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Instruction Manual
D104485X012
4. Check the position of the turning fork. If the mark on top of the turning fork is opposite the inlet flange, the valve is
in the closed position. (See figure 3.)
5. Screw the bolts of the internal wrench tool into the thread holes of the body-protecting bush. (See figure 4.)
6. The complete trim can be removed out of the body by turning down the nuts of the internal wrench tool.
7. Disassemble the internals by removing the locking wire, and lift the protection bush from the bean.
8. Examine the internals for foreign material that may affect the operation of the choke.
9. Inspect the front disk and bean. The surface where the orifice is located should be smooth and free of any damage.
If there is any visible damage, then the parts need to be replaced.
10. Clean the inside of the body very carefully. Special attention has to be given to places where soft seals are situated.
Clean the sealing surfaces and inspect them for corrosion, pitting or scratches. After inspection, lightly grease the
sealing faces (universal grease).
CAUTION
If a 'spring-energized seal' is used, use only a PTFE spray lubricant on the spring energized seal sealing face.
Assembly
1. Put one drop of light oil on the seating surface, and place the front disk on the bean.
2. Put the turning fork on the front disk, and ensure the mark on top of the turning fork is in the same position as the
orifice in the front disk.
3. Install the scraper over the turning fork. Lightly grease it with an anti-seize lubricant.
4. Place the guide-strip of the internal and the scraper around the front disk. Mount the protecting bush. The
protecting bush inlet hole should point to the same direction as the orifice of the bean. (See figure 3.)
5. Replace the locking-wire.
6. Using the turning fork, turn the orifice of the front disk and bean to a fully open position for valves with a
spring-to-open actuator. For an actuator with a spring-to-close action, the orifice has to be put in a position of 180
degrees (90 degrees for NPS 1 choke valves) from the fully open position.
7. Mount the new seal around the bean.
8. Grease (universal grease) the seal slightly and insert the complete internal in the body.
CAUTION
If a 'spring-energized seal' is used, use only a PTFE spray lubricant on the spring energized seal sealing face.
9. Recheck the position of the turning fork and put spring in position.
10. Place the bonnet and the actuator on the body. Be sure that the adjusting pin is placed in the hole of the protecting
bush.
11. Grease the stud bolts with anti-seize lubricant and tighten the nuts crosswise. See Retightening of Nuts Body
Bonnet Connection in this manual for more information.
12. Connect the air tubing.
13. After assembling the choke valve, perform a functional test to check whether the valve functions properly.
Vonk Choke Valves
September 2019
7
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