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4.3 ASSEMBLY OF FIRST STAGE
1. The part number for each regulator kit can be found in Sherwood’s Tools, Repair Kit and
Accessories – Assembly & Maintenance Guide. The kits contain the parts that are always
replaced at every annual service interval. The kit number for the regulators covered in this
manual is 4000-15.
2. Before installing new O-rings on the piston and moving orifice, lubricate the O-rings with LTI
Christo-Lube. Installation of the small O-ring on the piston is made much easier by using
the white-colored Sherwood O-ring installation cone (p/n TL109). Place the cone over the tip of
the piston. Slide the lubricated O-ring over the cone until it slips into the piston groove.
3. Place the new piston seat on a clean piece of paper on a hard flat surface. Press the piston tip
firmly over the seat until it is fully installed. The piston is now rebuilt and ready for installation.
4. Use the Sherwood installation cone to prevent damage to the new O-ring during installation
onto the moving orifice. Use the green O-ring installation cone (p/n 28-TL107) to install first the
new O-ring and then the used backup washer onto the groove on the moving orifice.
Position them so that the black O-ring is closest to the wide end of the moving orifice.
5. Using a greased soft probe,
lightly lubricate the first 1/8" of the small bore in the body
where the small piston and moving orifice O-rings seal.
6. With your finger, push the moving orifice assembly, pointed orifice end first, into the yoke end
of the main body as far as possible. Place the inlet filter , rough side up, on top of the
moving orifice. Place the retaining ring or star washer on top of the filter. Push the retaining
ring or star washer firmly into place with a dowel or screwdriver.
7. Install the used black washer into the hole in the main body where the flow element is
placed. A new washer may be installed if necessary.
8. Install the flow control element into the main body. Tighten the element with a 3/32" Allen
wrench with a torque of 3 in. lbs. (.4 nm). Do not overtighten.
9. Replace the cleaned and lightly lubricated O-ring on the cap .
10. Install the piston assembly squarely into the cap . If any shims were found when the
regulator was disassembled, place them over the piston stem. Then place the main spring
over the piston stem.
11. Install the cap assembly onto the body. Hand-tighten the assembly as tightly as possible, then
install the Sherwood regulator support handle into one of the low pressure ports. Using a 15"
adjustable wrench or a bench vice to hold the cap, tighten the cap onto the body until it
bottoms on the thread.
Do not tighten further.
12. Using your index finger, install the clean and dry one-way bleed valve into the body. No
particular orientation is necessary.
13. Lightly lubricate the body yoke nut threads with grease, and install the yoke and the yoke
nut onto the body.
14. Using the regulator support handle (p/n TL113) in one of the LP pressure ports of the body and
a 15" adjustable wrench, tighten the yoke nut snugly (see Photo #1).
15. Install the handwheel and the dust cap onto the yoke.
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