Tuesday, August 28, 2018

What Are Cryogenic Ball Valves?

Cryogenic Ball Valve
Cryogenic Ball Valve (Flowserve Worcester)
Cryogenic ball valves are high-performance shutoff valves for intermittent and continuous flow applications with temperatures to -425°F. They are used on tough applications involving all types of cryogens, such as oxygen, hydrogen, methane, ammonia, nitrogen, fluorine, LNG and deuterium.

Cryogenic ball valves include unique features to ensure safety and performance in cryogenic applications. Central to the cryogenic design is a rugged, one-piece, pressure safe stem with a Polyfill thrust bearing and stainless steel split ring. It provides design safety and low operational torque. Polyfill seats give you tight shutoff throughout the temperature range. With an orientation-controlled stem/ball connection and an upstream hole in the ball, you get positive overpressure protection.

Summary of specialized design features:
Brass Cryogenic Ball Valve
Brass Cryogenic Ball Valve
(Flowserve Worcester)
  • Positive Ball Cavity Relief – An upstream relief hole in the ball prevents dangerous overpressure due to thermal expansion. On extended stem valves through 2", a one-piece stem with alignment pin assures proper orientation of the ball.
  • Pressure Safe Stem – Both one-piece and two-piece, assembled inside-the-body stems are safe from blowout and are supported with Polyfill® thrust washers.
  • Zero Leak Packing – Belleville live-loaded TFE packing rings and stem centering followers assure zero leakage through the toughest, high-cycle applications.
  • Effective Bonnet Extensions – The stem extensions of cryogenic valves conform to standard industrial practices. That means wall thickness and lengths that keep heat transfer down, the packing frost-free, operational torques low, and actuators solidly supported.
  • High-Performance/Low-Thermal Stress – The special “part compatibility” design of valve parts, Polyfill seats and body seals assure tight shutoff, zero body leakage and low torque through large thermal excursions from ambient to -425°F.
Cryogenic valves are normally available in four body configuration, in either stainless steel or brass:
  1. Three-piece construction - makes it easy to install, versatile in application and simple to maintain.
  2. The cryogenic diverter valve - accepts media through the bottom inlet port and directs it to one of two side ports.
  3. The wafer design - a flangeless cryogenic valve that mounts between ANSI Class 150 or 300 flanges.
  4. A flanged design - has a body cast with ANSI Class 150 flanges.
Application for cryogenic ball valves:
  • Over-the-Road LNG-LPG Trailers
  • Terminal Unloading Stations
  • High-Purity Cryogenic/Gas Systems
  • LNG Storage and Distribution
  • CO2 and Nitrogen Injection for Enhanced Oil Recovery
  • Over-the-Road CO2, LNG, Food Carriers
  • Petroleum Refining Unleaded Gasoline (Gas Treatment Skids)
  • Lyophilization Systems
  • Air Separation Plants
  • Liquid and Gaseous Oxygen
  • Inerting and Heat Treatment
For more information on cryogenic ball valves, contact Swanson Flo by visiting https://swansonflo.com or by calling 800-288-7926.

Sunday, August 19, 2018

What Are Valve Positioners?

Digital Positioner
Digital Positioner (Valtek)
A valve positioner is used in combination with a valve actuator to precisely position a valve so that optimum flow accuracy may be achieved. The positioner does this by measuring a the process variable, comparing it to a desired condition (set point) and then pneumatically, electrically, or hydraulically changing the valve disc, globe, plug or ball position until the difference between the set point and actual position is zero.

Valve positioners are key elements in a closed loop control system where the final control element is a valve. They assist in maintaining tight control, overcoming the realities of imprecise calibration, differential pressure across the valve, valve wear and a host of other process control challenges.

A valve positioner responds to a signal from some type of master control system, typically a distributed control system (DCS), a programmable logic controller (PLC), or PID controller. The control system reads a signal from a process sensor (flowmeter, temperature sensor, pressure sensor, etc...) and compares that reading to the desired setpoint. A corrective signal, based on the difference,  is provided to the valve positioner which re-adjusts (if necessary) the valve position to bring the system in to equilibrium.

Valve positioners are available with pneumatic, electrical, electro-pneumatic, and digital operation. Here is a brief description of each:

Pneumatic
Pneumatic Positioner
Pneumatic Positioner (Valtek)
Pneumatic positioners receive pneumatic signals (3-15 or 6-30 PSIG). The positioner then throttles supply air to the valve actuator to move the valve to the required position. Pneumatic positioners are intrinsically safe and can provide a large amount of force to close a valve.

Electric
Electric valve positioners receive an electric signal, usually 4-20 mA, 1-5 VDC, 2-10 VCD or 0-10 VDC and generally drive the motors in electric actuators. They perform the same function as pneumatic positioners do, but use electricity instead of air pressure as an input signal.

Electro-Pneumatic
Electro-pneumatic Positioner
(PMV)
Electro-pneumatic valve positioners contain internal I/P (current to pneumatic) modules that converts the electrical input signal to a pneumatic output (4-20 mA to 3-15 PSIG for instance). Very similar to a pneumatic positioner except that its input is electrical.

Valve positioners are used throughout the process industries including power, pharmaceutical, chemicals, oil and gas, food and beverage, pulp and paper, refining and petrochemicals, pipelines, and many other processes.

For more information on valve positioners, contact Swanson Flo by visiting https://swansonflo.com or by calling 800-288-7926.

Thursday, August 9, 2018

Properties of Fluids: The Basics


This video introduces the viewer to basic fluid properties such as viscosity, viscosity index, compressibility, cleanliness, filtration and additives. These basics apply throughout process control, from flow instrumentation to valve automation.

Founded in 1960, Swanson Flo has long maintained our position as an industry leader in process automation with unmatched project success leveraging industry preferred products and services.

https://swansonflow.com
800-288-792