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Process Control Valves, Actuators & PositionersExample of sliding gate

National Utilities valve line of products is impressive.  Valve is our middle name!  Our extensive offering includes gate, check, ball, butterfly, globe, and sliding gate valves in Stainless Steel, Bronze, Cast Iron, Carbon Steel, and exotic materials.  Medias include steam, liquids or gas.  If you have to do it manually, control it, or have the valve control it’s self, National Utilities can offer the product that best fits your application.


Valve Basics:

Valves come in many styles and which one to choose depends on many factors.  Before a discussion of what valve type to choose, one item to cover is the valve function; manual, automated, or control.  National Utilities can help you in determining the right valve for your application.  This is for informational use only and only scratches the surface on applications, style, design, etc.

Manual valves are as the name implies, manual in operation.  You must manually turn the valve to change the flow.  Automated valves we will refer to as on/off.  Automated valves come in two main types; pneumatic and electric.  Pneumatic valves have an actuator, and when an air supply is sent to the actuator it rotates the valve to the open or closed position.  Electric actuators work under the same principle where the voltage signal (AC or DC) current is supplied to the actuator and it rotates until fully open or closed.  Pneumatic actuators are the quickest and come in normally open (N.O.), normally closed (N.C.) also called the fail function, or double acting (D.A.).  Upon loss of power, the actuator will return to its open or closed position by the use of springs.  Electric actuators usually don’t fail in any position.  They fail in the position they are, which could be in mid travel between open or closed.  Electric actuators are available in N.C. but are expensive.  They either use a coiled spring to force the valve closed or a battery backup.  Control valves are used to control the amount of flow through the valve other than just full open.  Control valves usually require positioners to aid in the control for an accurate flow rate.  The control signal can be several types but the most common are 4-20 mA or 3-15 PSI.  Positioners come in many styles and shapes.  The valve usually has a control cone to aid in the volume of the fluid going through the valve body making it more linear.  There is a difference between control valves and regulating valves and should be used in their respective application.  Call us at National Utilities 414.358.4400 for help with your application.

The types of valves in alphabetical order.

Ball Valve.  Used for manual, automated, or control.  Low cost, ¼ turn, no to low pressure drop depending on full or reduced port, easily repairable.  Available in NPT, weld ends, Tri-Clamp, and flanged.  A very versatile valve.  A ‘ball’ in the valve body rotates ¼ turn as the main function.  Many types of seats available as well as body material of construction.  Tight shut off.  Can be used in many applications with the right seat and body material.

There are a number of common types of ball valve styles; single body, 2-piece, 3-piece, split body, top entry, and welded.  They also go by other names.  The correct style choice can depend on the application as there are advantages to each style.

Ball valves come in 2-way, 3-way, and 4-way designs where most other valves are 2-way only.  3 and 4-way also called multi-port.

National Utilities offers Triac (AT Controls), Bi-Torq,  Bonomi, Boshart, Crane, FloTite,  Gemini, Habonim, J&M International (Jamflow), KTM, Matco-Norca, Sharpe, Tru-Flo, Warren.

Butterfly Valve.  Typically manual or automated, low cost, ¼ turn, low pressure drop, almost full port, usually flanged, repairable.  Principle operation is ¼ turn rotating disc.  There are two types lug and wafer.  Lug has locator holes that the bolts used in ANSI flanges go through the valve body aligning the valve in the pipe opening.  Wafer is slightly less cost but no locator holes and the valve is compressed between companion flanges to stay in place.  There are three main styles of butterfly valves; resilient seat with a flexible rubber seat for around 150 PSIG, high performance or double offset for around 500 PSIG, and TriCentric or triple offset for higher pressures.  The last two are also referred to as high performance and many times come with metal seats.

National Utilities offers ABZ, Center Line, Crane, Keystone, Matco-Norca.

Check Valve.  Used to allow flow in one direction while blocking flow in the reverse direction.  Available connections are NPT, flanged, weld, Tri-Clamp, others.  Common styles are swing checks, diaphragm, ball, and spring checks.  Swing checks are least expensive.  Spring checks, also called silent checks, help stop water hammer.

National Utilities offers DFT (Durabla), J&M International, Mueller, Lumaco, Warren.

Diaphragm Valve.  Typically manual or automated, multi turn, high pressure drop, reduced full port, many port connections, easily repairable.  Principle operation is a diaphragm that raises to allow flow.

National Utilities offers FluoroSeal, Schubert & Salzer.

Gate Valve.  Typically manual, multi turn, low pressure drop, full port, typically flanged, not easily repaired.  Principle operation is multi-turn and wedge/gate slides up and down.  Not a very good control valve unless it is a sliding gate design.  A sliding gate design is a very good control valve and works excellent is steam.  Used in larger sizes and slurries with particulates.

National Utilities offers Crane, Hancock, J&M International, Matco-Norca, Warren.

Globe Valve.  Manual or automated, multi turn, higher pressure drop, reduced port, usually flanged or NPT, not easily repaired.  Good for control as well as on/off.  The body has an ‘S’ pattern and the plug is tapered for control.

National Utilities offers Crane, Hancock, InterValve, Matco-Norca, Powers, Schubert & Salzer, Trerice, Warren.

Needle Valve. Manual, multi turn, extremely high pressure drop, typically NPT, not repairable.  Used for fine control applications with low flow.  Principle operation is tapered stem rising inside valve body to allow fine control of media.

National Utilities offers J&M, Marsh.

Plug Valve.  Manual, automated or control, 1/4 turn, usually flanged, full or reduced port, available in multi port designs.  Usually economical.  Available with lined bodies.

National Utilities offers FluoroSeal.

Solenoid Valve.  Automated, fast acting, usually electric and reduced port.  Electricity is sent to a valve coil where magnetic current pulls a stem up opening the valve.  Cost effective in smaller sizes.

National Utilities offers Asco, Allen Air, Gould, Granzow, Jefferson, Magnatrol, Mead-MFD, Spartan, Rexroth.