Heavy Duty Balanced Opposed Compressors - Ariel Corporation

Section 4 Part Replacement For Models: JGH:E:K:T
in place during piston and rod insertion.
NOTE: Stagger ring gaps around the piston; do not align them.
4. Follow the steps under “Piston and Rod Installation” on page 4-14.
High-Pressure Face-Cut Piston Rings
Face-cut piston rings are typically used in cylinders with 2500 psi MAWP or higher, and generally
with notched and fluted wear bands. The rings install with the face cuts toward the highest pressure,
or toward the nearest head. Gas pressure in the wear band area escapes past the piston rings via
the face cuts during the suction stroke to prevent loading the wear band and increase service life.
Also, do not align the ring end gaps; stagger them to minimize gas leakage.
Crank
End
Piston
Rod
Piston
Wear Bands
Notches
Pressure Pressure
Most JGK and JGT pistons use a single, one-piece angle-cut filled Teflon wear band. High-pressure
cylinders use two-piece thermoplastic wear bands (see Fig. 4-13).
Since wear bands do not work as sealing rings, end gap is not critical. Wear band projection beyond
the outer piston diameter is important. To check wear band projection, measure piston to cylinder
bore clearance at the bottom of the bore. There is no need to remove the piston from the cylinder.
Replace wear band before it wears enough to allow the piston to touch the cylinder bore. Install wear
bands in the same way as piston rings, above. See Table B-5 in Appendix B for wear band end gap
and radial projection tolerances.
Piston Rod Packing
Piston Rod Packing Removal
Piston Rings Wear Band Piston Rings
Staggered
End Gaps
Notches
FIGURE 4-13 High-Pressure Face-Cut Piston Ring Orientation
1. Remove piston and piston rod. See “Piston and Rod Removal” on page 4-8.
2. Remove packing diaphragm (if applicable) and oil wiper packing.
3. Disconnect all tubing and instrumentation (if applicable) from packing flange. Remove the twelvepoint
capscrews that hold the pressure packing gland to the crank end of the cylinder/head.
4. Do not remove the small nuts from the studs. They hold the packing case together for removal as
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Head
End