External sleeve with cage choke
- External sleeve moving outside of flow cage type trim uses a flow sleeve moving over the ported cage to control flow.
- Metal to metal or tungsten carbide seat design on the outside of the flow sleeve and out of the high-velocity flow area assure a positive shut off and extended seat life.
- The controlling element (flow sleeve) moves in a lower velocity regime and leads to the high erosion resistance of this trim design.
- Applications of these chokes include high-pressure drops and fluids with entrained solids such as formation sands.
- This trim is normally supplied as solid tungsten carbide 4 x 4 geometry gives an equal percentage characteristic.
- 4 diametrically opposite ports will provide the highest wear resistance in a 'cage' type flow trim. 4 small ports in the lower section provide fine control needed at low openings while 4 larger ports provide capacity for higher flows.
- The pressure balancing of the trim design reduces the operating torque.
- Flow is directed through ports into the center of the trim where it impinges on flow from the opposite port.
- Hydro dynamically designed body gallery maximizes flow capacity and minimizes body & outlet erosion.
- Bonnet design available in both options hammer union type and bolted type.
- Dynamic seal (stem packing) with spring energized seals.
- Linear non-rotating stem movement increases stem packing life.
- Position indicator marking in diametrical increments of either 1/32" or 1/64".
- Barrel type indicator is used for small trim sizes and micrometer type indicator is used for large trim sizes.
- Metal to metal shut off in accordance with ANSI class IV & V.
- Cartridge style trim installation uses no internal threads, hence no special tools are required for field maintenance.
4X4 Hole Geometry
Pressure Balance Seal
Stem Lock Assembly