background image

 

 
 
 
 

 

 

Marathon

®

 CP-8 Cryopump 

 

Technical Manual

 

 
 
 
 
 
 
 
 
 
 
 

Sumitomo (SHI) Cryogenics of America, Inc. 

1833 Vultee Street 

Allentown, PA  18103-4783 

U.S.A. 

 
 
 
 

 

 
 
 
 
 
 
 
 
 
 
 
 
 

Revision D:  April 2012 

 

 

 

 

 

 

 

        266810A 

 

Summary of Contents for Marathon CP-8

Page 1: ...Marathon CP 8 Cryopump Technical Manual Sumitomo SHI Cryogenics of America Inc 1833 Vultee Street Allentown PA 18103 4783 U S A Revision D April 2012 266810A ...

Page 2: ......

Page 3: ...sor Connector for MCC 12 Alternate Single Silicon Diode Temperature Sensor 12 Compressor 12 Refrigerant Quality 12 Adapter Fittings Optional Accessories 13 Environmental Requirements 13 Maintenance Interval 13 Supplier Name and Address 13 Regulatory Compliance 14 INSTALLATION 15 Introduction 15 Unpacking Inspection and Pressure Check 15 Cryopump Lifting Instructions 17 Compressor Position 18 Compr...

Page 4: ...Remove the Cryopump from the Vacuum Chamber 41 Disconnect the Gas Lines 42 Cryopanel Maintenance 43 Disassemble and Clean the Cryopanels 44 Reassemble the Cryopanels 44 Clean the Relief Valve 45 Clean the Relief Valve s Filter Screen 45 Rupture Disc 45 Standard Silicon Diode 46 Functional Check 46 Optional Dual Silicon Diode used with a Marathon Cryopump Controller MCC 46 Functional Check of the D...

Page 5: ...are Sensor Cable 20 Figure 8 Cryopump Mounting 21 Figure 9 Attach Identification Label 22 Figure 10 Connect Gas Line to Compressor or Cryopump 23 Figure 11a Relief Valve Vent Connection Detail 25 Figure 11b Vent Adapter Optional 26 Figure 12 Evacuate the Cryopump Vacuum Enclosure 31 Figure 13 Evacuate the Vacuum Chamber and Cool Down the Cryopump 31 Figure 14 Steady State Cryopumping 32 Figure 15 ...

Page 6: ...iv This page is intentionally blank ...

Page 7: ...ions or conditions that can result in damage to the equipment or in abnormal performance NOTE NOTES give important additional information explanations or recommendations related to the procedure or discussion presented WARNINGS and CAUTIONS appear in rectangles in the text where they are applicable Before installing and operating this equipment be sure to read the Safety section in the General Tec...

Page 8: ...2 This page is intentionally blank ...

Page 9: ...td 3 Hamilton Close Houndmills Industrial Estate Basingstoke Hampshire RG21 6YT United Kingdom TEL 44 1256 853333 FAX 44 1256 471507 Sumitomo SHI Cryogenics of Europe GmbH Daimlerweg 5a D 64293 Darmstadt Germany TEL 49 6151 860 610 FAX 49 6151 800 252 Asia Sumitomo Heavy Industries Ltd Service Section Cryogenics Division 2 1 1 Yato Cho Nishitokyo City Tokyo 188 8585 Japan TEL 81 424 68 4265 FAX 81...

Page 10: ...4 This page is intentionally blank ...

Page 11: ...s of typical cryopump systems helium compressor cryopump s gas lines cold head cable s optional gas manifold for connecting multiple cryopumps to the compressor The Marathon CP 8 Cryopump uses a model CH 204S Cold Head Both are designed to metric standards The information in this manual pertains only to the Marathon CP 8 Cryopump System Pressures are stated as gauge not absolute Psig is pounds per...

Page 12: ... Pump 3 Vent Relief Valve to a Safe Location 4 To Temperature Monitor Gas Lines Cold Head Cable Marathon CP 8 Cryopump Helium Compressor Gas Lines Cold Head Cables Helium Compressor 2 or 3 Marathon CP 8 Cryopumps 2 1 3 4 Multiple Cryopump Application S R Single Cryopump Application ...

Page 13: ...tage of the cold head which operates between 10 and 20 K cools the inner cryopanel that freezes out nitrogen oxygen and argon after they pass through the louver On the inside of the cold cryopanel charcoal adsorbs gases that will not freeze at second stage temperatures A cryopump can reduce the pressure in a vacuum chamber to very low levels Figure 2 shows the relationship between the equilibrium ...

Page 14: ...8 This page is intentionally blank ...

Page 15: ...to 20K Nitrogen Oxygen Argon First Stage Cryopanel 50K to 90K Vacuum Enclosure Hydrogen Adsorber on Charcoal Cold Head Cylinder Pumpout Port Purge Port Relief Valve Port Gas Return Coupling Gas Supply Coupling Cold Head Cold Head Receptacle Mounting Flange Louver Water Variable Orifice 135 from Gas Return Coupling ...

Page 16: ...s 124 kPa 18 psia Pumpout Port Allows the operator to connect a roughing pump to the cryopump for evacuating the cryopump vacuum enclosure Close the vacuum valve after the initial evacuation Second Stage Cryopanel Captures nitrogen oxygen and argon by solidification on copper surfaces and captures hydrogen and helium by adsorption in charcoal Temperature Sensors Two types of sensors encapsulated s...

Page 17: ...Connection See Figure 9b Temperature Sensor Port 5 pin electrical receptacle Gas Line Couplings Supply and return helium gas connections are size 8 male 8M Aeroquip self sealing couplings Cold Head Cable Receptacle The receptacle is a 4 pin 8 shell Detoronics connector Standard Single Silicon Diode Temperature Sensor and Optional Dual Temperature Sensor for MCC With a 10 µA DC current excitation t...

Page 18: ... cryopump has the following voltage temperature characteristics Temperature K Output Volts Temperature K Output Volts 10 1 392 24 1 099 12 1 355 40 1 061 14 1 299 60 1 007 16 1 226 80 0 952 18 1 114 100 0 898 20 1 110 200 0 626 22 1 104 300 0 352 Accuracy 2 0 K for 16 K to 26 K 4 0 K for 26 K to 120 K 5 0 K for 120 K to 300 K Compressor For Electrical Characteristics Cooling Requirements Helium Ga...

Page 19: ...ale Aeroquip coupling Figure 4 Typical Adapter Fitting Environmental Requirements Operating Environment Storage Ambient Temperature 4 C to 40 C 23 C to 65 C 40 F to 104 F 10 F to 149 F Relative Humidity 30 to 70 10 to 90 Atmospheric Pressure 52 kPa to 110 kPa 52 kPa to 110 kPa 7 5 psia to 16 0 psia 7 5 psia to 16 0 psia Magnetic Field Limits 150 gauss Maintenance Interval Cold head valve and displ...

Page 20: ... Representative s Address 3 Hamilton Close Houndmills Industrial Estate Basingstoke Hampshire RG21 6YT United Kingdom Type of Equipment Cryogenic Refrigeration Systems Application of Council Directives 2006 42 EC and 2004 108 EC Product Referenced Standards Marathon CP 8 Cryopump EN 61326 1 2006 Clause 7 2 emissions requirements EN 61326 1 2006 Table 2 immunity requirements I the undersigned hereb...

Page 21: ...on delivery inspect all shipping containers for damage 1 1 If there is any evidence of external damage to any of the containers be sure the carrier s driver sees the damage Note it on the shipping documents and have the driver acknowledge it by his initials on the delivery receipt 1 2 Remove all components from their shipping containers and inspect them for damage If there was external damage to t...

Page 22: ...esult in serious injury or death AVOID CONTAMINATION When checking the compressor for shipping damage do not connect gas lines and cryopump The components may become contaminated with compressor oil Connect power and water to the compressor See the next sections Compressor Positioning and Compressor Checkout Test run the compressor for two 2 hours minimum If there are no problems during this time ...

Page 23: ...Lifting Instructions PREVENT EQUIPMENT DAMAGE Always remove heater blanket before attempting to lift or move the cryopump PREVENT EQUIPMENT DAMAGE DO NOT lift or move the cryopump using the purge or rough valve and their piping the relief valve assembly the temperature sensor connector or the gas line connectors See Figure 5 Figure 5 Restricted Areas When Lifting Cryopump 1 Using properly rated co...

Page 24: ...he gauges Be sure the compressor cannot inadvertently roll from its location particularly if it is elevated Allow at least 610 mm 24 clearance from the front rear and from both sides of the compressor for maintenance Compressor Checkout The compressor should be operated before being connected to the system 1 Use plastic tubing nuts and ferrules from the compressor installation kit to connect coola...

Page 25: ...he compressor s power cord plug or at the customer s disconnect switch Reconnect the power and restart the compressor 4 When the pressures stabilize read the supply pressure gauge The pressure should match the operating supply pressure in the Specifications section of the Compressor manual 5 Run the compressor for 10 minutes then stop This completes the checkout of the compressor Remove the Existi...

Page 26: ...o another socket 3 Slip the cable clamp over the end of the cable 4 From the backside of the plug body insert the socket with the positive lead into the 4 position in the rubber isolator Use a small screwdriver to push the socket below the level of the rubber until it seats 5 Insert the socket with the negative lead into the 3 position in the rubber isolator as described above 6 Thread the cable c...

Page 27: ...to the isolation gate valve on the vacuum chamber Install the Gas Manifolds if used Tools required Open end wrenches 1 1 1 8 and 1 3 16 NOTE Gas manifolds are available from SCAI to be connected to the compressor s gas couplings when the compressor powers multiple cryopumps 1 Locate the gas manifolds and their installation drawing Remove the dust plugs from the female Aeroquip couplings 2 Remove t...

Page 28: ...ds having 99 995 pure helium gas available at the installation site in case gas needs to be added to the system See Refrigerant Quality in Specifications in this manual 1 SCAI furnishes identification labels for the customer to attach to the gas lines Before installing the gas lines identify each with its appropriate label SUPPLY color coded red or RETURN color coded green by applying the label ad...

Page 29: ...to the supply coupling on the compressor or to the supply gas manifold Use two wrenches to tighten the coupling See Figure 10 Torque all couplings to 4 85 0 7 kgf m 35 5 ft lbs Tighten each coupling before proceeding to the next one Figure 10 Connect a Gas Line to the Compressor or Cryopump 6 Connect the return gas line to the return coupling on the compressor or to the return gas manifold 7 Remov...

Page 30: ... pressurized gas lines and other pressurized equipment 2 Connect the roughing line to the pumpout port Use a pipe or hose with an inside diameter as large as possible to maximize pumping speed The roughing line should contain a valve to close to isolate the roughing pump 3 Connect a temperature sensor cable from the temperature controller indicator to the temperature sensor connector EXPLOSION HAZ...

Page 31: ...ows a typical stop configuration An aluminum vent adapter for mounting to the relief valve port provides a NW40 flange for connecting a vent line The optional vent adapter is SCAI P N 260936B See Figure 9b 5 The vent line connected to the vent adapter must have a minimum inside diameter of 22 mm 0 88 and a maximum length of 3 0 m 10 feet and be connected to a vent manifold at atmospheric pressure ...

Page 32: ...atic diagram in the Compressor manual 3 Connect the other end of the cable to the accessory receptacle on the compressor 4 Switch on the power to the compressor The system can now be operated from the compressor or from the remote switch When using the remote switch the power switch on the compressor must be in the stop position 5 To verify that the cable installation is correct close the remote s...

Page 33: ... MCC 266686A1 Hydrogen vapor bulb temperature sensor bottom mount 263387C Relief valve elbow 262889A2 Blanket heater 250 watts 208 V 1 insulated 130 thermostat with mounting springs 267358C HIGH PRESSURE GAS HAZARD A relief valve or a rupture disc must always be installed on a cryopump The cryopump will be preconfigured at the factory to customer s requirements so no assembly of components is nece...

Page 34: ...Maintenance section 2 Remove the old copper gasket Slip a new copper gasket over the end of the temperature probe 3 Feed the sensor probe through the utility port into the cryopump enclosure 4 Remove the screw from the sensor probe Insert the screw through the countersunk hole on the face of the cold head s second stage heat station Diode assemblies for use with a Marathon Cryopump Controller have...

Page 35: ...c welding Popping and or cracking sounds like from arcing or welding during regeneration indicate ozone s presence If ozone is present a Reduce the oxygen content in the process gas mixture to the lowest level allowable b Follow all of the above precautions for oxygen The cryopump must be regenerated daily Contact a SCAI Service Center if you have any questions Prestart Check 1 Check that the cool...

Page 36: ...relief devices Material failure and resulting pressure release can cause serious injury EXPLOSION HAZARD AVOID INJURY If flammable corrosive or toxic gases are cryopumped a vent pipe must be connected to the relief valve or the rupture disc outlet Vent to a safe location EXPLOSION HAZARD AVOID INJURY Provide a fail safe automatic shutdown of all ignition sources when the cryopump shuts down For ex...

Page 37: ...ump cools down Discussed later crossover pressure is the pressure at which changing from rough pumping to cryopumping occurs As the vacuum chamber is being rough pumped residual gases in the vacuum enclosure are cryopumped Pressure around the cryopump drops to low levels before the cryopump reaches minimum temperature Cooldown time to 20 K for the Marathon CP 8 Cryopump is approximately 75 minutes...

Page 38: ... on 60 Hz electrical service may damage the displacer The orifice in a cold head labeled Factory set for 50 60 Hz operation needs no adjustment The variable orifice has been set at the factory for maximum refrigeration capacity The orifice is located in the edge of the valve motor base 135º from the return gas coupling and in the same horizontal plane as the return gas coupling See Figure 3 In mos...

Page 39: ... vacuum chamber As a check if the volume of gases in the main chamber does not raise the second stage temperature above 20 K then the crossover pressure is correct Regeneration Regeneration removes the frozen trapped gases from the cryopump and returns it to its full rated capacity The process comprises four phases warm up purge evacuate and cooldown Because the time between regenerations depends ...

Page 40: ...ety and accelerated warm up the use of nitrogen to purge the cryopanels during warm up is recommended Inject warm dry nitrogen gas directly onto the charcoal coating through the N2 purge port Nitrogen purging hastens regeneration and displaces adsorbed gases from the charcoal Nitrogen purging dilutes hydrogen oxygen and other reactive or poisonous gases Vent all purged gases safely through the pre...

Page 41: ...and oil backstreaming into the cryopump Before proceeding with the cooldown phase SCAI recommends checking the rate of pressure rise in the cryopump vacuum enclosure Close the roughing valve and the purge valve if open Monitor the pressure in the cryopump vacuum enclosure If the pressure rises faster than 1 x 10 2 torr min 10 microns minute rough pump the cryopump for an additional 10 minutes and ...

Page 42: ...he power shuts off for the pump to warm up and release enough gas to break the vacuum If the pressure has risen to 1 x 10 2 torr the cryopump must be warmed up and regenerated after power has been restored In most applications the operator establishes an upper pressure or temperature limit for operation that designates when the cryopump should be regenerated or when it should be allowed to recool ...

Page 43: ...valve to isolate the cryopump from the main vacuum chamber 2 Disconnect the appropriate cold head cable from the compressor The cryopump will stop 3 Expect gas release through the disconnected cryopump s pressure relief valve as described in the section Regeneration Warm Up Phase 4 Begin nitrogen gas purge of the disconnected cryopump as described in Regeneration Purge Phase to dilute hazardous ga...

Page 44: ...38 This page is intentionally blank ...

Page 45: ...osed to hazardous materials it is generally possible to render the pump safe for handling by a combination of inert gas purging removal and proper disposal of the 2nd stage cryopanel and cleaning of the surfaces of the cryopump that have been exposed to hazardous materials Decontamination and cleaning of the exposed surfaces must be accomplished in accordance with methods recommended in Federal Go...

Page 46: ...pling with enough force to cause serious injury EXPLOSION HAZARD AVOID INJURY Disconnect the gas lines from the cold head only when the cold head is stopped and warmed to room temperature Disconnecting the cold head while it is cold can create excessively high internal pressure as the gas warms Material failure and uncontrolled pressure release can cause serious injury EXPLOSION HAZARD AVOID INJUR...

Page 47: ...sket seal on the male half of each Aeroquip coupling Be sure the gasket seal is in place and the sealing surfaces on both the male and female halves are clean before connecting Replace the gasket seal if it is damaged or missing Keep the gas line couplings aligned when making or breaking a coupling connection Leaks can occur due to the weight of the gas line or due to a sharp bend near the connect...

Page 48: ... can cause serious injury AVOID INJURY Use two wrenches when disconnecting a gas line coupling to avoid loosening the cold head coupling Gas pressure can project the coupling with enough force to cause serious injury AVOID GAS LEAKS Keep the gas line couplings aligned when making or breaking a coupling connection Leaks can occur due to the weight of the gas line or due to a sharp bend near the con...

Page 49: ...ontaminated the panel must be replaced The charcoal may degrade substantially if the minimum pressure is higher than normal 1 x 10 4 torr or 0 1 microns of mercury during cryopumping If the charcoal has degraded replace the second stage cryopanel EXPLOSION HAZARD AVOID INJURY Cryopumped gases are retained only while the cryopump is cold Cryopumped gases may be toxic flammable or may produce high p...

Page 50: ...e indium gasket Inspect the indium gasket 4 Clean the nickel plated surfaces of the cryopanels and the louver with a solvent recommended for oil and grease removal in high vacuum service Clean painted surfaces by wiping with a clean dry contaminant free cloth Do not use solvents to clean painted surfaces 5 Replace the cryopanels if they are corroded or contaminated with oil This completes the proc...

Page 51: ...s with a dry clean lint free cloth Examine both and replace them if they are damaged Be sure the seating O ring has no dirt inclusions embedded in its surface Apply vacuum grease sparingly to the O rings Use only enough grease to give a shiny appearance to the O rings Remove excess grease with a dry clean lint free cloth 5 Reassemble the valve Reinstall it turning the knurled cap only hand tight C...

Page 52: ...urce 10 microamps 1 Digital voltmeter 3 1 2 digits To check if the diode is functioning properly 1 Connect the positive side of a 10 microamp DC current source to pin A of the diode connector Connect the negative side to pin D See Figure 18 2 Measure the output voltage across the same two pins The output voltage should range from 0 54 to 0 59 volts DC at room temperature 20 to 24 C 68 to 76 F If t...

Page 53: ...ing properly 1 Connect the positive side of a 10 microamp DC current source to pin H of the diode connector Connect the negative side to pin F See Figure 19 2 Measure the output voltage across the same two pins The output voltage should range from 0 54 to 0 59 volts DC at room temperature 20 to 24 C 68 to 76 F If the voltage is outside this range replace the dual diode First Stage Connections Seco...

Page 54: ...he vacuum enclosure Carefully withdraw the cold head from the cryopump Cold Head Installation into the Cryopump NOTE The seal between the cold head s warm flange and the flange of the vacuum enclosure may be either an O ring or a metal seal Choose the appropriate procedure from step 1 below Procedure for cold head installation 1 Examine the O ring between the cold head s warm flange and the flange...

Page 55: ...ssors with a charge vent fitting use one wrench to support the body of the charge vent fitting while removing or installing the dust plug or the charge line nut with the other wrench Do not over torque AVOID CONTAMINATION Follow charging and venting procedure to prevent reversed flow of system gas Reversed flow can result in contamination of the system with compressor oil Do not charge through the...

Page 56: ...ead 3 Locate two adapter fittings P N 255919B2 optional accessories available from SCAI NOTE Omit Step 4 when the cold head has not been removed from the vacuum enclosure 4 Stand the cold head on a work surface resting on its valve motor housing 5 Connect an adapter fitting to the supply red coupling on the cold head 6 Connect another adapter fitting to the return green coupling of the cold head 7...

Page 57: ...qualization pressure specified for the compressor being used in this system 19 Close the charge valve on the adapter fitting 20 Close the gas cylinder valve 21 Disconnect the charge line from the adapter fitting Store the charge line to keep it clean 22 Remove the adapter fittings from the cold head supply and return couplings 23 Disconnect the cold head cable from the cold head 24 Reinstall the c...

Page 58: ...or sealing Figure 20 identifies points at which leaks in a cold head may be detected A motor housing to base or motor base to warm flange leak indicates a defective O ring seal improperly tightened bolts or dirty mating surfaces Except when torquing the bolts can stop the leak correction requires disassembly Electrical receptacle flange to housing adapter to housing adapter to base adapter to body...

Page 59: ... tape as required Leaks at the self sealing couplings can be repaired by replacing worn or damaged parts To repair a coupling refer to the procedure in the Maintenance section of the Gas Lines manual AVOID CONTAMINATION A leaking coupling on an adsorber should not be repaired in the field Consult a SCAI Service Center Venting the adsorber will introduce contaminants to the system that cannot be re...

Page 60: ...54 This page is intentionally blank ...

Page 61: ...ure to observe this warning can result in serious injury or death from electric shock PRESERVE YOUR WARRANTY Modification to equipment without the consent of the manufacturer will void the warranty Troubleshooting Guide Problem Possible Cause Corrective Action Compressor and items powered from it do not start when the start switch on the compressor is closed Run light is not on No electrical power...

Page 62: ...re Refer to Specifications in the compressor manual and the section on Charging and Venting in this manual Leak check the system if the pressure is low Low oil flow Look for oil leaks in the compressor capsule Consult a SCAI Service Center Orifice or the oil cooling line filter is blocked Replace the orifice and the filter Insufficient coolant for the compressor Check the coolant flow and the temp...

Page 63: ...s line couplings are not fully engaged Be sure that all Aeroquip couplings are fully engaged and torqued Gas lines are connected wrong Reconnect See the Installation section Gradual loss of helium gas pressure Gas is leaking from the compressor Leak check the compressor and repair Compressor runs but elapsed time meter does not Defective elapsed time meter or motor contactor Replace the defective ...

Page 64: ... that all Aeroquip couplings are fully engaged and torqued Compressor output is inadequate Troubleshoot the compressor See the compressor manual Shroud is sweating or is abnormally cold Loss of insulating vacuum Check the vacuum system for operation and leaks Abnormally noisy operation after a sustained period of five to fifteen minutes Incorrect compressor pressures Troubleshoot the compressor Se...

Page 65: ...ak Repair procedures in this manual Worn seals Use the appropriate cold head Disassembly and Repair procedures in the cold head manual Leaking seals will be confirmed by a streaming pattern of black particles on the displacer near the seal rings During rough pumping pressure in the vacuum enclosure will not fall low enough to maintain an adequate vacuum Vacuum chamber leaks Leak check the system R...

Page 66: ...check the system Refer to the Leak Checking and Leak Repair sections in this manual Thermal short Look for a cryopanel that touches the vacuum enclosure or another cryopanel Reposition it to leave space between the cryopanels or the vacuum enclosure Temperature of the second stage cryopanel cycles above 20 K Loss of refrigeration Refer to the Troubleshooting Guides in the compressor manual Excessi...

Page 67: ...a heat transfer load by conduction Evacuate the chamber to a lower initial pressure If the problem continues regenerate the cryopump Oil contaminates the charcoal coating Replace the second stage cryopanel Refer to Regeneration Evacuation Phase in the Operation section of this manual Cryopump suddenly warms up High gas or heat load Check the integrity of the vacuum chamber Check for leaks A therma...

Page 68: ...inoperative Refer to Silicon Diode in the Maintenance section of this manual Cold head does not start or starts and stops intermittently Cold head or compressor is inoperative Refer to the Troubleshooting Guide in the compressor manual Open circuit in the cold head cable Disconnect the cable Check each conductor for continuity Replace the cable if necessary ...

Page 69: ...0862A Kit includes Second stage cryopanel Indium gasket inlet louver Indium gasket first stage heat station Indium gasket second stage heat station 1 4 1 2 260862D 259602B 260866B 254986B 5 Single silicon diode temperature sensor assembly 4 pin standard 1 253995C2 6 Relief valve elbow including relief valve and O ring for relief valve seat O ring for relief valve body 1 1 1 262889A2 77213 77212 Op...

Page 70: ... 4 socket plug item 17 for single diode sensor 1 262437B1 20 Blanket heater 250 watts 208 V insulated 130º F thermostat with mounting springs 1 267358C Parts for Marathon CP 8 Cryopumps with an ISO 200 flange 21 O ring for ISO 200 main flange 1 77195 22 O ring and aluminum centering ring for ISO 200 main flange 1 42532 23 Centering ring for pumpout port 1 42518 16 O ring for nitrogen purge port 1 ...

Page 71: ...mber 25 Copper gasket for Conflat 10 O D main flange 1 43204 7 Metal seal Helicoflex between the cold head s warm flange and the vacuum enclosure 1 77204 17 Copper gasket for 1 33 O D accessory port 3 43100 11 or 12 Rupture disc Rupture disc elbow 1 1 260022A2 262900B1 9 Hydrogen vapor bulb temperature sensor bottom mount 1 263387C ...

Page 72: ...66 This page is intentionally blank ...

Reviews: