Educational information on process control, industrial instrumentation, valves, valve automation and control valves. For additional information visit IvesEquipment.com or call 877-768-1600
Cavitation can occur in control valves handling fluids, causing loud noise as well as damaging valve components and ultimately leading to additional costs in process plants. A standardized procedure to evaluate the destructiveness of cavitation-induced still does not exist whereas noise emission can reliably be predicted with the international EN 60534-8-4 standard. This white paper, courtesy of Samson Controls, describes a method to solve this problem by evaluating structure-borne noise in the ultrasonic range. DOWNLOAD THE WHITE PAPER HERE
For more information on the application of control valves, contact Ives Equipment. Call (877) 768-1600 or visit https://ivesequipment.com.
The Samson 82.7 double eccentric rotary plug control valve is designed for standard and critical service applications, including process events such as erosion, abrasion, corrosion, cavitation, and flashing. The double eccentric rotary plug design increases flow capacities with only minor reduction in the pressure recovery factor making the design an ideal replacement for linear globe control designs even with cavitation and flashing process conditions present.
The 82.7 control valve has several standard options such as temperature extensions, heating jacket, special packing designs, noise attenuation and cavitation prevention trim sets, etc. The Vetec 82.7 can be assembled with a pneumatic, electric, hydraulic, or electro-hydraulic actuator also offered by the SAMSON group to complete the control valve construction. These control valves are designed according to the modular assembly principle, can be equipped with SAMSON GROUP actuators and valve accessories such as positioners, limit switches, and solenoid valves.
WARNING: Actuators with preloaded springs are under tension. They can be identified by three long bolts protruding from the bottom of the actuator. These should be removed last, and installed first upon re-assembly.
With the actuator removed from the valve, unscrew the nuts and bolts on the diaphragm case.
Lift off the top diaphragm case.
Remove the diaphragm plate assembly consisting of the diaphragm plate, diaphragm, and actuator stem from the actuator case.
Remove the springs.
Clamp the bottom section of the actuator stem into a vise using protective jaws, ensuring the actuator stem is not damaged.
Remove the collar nut.
Remove the diaphragm plate from the actuator stem, flip upside-down and place them back onto the actuator stem.
Re-install the collar nut.
If necessary, apply a suitable lubricant to the actuator stem.
Install the diaphragm plate assembly together with the actuator stem pointing downward into the bottom diaphragm case.
Place the springs onto the diaphragm plate, centering them in the intended recesses. The final actuator spring range will determine the appropriate springs to be installed.
Place the top of the actuator case onto the assembly. Ensure that the air connections on the cases are correctly aligned with each other.
Fasten the top and bottom diaphragm cases together using the nuts and bolts. Observe tightening torques.
ABOUT THE SAMSON 3271/3277
The Type 3271 pneumatic rolling diaphragm actuator is designed for all industrial applications. This actuator is a linear motion device ideal for valve sizes ranging from the micro-flow valves to large 20"+ globe control valves.
The Type 3277 pneumatic rolling diaphragm actuator with an integrated accessory attachment area is designed for all industrial applications. This actuator is a linear motion device ideal for valve sizes ranging from the micro-flow valves to 4" globe control valves.
The thrust force of the actuator depends on the actuator area, pneumatic supply pressure, spring stiffness, distance traveled, initial compression of the spring, the number of springs internal to the actuator, etc.
The Type 3271 and Type 3277 Pneumatic Actuators contain a rolling diaphragm and internal springs and have the following special features:
Low overall height
Powerful thrust at high stroking speed
Low friction
Various bench ranges by varying the number of springs or
their compression
No special tools required to change the bench range or to
reverse the direction of action (also version with handwheel)
Permissible operating temperatures from –60 to +120 °C
Samson Controls, located in Baytown, TX, manufactures high-performance, industrial control valves designed to withstand the toughest applications.
Samson 3291
Samson 3291
The Samson 3291 control valve was specifically developed for heavy duty applications in the oil and gas industry. The construction is based on the proven SAMSON valve design, with one significant difference: while the seats in SAMSON valves are normally screwed in place, the 3291 has the seat held in place by a cage retainer. Unlike typical cage guided control valves, the 3291 control valve utilizes a top and seat guided design by means of a V-port plug. This open flow-path design minimizes friction and allows for the passage of small particulates without clogging the valve or getting “trapped” between the piston and cage. To download the Samson 3291 Control Valve brochure visit this page.
The Samson 3291 Special Length Version is a direct replacement for legacy split body valves without the need for spool pieces, piping modifications, or on-site modifications.
Samson 3522 "Little Tex"
Samson 3522 "Little Tex"
The Type 3522 threaded seat control valve is designed for standard process engineering applications with high industrial requirements for control and quality. This control valve offers a wide range of trim sets to meet required flow coefficient and sealing methods as would be found in general application type control valves. The Type 3522 can be assembled with a pneumatic, electric, hydraulic, or electro-hydraulic actuator also offered by the SAMSON group to complete the control valve construction. To download the Samson 3522 Control Valve brochure visit this page.
Control valve actuators control fluid in a pipe by varying the orifice size through which the fluid flows. Control valves contain two major components, the valve body and the valve actuator. The valve body provides the fluid connections and immovable restrictor comprised a valve stem and plug that is in contact with the fluid that varies the flow.
The valve actuator is the component that physically moves the restrictor to vary the fluid flow. Three actuator types are used in control valves and they include spring and diaphragm, solenoid, and motor. As the name suggests the spring in diaphragm actuator uses a spring and a diaphragm to move the valve stem and plug.
A 15 PSI pneumatic signal enters the housing at the top of the actuator. As pressure is exerted on the diaphragm a downward force is applied against the spring which moves the restrictor. The diaphragm moves until it creates an equal but opposing force against the spring at which time the motion stops as the plug meets the valve seat. With no air pressure the restrictor is pushed upward by the spring to act as a normally open control valve. To vary the position of the restrictor and flow through the valve, a current to pressure transducer can be used to provide a three to 15 PSI signal to the diaphragm. At 3 PSI the valve is maintained open, and 15 PSI the valve is maintained closed. Pressures between the three to 15 PSI range proportionally change the flow of the valve. For example a pressure of 9 PSI applied to the diaphragm moves the spring and valve stem to 50 percent operating range.
For on /off control of the valve, a solenoid is used to actuate the valve to a fully closed or fully open position. Applying current to the coil generates a magnetic field that moves the plunger downward against the return spring. With zero current applied to the coil the spring pulls the plunger upwards to the fully open position for a normally open state control valve.
Another method for variable valve positioning uses a motor and is referred to as proportional control mode. Using a gear motor attached to the valve stem a servo amplifier provides a DC control signal that moves the valve to the desired position. Feedback is achieved with the wiper arm attached to the valve stem that sends a signal back to the servo amplifier where the position is monitored the servo amplifier drives the motor until the control signal is equal to the feedback signal.
Watch the video below for an illustrated explanation. For more information on control valves, contact Ives Equipment at 877-768-1600 or visit http://www.ivesequipment.com.
The Samson 3277 is a pneumatic linear actuator suitable for attachment to Samson Series 240, 250, 280 and 290 control valves, as well as the type 3510 Micro-flow valves. Designed with a rolling diaphragm and internal springs, the Samson 3277 is popular because of its low overall height, fast response, low friction, and its ease to maintain. Attaching the actuator, or replacing one, can be done in minutes, without the need of special tools.
This video provide step-by-step instruction on how to install the 3277 actuator.
Cavitation can occur in control valves handling fluids, causing loud noise as well as damaging valve components and ultimately leading to additional costs in process plants. A standardized procedure to evaluate the destructiveness of cavitation-induced still does not exist whereas noise emission can reliably be predicted with the international EN 60534-8-4 standard. This white paper, courtesy of Samson Controls, describes a method to solve this problem by evaluating structure-borne noise in the ultrasonic range.
