Ariel JGJ Series, Technical Manual

Page: 109 / 141

F
OR
M
ODELS
: JGW, JGR
AND
JGJ S
ECTION
5 - M
AINTENANCE
1/01 PAGE 5 - 37
Maintenance
To replace or clean the VVCP packing, remove the bolts and flange that hold the packing in
place and remove the packing. Replace the VVCP packing when excessive leakage is noted
at the vent. Remove the VVCP piston ring; replace as necessary.
Clean all parts to remove all debris, rust, etc. The stem and piston are permanently pinned,
do not attempt to disassemble.
Reassemble the VVCP in reverse order, using a new O-ring at the bolt flange. While the
torque used for the socket head bolting is not critical, these bolts must be sufficiently tight to
prevent loosening during service. Be sure that thread protector bellows are properly aligned
when installing hand wheel. Lubricate stem with 3-4 pumps of all-purpose petroleum grease
with a hand pump grease gun at the grease fitting.
To re-install the VVCP on the cylinder, use a new head gasket. Lubricate threads and bolt-
ing seating surfaces with petroleum type lubricant and install bolting. Tighten each cap
screw until snug using a criss-cross pattern. Next tighten each cap screw to 25% of full
torque, moving from cap screw to cap screw in a criss-cross pattern. Repeat this step for
50%, 75% and 100% of full torque. See Table 1-11 on page 1-15 for tightening torque value.
Reconnect VVCP packing vent. When installing a new VVCP, check total piston end clear-
ance and re-set crank end/head end feeler clearances with VVCP completely closed. See
Table 1-3 on page 1-9 for clearances.
Adjustment
VVCP clearance volume may be changed with the compressor running or stopped. Consult
the Packager’s instructions regarding where to set the VVCP. Also reference the VVCP data
sheet in the Ariel Technical Manual Parts Book.
The VVCP piston ring is designed not to be gas tight, to allow a nearly balanced gas pres-
sure for ease of VVCP adjustment with the cylinder pressurized. Gas pressure behind the
VVCP piston normally vents when cylinder is vented. Process debris or rust around the pis-
ton ring can make a seal that takes some time to vent. If gas is trapped behind the piston,
CAUTION
TRAPPED GAS PRESSURE CAN PRESENT A PERSONAL
SAFETY HAZARD WHEN SERVICING THE VVCP. WORK IN A
WELL VENTILATED, NON SPARKING AREA. DO NOT
BREATHE GAS OMMITTED FROM VVCP WHEN VENTING
TRAPPED GAS.
!