneumatic actuators. This system consists of a volume tank, inline check valve and trip valve. Upon loss of supply pressure the trip valve causes the stored gas to drive the actuator to its fail safe position. Stand alone trip valves can be used to lock a double acting actuator in last position upon loss of supply pressure. Solenoid valves can be added to provide electric override or fail safe action.

Manual Overrides can be used to manually operate a valve in an emergency or to bypass automatic operation. A handwheel gear operator is mounted in between the valve and the actuator. The handwheel operator is engaged by locking the gear. Manual overrides should be considered on critical valve applications and for emergency shutdown valves.Valves comply with BS, ANSI, JIS, DIN& API standards.