1. Parker Abex – Jet Pipe Servos Electrohydraulic Servovalves
Nuclear, Steam and Gas Power Plant Applications
Unique Jet Pipe® First Stage Design

2. Presentation Abstract
Pedigree – Parker Non-Incendive Jetpipe Electro-Hydraulic Servovalve Design
Hydraulic Design Features & “Varnishing”
Special note on A160 varnishing
Performance of Jetpipe Design Versus Flapper Style Servovalves
“Intrinsically Safe” vs “Non-Incendive” Designs
Open Questions

3. Presentation Abstract (cont.)
Goal is 20 minutes ppt, 25 minutes questions/open discussion
Single task is to show how Jetpipe Servo design is more robust/fail resistant in harsh oil environments (i.e. A160 lube skid)
Presenter is Sr. Engineer at Electro Hydraulic Servovalve Division
Asst. will be handy to help with more specific 7FA related questions
Following Slides Give a Flavor of ppt

4. Servo Controls Division
Uniquely positioned for the powergen market
Over 40 years as a supplier to the Power Gen Market
EHSV’s specified on over 40 GE drawings
Unique Jet-Pipe® construction
5-70 GPM
1, 2 or 3 coil models available
Factory Mutual Approved Intrinsically Safe Models by 2Q ‘04
Complete R & O facilities-to OE requirements
Single sourcing within Parker enables access to over 500,000 parts

5. SERVO CONTROLS DIVISION JET-PIPE OPERATION
Figure 1 — Servovalve at null
High pressure filtered fluid flows to the flexible feed pipe attached at the base of the torque motor, to the top of the jet pipe, and out the projector jet.
Fluid from the projector jet impinges upon the receiver. Two small orifices are connected hydraulically to the ends of the second-stage spool.
With the servovalve at null, the projector jet is centered over the
receiver holes and equal pressures are developed at each end
of the spool.

6. SERVO CONTROLS DIVISION JET-PIPE OPERATION
Figure 2 — Actuation
Input current is applied to the torque motor. A magnetic torque is produced causing the armature and the attached jet pipe with projector jet to rotate through a very small angle. The polarity will cause the jet pipe to move left or right..
The projector jet movement causes differential pressure across the second-stage spool causing movement. As t he spool moves, the feedback spring pulls the jet pipe back against the magnetic torque toward the center of the receiver.
When the feedback spring force is equal to the magnetic force, the projector jet will again be centered over the receiver generating equal pressure at each end of the spool, and spool movement stops at the new position.
Fluid will now flow from the second stage pressure port to the cylinder port C2, through the actuator, and back through cylinder port C1 to return.
A reversal of the input current results in an opposite motion of the spool, changing
the direction of the flow to the actuator.

7. SERVO CONTROLS DIVISION JET-PIPE SERVO VALVES
Excellent contamination resistance.
Jet-Pipe allows larger particulate passage than nozzles. Additionally, high spool-driving forces and long power-stage strokes help our Jet-Pipe servovalves deliver premium contamination resistance – the highest in the industry.
 The reliability leader.
Rugged servovalve design and construction combine with excellent contamination resistance to make Parker’s Jet-Pipe servovalve the industry leader in performance and reliability.
Low life-cycle costs.
High reliability minimizes servovalve and actuator maintenance, significantly reducing life-cycle costs