Corken 91 Instruction manual

Model T91 Compressor
with 103 Mounting
Bare D91 Compressor
Installation, Operation
& Maintenance Manual
D- and T-Style Model 91 Compressors
ORIGINAL INSTRUCTIONS IE107A
Warning: (1) Periodic inspection and maintenance of Corken products is essential. (2) Inspection, maintenance and installation of
Corken products must be made only by experienced, trained and qualified personnel. (3) Maintenance, use and installation of Corken
products must comply with Corken instructions, applicable laws and safety standards. (4) Transfer of toxic, dangerous, flammable or
explosive substances using Corken products is at user’s risk and equipment should be operated only by qualified personnel according
to applicable laws and safety standards.
Solutions beyond products...

Warning
Install, use and maintain this equipment according to Corken’s instructions and all applicable federal, state, local laws
and codes. Periodic inspection and maintenance is essential.
Corken One Year Warranty
CORKEN, INC. warrants that its products will be free from defects in material and workmanship for a period of
one year from date of installation, provided that the warranty shall not extend beyond twenty-four (24) months from
the date of shipment from CORKEN. If a warranty dispute occurs, the DISTRIBUTOR may be required to provide
CORKEN with proof of date of sale. The minimum requirement would be a copy of the DISTRIBUTOR’S invoice to
the customer.
CORKEN products which fail within the warrant period due to defects in material or workmanship will be repaired
or replaced at CORKEN’s option, when returned, freight prepaid to CORKEN, INC., 9201 North I-35 Service Road,
Oklahoma City, OK. 73131.
Parts subject to wear or abuse, such as mechanical seals, blades, piston rings, valves and packing, and other parts
showing signs of abuse, neglect or failure to be properly maintained are not covered by this limited warranty. Also,
equipment, parts and accessories not manufactured by CORKEN but furnished with CORKEN products are not
covered by this limited warranty and the purchaser must look to the original manufacturer’s warranty, if any. This
limited warranty is void if the CORKEN product has been altered or repaired without the consent of CORKEN.
All implied warranties, including any implied warranty of merchantability or fitness for a particular purpose, are expressly
negated to the extent permitted by law and shall in no event extend beyond the expressed warrantee period.
CORKEN DISCLAIMS ANY LIABILITY FOR CONSEQUENTIAL DAMAGES DUE TO BREACH OF ANY WRITTEN OR
IMPLIED WARRANTY ON CORKEN PRODUCTS. Transfer of toxic, dangerous, flammable or explosive substances
using CORKEN products is at the user’s risk. Experienced, trained personnel in compliance with governmental and
industrial safety standards should handle such substances.
Important notes relating to the European Union (EU) Machinery Directive
Compressors delivered without electric motors are not considered as machines in the EU Machinery Directive. To
ensure EU compliance, the compressor should be ordered with the optional 3022-1X Declaration of Conformity. The
fabricator of the machinery must assure and declare full compliance with this Directive before the machine in which
the compressor will be incorporated, or of which it is a part, is put into service.
Contacting the Factory
Before contacting the factory, note the model and serial numbers. The serial number directs Corken personnel to a
file containing all information on material specifications and test data applying to the product. When ordering parts,
the Corken service manual or Installation, Operations, and Maintenance (IOM) manual should be consulted for the
proper part numbers. ALWAYS INCLUDE THE MODEL NUMBER AND SERIAL NUMBER WHEN ORDERING PARTS.
The model and serial numbers are shown on the nameplate of the unit. Record this information for future reference.
Model No.
Serial No.
Date Purchased
Date Installed
Purchased From
Installed By
2

Table of Contents
Chapter 1—Introduction........................................................................4
1.1 Construction Features ................................................................................ 5
1.2 Running Gear....................................................................................... 6
Chapter 2—Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Location ........................................................................................... 6
2.2 Foundation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Piping............................................................................................. 6
2.4 Liquid Traps ........................................................................................ 7
2.5 Driver and Flywheel.................................................................................. 8
2.6 Crankcase Lubrication ............................................................................... 8
2.6.1 Oils to Avoid.................................................................................... 9
2.6.2 Critical Oil Characteristics ........................................................................ 9
2.6.3 Crankcase Oil Recommendations ................................................................. 10
2.6.4 Basic Steps for Flushing Oil ...................................................................... 10
2.6.5 Oil Change Intervals ............................................................................ 11
2.6.6 Crankcase Oil Recommendations (Except Ammonia Service) ........................................... 11
2.6.7 Crankcase Oil Recommendations (Ammonia Service Only) ............................................. 11
2.6.8 Crankcase Oil Recommendations (Synthetic Food Grade Oils) .......................................... 12
2.6.9 Oil Analysis ................................................................................... 12
2.6.10 Oil Dilution ................................................................................... 12
2.6.11 Long Term Storage ............................................................................ 12
2.6.12 Engine Oils (Motor Oils) ......................................................................... 12
2.7 Relief Valves....................................................................................... 13
2.8 Shutdown/Alarm Devices ............................................................................ 13
Chapter 3—Start Up ..........................................................................14
3.1 Inspection After Extended Storage..................................................................... 14
3.2 Flywheel and V-belt Alignment ........................................................................ 14
3.3 Startup Check List ................................................................................. 14
Chapter 4—Routine Maintenance Chart .........................................................15
Chapter 5—Routine Service and Repair Procedures...............................................16
5.1 Valve s ............................................................................................ 16
5.2 Heads ........................................................................................... 17
5.3 Piston Rings and Piston Ring Expanders ................................................................ 17
5.4 Pistons........................................................................................... 18
5.5 Piston Rod Packing Adjustment ....................................................................... 18
5.6 Cylinder and Packing ............................................................................... 18
5.6.1 Model D91 (D-Style) Compressor .................................................................. 19
5.6.2 Model T91 (T-Style) Compressor .................................................................. 20
5.7 Bearing Replacement for Crankcase and Connecting Rod .................................................. 23
5.7.1 Wrist Pin Bushing Replacement ................................................................... 23
5.7.2 Replacing Connecting Rod Bearings ............................................................... 23
5.7.3 Replacing Crankcase Roller Bearings............................................................... 24
Chapter 6—Extended Storage Procedures .......................................................24
6.1 Gasket Sets ....................................................................................... 24
Appendices
A. Model Number Identification Code and Available Options ................................................... 25
B. Specifications ...................................................................................... 27
C. Compressor Selection ............................................................................... 30
D. Outline Dimensions.................................................................................. 31
E. Parts Details ....................................................................................... 36
F. Compressor Foundation Design Considerations ........................................................... 48
G. Troubleshooting .................................................................................... 57
3

Connections:
Available in threaded NPT or Class 300
RF flanges.
High-efficiency valves:
Valves are quiet and highly durable. Special
suction valves tolerating small amounts of
condensate are available.
O-ring seals:
Easy to install O-ring seals head and cylinder.
Ductile iron construction:
Cylinder and head are made of ductile iron
for maximum thermal shock endurance.
Self-lubricating PTFE piston rings:
State-of-the-art piston ring designs to
provide the most cost-effective operation
of compressors for non-lube service. The
step-cut design provides higher efficiencies
during the entire life of the piston ring.
Upper distance piece
Barrier 1
(purge, pad, or vent)
Piston rod seals:
Seals constructed of PTFE incorporating
special fillers to maximize leakage control.
Spring loaded seal design self adjusts to
compensate for normal wear.
Lower distance piece
Barrier 2
(purge, pad, or vent)
Adjustable packing screw
Upper packing
Deflector ring
Deflector ring
Middle packing
Lower packing
Nitrotec
®1 coated piston rods:
Impregnated nitride coating provides
superior corrosion and wear resistance.
Cast-iron crosshead:
Durable cast-iron crossheads provide
superior resistance to corrosion and galling.
Pressure-lubricated crankcase with filter:
Self-reversing oil pump ensures proper
lubrication regardless of directional rotation to
main and connecting rod bearings. Standard
10-micron filter ensures long-lasting bearing
life (not available on Model 91).
1 Registered trademark of TTI Group Ltd.
Chapter 1—Introduction
Construction Details—Model FT91 Compressor
4

1.1 Construction Features
The Corken liquid transfer-vapor recovery compressor
is a vertical single-stage, single-acting reciprocating
compressor designed to handle flammable gases
like LPG and toxic gases such as ammonia. Corken
compressors can handle these potentially dangerous
gases because the LPG/NH3is confined in the
compression chamber and isolated from the crankcase
and the atmosphere. A typical liquid transfer-vapor
recovery compressor package is shown in figure 1.1A.
Figure 1.1A: 107-style compressor mounting.
Corken compressors use iron pistons locked to the piston
rod. The standard piston ring material is a glass-filled
PTFE polymer specially formulated for non-lubricated
services. Piston ring expanders are placed behind the
rings to ensure that the piston rings seal tightly against
the cylinder wall.
Piston rod packing is used to seal the gas in the
compression chamber and prevent crankcase oil from
entering the compression chamber. The packing consists
of several PTFE V-rings sandwiched between a male and
female packing ring and held in place by a spring (see
figure 1.1B).
The typical Corken compressor valve consists of a seat,
bumper, one or more spring(s) and one or more valve(s)
and plates as shown in figure 1.1C. Special heat-treated
alloys are utilized to prolong life of the valve in punishing
non-lubricated services. The valve opens whenever the
pressure on the seat side exceeds the pressure on the
spring side.
Pipe plug
Cutaway of
crosshead guide
Cutaway of
packing cartridge
Retainer ring
Male packing
ring
Packing
Lock device
Adjusting screw
assembly
Washer
Spring
Packing box washer
V-ring
packing
Female
packing ring
Packing Set Orientation
Figure 1.1B: Compressor sealing system
Suction Valve
Spec 3
Discharge Valve
All Specs
Retainer ring
Suction valve
relief housing
Spring
Ball
Suction valve
seat
Suction valve
plate
Suction spring
Suction valve
bumper
Discharge
valve bumper
Discharge
spring
Discharge
valve plate
Discharge
valve seat
Figure 1.1C: Compressor sealing system
5

NOTE: To confirm the specifications for any compressor,
locate the model number on the nameplate and refer to
the model identification tables listed in Appendix A. The
model identification tables show the specifications for
each section of the compressor.
Figure 1.1D: Typical nameplate: The opening behind the nameplate is
used to fill the compressor crankcase with oil and adjust the lower set
of packing.
1.2 Running Gear
The D- and T-Style model 91 gas compressors are mounted
on oil lubricated crankcases remaining at atmospheric
pressure. Crankshafts are supported by heavy-duty roller
bearings and the connecting rods ride the crankshaft on
journal bearings. The model 91 compressor has a dipper
mounted to bottom of the connecting rod that splash
lubricates the journal bearings and wrist pins. Sturdy iron
crossheads transmit reciprocating motion to the piston.
Chapter 2—Installation
2.1 Location
NOTE: Always install the compressor in a well
ventilated area.
Corken compressors are designed and manufactured
for outdoor duty. When the compressor is subjected to
extreme conditions (i.e. corrosive environments and arctic
conditions) for extended periods of time, consult Corken.
Check local safety regulations and building codes and
ensure the installation meets all regulations and codes.
Compressors handling toxic or flammable gases should
be located outdoors. A minimum of 18 inches (457.2
mm) clearance between the compressor and the nearest
wall is recommended for easy access from all sides and
unrestricted air flow for adequate cooling.
Many factors affect the noise level generated by a compressor
installation. Several of these, including motor noise, piping
vibration, foundation/skid design, and surrounding structures
are outside Corken’s control. The use of sufficient pipe
supports, flexible hoses, and proper baseplate/skid support
will all reduce noise. Thus, Corken cannot guarantee a
particular noise level from our compressors. However, noise
levels from a properly installed Corken compressor typically
do not exceed 85 dBa at three feet (0.91 meters).
2.2 Foundation
A proper foundation is essential for a smooth running
compression system. The concrete slab should be
at least 8 inches thick with a 2 inch skirt around the
circumference of the baseplate. The total mass of the
foundation should be approximately twice the weight of
the compressor system (compressor, baseplate, motor,
etc.). For a model 91, the baseplate should be secured to
the foundation using 1/2" diameter x 12" long “J” bolts.
NOTE: Always use all anchor holes.
Hex nut
Washer
Compressor
baseplate
NOTE: Locate “J” bolts per compressor outline
dimension drawings.
8" minimum
Grout beneath
base
1/2"“J” bolts
12"long
2" minimum
all sides
Concrete foundation
with reinforcements
should be used on
all models
Figure 2.2A: Recommended foundation details for a
model 91 compressor.
After leveling and bolting down baseplate and/or skid,
the volume beneath the channel iron baseplate must
be grouted to prevent flexing between the top of
the baseplate and the “J” bolt that extends beyond
the foundation. Creating a solid interface between the
compressor and foundation improves the dampening
capabilities of the foundation.
For more information, see Compressor Foundation
Design Guide (item number ED410). See Appendix F.
2.3 Piping
A proper piping design is as important as a proper
foundation when it comes to a smooth operating
compressor. A poorly designed piping system results in
an undesirable transmission of compressor vibration to the
piping. For best results follow the recommendations below.
DO NOT SUPPORT PIPING WITH THE COMPRESSOR.
Unsupported piping is the most frequent cause of
vibration. To minimize the transmission of vibration from
the compressor to the piping, install flexible connectors
vertically as shown below (see figure 2.3A).
6

Concrete
foundation
Steel
structural skid
Pipe
support
Flexible
connections
Flexible
connections
Ground level
Figure 2.3A: Flexible connectors should be used to minimize
transmission of vibration to the piping.
Piping must be adequately sized to prevent excessive
pressure drops between the suction source and the
compressor and the final discharge point and the
compressor. In most cases, the piping should be at the
same diameter as the suction nozzle on the compressor.
Typically, liquid transfer systems are designed to limit
pressure drops to 20 psi (1.4 bar).
Care must be taken when a restrictive device (i.e. a valve,
pressure regulator, or back-check valve) is installed in the
compressor’s suction line. The volume of the suction line
between the restrictive device and the compressor suction
nozzle must be at least ten times the swept cylinder volume.
See Appendix B for specifications on cylinder and stroke.
2.4 Liquid Traps
Compressors are designed to pressurize gas and not pump
liquids. Even a small amount of liquid into a compressor
results in serious damage.
To prevent the entry of liquid into the compressor, a liquid
trap is always used on liquefied gas applications. Corken
offers three liquid trap options for removing liquids in the
gas stream (see figure 2.4A).
Standard Liquid Trap: The trap is the simplest design and
comes with a mechanical float. As the liquid enters the trap,
the gas velocity is greatly reduced, which allows the liquid
to drop out. If the liquid level rises above the inlet, the ball
float will plug the compressor suction. The compressor
creates a vacuum in the inlet piping and continues to
operate until the operator manually shuts it down. Before
restarting the compressor, the trap must be drained and the
Figure 2.4A: Liquid traps.
Standard liquid trap with
mechanical float assembly
and drain valve.
Connections:
1-1/4" In x 1-1/4" NPT Out
Automatic liquid trap, with one
NEMA 7 liquid-level switch for
compressor shutdown and
drain valve.
Connections:
1-1/4" In x 1-1/4" NPT Out
Code-stamped automatic liquid trap
with two NEMA 7 liquid-level switches
for compressor shutdown and alarm.
Equipped with relief valve, pressure gauge,
demister pad, and drain valve.
Connections:
1-1/2" In x 1-1/2" NPT Out
Standard Liquid Trap Automatic Liquid Trap ASME Automatic Liquid Trap
7

vacuum-breaker valve opened so the float can drop back.
This type of trap is used when the compressor is under
fairly close or constant observation. This trap is used with
the 109 and 107 compressor mountings.
Automatic Liquid Trap: When a compressor is not
under constant observation, an automatic trap is highly
recommended. With this design the mechanical float is
replaced with electrical float switches. If the liquid level
rises too high, the level switch opens and disconnects
the power to the motor starter and stops the compressor.
This design is standard on Corken's 109A and 107A
compressor mountings.
ASME Automatic Liquid Trap: This is Corken’s most
sophisticated design and provides the best liquid
separation. It's the largest design of the three traps,
ASME code stamped, and contains two level switches.
One sounds an alarm so the operator can manually drain
the liquid from the trap and one is used for shutdown. In
some cases the alarm switch is used to activate a dump
valve (not included with trap). This trap also features a
mist pad made of interwoven wire for catching fine liquid
mists. The ASME code trap is standard on the 109B and
107B compressor mountings.
A typical wiring diagram for the liquid level switch is
shown in figure 2.4B.
Typical Float Switch Wiring Diagram
1 = Common, black
2 = Normally closed, blue
3 = Normally open, red
Figure 2.4B: Typical float switch wiring diagram.
NOTE: The level switch MUST be removed from
the trap before grounding any welding devices to
the trap or associated piping! Failure to do so will
damage the switch contacts.
If Corken's compressor is equipped with a liquid trap
from a different manufacturer, make sure it is adequately
sized to remove all liquid in the suction stream.
2.5 Driver and Flywheel
Corken vertical compressors may be driven by either
electric motors or combustion engines (gasoline, diesel,
natural gas, etc.). Corken compressors are usually
V-belt driven but they are also suitable for direct drive
applications as well. Direct drive applications require an
extended crankshaft to allow the attachment of a rigid
metal coupling.
Select a driver that allows the compressor to operate
between 400 and 800 RPM. Do not operate the compressor
without the flywheel or severe torsional imbalances will result
causing vibration and a high horsepower requirement. The
flywheel should never be replaced by another pulley unless
it has a higher WK
2value than the flywheel.
A humid climate can cause problems, particularly
in explosion proof motors. The normal breathing of
the motor — alternating between being warm when
running and being cool when stopped — can draw
moist air into the motor. The moist air will condense
adding water to the inside the motor and may cause it
to fail. To prevent this from happening, run the motor
at least once a week on a bright, dry day for an hour
or so without the V-belts. During this period of time
the motor will heat up and vaporize the condensed
moisture within the motor. No motor manufacturer
guarantees an explosion proof or totally enclosed
(TEFC) motor against damage from moisture.
Before installing an engine driver, thoroughly review
installation instructions provided by the engine manufacturer.
2.6 Crankcase Lubrication
The crankcase is always drained prior to shipping.
Before starting the machine, fill the crankcase to the full
mark - not above - of the oil bayonet. To ensure proper
lubrication of the crossheads, crosshead guide, and
all critical parts, fill the crankcase through inspection/
nameplate (see figure 2.6A and 2.6B for the proper oil
filling location).
Compressor
Model
Approximate
Quarts Capacity Liters
91 0.9 0.8
Figure 2.6A: Oil capacity chart.
Crankcase
Adjustment screw
for lower packing
set
Fill crankcase
through the
inspection / nameplate
opening
Crosshead guide
Figure 2.6B.
8

General Notes on Crankcase Oil
Corken gas compressors handle a wide variety of gases
in a multitude of operating conditions. They are used in
all areas of the world from hot dusty deserts, to humid
coastal areas, to cold arctic climates. Some compressors
may be lightly loaded and run only occasionally, while
others may be heavily loaded and operate 24/7. Thus, no
single crankcase oil or maintenance schedule is right for
every compressor. Availability of brands and grades of
oil can vary from one location to another. These factors
can make it challenging for a Corken compressor user to
select a suitable crankcase oil. This guide is intended to
aid in that regard.
It is safe to say that purchasing a quality crankcase oil,
and changing it regularly, is significantly less costly than
the repair bill and downtime associated with a lubrication
failure in any gas compressor. Considering the relatively
small volume of oil used in Corken compressors, and the
critical nature of the services where these compressors
are used, selecting the appropriate high quality oil is
the most economical choice. It will help ensure the
dependability and longevity of the compressor.
Corken recommends using industrial oils (rather than
engine oil or “motor oil”). Industrial oils have additives
selected and blended for specific purposes. Many are
designed specifically for the challenges inherent in
compressor crankcases. Industrial oils are available as
a conventional (mineral based) oil, a synthetic oil, or a
blend of the two.
All new Corken compressors are tested at the factory
using a conventional mineral oil. This oil is drained
prior to shipment. An oil suitable for the anticipated
environmental and operating conditions must be selected
and added to the compressor prior to the initial startup.
2.6.1 Oils to Avoid
Selecting a crankcase oil based on low price or easy
availability is seldom the best decision. Following are oils
to avoid:
• Do not use any oil with a viscosity index below 95.
• Do not use any oil with a pour point less than 20°F
(11°C) lower than the anticipated minimum ambient
temperature (unless a crankcase oil heater is used).
• Do not use engine/motor oil.
See below for additional detail on each of these
parameters.
2.6.2 Critical Oil Characteristics
Viscosity
Viscosity is the most important physical property of
lubricating oil. Simply put, the viscosity of an oil is a
measure of its resistance to flow. In gas compressors,
oils with higher viscosity (like ISO 100) are thicker and
are used for higher ambient temperatures. Oils with lower
viscosity (like ISO 68) are thinner and are used at lower
ambient temperatures. If the oil’s viscosity is too high, the
oil may not circulate through the compressor adequately.
If the viscosity is too low, the lubricating film will be
unable to protect the components from wear.
Viscosity Index
Viscosity Index (VI) is a measure of how much the oil’s
viscosity changes as its temperature changes. A low
viscosity index is an indication that the viscosity changes
more as the temperature changes. Oils with low viscosity
index tend to become thin as the oil temperature
increases. This can cause lubrication failure as well as
unstable oil pressure. A high viscosity index reflects
a more stable viscosity, and is generally preferred for
Corken compressors. The minimum Viscosity Index
for oils used in Corken compressors is 95 (VI is a
unit-less number). This is particularly important when
operating at high or low temperature extremes, or at
a variety of ambient temperatures (seasonal changes).
Oils with a high viscosity index can be used at wider
ambient temperature range compared to oils with a lower
viscosity index.
It should be noted that a conventional oil (not synthetic)
with a high viscosity index may not necessarily be
suitable for continuous service at high temperature.
Such an oil will oxidize faster than a synthetic oil.
Synthetics have naturally high viscosity index, and are
therefore recommended for “heavy service” as described
below—including high temperature and continuous duty
applications. It many climates, the use of the correct
synthetic oil will eliminate the need to change oil viscosity
grades as the seasons change.
Pour Point
The pour point of an oil is the lowest temperature at
which the oil flows. At temperatures below the pour
point, the oil is essentially solid and can’t freely flow to
the compressor’s bearings and other wear surfaces, or
even to the compressor’s oil pump.
The oil’s pour point is particularly critical when starting a
compressor at low temperature conditions. An oil should
have a pour point at least 20°F (11°C) below the lowest
expected ambient temperature. For example, if the minimum
ambient temperature is expected to be 0°F (-18°C), the pour
point must be no higher than -20°F (-29°C).
Do not assume the pour point of an oil is low enough.
Consult the oil’s technical data sheet – generally available
on the oil manufacturer’s website. Many conventional oils
have a pour point around 0 to 15°F (-18 to -9°C) which is
too high to use at low ambient temperatures. Synthetic oils
generally have a lower pour point than conventional oils.
9

2.6.3 Crankcase Oil Recommendations
The primary factors for selecting a suitable crankcase oil
from the chart below are ambient temperature range and the
anticipated service – normal service or heavy service. The
ambient temperature determines the required oil viscosity.
Consider the full range of high and low ambient temperatures
at the compressor’s location when selecting an oil. It may
be necessary to use an ISO 100 in summer and an ISO
68 in winter. Synthetic oils generally have a wider ambient
temperature range due to their higher viscosity index.
For the purpose of selecting a suitable crankcase oil for
a Corken compressor, normal and heavy service are
defined below.
Normal Service
“Normal service” can be defined as anything that is not
considered “heavy service” as described below.
Common examples of “normal service” applications:
• LPG liquid transfer (intermittent duty)
• Ammonia liquid transfer (intermittent duty)
• Most tank evacuation applications
Conventional mineral based oils have been used
successfully for many years in these services.
Heavy Service
“Heavy Service” is defined as an application where the
compressor is subject to any one (or more) of the following:
• Continuous duty service (several hours each day or more)
• Compressor consistently loaded at or near its maximum
horsepower rating
• Compressor speed is at or near its maximum speed rating
• Services with a “wet” gas such as natural gas with
high content of heavy hydrocarbons such a butane,
pentane, etc.
• Services dealing with low vapor pressure hydrocarbons
(such as butane unloading in winter) where condensation
in the gas can result in dilution of the crankcase oil
• Compressors operating at high or low temperature
extremes
Synthetic oils are recommended for “heavy” services.
Ammonia Service
Compressing ammonia presents particular challenges
from a lubrication standpoint. Never use a detergent
oil in a compressor in ammonia service. Ammonia will
react with the detergent and cause lubrication failure.
Fortunately, some oils are specifically blended for use in
ammonia compressors — though some of these are best
suited only for cooler climates.
Consult these charts or the oil manufacturer’s product
data sheet for information regarding the oil’s viscosity,
viscosity index, pour point, etc. This information is
generally available on line or from the oil supplier. Do not
use an oil if it’s critical properties can not be confirmed,
of if there is any other reason to doubt its suitability.
Contact Corken if additional assistance is needed when
selecting a crankcase oil.
Food Grade Service
Oils used in “Food Grade” service fall under much more
restrictive rules than a typical industrial lubricating oil.
The various requirements for food grade oils are outlined
by NSF, FDA Title 21, Orthodox Union (Kosher, Pareve),
IFANCA (Halal), and others. The most prevalent requirement
seems to be NSF H1 which dictates the requirements of
lubricants that may have incidental food contact.
All lubricating oils consist of a base oil plus multiple
additives that improve various properties of the base oil.
For food safety reasons, many additives used in industrial
lubricants are not permissible for use in food grade service.
Thus, food grade oils generally have lesser lubricating
properties or require more frequent oil changes.
Like industrial oils, the basis for a food grade oil can be
either a conventional mineral oil or a synthetic oil. Since
synthetic-based oils have significantly better lubricating
properties and service life than mineral-based oils,
Corken recommends using a synthetic food grade oil
in applications requiring food grade oil. The inherent
properties of the synthetic-based oil help overcome
additives that may be less than ideal. Some synthetic
food-grade oils perform better than non-food grade
industrial mineral oils.
Due to the high viscosity index and low pour point of
synthetic oils, most Corken compressor operators can
use an ISO 100 grade oil year-round. Those in cooler
climates may need an ISO 68 oil with a lower viscosity.
All Corken compressors are tested at the factory using
a standard industrial (non-food grade) mineral oil. The
mineral oil is drained, but some residual oil will always
remain inside the crankcase. If the end user intends to use
any synthetic oil (or a synthetic food grade oil in particular),
the crankcase should be flushed with the new oil.
2.6.4 Basic Steps for Flushing Oil
• Confirm that the crankcase is drained to the lowest
extent possible.
• Remove and drain the oil filter or replace with a new
one (part number 4225). NOTE: The Corken model 91
compressor does not use an oil filter.
10

* Oil change intervals in this range should be confirmed
via oil analysis.
Environmental or operational issues such as dirty, dusty,
or humid conditions will require more frequent oil changes.
Contamination/dilution of the oil by liquids in the gas stream
can also shorten the life of the oil. Visually check the oil level
and the oil condition at least monthly (compare to unused oil).
Indications that dictate more frequent oil changes:
• Unusually dirty or discolored oil (or unusual smell)
• Oil dilution by condensation or other liquids in the gas
stream (see below)
• Change in viscosity for any reason (various oil additives
can break down over time)
• Changing ambient temperature may cause the need for
a different viscosity
The oil should be changed as often as necessary to
maintain clean, undiluted oil of the proper viscosity. Each
time the oil is changed, the oil filter (Corken part number
4225) should also be changed.
• Add the proper amount of new synthetic food grade oil
to the compressor.
• Run the compressor five minutes to circulate the new
synthetic oil.
• Drain the synthetic oil and discard since it will not be
reused.
• Refill the crankcase with the proper amount of new
synthetic food grade oil.
• Confirm proper oil level.
2.6.5 Oil Change Intervals
Oil change intervals can vary significantly depending
on local environmental conditions, the gas being
compressed, and the oil being used. Unless there are
factors that shorten the life of the oil, the following
recommendations apply:
Conventional oil: 2,200 hours or 6 months—whichever
comes first
Synthetic oil: 6,000–8,000 hours* or one year—whichever
comes first
2.6.6 Crankcase Oil Recommendations (Except Ammonia Service)
Normal Service
Ambient Temperature 1 Oil Product Oil Type 2 Viscosity ISO 3 Viscosity Index 3 Pour Point 3
40 to 100°F (4 to 38°C) Mobil DTE 10 Excel 100 C100 127 -27°F (-33°C)
Mobil Rarus 427 C100 100 16°F (-9°C)
Phillips 66 Gas Compressor Oil C100 102 -20°F (-29°C)
Chevron Regal R&O C100 97 5°F (-15°C)
Sunoco Sunvis 900 C100 95 -15°F (-26°C)
10 to 65°F (-12 to 18°C) Mobil DTE 10 Excel 68 C68 156 -38°F (-39°C)
Mobil DTE Heavy Medium C68 95 5°F (-15°C)
Phillips 66 Premium Gas Compressor Oil B68 133 -27°F (-33°C)
Chevron Regal R&O C68 99 -11° F (-24°C)
Sunoco Sunvis 900 C68 104 -21°F (-29°C)
Heavy Service
10 to 100°F (-12 to 38°C) Mobil SHC 627 4 S100 162 -49°F (-45°C)
Royal Purple Synfilm NGL 100 S100 130 -44°F (-42°C)
Dyna-Plex 21C Synzol CO ISO 100 S100 132 -49°F (-45°C)
-20 to 90°F (-29 to 32°C) Mobil SHC 626 4 S68 165 -59°F (-51°C)
Royal Purple Synfilm NGL 68 S68 132 -76°F (-60°C)
2.6.7 Crankcase Oil Recommendations (Ammonia Service Only)
Normal Service
Ambient Temperature 1 Oil Product Oil Type 2 Viscosity ISO 3 Viscosity Index 3 Pour Point 3
40 to 100°F (4 to 38°C) Mobil Rarus 427 C100 100 16°F (-9°C)
10 to 65°F (-12 to 18°C) Phillips 66 Ammonia Compressor Oil C68 102 -27°F (-33°C)
Chevron Capella P68 C68 96 -44°F (-42°C)
Mobil Rarus 426 C68 105 16°F (-9°C)
Heavy Service
10 to 100°F (-12 to 38°C) Mobil Gargoyle Arctic SHC 228 5 S100 147 -43°F (-45°C)
Royal Purple Uni-Temp 100 S100 124 -53°F (-47°C)
-20 to 90°F (-29 to 32°C) Mobil Gargoyle Arctic SHC 226E 5 S68 136 -58°F (-50°C)
Royal Purple Uni-Temp 68 S68 118 -51°F (-46°C)
1 Consult Corken for oil recommendations in very hot climates—ambient temperatures consistently above 100°F (38°C).
2 Oil type: C=Conventional, S=Synthetic, B=Conventional/Synthetic blend
3 Information available from oil manufacturers at the time of publication.
4 Mobil SHC oils are synthetic oils which require that the crankcase be flushed of residual mineral oil.
5 Mobil Gargoyle Arctic SHC oils are synthetic oils which require that the crankcase be flushed of residual mineral oil.
11

2.6.8 Crankcase Oil Recommendations (Synthetic Food Grade Oils)
Ambient
Temperature
°F (°C) 1
Oil Product Viscosity
ISO Grade 2
Viscosity
Index 2
Pour Point
°F (°C) 2 Registrations/Compliance/Certifications 2
10 to 100
(-12 to 38)
Mobil SHC Cibus 100 100 143 -49 (-45) NSF H1, Kosher, Halal, FDA 21 CFR 178.3570, ISO
22000, ISO 21469
Royal Purple
Poly-Guard FDA 100 100 136 -38 (-39) NSF H1, FDA 21 CFR 178.3620
Ultrachem Omnilube 5131 100 145 -38 (-39) NSF H1, FDA 21 CFR 178.3570, Halal, Kosher
Summit (Kluber) R Series
R300 100 149 -60 (-51) NSF H1, Kosher, Halal, ISO 21469
Petro-Canada Purity FG
Synthetic 100 100 147 -71 (-57) NSF H1, FDA 21 CFR 178.3570, Kosher, Pareve, Halal
-20 to 80
(-29 to 27)
Mobil SHC Cibus 68 68 140 -52 (-47) NSF H1, Kosher, Halal, FDA 21 CFR 178.3570, ISO
22000, ISO 21469
Royal Purple Poly-Guard
FDA 68 68 140 -38 (-39) NSF H1, FDA 21 CFR 178.3620
Citgo Clarion
CompressorGuard 68 68 135 -65 (-54) NSF H1, FDA 21 CFR 178.3570
NOTES:
1 Consult Corken for Oil Recommendations in very hot climates—ambient temperatures consistently above 100ºF (38ºC)
2 Information stated by oil manufacturers at the time of publication. See oil manufacturer's product data sheets for additional details.
2.6.9 Oil Analysis
The best way to determine the needed oil change interval
for any particular compressor is to have an oil analysis
conducted. Numerous labs can analyze a used oil sample
and advise its condition. After 2–3 such tests, a determination
can be made for a recommended oil change interval for a
particular compressor in its specific environmental situation
and operating conditions. Regular oil analysis can help
improve the compressor durability and decrease oil usage
by maximizing the oil change intervals. Based on the oil
analysis, the oil can be changed when it is needed, and not
changed when it is not yet necessary.
2.6.10 Oil Dilution
Crankcase oil can be diluted by various products in the
gas stream. As an example, when compressing butane
in winter, the vapor pressure is very low and there can
be a lot of entrained liquid butane with the gas stream.
This liquid can collect in the compressor and dilute the
crankcase oil. This thins the oil and reduces its ability to
properly lubricate the compressor.
Hydrocarbon mixtures containing heavy hydrocarbons
such as butane, pentane, hexane, etc. often operate
at pressure above the vapor pressure of these heavier
constituents. Thus, they often produce a “wet” gas which
can dilute the crankcase oil.
2.6.11 Long Term Storage
When a compressor is removed from long term storage,
the oil should be changed before putting the compressor
back into service. Specifically, if it has been unused over a
season (such as over a winter), the oil should be changed.
2.6.12 Engine Oils (Motor Oils)
At noted above, engine oils (or motor oils) are not
recommended for use in Corken compressor crankcases
or cylinders. Engine oils are formulated for use in internal
combustion engines and contain additives that specifically
counter the contaminants created by the combustion
of fuel (soot, CO2, water, etc.). As such, they are not
necessarily the best oils to use in a gas compressor.
Detergents and dispersants in engine oils can react
with the compressor’s process gas, or form emulsions
inside the compressor’s crankcase that are detrimental
to lubrication. Ultimately, this negatively effects the
oil’s properties and damages the compressor’s critical
internal components.
If a suitable industrial oil is not readily available, engine
oils can temporarily be used in Corken compressors in
normal service, but only until a suitable industrial oil can
be sourced (see above for definition of “normal service”).
Engine oils should not be used for compressors in
“heavy service”.
Engine oil is labeled with an API “donut” indicating the
API Service Grade. It is critical that the engine oil have
an API Service Grade of SJ or better. Engine oils with an
API Service Grade of SA and SB are obsolete, but still
readily available. These very low quality oils should never
be used in Corken compressors. Industrial oils do not
receive an API Service Grade like engine oil does.
12

2.7 Relief Valves
An relief valve must be installed at the compressor
discharge. On Corken's 107-style mountings, a relief valve
should be fitted in the piping between the compressor
discharge and the four-way valve (see figure 1.1A). The
material specification for the relief valve should be
compatible with the gas being compressed. Review
the local codes and regulations for specific relief valve
requirements. Additional relief valves may be required at
other points in the compressor’s piping system.
2.8 Shutdown/Alarm Devices
Shutdown and alarm sensors (switches or transmitters)
protect the compressor system from potential damage
and are recommended for any application. All electronic
devices must meet local codes.
The following shutdown and alarm devices are typically
used with Corken compressors:
1. High Discharge Temperature Sensor: This sensor
is strongly recommended for all applications. Both
the sensor and compressor have an operating range.
The preferred sensor set point is 30°F (17°C) above
the normal compressor discharge temperature,
but below the maximum design temperature of the
O-ring material used on the compressor.
NOTE: To confirm the O-ring used the compressor,
refer to the Appendix A.
Maximum O-ring temperature for the following material
specifications:
• Buna-N and Neoprene®1 250°F (121°C)
• Viton®1 and PTFE 350°F (177°C)
1 Registered trademark of the DuPont Company.
2. Low Suction Pressure Sensor: Shuts down the unit
if inlet pressure is below a preset limit (set point). The
set point should follow these guidelines:
• For safety shut off, it must be greater than
the compressor minimum suction pressure
(atmospheric) to prevent pulling oil from the
crankcase into the gas stream.
• For process shut off, the set point should be 25%
of product vapor pressure. It can be lower or
higher based on economic decision on how much
product can be recovered. This decision must be
made by the customer.
3. High Discharge Pressure Sensor: Shuts down
the unit if outlet pressure is above a preset limit (set
point). The set point should follow these guidelines:
• Less than the compressor’s maximum working
pressure.
• Less than 80–90% of the relief valve pressure set
point (consult relief valve manufacturer)
• Greater than the compressor’s discharge pressure
based on normal operating conditions.
4. Vibration Switch: Shuts down the unit if vibration
becomes excessive. Recommended for units mounted
to a portable skid.
13

Chapter 3—Start Up
NOTE: Before starting up the compressor, review
and understand the principles of liquefied gas
transfer and vapor recovery using a compressor
listed in Chapter 1. Read the entire chapter before
proceeding to the startup checklist.
3.1 Inspection After
Extended Storage
If the compressor has been out of service for a long period
of time, make sure the cylinder bore and valve areas are free
of rust and other debris (see chapter 5 of this IOM manual
for valve and/or cylinder head removal instructions).
Drain the oil from the crankcase and remove the
nameplate and crankcase inspection plate. Inspect the
running gear for signs of rust and clean or replace parts
as necessary. Replace the crankcase inspection plate
and fill crankcase with the appropriate oil. Squirt oil on
the crossheads and rotate the crankshaft by hand to
ensure that all bearing surfaces are coated with oil.
Rotate unit manually to ensure running gear functions
properly. Replace nameplate and proceed with startup.
3.2 Flywheel and V-belt Alignment
Before working on the drive assembly, disconnect the
electric power. Before removing old belts or mounting
new ones, always make sure the motor driver and
compressor are close enough together to slide the belts
off by hand. Never pry or force the belts on or off.
Improper belt tension and sheave alignment can cause
vibration, excessive belt wear, and premature bearing
failure. Before operating the compressor, check V-groove
alignment between the flywheel and driver sheave. Visual
inspection often will indicate if the belts are properly
aligned, but use of a square is the best method. For more
details, see How To Align the Sheave to the Flywheel on
Corken's YouTube channel.
The flywheel is mounted on the shaft via a split, tapered
bushing and three bolts (refer to figure 3.2A). These bolts
should be tightened in an even and progressive manner
until the torque specification listed below is reached. There
must be a gap between the bushing flange and the flywheel
when installation is complete. Always check the flywheel
runout before startup and readjust if it exceeds the value
listed in Appendix B.
Hub
Size
Diameter
in. (cm)
Bolt Torque
Ft-lb (kg-meter)
Set Screw
Torque Ft-lb
(kg-meter)
SF 4.625 (11.7) 12-18 (1.7–2.5) 22 (3.1)
Figure 3.2A: Flywheel installation.
Tighten the belts until they are taut, but not extremely
tight. Consult your V-belt supplier for specific tension
recommendations. Belts that are too tight may cause
premature bearing failure. Refer to figure 3.2B.
Figure 3.2B: Belt tension.
3.3 Startup Check List
Please verify all of the items on this list before
starting the compressor! Failure to do so may result
in a costly (or dangerous) mistake.
Before Starting the Compressor
1. Become familiar with the function of all piping
associated with the compressor. Know each line’s use!
2. Verify that actual operating conditions will match the
anticipated conditions.
3. Ensure that line pressures are within cylinder
pressure ratings.
4. Clean out all piping.
14

5. Check all mounting shims, cylinder and piping
supports to ensure that no undue twisting forces exist
on the compressor.
6. Verify that strainer elements are in place and clean.
7. Verify that cylinder bore and valve areas are clean.
8. Check V-belt tension and alignment. Check drive
alignment on direct drive units.
9. Rotate unit by hand. Check flywheel for wobble or play.
10.Check crankcase oil level.
11. Drain all liquid traps, separators, etc.
12.Verify proper electrical supply to motor and panel.
13.Make sure all gauges are at zero level reading.
14. Test piping system for leaks.
15.Purge unit of air before pressurizing with gas.
16.Carefully check for any loose connections or bolts.
17. Remove all stray objects (rags, tools, etc.) from
vicinity of unit.
18.Verify that all valves are open or closed as required.
19.Double-check all of the above.
After Starting Compressor
1. Observe noise and vibration levels. Correct
immediately if excessive.
2. Verify proper compressor speed.
3. Examine entire system for gas, oil, or water levels.
4. Note rotation direction.
5. Check start-up voltage drop, running amperage, and
voltage at motor junction box (not at the starter).
6. Test each shutdown device and record set points.
7. Test all relief valves.
8. Check and record all temperatures, pressures, and
volumes after 30 minutes and 1 hour.
9. After 1 hour running time, tighten all head bolts, valve
holddown bolts, and baseplate bolts. See Appendix B
for torque values.
Chapter 4—Routine Maintenance Chart
Item to Check Daily Weekly Monthly Six
Months Yearly
Compressor discharge pressure
Overall visual check
Crankcase oil level 1 1
Drain liquid from accumulation points 2
Drain distance pieces 4
Clean cooling surfaces on
compressor and intercooler (if any)
Lubricator supply tank level (if any)
Check belts for correct tension
Inspect valve assemblies
Lubricate motor bearings in
accordance with manufacturers’
recommendations
Inspect motor starter contact points
Inspect piston rings
13
1 Conventional oil: change oil every 2,200 hours of operation or every 6 months, whichever occurs first. Synthetic oil:
change oil every 6,000–8,000 hours or one year, whichever comes first. If the oil is unusually dirty, change it as often
as needed to maintain a clean oil condition. Change replacement filter 4225 with every oil change.
2 Liquid traps should be drained prior to startup.
3 Piston ring life varies greatly, depending on application, gas, and operating pressures. Consult factory for additional
recommendations for your specific application.
4 Drain distance piece. See figure 4.1.
Drain
distance
piece here
Figur e 4.1
15

Chapter 5—Routine Service and
Repair Procedures
CAUTION: Always relieve pressure in the unit
before attempting any repairs. After repairs
have been completed, the unit should be pressure
tested and checked for leaks at all joints and
sealing surfaces.
If routine maintenance is performed as listed in chapter 4,
repairs are generally limited to replacing valves or piston
rings. When it comes time to order replacement parts, be
sure to consult the part details appendix in the back of
this Installation, Operation & Maintenance (IOM) manual
for a complete list of part numbers and descriptions.
5.1 Valves
Test the compressor valves by closing the inlet piping
shutoff valves while the unit is running; however, do
not allow the machine to operate this way very long. If
the compressors valves are still in good working order,
the inlet pressure gauge should drop to zero almost
immediately. Assuming the pressure gauge itself is not
faulty, if it does not drop to zero, one or more of the
valves are likely damaged or dirty.
For inspection purposes, each suction and/or discharge
valve assembly can be removed as one unit. If any part of
the valve assembly is broken, the complete valve assembly
should be replaced. See parts details in the appendices for
a complete list of part numbers and descriptions.
If a valve is leaking due to dirt or any other foreign
material that keeps the valve plate and seat from sealing,
the valve may be cleaned and reused. New gaskets and/
or O-rings should be used to assure a good seal.
For a complete list of the valve specifications, refer to the
parts details for head and valve assemblies in Appendix
E. Since more than one suction valve arrangement is
available for each model of compressor, it is necessary
to know the complete model number. In most cases for
liquid transfer and/or vapor recovery compressors, the
valve type will be spec 3 or 3P (see below).
Model number D91AJ 3 FBANSNN
Valve type = spec 3
Model number T91GJ 3P FBANSNN
Valve type = spec 3P
Valve Holddown Assemblies: Depending on the model
of compressor, the valve holddown assembly has all or a
combination of the following (Spec 9 shown below):
Unloader assembly
Unloader cap
Holddown screw
O-ring
Bolt
Unloader actuator
Unloader spring
Unloader piston
Coro seal
Gasket
Unloader piston cap
Coro seal
Valve assembly
Valve gasket
Valve Assemblies: Depending on the valve specification,
the valve assembly has all or a combination of the following
(Spec 3 shown below):
Retainer ring
Relief housing
Relief ball spring
Relief ball
Suction valve seat
Suction plate
Valve gasket
Suction spring
Suction valve bumper
16

For a complete list of part numbers, parts details for
head and valve assemblies in the Appendix E.
Valve Inspection and/or Replacement
Before removing and inspecting the valves, begin by
depressurizing and purging (if necessary) the compressor.
Disassembly
1. Unscrew the valve cap and remove O-ring.
2. Remove the holddown screw with the special wrench
supplied with the compressor at time of purchase.
3. After the holddown screw has been removed, the
valve assembly and gasket can be lifted out.
4. Carefully inspect for dirt or damaged parts.
5. Inspect the valves for breakage, corrosion, debris, and
scratches on the valve disc. In many cases, the valves
may be cleaned and reinstalled. If the valves show
any damage, they should be repaired or replaced.
Replacement is usually preferred, although individual
parts are available. If valve discs are replaced, seats
should also be lapped until they are perfectly smooth.
A maximum of .005 inch can be removed during the
lapping process. If more than .005 inch is removed
to achieve a smooth surface, the valve should be
discarded. If discs are replaced without relapping the
seat, rapid wear and leakage may occur.
Assembly
1. Insert metal valve gasket into the suction and/or
discharge opening of the head.
NOTE: Never use old gaskets. Always replace the
metal valve gasket before re-installing the valve
assembly.
2. Insert the cleaned or new valve assembly. Make sure
the suction and discharge valves are in the proper
opening in the head. NOTE: The spec 3 suction valves
for a model 91 are pre-set so no adjustments to the
liquid relief pressure are necessary.
3. Replace the holddown screw and tighten to the
torque value listed in Appendix B.This ensures the
valve gasket is properly seated.
4. Install the valve cap with a new O-ring and tighten to
the torque value listed in Appendix B. Never re-use
old O-rings for re-assembly.
5. Check bolts and valve holddown screws after first
week of operation. Re-torque if necessary. See
Appendix B for torque values.
5.2 Heads
If the compressor is properly maintained, head
replacement is rarely required. The primary cause of
damage to a head is corrosion or the entry of solid debris
or liquid into the compression chamber. An improperly
stored compressor can cause corrosion on the inside
and damage the head. For proper storage procedures,
see chapter 6.
Many compressor repair services require removal of
the head. While the compressor is disassembled, avoid
leaving the compressor open more than a few hours.
All bare metal surfaces - including the head - should be
coated with a rust preventative.
When reassembling the compressor, make sure the
bolts are retightened to the torque specification shown
in Appendix B.
5.3 Piston Rings and Piston Ring
Expanders
Piston ring life will vary considerably from application to
application. Ring life will improve dramatically at lower
speeds and temperatures.
1. To replace the piston rings, depressurize the
compressor and purge if necessary.
2. Remove the head to gain access to the compressor
cylinder.
3. Loosen the piston head bolts. Remove the piston as
shown in figure 5.3A by pinching two loose bolts together.
Figure 5.3A: Piston removal
4. Piston rings and expanders may then be easily
removed and replaced. Corken recommends replacing
expanders when the piston rings are replaced.
NOTE: To determine if rings should be replaced, measure
the radial thickness and compare it to the chart in
Appendix C.
17

5.4 Pistons
1. To replace the pistons, depressurize the compressor
and purge if necessary.
2. Remove the compressor cylinder and head (see
section 5.2).
3. Remove the piston head by loosening and removing
the socket head bolts holding the piston head to the
piston platform (see figure 5.3A).
4. Next, remove the lock pin with a pair of needle nose
pliers. The locknut may then be removed and the
piston platform lifted off the end of the piston rod.
5. Check the thrust washer and shims for damage and
replace if necessary.
6. Before installing the new piston, measure the thickness
of the existing shims. The shims are placed between
the thrust washer and piston platform (see figures
5.4A and 5.4B).
“X” Piston
Clearance
Piston Head
Shims
Thrust
Washer
Lock Pin Piston
Bolt
Piston Locknut
Piston Ring Expander
Piston Ring
Piston
Platform
Cylinder
Piston Rod
Figure 5.4A: Piston cross section model sizes 91 through 491
7. Reinstall the piston platform with the same thickness
of shims as before, BUT DO NOT REINSTALL THE
LOCK PIN.
8. Install the cylinder and install the piston heads with
new piston rings and expanders.
9. Now measure dimension “X” shown in the illustration.
If this measurement does not fall within the tolerances
shown in Appendix B, remove the piston, adjust the
shims as necessary and remeasure the “X” dimension.
10.When the piston is properly shimmed, tighten the lock
nut to the torque value shown in Appendix B.
11. Now install a new lock pin and lock the piston nut
in place.
12.Install the piston head and tighten the socket head
bolts in an alternating sequence.
13.Reinstall the head (see section 5.2) and follow standard
startup procedure. (Note: Some compressors may
have self-locking nuts without roll pins.)
5.5 Piston Rod Packing
Adjustment
Piston rod packing should be adjusted or replaced
whenever leakage becomes noticeable. Start with one
quarter turn, run the compressor and check for leakage
after each quarter turn. NOTE: DO NOT overtighten.
Repeat this process until leakage is minimized. If the
adjusting nut bottoms out and leakage is still noticeable,
all packing must be replaced. Typically, it is a good idea
to replace piston rod packing and piston rings at the
same time. For instructions on replacing the piston rod
packing, see section 5.6.
NOTE: Packing that cannot be adjusted should be
replaced.
Crankcase
Adjustment screw
for lower packing
Inspection / nameplate
opening
Crosshead guide
Compressor
wrench
Figure 5.5A: Packing adjusting nuts.
5.6 Cylinder and Packing
If the compressor is properly maintained, the cylinder
is rarely replaced. The primary causes for a damaged
cylinder are corrosion and the entry of solid debris or
liquid into the compression chamber. An improperly
stored compressor can also cause corrosion in the
cylinder. See Chapter 6 for proper storage procedures.
If the cylinder wall is damaged or corroded, use a hone
to smooth the cylinder bore and then polish it to the
value shown in Appendix B. If more than .005 in. must
be removed to smooth the bore, replace the cylinder.
Cylinder liners or oversized rings are not available.
NOTE: Overboring the cylinder reduces the ring life.
Many repair services require removal of the cylinder.
While the compressor is disassembled, avoid leaving the
compressor open more than a few hours. All bare metal
18

surfaces - including the head - should be coated with a
rust preventative.
When reassembling the compressor, make sure the bolts
are torqued to the valves shown in Appendix B.
Packing Replacement Instructions
CAUTION: Bleed all pressure from the compressor and
piping, and purge (if necessary) BEFORE installing new
piston rod packing. After all repairs have been completed,
the unit should be pressure tested and checked for leaks
at all joints, gaskets, and O-ring connections. When the
compressor is used with toxic, dangerous, flammable or
explosive gases, use air or a dry inert gas such as nitrogen
to pressurize the compressor during the leak test.
For simplicity, heads, pistons, and inspection plates are
not shown. For specific construction details and actual
part numbers, consult the appendix in the back of this
IOM manual. Use the instructions below that apply to the
MODEL on the nameplate of the compressor and make
sure packing sets are arranged in the proper order as
shown in the parts details.
Cleanliness:
Prior to installation, inspect all parts for cleanliness
and visible defects. There should not be any scratches,
dings, porosity issues, or foreign materials on bearing
surfaces, sealing surfaces, and inner and outer
surfaces of the packing cartridge.
Workmanship:
Corken's compressor is a precision piece of equipment
with very close tolerances so treat it with care and never
force parts in or out.
5.6.1 Model D91 (D-Style) Compressor
Before starting these instructions, refer the parts details
for packing listed in Appendix E during disassembly
and assembly.
Disassembly of Packing (D-Style)
NOTE: Refer to the parts details pages while performing
the following procedures.
1. Depressurize and open the compressor.
2. Remove the head, piston, cylinder, and the inspection/
nameplate on the side of the crosshead guide.
3. Locate the cartridge holddown screw on top of the
crosshead guide and packing barrel. Remove the
cartridge holddown screw, spacer, and O-ring.
4. Reach through the opening behind the inspection/
nameplate on the side of the crosshead guide with a
screw driver and lightly pry up on the adjusting screw
on the bottom of the packing cartridge. The packing
cartridge should pop up (see Figure 5.5A).
5. Slowly rotate the flywheel until the packing cartridge
moves up and out of the crosshead guide.
6. Remove the packing cartridge, oil deflector ring (inside
cartridge), and second O-ring from the bottom of the
crosshead guide.
7. Starting with the top of the packing cartridge, remove
the top retainer ring, washer, spring, second washer,
old packing set, and third washer.
8. On the bottom of the packing cartridge, remove the
adjusting screw, old packing set, washer, spring and
second washer.
NOTE: The retainer ring does not need to be removed
unless it is being replaced.
Assembly of Packing (D-Style)
Clean and lightly oil the inside and outside of the
packing cartridge.
Lower packing set for Specs A and B:
NOTE: Make sure the new packing set is in the
proper orientation. Refer to the parts details listed
in Appendix E while following the instructions below.
Install the male, V-ring, and female packing one at a
time in the order shown. Push in each one completely
before adding the next ring.
1. Start at the bottom of the packing cartridge and insert
all parts in the following order:
1. Retainer ring
2. Washer
3. Spring
4. Washer
5. New packing
Male
packing
ring
Female
packing
ring
V-ring up
2. After installing the new packing set, install PTFE
locking device (part number 1192) into adjusting screw
and cut, leaving 1/8" exposed. Tighten adjusting
screw until plastic locking device engages the first
thread in the crosshead guide.
19

Upper packing set (Spec A or B):
NOTE: Make sure the new packing set is in the
proper orientation. Refer to the parts details listed
in Appendix E while following the instructions below.
Install the male, V-ring, and female packing one at a
time in the order shown. Push in each one completely
before adding the next ring.
1. Spec A only: Before inserting the packing assembly,
insert the oil wiper ring through the top of the packing
cartridge and lay loose until it is time to slide the
packing cartridge over the piston rod. Insert all
remaining parts in the following order:
1. Oil wiper ring
2. Retainer ring
3. Washer
4. New packing
set
5. Washer
6. Spring
7. Wa s h e r
8. Retainer ring
Male
packing
ring
Female
packing
ring
V-ring up
1. Spec B only: Before inserting the packing assembly,
insert the oil wiper ring through the top of the packing
cartridge and lay loose until it is time to slide the
packing cartridge over the crosshead guide. Insert all
remaining parts in the following order:
1. Oil wiper ring
2. Retainer ring
3. Washer
6. New packing
set
5. Washer
4. Spring
7. Wa s h e r
8. Retainer ring
Male
packing
ring
Female
packing
ring
V-ring
down
2. Oil piston rod and install the packing installation cone
(part number 4005) over the threaded end of the
piston rod.
3. Carefully slide the packing cartridge over the piston
rod; otherwise, the lips of the packing rings may be
damaged. NOTE: As the piston rod comes through
the bottom set of packing, make sure the oil wiper
ring is centered with the piston rod and pushes
through to the upper set of packing.
4. After the packing cartridge is properly seated, remove
packing installation cone.
5. Re-install the O-ring, spacer, and cartridge holddown
screw.
6. Install the crosshead guide O-ring, cylinder, piston,
O-ring, and head.
7. Rotate unit by hand to ensure proper assembly.
5.6.2 Model T91 (T-Style) Compressor
Before starting these instructions, refer the parts details
for packing listed in Appendix E during disassembly
and assembly.
Disassembly of Packing (T-Style)
NOTE: Refer to the parts details pages while performing
the following procedures.
1. Depressurize and open the compressor.
2. Remove the head, piston, cylinder, distance piece,
and the inspection/nameplate on the side of the
crosshead guide.
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