Corken D791, T791, T891, D891 Installation, Operation & Maintenance Manual
IJ110 E
Installation, Operation
& Maintenance Manual
D and T-Style Double-Acting Gas Compressors
Models D791, T791, D891 and T891
Model D891
Compressor Package
Model T891
Compressor
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 (such as NFPA Pamphlet 58 for LP-Gas and ANSI K61.1-1972 for Anhydrous Ammonia). (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.
Warning
Install, use and maintain this equipment according to Corken, Inc. instructions and all applicable federal, state, local
laws and codes, and NFPA Pamphlet 58 for LP-Gas or ANSI K61.1-1989 for Anhydrous Ammonia. Periodic inspection
and maintenance is essential.
Corken One Year Limited Warranty
Corken, Inc. warrants that its products will be free from defects in material and workmanship for a period of 12
months following date of purchase from Corken. Corken products which fail within the warranty period due to defects
in material or workmanship will be repaired or replaced at Corken’s option, when returned freight prepaid to: Corken,
Inc., 3805 N.W. 36th Street, Oklahoma City, Oklahoma 73112.
Parts subject to wear or abuse, such as mechanical seals, blades, piston rings, valves, and packing, and other
parts showing signs of abuse 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 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 WARRANTY 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. Such substances should be handled by experienced, trained personnel in compliance with governmental
and industrial safety standards.
Contacting The Factory
For your convenience, the model number and serial number are given on the compressor nameplate. Space is
provided below for you to keep a written record of this information.
Always include the model number and serial number when ordering parts.
Model No.
Serial No.
Date Purchased
Date Installed
Purchased From
Installed By
2
Table of Contents
FEATURES AND BENEFITS .....................................................................4
CHAPTER 1—INSTALLING YOUR CORKEN COMPRESSOR ..........................................5
1.1 Location .................................................................................5
1.2 Foundation ...............................................................................5
1.3 Piping ...................................................................................5
1.4 Liquid Trap ...............................................................................6
1.5 Driver Installation/Flywheels .................................................................6
1.6 Crankcase Lubrication ......................................................................6
1.7 Purging, Padding, Venting and Draining of Distance Pieces .........................................7
1.8 Relief Valves ..............................................................................8
1.9 Shutdown/Alarm Devices ....................................................................8
CHAPTER 2—STARTING UP YOUR CORKEN COMPRESSOR ........................................9
2.1 Inspection After Extended Storage ............................................................9
2.2 Flywheel and V-belt Alignment ...............................................................9
2.3 Crankcase Oil Pressure Adjustment ...........................................................9
2.4 Startup Check List ........................................................................10
CHAPTER 3—ROUTINE MAINTENANCE CHART ..................................................11
CHAPTER 4—ROUTINE SERVICE AND REPAIR PROCEDURES ......................................12
4.1 Valve s ..................................................................................12
4.2 Heads ..................................................................................13
4.3 Piston Rings and Piston Ring Expanders ......................................................13
4.4 Piston Replacement .......................................................................13
4.5 Piston Rod Packing Adjustment .............................................................14
4.6 Cylinder and Packing Replacement ..........................................................14
4.7 Bearing Replacement for Crankcase and Connecting Rod ........................................17
4.8 Oil Pump Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
CHAPTER 5—EXTENDED STORAGE PROCEDURES ...............................................19
APPENDICES
A. Vertical Double-Acting Model Number Identification Code .........................................20
B. Vertical Double-Acting Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
C. Outline Dimensions ........................................................................24
D. Troubleshooting ...........................................................................32
E. Assembly Details ..........................................................................34
3
Features and Benefits
High-efficiency valves:
Corken valves offer quiet operation and high
durability in oil-free gas applications.
Ductile iron construction:
All cylinders and heads are ductile iron for maximum
thermal shock endurance.
Self-lubricating PTFE piston rings:
Corken provides a variety of 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 packing
(Segmented)
Upper distance piece
Positively locked pistons:
Simple piston design allows end clearance to be
precisely set to provide maximum efficiency and
long life.
Self-lubricating piston rod seals:
Seals constructed of PTFE incorporating special
fillers to ensure no oil carry over and maximize
leakage control. Spring loaded seal design self
adjusts to compensate for normal wear.
Nitride-coated piston rods:
Impregnated nitride coating provides superior
corrosion and wear resistance.
Adjustable packing screw:
Ensures maximum sealing capacity during the life of
the packing (T791 and T891 models only).
Cast iron crossheads:
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.
Middle packing (V-ring)
Lower distance piece
Oil deflector ring
Lower packing (V-ring)
Construction details: Model T891 compressor
4
Chapter 1—Installing Your Corken Compressor
Ground level
Note: The depth of the concrete foundation will
1.1 Location
NOTE: Compressor must be installed in a well
ventilated area.
Corken compressors are designed and manufactured for
outdoor duty. For applications where the compressor will
be subjected to extreme conditions for extended periods
such as corrosive environments, arctic conditions, etc.,
consult Corken. Check local safety regulations and building
codes to assure installation will meet local safety standards.
Corken compressors handling toxic or flammable
gases such as LPG/NH3 should be located outdoors in
a well ventilated area. A minimum of 18 inches (45 cm)
clearance between the compressor and the nearest wall
is advised to make it accessible from all sides and to
provide unrestricted air flow for adequate cooling.
Noise:
Corken vertical compressors should not exceed an 85
DBA noise level when properly installed.
Concrete foundation
be at least the same diameter as the suction nozzle on
the compressor.
vary based on local soil conditions.
Figure 1.2: Recommended foundation details
Main beam (C-Beam)
Cross beam (H-Beam)
Hex nut
&
washer
3/4″ diameter “J” bolt
for Corken compressors
1.2 Foundation
Proper foundations are essential for a smooth running
compression system. Corken recommends the
compressor be attached to a concrete slab at least 8
inches thick with a 2 inch skirt around the circumference
of the steel structural skid. The steel structural skid
should be securely anchored into the foundation by 3/4
inch diameter “J” bolts that are 8 inches long. The total
mass of the foundation should be approximately twice
the weight of the compressor system (compressor,
baseplate, motor, etc.). See figure 1.2 for details.
For a more detailed explanation of a proper fou ndation
design, please refer to ED410, Important Instructions
for Compressor Foundation Design.
1.3 Piping
Proper piping design and installation is as important as a
proper foundation is to a smooth operating compressor.
Improper piping installation will result in undesirable
transmission of compressor vibration to the piping.
DO NOT SUPPORT PIPING WITH THE COMPRESSOR.
Unsupported piping is the most frequent cause of vibration
of the pipe. The best method to minimize transmission of
vibration from the compressor to the piping is to use
flexible connectors (see figure 1.3 for details).
If a restrictive device such as a valve, pressure regulator,
or back-check valve is to be installed in the compressor’s
suction line, care must be taken. The suction line volume
between the restrictive device and the compressor
suction nozzle must be at least ten times the swept
cylinder volume.
On liquefied gas applications such as LPG/NH3, it is of
extreme importance to prevent the entry of liquid into the
compressor. Installing a liquid trap on the inlet side will
prevent liquid from entering the compressor (see section 1.4).
It is of equal importance to protect the discharge side
of the compressor from liquid entry. This may be done
by installing a check valve on the discharge side of the
compressor and using a piping design that does not
allow liquid to gravity drain into the compressor.
Flexible connector
Pipe support
Steel structural skid
Concrete
foundation
Flexible connector
Pipe support
Pipe must be adequately sized to prevent excessive
pressure drop between the suction source and the
compressor as well as between the compressor and
the final discharge point. In most cases, piping should
Figure 1.3: Flexible connectors should be used to minimize
transmission of vibration to the piping.
5
For vapor recovery applications, be certain to install
a check valve on vapor lines discharging to the liquid
space of the tank.
All piping must be in accordance with the laws and codes
governing the service. In the United States, the following
codes apply:
For LP Gas—The National Fire Protection Association
Pamphlet No. 58, Standard for the Storage and Handling
of Liquefied Petroleum Gases.
For Ammonia—The American National Standards
Institute, Inc., K61.1-1989, Storage and Handling of
Anhydrous Ammonia.
Corken’s liquid trap provides the most thorough liquid
separation (see figure 1.4) and is ASME code stamped.
It contains two level switches, one for alarm and one
for shutdown. In some cases the alarm switch is used
to activate a dump valve (not included with trap) or
sound an alarm for the trap to be manually drained by
the operator. This trap also contains a mist pad. A mist
pad is a mesh of interwoven wire designed to remove
fine liquid mists. The ASME code trap is standard in
the 109B and 107B mounting configurations.
NOTE: The liquid 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.
Copies of these are available from NFPA, 60 Baterymarch
Street, Boston, Mass, 02110 and ANSI, 1430 Broadway, New
York, N.Y., 10018. Install, use and maintain this equipment
according to Corken instructions and all applicable federal,
state, and local laws and previously mentioned codes. Other
laws may apply in different industries and applications.
1.4 Liquid Trap
Compressors are designed to pressurize gas—not to
pump liquids. The entry of even a small amount of liquid
into the compressor will result in serious damage.
On liquefied gas applications, a liquid trap must be
used to prevent the entry of liquid into the compressor.
If your compressor is equipped with a liquid trap not
manufactured by Corken, make sure it is adequately
sized; otherwise it may not be able to remove the liquid
entrained in the suction stream.
1.5 Driver Installation/Flywheels
Corken vertical compressors may be driven by either
electric motors or combustion engines (gasoline, diesel,
natural gas, etc.).
Note: Never operate a reciprocating compressor without
a flywheel.
Drivers should be selected so the compressor operates
between 400 and 900 RPM. The unit must not be
operated without the flywheel or severe torsional
imbalances will result that could cause vibration and
a high horsepower requirement. The flywheel should
never be replaced by another pulley unless it has a
higher wk2 value than the flywheel.
Humid climates can cause problems with explosion
proof motors. The normal breathing of the motor and
alternating between being warm when running and cool
when stopped can cause moist air to be drawn into the
motor. This moist air will condense, and may eventually
add enough water inside the motor to cause it to fail. To
prevent this, make a practice of running 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. No motor
manufacturer will guarantee their explosion proof or totally
enclosed (TEFC) motor against damage from moisture.
Figure 1.4: ASME automatic liquid trap
For installation with engine drivers, thoroughly review
instructions from the engine manufacturer to assure the
unit is properly installed.
1.6 Crankcase Lubrication
To ensure proper lubrication of the crankcase parts
before startup, the crankcase should be filled through the
nameplate inspection opening.
6
Non-detergent oil is recommended for Corken vertical
compressors. Detergent oils tend to keep wear particles
and debris suspended in the oil, whereas non-detergent
oils let them settle in the bottom of the crankcase.
When non-detergent oils are not available, detergent
oils may usually be successfully substituted, although
compressors handling ammonia, amine, or imine gases are
notable exceptions. These gases react with the detergent
and cause the crankcase oil to become corrosive and
contaminated. Figures 1.6A and 1.6B show recommended
oil viscosities and crankcase capacities. Ensure oil is
compatible with the product being compressed.
Synthetic lubricants are generally not necessary. Please
consult your lubricant supplier if you are considering the
use of synthetic oil.
1.7 Purging, Padding, Venting and
Draining of Distance Pieces
The key to leakage control and oil-free operation of
Corken compressors is the distance piece. The distance
piece is integral with the crosshead guide and forms
the upper portion of it. Distance pieces are equipped
with tapped holes to allow purging, padding, venting,
and draining (see Figure 1.7). Proper connections to
and from these tapped holes are essential for optimum
compressor performance.
Corrosive gases should be prevented from entering the
crankcase, since even small amounts of gas leakage into
the crankcase can seriously contaminate the crankcase
oil. To prevent this contamination, the distance piece
may be purged, padded, or vented using a clean, noncorrosive gas like dry air or nitrogen.
Purging:
Purging of the distance piece controls leakage of process
gas to the atmosphere. Process gas leakage into the
distance piece is quickly diluted by the purge gas and
swept away. The purge gas should be vented to a safe
release area, flare, compressor’s inlet, or treatment
facility, depending on the gas and local regulations.
When purging, it is critical to maintain the proper
pressure loading across each set of packing. The higher
pressure should be on the open side of the “V”, which is
also the side with the spring.
Moisture, oil, or condensate can be removed from the
distance piece with the purge gas by using the lower
distance piece connection (drain location) as the purge
gas outlet connection.
Acceptable Crankcase Oil Products for Corken
Compressors
Constant Weight - Non-Detergent - R&O Inhibited
Oil product ISO VI SAE Ambient Temp.
Exxon®
TERESSTIC 100 95 30 65° - 100° F
68 95 20+ 45° - 70° F
46 95 20 35° - 50° F
Mobil®
RARUS 427 Reciprocating 100 95 30 65° - 100° F
Compressor Oil
DTE Oil Heavy Medium 64 95 20+ 45° - 100° F
Dectol R&O Oil 44 95 20 35° - 50° F
Conoco®
Dectol R&O Oil 100 98 30 35° - 50° F
68 97 20+ 45° - 70° F
46 99 20 35° - 50° F
Texaco®
Regal R&O Oil 100 92 30 65° - 100° F
68 97 20+ 45° - 70° F
46 102 20 35° - 50° F
Sun®
SunVis 900 Oil 100 100 30 65° - 100° F
68 100 20+ 45° - 70° F
46 100 20 35° - 50° F
Figure 1.6A: Oil selection chart
Upper
Distance
Piece
Drain Plug
Lower
Distance
Piece
Drain Plug
Compressor
Model
Approximate
Quarts
791, 891 7.0 6.6
Figure 1.6B: Oil capacity char t
Capacity
Liters
Figure 1.7: Distance piece details
7
Corken offers Purge Kits which include the necessary
regulator, valves, fittings, etc. Consult the factory or see
Important Instruction, item number IE210, for details.
devices should be selected to meet local code
requirements. Shutdown/alarm devices typically used on
Corken compressors are as follows:
Padding (Buffering):
If purging is not practical, the distance piece can be
pressurized with a static pressure. This is called padding
or buffering. Padding is done at a pressure above the
compressor’s suction pressure using a clean noncorrosive gas like dry air or nitrogen. The higher pressure
in the distance piece tends to reduce the process gas
leakage to the atmosphere. A small amount of purge gas
will likely get into the process gas. A pressure regulator
can be used to maintain proper distance piece pressure.
When padding, it is critical to maintain the proper
pressure loading across each set of packing. The higher
pressure should be on the open side of the “V”, which is
also the side with the spring.
Venting:
The distance piece can also simply be vented to an
appropriate release area, flare, or treatment facility. This
is sometimes useful for indoor installations.
Draining:
Since some oil will pass the lower packing set, regular
draining of the distance piece is essential to maintain
oil-free operation (See Figure 1.7). Corken recommends
draining the distance piece once a week for units in
continuous-duty operation. Installing a drain cock to the
distance piece drain will help simplify draining of the
distance piece.
Low Oil Pressure Switch—shuts down the unit if
crankcase oil pressure falls below 12 psi due to oil pump
failure or low oil level in crankcase.
High Temperature Switch—shuts down the unit if
the normal discharge temperature is exceeded. This is
strongly recommended for all applications. Typically,
the set point is about 30°F (-1°C) above the normal
discharge temperature.
Low Suction, High Discharge Pressure Switch—
shuts down the unit if inlet or outlet pressures are not
within preset limits.
Vibration Switch —shuts down the unit if vibration
becomes excessive. Recommended for units mounted
on portable skids.
Highly Corrosive Gases:
The compressor should be blocked from the system via
valves on the suction and discharge piping, then purged
with dry inert gas before being shut down. Experience
has proven this significantly lowers corrosion damage to
the machine.
1.8 Relief Valves
An appropriate relief valve must be installed on the
discharge side of the compressor. On Corken 107-style
mounted units, a relief valve should be fitted in the
piping between the compressor discharge and the fourway valve. Relief valves should be made of a material
compatible with the gas being compressed. Local codes
and regulations should be checked for specific relief
valve requirements. Also, relief valves may be required at
other points in the compressor’s system piping.
1.9 Shutdown/Alarm Devices
For many applications, shutdown/alarm switches will
provide worthwhile protection that may prevent serious
damage to your compressor system. All electronic
8
Chapter 2—Starting Up Your Corken Compressor
NOTE: Read this entire chapter, then proceed with
the startup checklist.
2.1 Inspection After
Extended Storage
If your compressor has been out of service for a long
period of time, you should verify that the cylinder bore
and valve areas are free of rust and other debris. For
valve and/or cylinder head removal instructions, refer to
chapter 4 of this IOM manual.
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 lubricant through
the nameplate inspection opening. 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.
Figure 2.2A: Flywheel installation
2.2 Flywheel and V-belt Alignment
Before working on the drive assembly, be sure that the
electric power is disconnected. When mounting new
belts, always make sure the driver and compressor are
close enough together to avoid forcing.
Improper belt tension and sheave alignment can cause
vibration, excessive belt wear and premature bearing
failures. Before operating your compressor, check
alignment of the V-grooves of the compressor flywheel
and driver sheave. Visual inspection often will indicate if
the belts are properly aligned, but use of a square is the
best method.
The flywheel is mounted on the shaft via a split, tapered
hub and three bolts (see figure 2.2A). These bolts should
be tightened in an even and progressive manner to the
specified torque values listed below. 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
SF 4.625 (11.7) 12-18 (1.7–2.5) 22 (3.1)
Diameter
in. (cm)
E 6.0 (15. 2) 30-36 (4.1–4.9) 22 (3.1)
J 7.25 (18.4) 75-81 (10.3 –11.1) 109 (15 .1)
Bolt Torque
Ft-lb (kg-meter)
Set Screw
Torque Ft-lb
(kg-meter)
Figure 2.2B: Belt tension
Tighten the belts so that 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 2.2B.
2.3 Crankcase Oil
Pressure Adjustment
Your Corken compr essor is equipped with an automatic ally
reversible gear type oil pump. It is essential to ensure
the pumping system is primed and the oil pressure is
properly adjusted in order to assure smooth operation.
Before starting your compressor, check and fill the
crankcase with the proper amount of lubricating oil.
When the compressor is first started, observe the
crankcase oil pressure gauge. If the gauge fails to
indicate pressure within 30 seconds, stop the machine.
Loosen the oil filter and remove the pressure gauge.
Restart the compressor and run it until oil comes out of
the pressure gauge opening or around the filter. Tighten
the filter and reinstall the gauge.
9
The oil pressure should be about 20 psi (1.4 bars) minimum
for normal service. If the compressor discharge pressure
is above 200 psi (14.8 bars), the oil pressure must be
maintained at a minimum of 25 psi (1.7 bars). A springloaded relief valve mounted on the bearing housing opposite
the flywheel regulates the oil pressure. As shown in figure
2.3, turn the adjusting screw clockwise to increase the
oil pressure and counterclockwise to lower it. Be sure to
loosen the adjusting screw locknut before trying to turn the
screw and retighten it after making any adjustment.
Oil pressure
relief valve and
adjustment screw
10. Rotate unit by hand and make certain there is no
wobble or play.
11. Check crankcase oil level.
12. Drain all liquid traps, separators, etc.
13. Verify proper electrical supply to motor and panel.
14. Check all gauges and confirm a zero level reading.
15. Test piping system for leaks.
16. Purge unit of air before pressurizing with gas.
17. Carefully check for any loose connections or bolts.
18. Remove all stray objects (rags, tools, etc.) from vicinity
of the unit.
Oil lter
Oil pressure gauge
Figure 2.3: Oil pressure adjustment
Breather cap
2.4 Startup Check List
Please verify each item on this list below before
starting your 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. Make certain actual operating conditions will match the
anticipated conditions.
3. Ensure line pressures are within cylinder pressure
ratings.
4. Clean out all piping.
5. Ensure all distance piece openings are tubed or
plugged as desired.
6. Check all mounting shims, cylinder and piping supports
to ensure that no undue twisting forces exist on the
compressor.
19. Confirm all valves are open or closed as required.
20. Double-check all of the above.
After Starting Compressor
1. Verify and note proper oil pressure. Shut down and
correct any problems immediately.
2. Observe noise and vibration levels. Correct immediately
if excessive.
3. Verify proper compressor speed.
4. Examine entire system for gas or oil leaks.
5. Note rotation direction.
6. Check start-up voltage drop, running amperage and
voltage at motor junction box (not at the starter).
7. Verify proper lubrication rate (lubed units only).
8. Test each shutdown device and record set points.
9. Test or confirm set point on all relief valves.
10. Check and record all temperatures, pressures and
volumes after 30 minutes and 1 hour.
11. After 1 hour running time, tighten all head bolts, valve
holddown bolts, and baseplate bolts. See Appendix B
for torque values.
7. Make certain strainer elements are in place and clean.
8. Make certain cylinder bore and valve areas are clean.
9. Check V-belt tension and alignment or drive alignment
on direct drive units.
10
Chapter 3—Routine Maintenance Chart
Item to Check Daily Weekly Monthly
Six
Months
Year l y
Crankcase oil pressure
Compressor discharge pressure
Overall visual check
Crankcase oil level
Drain liquid from accumulation points
3
2 2
Drain distance pieces
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
1
Piston ring life varies greatly, depending on application, gas, and operating pressures. Consult factory for additional recommendations for
your specific application.
2
Change oil every 2,200 hours of operation or every 6 months, whichever occurs 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.
3
Liquid traps should be drained prior to star tup.
1
1
11
Chapter 4—Routine Service and Repair Procedures
CAUTION: Always relieve pressure in the unit before
attempting any repairs. After repair, the unit should
be pressure tested and checked for leaks at all joints
and gasket surfaces.
If routine maintenance is performed as listed in chapter
3, repair service on your Corken gas compressor is
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.
4.1 Valves
Test the compressor valves by closing the inlet piping valves
while the unit is running; however, do not allow the machine
to operate in this way very long. If the inlet pressure gauge
does not drop to zero almost immediately, one or more
of the valves is probably damaged or dirty. However, it is
possible for the pressure gauge itself to be faulty.
In most cases, if a valve or gasket is leaking, it will create
more heat. On a single-stage compressor, you may be
able to compare the operating temperatures of the two
suction or discharge valves and cover plates to each
other. If a valve or gasket is leaking, it will have a higher
operating temperature. NOTE: This method will not be
suitable for two-stage compressors if each stage does
not have more than one valve.
Valve Inspection and/or Replacement
Before removing and inspecting the valves, begin by
depressurizing and purging (if necessary) the unit.
Disassembly
1. Unscrew the valve cap and remove the O-ring.
2. Remove the valve cover plate, O-ring and holddown
screw by removing each of the four bolts. The holddown
screw is easily removed with the special wrench
supplied with your compressor.
3. After the cover plate and O-ring have been removed,
the valve cage, valve assembly and valve gasket can
be lifted out.
4. Inspect valves for breakage, corrosion, debris and
scratches on the valve plate. In many cases, valves
may simply be cleaned and reinstalled. If the valves
show any damage, they should be repaired or replaced.
Replacement is usually preferable although repair parts
are available. If valve plates are replaced, seats should
also be lapped until they are perfectly smooth. If more
than .005 of an inch must be removed to achieve a
smooth surface, the valve should be discarded. If
plates are replaced without relapping the seat, rapid
wear and leakage may occur.
Assembly
Each suction and/or discharge valve assembly is easily
removed as a unit for inspection. If any part of the
valve assembly is broken, the valve assembly should be
replaced. See valve assembly parts details in the Appendix
E 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 valve gaskets
and O-rings should be used to assure a good seal.
The valve holddown assemblies and valve assemblies
on the following pages show the various specifications
used on models 791 and 891 compressors. Since more
than one suction valve arrangement is available for
each model of compressor, it is necessary to know your
complete model number so you can identify the valve
type specification number (see example listed below).
Model number D891AM 4 FBANSNN
Valve type = spec 4
1. Insert metal valve gasket into the suction and/or
discharge opening of the head. The metal valve
gasket should always be replaced when the valve
is reinstalled.
2. Insert cleaned or new valve assembly. Make sure the
suction and discharge valves are in the proper suction
and discharge opening in the head.
3. Insert the valve cage.
4. Replace the O-ring and valve cover plate. Torque the
bolts to the value listed in Appendix B. CAUTION: Be
sure the holddown screw has been removed.
5. To ensure the valve gasket is properly seated, insert
the holddown screw and tighten to the value listed
in Appendix B. NOTE: Gaskets and O-rings are not
normally reusable.
6. Replace the O-ring and valve cap and tighten to the
value listed in Appendix B.
7. Check bolts and valve holddown screws after first week
of operation. Re-torque if necessary. See Appendix B
for torque values.
12
4.2 Heads
A compressor cylinder cap and head very seldom requires
replacement if the compressor is properly maintained.
The primary cause of damage to a cylinder cap or head
is corrosion and the entry of solid debris or liquid into the
compression chamber. Improper storage can also result
in corrosion damage to the cylinder cap and heads (for
proper storage instructions see chapter 5).
Many compressor repair operations require removal of
the cylinder cap and heads. While the compressor is
disassembled, special care should be taken to avoid
damage or corrosion. If the compressor is to be left open
for more than a few hours, bare metal surfaces should be
coated with rust preventative.
When reassembling the compressor, make sure the
bolts are retightened per the torque values listed in
Appendix B.
rings should be replaced, measure the radial thickness
and compare it to the chart in Appendix B.
4.4 Piston Replacement
1. To replace the pistons, depressurize the compressor
and purge if necessary.
2. Remove the compressor cylinder cap, head and
cylinder (see section 4.2).
3. Remove the piston cap by loosening and removing the
socket head bolts holding the piston cap to the piston
(see figure 4.3).
4. Next, remove the lock nut and lift the piston off the end
of the piston rod.
5. Check the thrust washer and shims for damage and
replace if necessary.
4.3 Piston Rings and Piston
Ring Expanders
Figure 4.3: Piston cap removal
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 cylinder cap and heads to gain access to
the compressor cylinder.
3. Loosen the piston cap bolts and remove the piston
cap as shown in figure 4.3 by pinching two loose
bolts together.
4. Remove the lock nut and lift the piston off the end of
the piston rod.
5. Piston rings and expanders may then be easily
removed and replaced. Corken recommends replacing
expanders whenever rings are replaced. To determine if
6. Before installing the new piston, measure the thickness
of the existing shims.
7. Replace the cylinder.
8. Install the piston with the same thickness of shims as
before, and with new piston rings and expanders.
9. Now remove a lower valve and measure dimension
“Y” at the bottom of the piston shown in Appendix E—
Piston Assembly Details. If this measurement does not
fall within the tolerances listed in the piston assembly
details (Appendix E), remove the piston, adjust the
shims as necessary and remeasure the “Y” dimension.
10. When the piston is properly shimmed, tighten the lock
nut as shown in Appendix B.
11. Replace the piston cap with the same thickness of
shims as before.
12. Reinstall the piston cap and cylinder head.
13. Now remove an upper valve and measure dimension
“X” at the top of the piston shown in Appendix E—
Piston Assembly Details. If this measurement does
not fall within the tolerances in Appendix E, remove
the cylinder head and piston cap and adjust the shims
as necessary. Repeat the steps and measure the “X”
dimension again.
14. When the piston cap is properly shimmed, tighten the
socket head bolts in an alternating sequence. Torque
socket head bolt to the values listed in Appendix B.
15. Replace the previously removed valves. Best results
will be obtained if new valve gaskets are used.
16. Follow standard startup procedures.
13
4.5 Piston Rod Packing Adjustment
Piston rod packing should be adjusted or replaced
whenever leakage becomes noticeable. Adjust packing
by tightening packing nuts as shown in Figure 4.5.
Packing Replacement Instructions
For specific construction details and actual part numbers,
consult Appendix E in the back of this Installation,
Operation & Maintenance (IOM) manual. Use instructions
below and on the following pages that apply to the
MODEL and SERIAL NUMBER of your compressor. Be
careful to arrange packing sets in the proper order.
CAUTION: Before installing the new piston rod
packing, bleed all pressure from the compressor and
piping and purge if necessary. After the new piston
rod packing has been installed, the unit should be
pressure tested and checked for leaks at all joints
and gasket surfaces. When the compressor is being
used with toxic, dangerous, flammable or explosive
gases, this pressure and leak testing should be done
with air or a dry, inert gas such as nitrogen.
Figure 4.5: Packing adjusting nuts (models T791 and T891 only)
NOTE: Compressor models D791 and D891 do not
have adjustable packing nuts so the packing sets on
models D791 and D891 are not adjustable, the piston
rod packing should be replaced whenever leakage
becomes noticeable.
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 4.6.
4.6 Cylinder and Packing
Replacement
Cylinders very seldom require replacement if the
compressor is properly maintained. The primary cause
of damage to cylinders is corrosion and the entry of
solid debris or liquid into the compression chamber.
Improper storage can also result in corrosion damage to
cylinder (for proper storage instructions see chapter 5).
If the cylinder does become 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 of
an inch must be removed to smooth the bore, replace
the cylinder. Cylinder liners and oversized rings are
not available. OVERBORING THE CYLINDER WILL
RESULT IN GREATLY REDUCED RING LIFE.
Many compressor repair operations require removal of
the cylinder. While the compressor is disassembled,
special care should be taken to avoid damage or
corrosion to the cylinder. If the compressor is to be left
open for more than a few hours, bare metal surfaces
should be coated with rust preventative.
When reassembling the compressor, make sure the
bolts are retightened using the torque values listed in
Appendix B.
Cleanliness:
Sealing a reciprocating piston rod is a very difficult
task. Keep all parts, tools and your hands clean during
installation. Your new packing needs every chance it can
get, so keep it clean.
Workmanship:
Your Corken compressor is a precision piece of equipment
with very close tolerances. Treat it as such. Never beat
on it to get parts in or out.
Packing Configuration
The packing for these compressors includes segmented
packing in a packing barrel at the lower end of the
cylinder and V-ring packing in a packing box cartridge
below the segmented packing.
Refer to Appendix E for packing assembly details. Note
the arrangement of the particular packing sets for the
model of machine that you have.
4.6.1 Model D791 and D891 Compressors (D-Style)
On Models D791 and D891, there is one set of V-ring
packing in a packing box cartridge attached to the
packing barrel. The packing box cartridge holds the
segmented packing inside the barrel.
Disassembly of Packing (D-Style)
1. Depressurize and open the compressor.
2. Remove the cylinder cap, heads, pistons and cylinder.
3. Remove the packing barrels by prying upwardly under
each one and lifting entire packing barrel/cartridge
assembly up from piston rod.
14
4. Remove the four socket head screws that hold the
packing box cartridge to the barrel.
a. Clean the segmented packing cups and the area
inside the packing barrel.
5. Remove segmented packing and cups from barrel.
6. Remove lower retainer ring, washers, packing spring
and old V-ring packing from packing box cartridge.
Assembly of Packing (D-Style)
1. Replace packing as required. The segmented packing
and cups are located in the packing barrel while the
V-ring packing is located in the packing box cartridge.
NOTE: Always use new O-rings when replacing
the packing.
2. V-ring packing set:
NOTE: The instructions below are for packing
specification “J”. Depending on the packing
specification used in your compressor, the order
of assembly for the packing rings, V-ring packing,
washers and packing spring will vary. Refer to
Appendix E to view the V-ring packing arrangements
and follow the order of assembly and V-ring direction.
If you do not know the packing arrangement used
in your compressor, refer to the model number
identification codes listed in Appendix A.
b. Insert the segmented packing cups, segmented
packing pairs and backup rings one at a time in
the order shown in Appendix E.
c. Reattach the packing box cartridge to the packing
barrel using the four socket head screws.
4. Install three O-rings on the packing barrel and packing
box cartridge as shown in the D-Style Crosshead
Guide Assembly Details in Appendix E.
5. Install packing installation cone part number 3905 over
the threaded end of the piston rod.
6. Carefully install barrel/cartridge assemblies over the
piston rods, noting the alignment of the barrels as they sit
on the crosshead guide. The valve scallops on the barrels
must align properly with the valves in the cylinder.
7. Remove packing installation cone.
8. Replace pistons, cylinders, heads and cylinder cap. See
details in Section 4.4 for proper assembly of pistons.
9. Rotate unit by hand to ensure proper assembly.
a. Clean and lightly oil the packing area inside the
packing box cartridge.
b. Insert the oil deflector ring through the bottom
opening of the packing box cartridge.
c. Insert the first retainer ring followed by a washer.
d. Insert the packing spring followed by another
wa sher.
e. Insert a male packing ring followed by four V-rings
and one female packing ring. NOTE: Insert
packing rings and V-rings one at a time. Refer
to Appendix E for the proper direction of the
male and female packing rings and V-rings.
f. Lastly, insert the final washer. Push in on the
washer and install the second retainer ring.
3. Segmented packing:
NOTE: The instructions below are for packing
specification “J”. Depending on the packing
specification used in your compressor, the order of
assembly for the segmented packing arrangement
(radial or tangent) will vary. Refer to Appendix E
to view the segmented packing arrangements. If
you do not know the packing arrangement used
in your compressor, refer to the model number
identification codes listed in Appendix A.
4.6.2 Model T791 and T891 Compressors (T-Style)
On Models T791 and T891 there are two sets of V-ring
packing in a separate packing box cartridge held in
the crosshead guide by a cartridge holddown screw. A
packing adapter holds the segmented packing inside the
packing barrel.
Disassembly of Packing (T-Style)
1. Depressurize and open the compressor.
2. Remove the cylinder cap, heads, pistons and cylinder.
3. Remove the packing barrels.
4. Remove the four socket head screws that hold packing
adapter to the barrel.
5. Remove segmented packing and cups from barrel.
6. Remove cartridge holddown screws with special
wrench supplied with the compressor, and remove
cages and packing box cartridges.
7. On the lower V-ring packing set, remove adjusting
screw, washers, packing spring and old packing from
each packing box cartridge.
8. On the middle V-ring packing set, remove upper
retainer ring, washers, packing spring and old packing
from each packing box cartridge.
15
Assembly of Packing (T-Style)
1. Replace packing as required. The segmented packing
and cups are located in the packing barrel while the
V-ring packing is located in the packing box cartridge.
NOTE: Always use new O-rings when replacing
the packing.
2. Lower V-ring packing set:
NOTE: The instructions below are for packing
specification “G”. Depending on the packing
specification used in your compressor, the
order of assembly for the packing rings, V-ring
packing, washers and packing spring will vary.
Refer to Appendix E to view the V-ring packing
arrangements and follow the order of assembly
and V-ring direction. If you do not know the packing
arrangement used in your compressor, refer to
the model number identification codes listed in
Appendix A.
e. Lastly, push in on the washer and insert the third
retainer ring.
f. Install two O-rings on the packing box cartridge as
shown in the T-Style Crosshead Guide Assembly
Details in Appendix E.
4. Segmented packing:
NOTE: The instructions below are for packing
specification “G”. Depending on the packing
specification used in your compressor, the order of
assembly for the segmented packing arrangement
(radial or tangent) will vary. Refer to Appendix E
to view the segmented packing arrangements. If
you do not know the packing arrangement used
in your compressor, refer to the model number
identification codes listed in Appendix A.
a. Clean the segmented packing cups and the area
inside the packing barrel.
a. Clean and lightly oil the packing area inside the
packing box cartridge.
b. Insert the first retainer ring followed by a washer
through the bottom of the packing box cartridge.
c. Insert the packing spring followed by another
wa sher.
d. Insert a male packing ring followed by four V-rings
and one female packing ring. NOTE: Insert
packing rings and V-rings one at a time. Refer
to Appendix E for the proper direction of the
packing rings and V-rings.
e. Lastly, install and tightened the adjusting screw
until the PTFE locking device located on the side
of the adjusting screw is engaged with the first
thread of the packing box cartridge. DO NOT OVER
TIGHTEN! The PTFE locking device should engage
(slightly bent) the first thread but not break off.
3. Middle V-ring packing set:
a. Clean and lightly oil the packing area inside the
packing box cartridge.
b. Insert the second retainer ring followed by a washer
through the top of the packing box cartridge.
c. Insert a female packing ring followed by four
V-rings and one male packing ring. NOTE: Insert
packing rings and V-rings one at a time. Refer
to Appendix E for the proper direction of the
male and female packing rings and V-rings.
d. Insert a washer and a packing spring followed by
another washer.
b. Insert the segmented packing cups, segmented
packing pairs and backup rings one at a time in
the order shown in Appendix E.
c. Reattach the packing adapter to the packing barrel
using the four socket head screws.
d. Install two O-rings on the packing barrel as shown
in the T-Style Crosshead Guide Assembly Details
in Appendix E.
5. Install packing installation cone part number 3905 over
the threaded end of the piston rod.
6. Before installing the packing box cartridge over the
packing cone and piston rod, you must insert the oil
deflector ring through the side opening of the packing
box cartridge. The oil deflector ring should rest on top
of the lower packing set. Make sure the oil deflector
ring is centered over the piston rod opening before
sliding packing cartridge over the installation cone and
piston rod.
7. Install cages.
8. Install and tighten holddown screws with special
wrench.
9. Install packing barrels, noting the alignment of the
barrels as they sit on the crosshead guide. The valve
scallops on the barrels must align properly with the
valves in the cylinder.
10. Remove packing installation cone.
11. Replace cylinder, pistons, heads and cylinder cap. See
details in Section 4.4 for proper assembly of pistons.
12. Rotate unit by hand to ensure proper assembly.
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