Saturday, February 21, 2015

Shot Blasting Machines

RPS Butter Fly Valves

Sunday, January 11, 2015

Butterfly Valve




with thanks : Jackie Chow

How & Why Are Butterfly Valves Used ?


A Butterfly Valve is used to control the flow of material through a circular pipe or tube. Typically the material is air, gas, steam, or liquid. Certain dry materials may also be handled through a butterfly valve.

Simply, a butterfly valve consists of a circular disc with its pivot axis at right angles to the direction material is flowing. The valve is made up of a body, seat, disc, stem, and actuator. Each component part is available in a variety of materials called “trim features.” Properly combining trim features to address material handled and environment is important in selecting the correct model valve for its intended service.

Body 
A butterfly valve body can be made of cast iron, ductile iron, aluminum, carbon steel, stainless steel and exotic metals. 

Butterfly valves are available in wafer and lug style. Wafer style valves are installed “sandwiched” between pipe flanges. This style of valve is easier to replace or install. However, replacing a wafer valve requires the conveying line to be drained. Once the valve is removed, there is nothing to seal material either upstream or downstream from the removal point.

Lug style valves contain tapped holes that allow them to be bolted directly to a mating flange. In the closed position, the valve independently seals material to the upstream and downstream side. Because of this independent sealing, lug valves may be used to isolate downstream equipment that may require replacement or maintenance.

Seat 
Resilient seated valves are the most commonly used types. The interior of the valve body is lined with an elastomer seat. Seats may be made of EPDM, buna, viton, Teflon, natural rubber, carbox, chlorbutyl, white buna, or white neoprene as well as other materials. Choice of seat material depends on temperatures, pressures and material handled.

The seats of some inexpensive butterfly valves are typically molded into the body and cannot be repaired or replaced. Precision butterfly valves typically contain removable seats that are repairable or replaceable.

Disc 
The valve disc (controlled by the actuator) regulates the flow of material within the conveying line. Disc materials are available to meet a variety of application demands: stainless steel, aluminum/bronze, ductile iron, ductile/epoxy coated, ductile/nickel plated, ductile/nylon II coated as well as others. As the disc is directly in the material flow stream, care must be taken in specifying the proper material of construction and disc shape. Some discs are designed to allow increased flow patterns through the piping.

Stem 
The stem passes through the center of the valve, attaches to the actuator, and positions the disc for material flow control and shut off. Depending on the application and valve size, stems may be one or two-piece construction. Typical materials of construction include carbon steel and different grades of stainless steel.

Actuator 
A variety of actuators are available for butterfly valves: manual handle, gear, pneumatic, electric and electro-hydraulic. Also, actuators that may be enclosed in special housings and buried are available for certain underground applications.

Other considerations 
Depending on the application, additional valve features that may need to be considered. Some of these features include: the manner in which the stem and disc are attached, the way the stem and disc assembly mount inside the valve body, undercutting of disc, type of material used in stem bushings and packing, and availability of a ring seal between the seat and valve body.

Working with a company that can offer and properly apply a variety of trim features will enhance the success of the butterfly valve in a specific application.

Applications

As stated earlier, Butterfly Valves are generally specified for most air, gas, steam, and liquid applications. They offer an excellent, economically priced, positive shut-off valve for handling materials (e.g. gases and liquids) that are easily displaced by the valve disc as it closes. When handling this type of material, butterfly valves provide a reliable, bubble-tight, bi-directional shut off.

Care must be taken when applying a butterfly valve in semi-abrasive or abrasive dry material applications (this includes slurry applications that contain suspended particles because: 
1) A valve disc closing on dry bulk material will create premature wear to the rubber seat. 

2) The obstructed orifice created by the disc may cause bridging of material on the inlet side of the valve. 

3) A disc opening or closing on a standing column of dry material may cause the material to jam / pack. 

4) Particles of dry material or suspended particles in slurries may become trapped between the disc and seat, causing conveying line inefficiencies.

Other Types of Butterfly Valves

As a person becomes familiar with butterfly valves, they will undoubtedly discover other types of butterfly valves on the market. Listed below is a brief introduction to some of these other types.

Inflatable Seated Butterfly Valves
Inflatable seated butterfly valves utilize an inflatable seat or bladder to create a seal around the disc. Once the disc is brought to the closed position, the bladder is inflated pneumatically.

Pros: 
1) Since the seal is created after the disc closes, less torque is required to move the disc into the closed position. A smaller sized actuator costing less money is can be used.

2) Again, because the seal is created after the disc closes, minimal abrasion exists between the disc and the seat.

Cons: 
1) In addition to the controls needed to verify the position of the disc, additional controls are needed to identify whether the bladder is inflated or not. These controls add cost to the valve.

2) The bladder may be damaged and not creating a seal, even though controls identify that a seal has been established.

3) The valve must be located near an air supply to pneumatically inflate the bladder. 

4) The inflatable bladder is subject to damage and abrasion, requiring periodic replacement.

High Performance -- Double Offset Butterfly Valve
This type of butterfly valve is ideal for applications involving higher temperatures (up to 1200º F) and higher pressures (up to 1440 psig). The disc and stem are double offset, causing the disc to “cam” into place upon closure.

Pros:
1) A reliable butterfly valve for handling higher temperature and pressure applications.

Cons:
1) Cost -- considerably more expensive than standard butterfly valves.


High Performance -- Triple Offset Butterfly Valve
This type of butterfly valve is often used in refinery and off shore applications where more extreme conditions exist. Most triple offsets utilize a metal on metal seat and disc closure, are rated up to 600# class, and are fire safe.

Pros:
1) A reliable valve for extreme applications.

Cons:
1) Cost -- more expensive than the double-offset butterfly valve.


The double and triple offset butterfly valves are specialized valves for extreme applications.

Salina Vortex Corporation manufacturers a variety of slide gates, diverter valves and iris valves for handling dry bulk material. Vortex butterfly valves are available for air, steam, liquid and certain dry material applications. 

For additional information, please visit:

with thanks : LINK

Wednesday, December 24, 2014

Robotic Finishing Machine Blasts Shot or Grit

Guyson Corp. has introduced a new version of its RB-RSSA-8 robotic blast system and has customized it according to the special requirements for cleaning and surface preparation of machined aerospace castings using either shot or grit media.
The new variant of the long-established model has a Fanuc Robotics LR Mate-200iD 6-axis robot mounted on the reinforced back wall of the blast chamber, a position that allows greater reach and motion capability to accommodate the range of components to be processed by the customer. In previous versions, a larger robot is mounted on a pedestal or hung from the roof of the cabinet.
A 24-inch diameter turntable is adapted to accept the component-holding fixtures for all parts to be blasted and is servomotor-driven, so the radial orientation of the component is coordinated as a seventh axis by the robot’s R-30iB controller. A jib crane mounted on the roof of the blast enclosure and a rubber-flapped crane slot facilitate loading of heavy parts onto the table, which is designed with a weight capacity of 250 pounds.

with thanks : pfonline : LINK : for detailed news report.

Dry Ice Blast Cleaning Machines

THE DRY ICE BLASTER TECHNOLOGY
 How it works
The dry ice blasting uses small pellets of dry ice sprayed through a jet nozzle with compressed air to remove paints, oil, grease, dirt,ink, adhesives and other materials you want to remove. The frigid temperature of the dry ice against the dirty surface causes adhesion to shrink and loosen from the surface. On immediate impact, the dry ice evaporates into environmentally safe and innocuous CO2 gas.
The kinetic energy ( E = ½ mv 2)
The energy associated to the mass and to the speed is transferred to the surface to be cleaned / coating removal. This is the fundamental way to work either with this dry ice method or with sand / water etc.
Thermal differential
When the dry ice pellets cold touch the surface, a small thermic difference occurs between the coating material, the contaminant and the substrate. This provokes cracks and the detaching facilitating the removal process.
Micro – Explosion
When the dry ice touches the surface and it transforms into innocuous CO2 gas, , this tends to invade the cracks and the pores penetrating into the coating / contaminant.Then it warms up and it expands rapidly and it makes the coating / contaminant detaching from the substrate, favouring still further the coating removal or the cleaning process.
Sublimation
With an inferior pressure at 5.2 bar, the solid CO2 transforms directly in gaseous state without turning into the Liquid state. But if the blasting pressure is superior at 5.2 bar ( 5.2 x 14.7 = 76.44 psi ),the CO2 in the sublimation state will show some characteristics of the Liquid CO2 while the same reaches its "triple point". Has been proved that the Liquid CO2 is a strong organic solvent so it is reasonable to suppose that this solvent action can be present when the blasting pressure is superior at 5.2 bar.






Detailed information can be viewed at :