CHECK VALVES
Contents
1. CHECK VALVES FREE FLOW REVERSE CURRENT VALVE TABLE OF DIMENSIONS CLASS 400 600 SIZE Weight CV Lbs 4 300 510 6 300 870 8 14 63 650 2500 10 13 38 970 4025 12 1470 5960 21 11 5 19 81 10 38 15 13 18 0 25 11 75 14 63 800 2500 22 75 12 21 38 9 88 14 5 17 38 1 5 10 69 13 38 1150 4025 NOTE ALL DIMENSIONS IN INCHES Q VALVE VALVE l SEE GLOBE OR TRICENTRIC VALVES FOR OTHER CHECK AND COMBINATION CHECK VALVES The Atwood amp Morrill Cold Reheat Check is a reliable sturdy valve that protects the High Pressure HP Steam Turbine from damage caused by reverse flow during unit trip In newer Rankine and Combined Cycle plants the Cold Reheat Check Valve must also accommodate the increased demands of a Turbine Bypass System and isolate the HP Turbine Exhaust when the bypass is in use APPLICATIONS Rankine and Combined Cycle Power Plants with Reheat Prevents Reheat Steam from Returning to Turbine on Trip Simplifies Hydrotesting of the Reheater Protects the High Pressure Turbine Exhaust from Bypass Steam and Water when the Turbine Bypass system operates Isolates High Pressure turbine exhaust when auxiliary steam is supplied to the IP turbine in a combined cycle unit to synchronize the steam turbine generator or start the gas turbine on a single shaft machine FEATU2. PIPE STRESS PRESSURE STRESS With Positive Closing Cylinder FEATURES AND DESIGN ADVANTAGES DEPENDABILITY AND POSITIVE CLOSURE Positive Closing Check Valves are protective devices that must be completely reliable over extended periods of time An average pump is on stream for a number of months and flow holds the valve in a wide open position for long intervals Serious damage may result if foreign matter or sediment accumulates between the shaft and the bushings and retards or prevents free self closure A amp M valves offer positive protection against sticking or hanging up and insure rapid reliable closing in the event of a trip out or shutdown DOUBLE PROTECTION Some plants use two simple check valves in series as a means of insuring positive closure Such dou ble valving may be unnecessary since a single Atwood amp Morrill valve provides double protection with two methods of closure First the A amp M Valve acts as a self closing Check Valve when air pressure is admitted to the cylinder Second it acts as a Power Actuated Valve when air pressure is released from the cylinder on a trip out MINIMUM PRESSURE DROP AND FULL FLOW EFFICIENCY A amp M Boiler Feed Pump Check Valves assist in keep in
3. Atwood amp Morrill Check Valves are engineered products It is strongly recommended that a representative or factory sales engineer be consulted before selecting a valve When specifying Check Valves please supply _ og FP wD Flow Conditions Temperature Pressure and Flow Rate Style of valve series or description Number of valves Service Size or Flow capacity Operating and design temperatures and pressures Special material requirements Maximum allowable pressure drop Pipe run horizontal or vertical Mounting of auxiliary equipment left or right side when facing inlet Other pertinent data Accessory equipment Available air and electrical supply
4. upward by air pressure the disc assembly of the valve is free to swing from a closed to a wide open position solely in response to feedwater flow Disc movement is completely independent of the shaft E gt A stop on the back of the disc holds it at a slight HIL HE incline into the flow when the valve is wide open Normal velocities swing the disc to the full open position and the stop prevents undue flutter or movement WATER HAMMER PROTECTION High pressure Boiler Feed Pumps operating at high speeds and low inertia can lose speed and stop almost instantaneously particularly in close coupled systems with short runs of pipe Should one of these pumps be tripped out or shut off it could go into reverse rotation in a matter of seconds If reverse flow starts due to the slow closing or failure of a check valve serious water hammer will result when the valve finally closes In systems where par allel pumps are used if one pump is shut down any surges caused by the working pump will be iso lated from the pump which the valve is protecting Tests and experience have shown that when an A amp M Positive Closing Check Valve is used water hammer is reduced to a minimum and the pump is assured maximum protection against reverse flow WATER HAMMER TESTS AND RESULTS Portions of oscillograph tapes of tests made on pro duction line A amp M Valves are shown The tests were conducted by an independent research facility to veri
5. 5 394 7 5 191 200 91 868 8 200 17 5 445 9 25 235 310 141 1628 10 250 20 508 10 75 273 450 204 2651 12 300 21 5 546 12 305 669 299 3838 14 350 24 610 13 330 698 313 4892 16 400 25 635 14 356 825 374 6420 18 450 27 5 699 15 5 394 1215 551 8559 20 500 31 787 23 125 587 2474 1113 16400 24 600 37 940 25 125 638 3495 1573 21900 26 650 44 1118 28 625 727 3780 1701 27200 30 750 50 1270 25 625 651 5030 2264 36800 CLASS 600 BOLTED BONNET NOMINAL SIZE A DIMENSION B DIMENSION WEIGHT Cv INCH MM INCH MM INCH MM LB KG 2 5 65 12 5 318 6 25 159 125 57 187 3 75 12 5 318 6 25 159 125 57 193 4 100 13 5 343 7 178 150 68 370 6 150 15 5 394 9 25 235 250 113 868 8 200 17 5 445 10 5 267 375 170 1796 10 250 20 508 12 25 311 550 249 2651 12 300 21 5 546 13 330 780 354 3838 14 350 25 635 14 5 368 975 442 4833 16 400 27 686 15 52 394 1315 596 6295 18 450 31 787 17 5 445 1950 885 8290 20 500 40 1016 34 864 4000 1800 15300 24 600 40 1016 31 25 794 5270 2372 17500 26 650 50 1270 28 5 724 5700 2565 31650 30 750 52 1321 37 5 953 8300 3735 35700 SEE GLOBE OR TRICENTRIC VALVES FOR OTHER CHECK AND COMBINATION CHECK VALVES CHECK VALVES SWING CHECK VALVE CLASS 900 PRESSURE SEAL BONNET NOMINAL SIZE A DIMENSION B DIMENSION WEIGHT Cv INCH MM INCH MM INCH MM LB KG OR 2 5 65 12 5 318 7 5 191 9 43 202 3 75 12 5 318 7 5 191 95 43 209 4 100 13 330 8 75 222 120 54 363 6 150 15 5 394 11 279 235 107 801 8 200 17 5 445 12 5 318 370 168 1517 10 250 22 5 572 19 483
6. 8 Steam to heater or feed pump turbine Extraction line Electrical signal from heater high water level alarm or turbine trip 60 125 PSIG 4 25 8 75 Kg cm Air supply 60 125 PSIG 4 25 8 75 Kg cm Solenoid operated 3 way valve with integral test button SEE GLOBE OR TRICENTRIC VALVES FOR OTHER CHECK AND COMBINATION CHECK VALVES CHECK VALVES FREE FLOW REVERSE CURRENT VALVE DIMENSIONS CLASS 150 300 SIZE A K L M N Weight CV Lhs 4 14 15 13 3 88 7 75 18 75 300 B10 6 14 00 15 13 388 7 75 18 75 300 870 8 21 00 16 13 69 10 75 15 50 490 1180 10 22 7 17 63 88 10 25 14 00 700 3180 12 24 75 18 63 94 10 50 14 00 730 4810 14 24 00 19 50 1 88 10 00 13 00 1100 6300 16 26 00 20 75 2 38 13 88 19 31 1900 8940 18 29 00 22 50 3 69 14 50 18 00 2100 10720 20 31 00 25 50 5 19 15 00 16 50 3100 13650 24 37 00 25 50 6 50 16 00 15 19 3700 17050 26 44 00 26 75 16 38 13 50 3850 24120 28 46 00 26 75 17 38 13 50 3960 25120 30 50 00 27 13 17 94 13 50 5200 29800 32 50 00 27 13 17 94 13 50 5200 36200 34 53 00 29 50 12 13 17 69 9 56 5800 36 53 00 29 50 12 13 17 69 9 56 6100 40120 42 66 00 32 75 17 50 21 50 4 19 14250 58320 44 66 00 32 75 17 50 21 50 4 19 14250 58320 NOTE ALL DIMENSIONS IN INCHES G VALVE VALVE 1
7. 800 363 2346 12 300 27 686 17 25 438 1150 522 3658 14 350 27 686 125 438 1150 522 4207 16 400 31 787 20 508 1600 726 5629 18 457 34 864 22 559 2300 1043 7558 20 500 44 1118 2837 720 6380 14036 15235 A 24 600 44 1118 29 5 750 6000 13200 18878 CLASS 1500 PRESSURE SEAL BONNET NOMINAL SIZE A DIMENSION B DIMENSION WEIGHT Cv INCH MM INCH MM INCH MM LB KG 2 5 65 12 5 318 8 203 140 64 202 3 75 12 5 318 8 203 140 64 209 4 100 14 356 8 75 222 336 152 345 6 150 16 5 419 13 5 343 800 363 801 8 200 19 5 495 15 5 394 1200 544 1517 10 250 25 635 19 5 495 1600 726 2346 12 300 30 762 23 584 2170 984 3658 14 350 30 762 23 584 2170 984 4207 16 400 34 5 876 27 686 2800 1270 5629 18 450 38 965 30 762 3500 1588 7558 CHECK VALVES RECOMMENDATIONS AND REQUIREMENTS ORDERS AND INQUIRIES MAINTENANCE INSPECTION EXERCISING Atwood amp Morrill Co Inc recommends a standard program of maintenance inspection and exercise for their products For more information please refer to the service manual supplied with each valve or contact your local A amp M representative or the home office in Salem Massachusetts INSTALLATION RECOMMENDATIONS For longest service life of these or any check valves installation near sharp bends elbows eccentric reducers or expanders or other valves should be avoided When possible a length of 10 pipe diame ters of straight pipe upstream and 5 pipe diameters of straight pipe downstream is recommended
8. optimum operating conditions and full open disc CHECK VALVES COLD REHEAT CHECK VALVES BLOWDOWN COVERS protector ring is available When blowdown is FOR COLD REHEAT CHECK VALVES required but a cover is not provided field fabrication Www can be time consuming If blowdown is expected to The Atwood amp Morrill Blowdown Cover allows carry a lot of debris an additional disc may be useful cleanout blowdown of the pipeline to be easily and For help meeting your system s requirements contact efficiently done The simple design bolts on in place A amp M s sales or service department of the valve s existing cover and provides an easy blowdown connection An optional blowdown disc can also be supplied when large amounts of dam aging debris are anticipated BLOWDOWN COVER LIFTING HOLES CONSTRUCTION The fabricated blowdown cover has a weld end for easy pipe connection and lifting holes for easy removal after blowdown is complete The optional valve disc is carbon or alloy steel OPERATION BLOWDOWN DISC After startup and blowdown the Cold Reheat Check Valve s standard cover is replaced When using Cold Reheat Check Valves consider your blowout requirements carefully When blow down is started upstream of the Cold Reheat Check Valve remove the disc to prevent damage A seat A amp M has 70 Years Extraction and Reheat Steam Service Experience 44 Cold Reheat Check Valves SEE GLOBE OR TRICENT
9. RES Proven Swinging Disc Design Wide Flat Non jamming Seats for Tight Seal Closure Assisting or Double Acting Air Cylinder Smooth Flow Passages for Low Pressure Drop In Line Maintenance through Bolted Top Cover Inclined Seat for Short Travel amp Quick Operation Rugged Construction Ability to Withstand Multiple Rapid Closures OPERATION During normal operation the Atwood amp Morrill Cold Reheat Check is open to forward flow It becomes a critical quick closing valve which protects the turbine during trips or equipment failure CHECK VALVES COLD REHEAT CHECK VALVES 42 Class 600 Cold Reheat Check DEMANDS Quick Acting Turbine Bypass Systems rapidly change pressure and flow in the reheat piping requiring the Cold Reheat Check valve to close quickly The frequent Start ups and Shutdowns of Cycling Units require the Cold Reheat Check valve to operate several times per day Very Tight Sealing is necessary to prevent steam and water from entering the HP turbine Low pressure drop is important to overall combined cycle unit performance AVAILABLE Sizes 20 to 42 and ANSI Classes 300 to 600 Materials Carbon and Alloy Steels SIZING AND SELECTION Proper sizing requires verification of flow condi tions Ideally the disc should be in the Full Open Position Not Chattering or Fluttering in Flow Stream This allows for Low Wear and Low Pressure Drop The counterweight must be properly sized to allow
10. RIC VALVES FOR OTHER CHECK AND COMBINATION CHECK VALVES CHECK VALVES COLD REHEAT CHECK VALVES TABLE OF DIMENSIONS CLASS 300 SIZE A Weight CV Lhs 28 46 00 3960 25120 30 50 00 5200 29800 32 50 00 5200 36200 34 53 00 5800 _ 36 53 00 6100 40120 42 66 00 29 88 32 75 14250 58320 44 66 00 29 88 32 75 14250 58320 CLASS 600 SIZE A Weight CV Lhs 14 28 00 2100 8050 16 28 00 2100 8470 18 30 00 2750 10780 20 33 00 3100 13460 24 44 00 7600 19960 26 44 00 7600 23560 28 50 00 7800 27500 30 50 00 7800 32330 32 55 00 9500 37650 34 55 00 9500 43425 36 59 00 15000 49665 38 59 00 15000 56425 VALVE CHECK VALVES COMPRESSOR CHECK VALVES The Atwood amp Morrill Co Inc Compressor Check Valve is designed to provide positive protection for the blower or compressor It is installed in the compressor discharge line when specified as Tight sealing pressure Low differential pressure Power assisted Dashpot non slam valve APPLICATIONS Fluid Catalytic Cracking Air Blower Discharge Compressor Discharge and Process Application Fluids Hydrocarbon Cracked Gas Ethylene Propylene Other Process Fluids OPERATION FEATURES The A amp M Compressor Discharge Check Valve is important in providing protection for critical equipment CLOSURE ASSIST AIR CYLINDER The Compressor Check
11. SEE GLOBE OR TRICENTRIC VALVES FOR OTHER CHECK AND COMBINATION CHECK VALVES CHECK VALVES FREE FLOW REVERSE CURRENT VALVE Atwood amp Morrill Free Flow Reverse Current Valves are designed to give maximum protection to extraction steam turbines Their rapid tight closure insures that the high level of energy found in feed water heaters or process lines is quickly isolated from the turbine in the event of a load rejection The power cylinder is designed to give a strong closing moment to the valve when signalled to do so by plant instrumentation A lost motion feature allows the valve disc to close independently of the power cylinder APPLICATIONS Turbine Protection Extraction steam non return Bled steam non return Over 70 years of experience SPECIFICATIONS Design Standard ANSI B16 34 and applicable international specifications as required Pressure Classes ANSI 150 1500 Sizes Cast construction 3 44 Carbon steel alloy steel and stainless steel per ASTM specifications or applicable international standards Materials Cylinder Valves Trim Stainless steel ASTM A479 Type 410 Exerciser Valves Seats Stainless steel overlay or hardfacing alloy Bolted bonnet with non asbestos gasket Bonnet Design End Connections Butt weld or flange end Power Cylinder Pneumatic or hydraulic Drain Connections As required 1 2 or 3 SPDT or DPDT switches available Limit Switches Ins
12. Valve operates normally with the disc in the open position for long periods To ensure the check valve will close in the event of a blower compressor trip it is furnished with a clo sure assist air cylinder Upon loss of power to the drive device of the blower compressor a three way solenoid valve is de energized When the solenoid valve is tripped the side air cylinder is vented allowing the internal spring to apply a closing force to the lever arm which in turn rotates the shaft and disc assembly to the closed position EXTERNAL COUNTER WEIGHTS External counter weights help the valve remain in the full open position at normal operating flow These weights counter balance approximately 50 of the disc closing moment assuring the valve disc will be fully open providing the lowest pressure drop possible A amp M check valves will be fully open at lower flow rates compared to conventional swing or wafer type check valves 32 Class 300 Compressor Discharge Check Valve OIL DASHPOT Years of experience with blower check valves has indicated that the valve disc will tend to flutter at various flow rates This constant motion during operation may result in premature packing wear and or valve failure To prevent this flutter motion A amp M Compressor check valves are supplied with an oil dashpot which can be adjusted to dampen the motion and reduce disc slamming DEPENDABILITY Compressor Check Valves are protective dev
13. at Design Fig 3 Atwood amp Morrill Free Flow Reverse Current Valves have an inclined seat to improve the perfor mance and operating characteristics of the valve This design offers advantages not available with other seat configurations The inclined seat combined with flat disc and body seat contact provides the best configuration available in Check Valve design An opening angle of 75 from the vertical or 45 from Figure 3 the inclined seat results in low pressure drop The reduced swing also enables the valve to close y quickly Full opening with a vertical seat would require a greater swing and a longer closing time The center of gravity of the disc assembly causes a positive seating moment therefore the weight of the disc is always acting to seat it and hold it firmly against its seat A portion of the disc weight can be counterbalanced in larger valves to reduce pressure drop at low flows so the flow is not required to raise the full weight of the disc The Atwood amp Morrill inclined seat design features POSITIVE TIGHT SEATING FAST CLOSURE LOW PRESSURE DROP all important Check Valve considerations SEE GLOBE OR TRICENTRIC VALVES FOR OTHER CHECK AND COMBINATION CHECK VALVES CHECK VALVES Figure 4 Figure 5 Figure 6 FREE FLOW REVERSE CURRENT VALVE DESIGN FEATURES Shaft and Bushing Assembly Fig 4 Large diameter stainless steel shafts together with hardened stainless steel
14. ation Body Type Optional Equipment ANSI B16 34 4 60 inches sizes 44 thru 60 fabricated ANSI Class 150 through 2500 Bolted Bonnet pressure seal for class 900 and higher Butt weld or flanged Spring loaded cylinder air controlled Oil Dashpot Swinging disc design with inclined seat Hand Test valve Three way solenoid valve Limit switches Protective Sleeves Compressor Check Valve with Oil Dashpot Oil Dashpot Actual Oil Dashpot SEE GLOBE OR TRICENTRIC VALVES FOR OTHER CHECK AND COMBINATION CHECK VALVES CHECK VALVES POSITIVE CLOSING CHECK VALVES FEEDWATER APPLICATION Atwood amp Morrill Co Inc manufactures Positive Closing Check Valves for the discharge lines of boiler feed pumps These valves provide positive protection for feedwater systems and can prevent damage to costly pumping equipment Failure to provide such protection could cause serious damage to the feed pumps and their drive mechanisms and may result in a plant outage with a loss of revenues far exceeding the initial investment necessary to provide protective equipment Figure No 1 illustrates the typical use of an A amp M Valve with a motor driven feed pump Positive Closing Check Valves can be used to protect pumps that are motor driven turbine driven or those that are run by drive shaft off the main turbine thereby improving the reliability and dependability of the entire feed water sy
15. bushings are used on all A amp M Free Flow Reverse Current Valves The results are lower stresses less wear and longer life Positive Closing The powerful spring in the power cylinder assures rapid positive closing before reverse flow can occur Balanced Shaft Construction Internal Lost Motion Device An internally balanced design is standard on all 12 and smaller valves equipped with a closure assisting cylinder This feature eliminates stuffing box friction and shaft end thrust which might prevent free swing ing of the valve disc Valve Body amp Bonnet Atwood amp Morrill employs a streamlined body con tour designed for minimum flow resistance Heavy body wall thickness assures rigidity and resistance to pipe strain distortion A bolted top cover is provided for ease of access to valve internals thus the valve need not be removed from the line for maintenance and inspections External Lever Fig 5 Valves of all sizes are available with shaft mounted lever to manually exercise the valve Larger size valves are supplied with a counter weight to reduce pressure drop at low flows to maintain full disc opening and reduce disc slamming Cylinder Operated Fig 6 Spring loaded positive closing air cylinders can be provided on all Free Flow Reverse Current Valves Oil operated cylinders are also available Oil cylinders may be ordered with an optional oil relay valve Both types can be exercised by a lever operated T
16. er cises the valve during operation The system shown in Figure 8 differs from Figure 7 as the oil operated Air Relay Dump Valve is replaced by an oil pressure switch which converts the loss of oil pressure due to a turbine overspeed trip to an electrical signal This signal is connected to the solenoid valve in series with the heater high water level alarm circuit and trips the solenoid oper ated 3 Way Valve as in Figure 7 The quick exhaust valve shown in Figure 8 senses a loss of pressure at its inlet and will shift allowing the air cylinder to exhaust more rapidly through its vent port This valve can be used in any control sys tem and is recommended whenever a solenoid valve with a low Cv factor is used Local exercising of the Free Flow Reverse Current Valve can also be accomplished by actuating an integral test switch on the solenoid operated 3 Way Valve Using this method for exercising the sole noid valve is exercised as well as the Free Flow Reverse Current Valve Combinations of control systems shown in Figures 7 and 8 can also be used Control for Turbine Extraction Systems Free flow reverse current valve Steam to heater or feed pump turbine Electrical signal from heater high water Lever operated level alarm 3 way valve Solenoid operated 3 way valve Air to other free n reverse current valves Oil operated air pilot valve Air exhaust on turbine trip Quick exhaust valve Figure
17. est Valve or Solenoid Valve CHECK VALVES FREE FLOW REVERSE CURRENT VALVE APPLICATIONS FOR TURBINE EXTRACTION SYSTEMS Air Operated Systems Figure 7 shows an A amp M Air Operated Free Flow Reverse Current Valve operated by turbine overspeed trip and high water level in the feedwater heater The oil operated Air Relay Dump valve normally supplied by the turbine manufacturer translates oil pressure from the turbine overspeed trip system into air pressure With oil pressure established compressed air flows through the Air Relay Dump Valve with the atmospheric vent closed Upon loss of oil pressure due to turbine overspeed trip incom ing air pressure is closed off and the atmospheric vent is opened to release air pressure from the Check Valve cylinder This action allows the spring force to assist in closing the Free Flow Reverse Current Valve IT IS IMPORTANT THAT THE SOLENOID OPERATED 3 WAY VALVE USED ALLOWS FLOW IN THE REVERSE DIRECTION The Solenoid Operated 3 Way Valve is installed in the air supply line to the cylinder Upon receipt or loss of an electrical signal from the heater high water level alarm the Solenoid Valve trips closing the air supply and opening the vent to atmosphere Air is exhausted from the air cylinder and the spring starts to close the valve The lever operated Air Test Valve equalizes pressure on both sides of the cylinder piston so that the spring force moves the piston downward and ex
18. fy the advantages of fast closing and to demon strate the effect of positive closing over a swinging disc check valve which was not positive closing No numerical values are indicated The following tests were run with the valve in the discharge of a motor driven pump I A Swinging Disc Check Valve with added weight at the outer edge of the disc with the valve depend ing only on gravity for its closing moment ll The same valve as in I above but with a posi tive closing cylinder arranged so that air pressure could be released simultaneously with the open ing of the electrical circuit of the motor drive The trace lines indicate pressure during the test and at the moment of valve closure The height of the line indicates the magnitude of the water hammer SEE GLOBE OR TRICENTRIC VALVES FOR OTHER CHECK AND COMBINATION CHECK VALVES CHECK VALVES POSITIVE CLOSING CHECK VALVES FEEDWATER A comparison of the tapes shows the almost amazing results obtained when the positive closing cylinder was used During the series of tests it was also demonstrated that sluggish or retarded closing would severely increase water hammer further proving the advantage of fast positive closing When summarizing the results of the tests the laboratory report states This intensity of water hammer i e when positive closing was used was almost inaudible and with no apparent vibration Valve Closure Test Tapes PRESSURE SURGE
19. g pressure drop in the feedwater piping system at a minimum particularly when a single A amp M Valve replaces a double valve installation The stream lined characteristics of the A amp M design make it an efficient valve to use which is particularly important when longterm installed costs are considered INTERNAL BALANCE The A amp M Valve is designed so that the disc assem bly is pressure balanced This means that the disc assembly is free to swing independently of the operating shaft The disc is not subject to stuffing box friction or end thrust tending to force it against the side of the valve The operating shaft which passes through the stuffing box is stationary under normal operating conditions It is rotated only on a trip out or shut down by the closing cylin der which has ample power to overcome stuffing box friction or other causes for sticking In very high pressure installations the operating shaft is pressure balanced by using double stuffing box construction ONE PIECE BODY CONSTRUCTION AND SIMPLE DESIGN A amp M Boiler Feed Pump Check Valves are designed with a one piece body and relatively few moving parts to minimize operating difficulties and simplify maintenance Once installed a valve can be inspect ed easily without removing it from line and the internals can be removed through the top cover The closing mechanism can also be inspected easily without removing it from the valve by taki
20. ices critical to safeguard the compressor blower systems A amp M valves are designed to be completely reliable over extended periods of time Severe damage may occur if the disc in a check valve is prevented from self closure The A amp M Compressor Check Valve offers positive protection against sticking or hang up and insures rapid reliable closing in the event of a trip out or system shutdown SEE GLOBE OR TRICENTRIC VALVES FOR OTHER CHECK AND COMBINATION CHECK VALVES CHECK VALVES COMPRESSOR CHECK VALVES PRESSURIZED FLU GAS COMPRESSOR DISCHARGE CHECK VALVE REGENERATOR REACTOR REGENERATOR AIR FCC FEED AIR SUPPLY TRIP SIGNAL HAND TEST VALVE T GEAR DRIVE pk SOLENOID VALVE AIR BLOWER Figure 1 DEVICE COMPRESSOR Typical Installation of A amp M Compressor Discharge Check Valve in a Fluid Catalytic Cracking Process Unit Bolted Bonnet design allows full access to internals in line DIZZZIZZZZ y Self Aligning disc and disc arm 1 Closure Assist Air Cylinder 2 Oil Dashpot 3 Counterweights act to counterbalance the disc providing the lowest pressure drop 4 Protective Sleeves cover external linkages 5 Lubricated Stuffing Boxes CHECK VALVES COMPRESSOR CHECK VALVES MATERIALS Cast Carbon Alloy and Stainless Steel CONSTRUCTION Design Standard Sizes Pressure Ratings Cover Design End Connection Positive Closing Device Disc Stabiliz
21. ng off the cylinder to expose the piston The cylinder and piston assembly can then be examined for wear If it becomes necessary to remove the piston the threaded piston rod allows gradual backing off of the spring load so the rest of the cylinder can be dismantled without danger or the need for any special tools Atwood amp Morrill does not use internal springs which are difficult to replace A amp M provides a closing spring external to valve which is readily CHECK VALVES POSITIVE CLOSING CHECK VALVES FEEDWATER accessible and can be removed from the cylinder assembly with ease Possible spring failure could not seize the shaft or prevent self closing of the valve SPECIFICATIONS Size Pressure Ratings Materials Cover Design Closing Device Body Type Disc Assembly Shaft Bearing Design Seats Stuffing Box Packing 3 through 24 standard ANSI Class 400 600 900 1500 2500 Special and higher ratings as applicable Cast steel with stainless steel or Cobalt Alloy Hard Facing trim Other materi als furnished on request Pressure Seal Bolted Bonnet as specified Spring loaded cylinder air controlled Swinging disc design with inclined seat Suitable for full ANSI test pressures One piece construction pressure balanced against lateral thrust Positive stop on disc Disc suitable for full pump shut off pressure Single stuffing box for lower pressures Double
22. stem The A amp M Valve also offers minimum pressure drop for every day operation DESCRIPTION Atwood amp Morrill Positive Closing Check Valves achieve reliable and rapid closure by means of an auxiliary spring loaded cylinder usually actuated by compressed air The positive closing cylinder acts to close the disc of the valve through a simple engaging mechanism But the engaging mechanism does not permit the cylinder to open the valve In the case of a turbine drive an Oil Operated Air Relay Valve is used to translate turbine control oil pressure to air pressure An alternate method is to use a switch actuated by the turbine trip mecha nism operating a solenoid valve which controls air pressure to the closing cylinder ELECTRIC POWER SUPPLY _ PUMP CHECK VALVE WITH AIR CYL Figure 1 lt 1 FEATURES Positive power assisted closure provides fast and reliable protection Valve closure before backflow Double protection including positive closure and power assisted closure Streamlined flow design minimizes pressure drop Fast closing minimizes water hammer Flat seats for maximum tightness without wedging action TEST VALVE AIR SUPPLY oS 3 WAY SOLENOID VALVE VENT TO ATMOS CHECK VALVES POSITIVE CLOSING CHECK VALVES FEEDWATER OPERATION Cross Section Showing Positive Closing Cylinder amp Shaft When the piston of the closing cylinder is pushed
23. stuffing box for higher pressures Outboard shaft support bearing on cylinder side Shaft bushings are nitrid ed stainless steel Integral stainless steel facings on both disc and body Cobalt Alloy Hard Facings also available Graphoil type Leak off bushings available DIMENSIONS Class 1500 SIZE END TO END Cv 4 13 357 6 15 826 8 18 1603 10 23 2585 12 25 3926 14 25 3926 16 29 5927 Class 2500 SIZE END TO END Cv 4 13 357 6 18 5 826 8 23 5 1603 10 23 5 1603 12 28 2585 14 35 3926 16 35 3926 18 41 5927 NOTE ALL DIMENSIONS IN INCHES Cover Disc Seats mW N SEE GLOBE OR TRICENTRIC VALVES FOR OTHER CHECK AND COMBINATION CHECK VALVES CHECK VALVES SWING CHECK VALVE BALANCE OF PLANT The Atwood amp Morrill Swing Check Valve is designed to effectively prevent reverse flow and is ideally suited for liquid steam and other gases requiring assured performance tight shutoff and low maintenance APPLICATION Condensate pump discharge Heater drains Liquid steam and gas check valve DESCRIPTION A unique one piece disc and disc arm that cannot spin or flutter The valve is flow engineered to hold the disc in the full open position during a wider range of flows and the swinging disc design prevents wedging or jamming Wide flat permanently aligned seats that minimize leakage Stainless steel seat facings and hardsurfacing alloy available Bolted bonnet on 150 through 600 class
24. tallation Special Features Solenoid operated air valves or pilot operated oil relay valves Optional solenoid or manual valves available Low friction stuffing boxes standard Very low friction mechanical seals optional can not be overtightened Nondestructive examina tion as required by cus tomer specification or ANSI B16 34 Special Class Horizontal or vertical upflow as specified CHECK VALVES FREE FLOW REVERSE CURRENT VALVE Figure 1 DESIGN FEATURES The important role of a Non Return Valve as a protec tive device demands a high level of reliability The features found in all Atwood amp Morrill Free Flow Reverse Current Valves assure that reliability These features along with a high grade of workmanship and materials assure a superior and completely dependable valve Free Swinging Disc Fig 1 Atwood amp Morrill utilizes a basic swinging disc Check Valve design This uncomplicated design provides independent movement of the disc in the flow stream with fast closure upon loss or reversal of flow The valve disc is of sturdy construction to prevent distortion under full design pressure Self Aligning Disc and Disc Arm Fig 2 The disc and disc arm assembly are self align ing with the seat assuring tight sealing An internal stop provides the proper degree of disc opening while maintaining the edge of the disc within the flow stream so that flow reversal will cause closure Inclined Se
25. valves and pressure seal bonnet on 900 through 1500 class valves An internal bracket on 21 2 18 inch valves eliminates side body penetrations for the shaft removing two potential leak paths For larger sizes a conventional double bearing cover design is used SPECIFICATIONS Size 21 2 48 inch Pressure Ratings ANSI Class 150 1500 Materials Carbon steel Alloy steel or stainless steel all with stainless steel trim Ar Internal bracket n Wide flat seats N Internal disc and arm Rugged disc stop CHECK VALVES SWING CHECK VALVE CLASS 150 BOLTED BONNET NOMINAL SIZE A DIMENSION B DIMENSION WEIGHT Cv INCH MM INCH MM INCH MM LB KG 2 5 65 12 305 5 25 133 95 43 198 a DN 3 75 12 305 5 25 133 95 43 208 mang 4 100 12 330 5 375 137 110 50 370 6 150 14 5 368 6 5 165 140 64 868 8 200 17 432 8 5 216 235 107 1672 B 10 250 18 5 470 9 5 241 300 136 2688 12 300 20 5 521 10 75 273 450 204 3983 14 350 23 584 11 5 292 550 249 4892 16 400 25 635 13 330 660 299 6582 18 450 27 686 14 75 375 1015 460 8559 20 500 31 787 23 125 587 2474 1113 16400 24 600 37 940 23 75 603 3445 1550 21900 26 650 44 1118 27 686 3730 1679 27200 as m 30 750 50 1270 25625 651 4608 2074 36800 CLASS 300 BOLTED BONNET NOMINAL SIZE A DIMENSION B DIMENSION WEIGHT Cv INCH MM INCH MM INCH MM LB KG 2 5 65 12 305 5 25 133 95 43 198 3 75 12 305 5 25 133 95 43 204 4 100 13 330 6 152 110 50 370 6 150 15
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