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Water Jet Pumps Water Jet Pump Maintenance Series – Part 2: Bleed Down Valve Repair

For as long as we’ve been around, Jet Edge has been dedicated to educating end-users of water jet cutting systems regardless of what equipment they’re using. Part of that commitment is a dedication to helping our end-users maintain their equipment. The high-pressure pump is at the heart of your system and it’s critical to the high-performance and longevity of that system that it is serviced in regular intervals.

In part 2 of our water jet pump maintenance series, we’ll be discussing the repair and/or maintenance of the bleed down valve in your pump.


Check out the full video guide to maintaining and/or repairing your bleed down valve by clicking the video below:




What is a Bleed Down Valve?

A bleed down valve is a safety device built into your high-pressure water jet pump. It is designed to relieve any ultra-high-pressure water from the system during shutdown or emergency shut down situations.

The valve consists of a solenoid and coil, hydraulic body, valve body with needle and seat components, diffuser, and drain line. Take a look at the diagram on this page to get a good idea of the different parts.


Water jet pump bleed down valve diagram, Jet Edge Waterjets


How Do I Know When My Bleed Down Valve Needs to be Repaired and/or Replaced?

There are a few signs that a bleed down valve is failing and needs to be repaired and or completely replaced. They include:

  1. If the pump is unable to maintain constant high-pressure during operation/cutting, the bleed down valve should be immediately inspected.
  2. If the intensifier is shifting after the tool is closed, the bleed down valve should be examined.


It’s important to service your bleed down valve immediately upon any of the symptoms listed above. When a bleed down valve is failing, specifically when the needle seat connections are leaking, heat can build up in the system. This heat can build up to the point where it can damage the various components in your system.


The Bleed Down Valve Repair Process

You’ll need a few tools and parts to complete this repair. Here is the list of those parts/tools and their corresponding part #’s in the Jet Edge catalog:

  • On/Off Repair Kit – Part number 104497. This includes the needle, seat, bearing, and seal needed to replace the bleed down valve
  • Seal Tool – Part number 36873
  • High Pressure Grease – Part number 110567
  • Precision Lube – Part number 25750
tool kit-web


Repairing Your Bleed Down Valve

  1. Start by breaking loose the four cap screws holding the valve mount ring
    • loosen cap screws-web
  2. Disconnect the inlet water connection
    • inlet water disconnect-web
  3. Unthread the four cap screws that attach the valve mount ring to the piston housing
    • loosen cap screws-web-1
  4. Remove the valve body assembly
  5. Inspect the hydraulic piston seal, if deteriorated, replace it
    • inspect piston seal-web
  6. Put the seal backup in vice, remove the adapter nut from the valve body – use two wrenches, one on the flats of the adapter nut, one on the flats valve body to loosen the connection
    • vice and remove-web
  7. While in the vice, unthread the valve body from the seal backup screw, this also releases the valve mount ring
    • unthread valve body-web
  8. Insert the small end of the seal tool into the outlet end of the valve body, and press the entire needle, needle bearing, and seal out of the valve body. Note that some effort is needed to get the components out of the valve body
    • insert seal tool-web
  9. Inspect the components carefully for wear. When inspecting the valve body, pay close attention to the bore, sealing cone angle, and the seat contact points
  10. Slide the seal on the needle, notice the orientation of the O-ring on the seal
    • o-ring orientation-web
  11. Apply high pressure lubricant to the seal
  12. Slide the needle through the needle bearing. Be sure to note the needle bearing orientation
    • needle bearing-web
  13. Press the seal down, until it contacts the wide diameter end of the needle bearing
    • seal into valve-web
  14. Insert the assembly into the valve body, use the flat end of the seal tool to press the assembly into the valve body, until it is fully seated
    • use tool to secure-web
  15. Note the entire housing assembly:
    • housing reassembly-web
  16. Install collar around the valve body and tighten the connection. Note that the components use locking features to ensure the cone fits into the valve body correctly. TIP: Always use precision lube on stainless steel threads and mating surfaces
    • insert valve body-web
  17. Apply precision lube to the threads of the seal backup screw
  18. Assemble the seal backup screw into the valve mount ring
    • reassembly 1-web
  19. Thread the seal backup screw and mount ring into the valve body, and tighten securely
    • reassembly 2-web
  20. Apply precision lube to the threads of the four cap screws and use them to mount the valve assembly to the piston housing – DO NOT tighten yet
    • assembly to piston housing-web
  21. Ensure the inlet water connection is aligned with the ultra-high-pressure water line, connect the inlet water line
    • reattach inlet water-web
  22. Place the seat on the adapter nut, with the counter sunk cavity facing the adapter nut, and thread it onto the adapter body
    • seat on adapter nut-web
  23. Tighten the four cap screws, this also locks the inlet water connection in place. Ensure the valve mount ring has an even gap to the piston housing
    • tighten cap screws-web
  24. Use two wrenches, one on the flats of the adapter nut and one on the flats of the valve body, to tighten the connection
    • tighten valve body-web
  25. Use two wrenches to tighten the quarter inch high pressure line to the 3/8ths inch adapter
    • tighten high pressure line-web


You have successfully completed the repair to your bleed down valve.


The Benefits of Maintaining Your Water Jet Pump

Just like all parts in your system, maintaining the bleed down valve will ensure consistent operation of your pump. A failing bleed down valve can cause your pump to fail to keep consistent pressure, resulting in a poorer performing pump during cuts – something that can significantly impact the quality of your cuts. A failing bleed down valve can also cause an unwanted buildup of heat in your system damaging key components and possibly taking your system offline creating costly downtime.




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