A Guide Used to Assist in Equipment Selection for Aboveground Storage Tanks VENTING GUIDE This guide is intended for reference use only. All final details of design and construction shall meet the requirements of federal, state, and local codes. In cases where plan approval is required, such approval shall be obtained from the authority having jurisdiction before any work is performed. The equipment presented in the Guide applies only to shop fabricated tanks. for aboveground storage tanks September 2017
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A Guide Used to Assist in Equipment Selection for Aboveground Storage Tanks
VENTINGGUIDE
This guide is intended for reference use only. All final details of design and construction shall meet the requirements of federal, state, and local codes. In cases where plan approval is required, such approval shall be obtained from the authority having jurisdiction before any work is performed. The equipment presented in the Guide applies only to shop fabricated tanks.
for aboveground storage tanks
September 2017
Page ii
Morrison Bros. Co.
Page ii Page 1
Venting Guide
Contents PageI. Background Information Introduction 2 Definitions 2
II. Example Calculations for Vent Selection Horizontal Cylindrical Storage Tank 3 Vertical Cylindrical Storage Tank 4 Horizontal Rectangular Storage Tank 5
III. Calculation TablesPre-calculatedHorizontalCylindricalTanks 6-7Pre-calculatedVerticalCylindricalStorageTanks 8-9Pre-calculatedHorizontalRectangularStorageTanks 10WettedAreasforHorizontalCylindricalTanks 11WettedAreasforVerticalCylindricalTanks 12EmergencyVentingCapacity 13GallonCapacityperFootofLength 14
IV. Vent SelectionVentCapacity 15VentCombinationExamples 16MorrisonEmergencyVentSpecifications 17MorrisonVentingEquipment 18-26
V. Aboveground Fuel Storage DiagramsPressureSystems 27-28SuctionSystems 29-30BulkStorage 31Generator 32
TheMorrison Bros. Co. VentingGuidewas created to assist in the selection of venting equipment forabovegroundstoragetanks.Examplesonthenexttwopagesillustrateaventselectionprocess.Itisbesttoworkthroughtheexamplesbeforeattemptingtouseanyofthetablesinthisbook.
The vent selection chapter includes venting capacities of specific Morrison vents. This data was obtained from results of laboratory testing and engineering calculations. Catalog pages of the Morrisonequipmentfollowtheventcapacitychart.
Atmospheric Tank —Astoragetankthathasbeendesignedtooperateatpressuresfromatmosphericthroughagaugepressureof1.0psi(6.9kPa)(i.e.,760mmHgthrough812mmHg)measuredatthetopofthetank.
Normal Vent —Anopening,constructionmethod,ordevicethatallowsthereliefofexcessiveinternalpressureorvacuumduringnormalstorageandoperations.
Wetted Area —Exposedsurfaceorshellareaofatankusedindeterminingtheventingrequirementsneededforthatsizetankineventofanexposurefire.Inahorizontaltank,thewettedareaiscalculatedas75%oftheexposedsurfacearea.Inaverticaltank,thewettedareaiscalculatedasthefirst30ft.abovegradeoftheexposedshellareaofthetank.Inarectangulartank,thewettedareaiscalculatedasthetotalsurfaceareaofthetankbottomandthefoursides,excludingthetanktop.
RefertoTableIonpage16showingventcombinationsandverifythetotalSCFHfigure.Alsorefertotheproductillustrationsonpages17-26andverifytheselectionforcorrect option on material compatibility and mounting requirements.
RefertoTableIonpage16showingventcombinationsandverifythetotalSCFHfigure.Alsorefertotheproductillustrationsonpages17-26andverifytheselectionforcorrect option on material compatibility and mounting requirements.
RefertoTableIonpage16showingventcombinationsandverifythetotalSCFHfigure.Alsorefertotheproduct illustrationsonpages17-26andverifytheselectionfor correct option on material compatibility and mounting requirements.
Tank Capacity 10,000gallons
Tank Size 274”Lx130”Wx65”H
(22’-10”Lx10’-10”Wx5’5”H)
HORIZONTAL RECTANGULAR STORAGE TANK
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Morrison Bros. Co.
TANK
WETTEDAREA(Sq Ft)
REQ’D VENTCAPACITY
(SCFH)
EMERGENCYVENT SIZE
WITHOUT SCREEN (Inches)
EMERGENCYVENT SIZE
WITH SCREEN (Inches)
CAPACITY (Gallons)
DIAMETER(Ft or In)
LENGTH(Ft-In)
280 36” 5’-2” 47 49,520 3 3
300 38” 5’-0” 49 51,640 3 4
500 48” 5’-5” 69 72,650 4 4
530 46” 6’-0” 71 74,750 4 4
550 48" 6’-0” 75 78,950 4 4
1,000 48” 10’-8” 119 124,950 4 5
1,000 64” 6’-0” 109 114,450 4 4
1,500 64” 9’-0” 147 154,350 5 5
2,000 64” 12’-0” 184 193,200 6 6
2,500 64” 15’-0” 222 223,320 6 6
3,000 64” 18’-0” 259 243,680 6 6
3,000 6’-0” 14’-0” 240 233,400 6 6
4,000 64” 24’-0” 335 281,100 6 NA
4,000 6’-0” 19’-0” 311 270,060 6 NA
5,000 8’-0” 13’-4” 326 276,960 6 NA
6,000 8’-0” 16’-0” 376 300,480 8 NA
8,000 8’-0” 21’-4” 477 344,340 8 NA
10,000 8’-0” 27’-0” 584 385,920 8 NA
10,000 9’-0” 21’-0” 540 369,200 8 NA
10,000 10’-0” 17’-0” 518 360,840 8 NA
10,000 10’-6” 15’-7” 515 359,700 8 NA
12,000 8’-0” 32’-0” 678 420,080 8 NA
12,000 9’-0” 25’-0” 625 401,000 8 NA
12,000 10’-0” 20’-6” 600 392,000 8 NA
12,000 11’-0” 17’-0” 583 385,540 8 NA
15,000 8’-0” 40’-0” 829 470,990 8 NA
15,000 10’-6” 23’-5” 703 429,020 8 NA
20,000 10’-0” 34’-2” 922 499,820 8 NA
20,000 10’-6” 31’-0” 896 491,760 8 NA
20,000 11’-0” 28’-0” 868 483,080 8 NA
25,000 10’-6” 38’-6” 1,082 537,530 10 NA
Table A: Pre-Calculated Data
Table A: Pre-Calculated Data
HORIZONTAL CYLINDRICAL TANKS
(TABLE CONTINUES ON NEXT PAGE)
Page 6 Page 7
Venting Guide
TANK
WETTEDAREA(Sq Ft)
REQ’D VENTCAPACITY
(SCFH)
EMERGENCYVENT SIZEWITHOUT
SCREEN (Inches)
EMERGENCYVENT SIZE
WITH SCREEN (Inches)
CAPACITY(Gallons)
DIAMETER(Ft or In)
LENGTH(Ft-In)
30,000 10'-0" 51'-2" 1,324 575,600 10 NA
30,000 10’-6” 46’-3” 1,274 568,100 10 NA
40,000 12'-0" 47'-6" 1,512 602,120 10 NA
50,000 12'-0" 59'-6" 1,852 664,980 10 NA
50,000 12'-6" 54'-6" 1,789 637,735 10 NA
60,000 12'-0" 71'-0" 2,177 680,585 10 NA
60,000 12'6" 65'5" 2,110 637,550 10 NA
60,000 13'-0" 60'-6" 2,052 667,460 10 NA
70,000 13'-0" 72'-0" 2,404 704,380 10 NA
Table A: Pre-Calculated Data
HORIZONTAL CYLINDRICAL TANKS (CONTINUED)
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Morrison Bros. Co.
Table B: Pre-Calculated Data
VERTICAL CYLINDRICAL TANKS
(TABLE CONTINUES ON NEXT PAGE)
TANK
WETTEDAREA(Sq Ft)
REQ’D VENTCAPACITY
(SCFH)
EMERGENCYVENT SIZEWITHOUT
SCREEN (Inches)
EMERGENCYVENT SIZE
WITH SCREEN (Inches)
CAPACITY(Gallons)
DIAMETER(Ft or In)
LENGTH (Ft-In)
280 36” 5’-2” 48 50,580 3 3
300 38” 5’-0” 49 51,640 3 4
500 48” 5’-5” 68 71,600 4 4
530 46” 6’-0” 72 75,800 4 4
550 48” 6’-0” 75 78,950 4 4
1,000 48” 10’-8” 134 140,700 5 5
1,000 64” 6’-0” 100 105,000 5 5
1,500 64” 9’-0” 151 158,550 5 5
2,000 64” 12’-0” 201 213,100 6 6
2,500 64” 15’-0” 251 239,520 6 6
3,000 6’-0” 14’-0” 263 245,760 6 6
3,000 64” 18’-0” 301 265,460 6 NA
4,000 64” 24’-0” 402 312,840 8 NA
4,000 6’-0” 19’-0” 358 291,840 6 NA
5,000 8’-0” 13’-4” 335 281,100 6 NA
6,000 8’-0” 16’-0” 402 312,840 8 NA
8,000 8’-0” 21’-4” 536 367,680 8 NA
10,000 8’-0” 27’-0” 678 420,080 8 NA
10,000 9’-0” 21’-0” 593 389,340 8 NA
10,000 10’-0” 17’-0” 534 366,920 8 NA
10,000 10’-6” 15’-7” 514 359,320 8 NA
12,000 8’-0” 32’-0” 754 446,360 8 NA
12,000 9’-0” 25’-0” 706 430,040 8 NA
12,000 10’-0” 20’-6” 644 407,840 8 NA
12,000 11’-0” 17’-0” 587 387,060 8 NA
15,000 8’-0” 40’-0” 754 446,360 8 NA
15,000 10’-6” 23’-5” 764 449,760 8 NA
20,000 10’-0” 34’-2” 942 506,020 10 NA
20,000 10’-6” 31’-0” 990 520,900 10 NA
20,000 11’-0” 28’-0” 967 513,770 10 NA
25,000 10’-6” 38’-6” 990 520,900 10 NA
Page 8 Page 9
Venting Guide
TANK
WETTEDAREA(Sq Ft)
REQ’D VENTCAPACITY
(SCFH)
EMERGENCYVENT SIZEWITHOUT
SCREEN (Inches)
EMERGENCYVENT SIZE
WITH SCREEN (Inches)
CAPACITY(Gallons)
DIAMETER(Ft or In)
LENGTH(Ft-In)
30,000 10’-6” 46’-3” 990 520,900 10 NA
30,000 12'-0" 35'-6" 1,131 545,615 10 NA
30,000 12'-6" 32'-9" 1,176 553,040 10 NA
40,000 12'-0" 47'-6" 1,131 545,615 10 NA
40,000 12'-6" 43'-8" 1,178 553,370 10 NA
40,000 13'-0" 40'-4" 1,225 560,750 10 NA
49,500 13'-0" 50'-0" 1,225 560,750 10 NA
57,000 14'-0" 50'-0" 1,319 574,850 10 NA
Table B: Pre-Calculated Data
VERTICAL CYLINDRICAL TANKS (CONTINUED)
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Morrison Bros. Co.
TANK
WETTED AREA (Sq Ft)
REQ’D VENT CAPACITY
(SCFH)
EMERGENCY VENT SIZE WITHOUT
SCREEN (Inches)
EMERGENCY VENT SIZE
WITH SCREEN (Inches)
CAPACITY(Gallons)
LENGTH(Ft-In)
WIDTH(Ft-In)
HEIGHT(Ft-In)
125 6’-8” 2’-9” 1’-0” 37 38,950 3 3
186 2’-8” 2’-8” 3’-6” 44 46,340 3 3
250 4’-4” 4’-0” 1’-11” 49 51,640 3 4
250 6’-8” 2’-9” 1’-11” 54 56,900 3 4
500 7’-6” 3’-0” 3’-0” 86 90,560 4 4
500 10’-0” 3’-6” 2’-0” 89 93,740 4 4
1,000 9’-8” 4’-8” 3’-0” 131 137,550 5 5
1,000 10’-0” 4’-7” 2'-11" 133 139,650 5 5
2,000 10’-2” 6’-11” 3’-10” 201 211,560 6 6
2,000 10’-8” 6’-4” 4’-0” 204 213,240 6 6
2,500 10’-2” 6’-11” 4’-9” 233 229,480 6 6
3,000 8’-6” 6’-10” 7’-2” 278 253,560 6 NA
3,000 13’-9” 5’-5” 5’-5” 282 255,640 6 NA
4,000 11’-4” 6’-10” 7’-2” 338 282,480 6 NA
4,000 18’-2” 5’-5” 5’-5” 354 289,920 6 NA
5,000 22’-9” 5’-5” 5’-5” 428 323,760 8 NA
6,000 13’-8” 10’-10” 5’-5” 413 317,460 8 NA
6,000 16’-5” 6’-10” 7’-2” 445 330,900 8 NA
6,000 27’-4” 5’-5” 5’-5” 503 355,140 8 NA
8,000 18’-2” 10’-10” 5’-5” 511 358,180 8 NA
8,000 21’-11” 6’-10” 7’-2” 562 377,560 8 NA
10,000 22’-10” 10’-10” 5’-5” 612 396,320 8 NA
10,000 27’-5” 6’-10” 7’-2” 678 420,080 8 NA
12,000 27’-4” 10’-10” 5’-5” 710 431,400 8 NA
12,000 32’-11” 6’-10” 7’-2” 795 460,300 8 NA
Table C: Pre-Calculated Data
HORIZONTAL RECTANGULAR TANKS
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Venting Guide
SI Units: 1 Ft = 0.30 m; 1 sq ft = 0.09 sq mSource for Chart: UL 142, Table A-2, 9th Edition, July 19, 2013
Table D: Approximate Wetted Areas
HORIZONTAL CYLINDRICAL TANKS
Tank Diameter
3 Ft 4 Ft 5 Ft 6 Ft 7 Ft 8 Ft 9 Ft 10 Ft 11 Ft 12 Ft 13 Ft
Tank Length
Approximate Wetter Area of Tanks With Flat Heads, Square Feet
3 Ft 32
4 Ft 39 55
5 Ft 46 65 88
6 Ft 53 74 100 128
7 Ft 60 84 112 142 173
8 Ft 67 93 124 156 190 226
9 Ft 74 102 136 170 206 245 286
10 Ft 81 112 147 184 223 264 308 353
11 Ft 88 121 159 198 239 283 329 377 428
12 Ft 95 131 171 213 256 301 350 400 454 509
13 Ft 102 140 183 227 272 320 371 424 480 537 598
14 Ft 109 150 194 241 289 339 393 447 506 565 628
15 Ft 116 159 206 255 305 358 414 471 532 594 659
16 Ft 123 169 218 269 322 377 435 495 558 622 690
17 Ft 130 178 230 283 338 395 456 518 584 650 720
18 Ft 137 188 242 298 355 414 477 542 610 678 751
19 Ft 197 253 312 371 433 499 565 636 707 781
20 Ft 206 265 326 388 452 520 589 662 735 812
21 Ft 216 277 340 404 471 541 612 688 763 843
22 Ft 225 289 354 421 490 562 636 714 792 873
23 Ft 235 300 368 437 508 584 659 740 820 904
24 Ft 244 312 383 454 527 605 683 765 848 935
25 Ft 324 397 470 546 626 706 791 876 965
26 Ft 336 411 487 565 647 730 817 905 996
27 Ft 347 425 503 584 668 754 843 933 1027
28 Ft 359 440 520 603 690 777 869 961 1057
29 Ft 371 454 536 621 711 801 895 989 1088
30 Ft 383 468 553 640 732 824 921 1018 1118
31 Ft 395 482 569 659 753 848 947 1046 1149
32 Ft 496 586 678 775 871 973 1074 1180
33 Ft 510 602 697 796 895 999 1103 1210
34 Ft 524 619 715 817 918 1025 1131 1241
35 Ft 539 635 734 838 942 1051 1159 1272
36 Ft 553 652 753 860 966 1077 1187 1302
37 Ft 567 668 772 881 989 1103 1216 1333
Tank Diameter
3 Ft 4 Ft 5 Ft 6 Ft 7 Ft 8 Ft 9 Ft 10 Ft 11 Ft 12 Ft 13 Ft
Tank Length
Approximate Wetter Area of Tanks With Flat Heads, Square Feet
NFPA 30 — 201521.4.3.3 Normal vents shall be sized in accordance with either API Standard 2000, Venting Atmospheric and Low-Pressure Storage Tanks, or another approved standard. Alternatively, the normal vent shall be at least as large as the largest filling or withdrawal connection, but in no case shall it be less than 1¼ in. (3.2 cm) nominal inside diameter.
Normal Venting Recommendations
Venting Guide
Page 13
Table F: Emergency Venting Capacity
a Interpolate for intermediate values. b These values taken from NFPA 30–2015, Table 22.7.3.2Notes:• Emergency venting capacity is based on atmospheric pressure of 14.7 psia and 60° F (101.4 kPa and 16° C). • These pipe sizes apply only to open vent pipes to the specified diameter not more than 12 inches (0.3m) long and a pressure in tank of not more than 2.5 psig (17.1 kPa). • If tank is to be equipped with a venting device or flame arrestor, the vent opening is to accommodate the venting device or flame arrestor in accordance with the listed SCFH.
Page 14
Morrison Bros. Co.
Table G: Gallon Capacity Per Foot of LengthDiameter(Inches)
WARNINGS: The244emergencyventisfor"emergencypressurereliefonly"andmustbeusedinconjunctionwitha"normalvent"orpressurevacuumventsuchasaMorrisonFig.354,748,948A,749or922.The244emergencyventmustbeproperlysizedand selected for each specific tankapplication in order tomeet theproper"ventingcapacity"requirements.SeetheMorrisonVentGuideforfurtherinstructions.
WARNING: DO NOT FILL OR UNLOAD FUEL FROM A STORAGE TANK UNLESS IT IS CERTAIN THAT THE TANK VENTS WILL OPERATE PROPERLY. Morrisontankventsaredesignedonly foruseonshop fabricatedatmospheric tankswhichhavebeenbuiltand tested inaccordancewithUL142,NFPA30&30A,andAPI650and inaccordancewithallapplicable local,stateand federal laws. Innormaloperation,dustanddebriscanaccumulateinventopeningsandblockairpassages.Certainatmosphericconditionssuchasasuddendropintemperature,belowfreezingtemperatures,andfreezingraincancausemoisturetoentertheventandfreezewhichcanrestrictinternalmovementofventmechanismsandblockairpassages.Allstoragetankventairpassagesmustbecompletelyfreeofrestrictionandallventmechanismsmusthavefreemovementinordertoinsureproperoperation.Anyrestrictionofairflowcancauseexcessivepressureorvacuumtobuildupinthestoragetank,whichcanresultinstructuraldamagetothetank,fuelspillage,propertydamage,fire,injury,anddeath.Monthlyinspection,andimmediateinspectionduringfreezingconditions,bysomeonefamiliarwiththeproperoperationofstoragetankvents,isrequiredtoinsureventingdevicesarefunctioningproperlybeforefillingorunloadingatank.NormalventssuchaspressurevacuumandupdraftventsforabovegroundstoragetanksshouldbesizedaccordingtoNFPA30(2008)21.4.3
Construction Details2″ VentBody...Aluminum,iron,orbrassCover...AluminumorbrassO-Ring...FKMScreen...4meshstainlesssteel(optional)CenterPin...Zinc-platedsteel
Emergency vent should be set higher than the normal vent so thenormal vent operates first.
Use EVR models to comply with pressure decay test. Contact factory for assistance.
Certifications and ListingsUL2583Listed;948APressureVacuumVentsmeettherequirementsofEPA40CFRpart63forGasolineDispensingFacilities;MissouriAirConservationCommissionApprovedforRule10CSR10.2.260and10.5.220
WARNING: DO NOT FILL OR UNLOAD FUEL FROM A STORAGE TANK UNLESS IT IS CERTAIN THAT THE TANK VENTS WILLOPERATE PROPERLY. MorrisontankventsaredesignedonlyforuseonshopfabricatedatmospherictankswhichhavebeenbuiltandtestedinaccordancewithUL142,NFPA30&30A,andAPI650andinaccordancewithallapplicablelocal,state,andfederallaws.Innormaloperation,dustanddebriscanaccumulateinventopeningsandblockairpassages.Certainatmosphericconditionssuchasasuddendropintemperature,belowfreezingtemperatures,andfreezingraincancausemoisturetoentertheventandfreezewhichcanrestrictinternalmovementofventmechanismsandblockairpassages.Allstoragetankventairpassagesmustbecompletelyfreeofrestrictionandallventmechanismsmusthavefreemovementinordertoinsureproperoperation.Anyrestrictionofairflowcancauseexcessivepressureorvacuumtobuildupinthestoragetank,whichcanresultinstructuraldamagetothetank,fuelspillage,propertydamage,fire,injury,anddeath.Monthlyinspection,andimmediateinspectionduringfreezingconditions,bysomeonefamiliarwiththeproperoperationofstoragetankvents,isrequiredtoinsureventingdevicesarefunctioningproperlybeforefillingorunloadingatank.
Normal vents such as pressure vacuum and updraft vents for aboveground storage tanks
should be sized according to NFPA 30 (2015) 21.4.3.3
NOTE
WARNING: DO NOT FILL OR UNLOAD FUEL FROM A STORAGE TANK UNLESS IT IS CERTAIN THAT THE TANK VENTS WILLOPERATE PROPERLY. MorrisontankventsaredesignedonlyforuseonshopfabricatedatmospherictankswhichhavebeenbuiltandtestedinaccordancewithUL142,NFPA30&30A,andAPI650andinaccordancewithallapplicablelocal,state,andfederallaws.Innormaloperation,dustanddebriscanaccumulateinventopeningsandblockairpassages.Certainatmosphericconditionssuchasasuddendropintemperature,belowfreezingtemperatures,andfreezingraincancausemoisturetoentertheventandfreezewhichcanrestrictinternalmovementofventmechanismsandblockairpassages.Allstoragetankventairpassagesmustbecompletelyfreeofrestrictionandallventmechanismsmusthavefreemovementinordertoinsureproperoperation.Anyrestrictionofairflowcancauseexcessivepressureorvacuumtobuildupinthestoragetank,whichcanresultinstructuraldamagetothetank,fuelspillage,propertydamage,fire,injury,anddeath.Monthlyinspection,andimmediateinspectionduringfreezingconditions,bysomeonefamiliarwiththeproperoperationofstoragetankvents,isrequiredtoinsureventingdevicesarefunctioningproperlybeforefillingorunloadingatank.
Construction DetailsSize…2"NPTBodyandCap…AluminumPoppets…PTFEcoatedAluminumScreens…StainlesssteelOption(mustspecify)…MaleNPTconnectionfordryerapplicationOption…PressuredischargeNPThood
WARNING: DO NOT FILL OR UNLOAD FUEL FROM A STORAGE TANK UNLESS IT IS CERTAIN THAT THE TANK VENTS WILLOPERATE PROPERLY. Morrison tank vents are designed only for use on shop fabricated atmospheric tanks which have been built and tested in accordance with UL 142, NFPA 30 & 30A, and API 650 and in accordance with all applicable local, state, and federal laws. In normal operation, dust and debris can accumulate in vent openings and block air passages. Certain atmospheric conditions such as a sudden drop in temperature, below freezing temperatures, and freezing rain can cause moisture to enter the vent and freeze which can restrict internal movement of vent mechanisms and block air passages. All storage tank vent air passages must be completely free of restriction and all vent mechanisms must have free movement in order to insure proper operation. Any restriction of airflow can cause excessive pressure or vacuum to build up in the storage tank, which can result in structural damage to the tank, fuel spillage, property damage, fire, injury, and death. Monthly inspection, and immediate inspection during freezing conditions, by someone familiar with the proper operation of storage tank vents, is required to insure venting devices are functioning properly before filling or unloading a tank.
Construction DetailsBodyandhood…AnodizedaluminumPressurepoppet…AnodizedaluminumVacuumpoppet…BrassBodyseal…Buna-NScreen…40meshbrassSprings...StainlesssteelSetscrews...Zinc-platedsteel
Fig. 749 P/V vent must only be used in conjunction with motor fueling
and/or low capacity flow. Fluid handling in lines larger than that used for retail service stations
can cause tank to rupture or implode.
WARNING
WARNING: DO NOT FILL OR UNLOAD FUEL FROM A STORAGE TANK UNLESS IT IS CERTAIN THAT THE TANK VENTS WILL OPERATE PROPERLY. MorrisontankventsaredesignedonlyforuseonshopfabricatedatmospherictankswhichhavebeenbuiltandtestedinaccordancewithUL142,NFPA30&30A,andAPI650andinaccordancewithallapplicablelocal,stateandfederallaws.Innormaloperation,dustanddebriscanaccumulateinventopeningsandblockairpassages.Certainatmosphericconditionssuchasasuddendropintemperature,belowfreezingtemperatures,andfreezingraincancausemoisturetoentertheventandfreezewhichcanrestrictinternalmovementofventmechanismsandblockairpassages.Allstoragetankventairpassagesmustbecompletelyfreeofrestrictionandallventmechanismsmusthavefreemovementinordertoinsureproperoperation.Anyrestrictionofairflowcancauseexcessivepressureorvacuumtobuildupinthestoragetank,whichcanresultinstructuraldamagetothetank,fuelspillage,propertydamage,fire,injury,anddeath.Monthlyinspection,andimmediateinspectionduringfreezingconditions,bysomeonefamiliarwiththeproperoperationofstoragetankvents,isrequiredtoinsureventingdevicesarefunctioningproperlybeforefillingorunloadingatank.NormalventssuchaspressurevacuumandupdraftventsforabovegroundstoragetanksshouldbesizedaccordingtoNFPA30(2008)21.4.3.
Page 22 Page 23
Venting Guide
Fig. 922
2” Pressure relief setting 6 oz/in2 or 8 oz/in2
2” Vacuum relief setting 1 oz/in2
2” Venting capacity (SCFH) 30,120 or 30,3002" Weight 7.50 lbs
3” Pressure relief setting 6 oz/in2 or 8 oz/in2
3” Vacuum relief setting 1 oz/in2
3” Venting capacity (SCFH) 43,020 or 44,1603" Weight 5.25 lbs
Construction DetailsBody...AnodizedaluminumScreens...StainlesssteelRainguard...AluminumSeals...FKMBall...PTFEFloat...Stainlesssteel
Certifications & ListingsFloridaDEPEQ-227
All emergency vents, fill connections, tank openings, and piping connections must be
airtight. Alarm/vent airway must be free of any obstruction such as dirt or ice when filling or
unloading tank. Emergency vent should be set at least 2 oz. higher than combination vent.
WARNING
WARNING: DO NOT FILL OR UNLOAD FUEL FROM A STORAGE TANK UNLESS IT IS CERTAIN THAT THE TANK VENTS WILL OPERATE PROPERLY. MorrisontankventsaredesignedonlyforuseonshopfabricatedatmospherictankswhichhavebeenbuiltandtestedinaccordancewithUL142,NFPA30&30A,andAPI650andinaccordancewithallapplicablelocal,stateandfederallaws.Innormaloperation,dustanddebriscanaccumulateinventopeningsandblockairpassages.Certainatmosphericconditionssuchasasuddendropintemperature,belowfreezingtemperatures,andfreezingraincancausemoisturetoentertheventandfreezewhichcanrestrictinternalmovementofventmechanismsandblockairpassages.Allstoragetankventairpassagesmustbecompletelyfreeofrestrictionandallventmechanismsmusthavefreemovementinordertoinsureproperoperation.Anyrestrictionofairflowcancauseexcessivepressureorvacuumtobuildupinthestoragetank,whichcanresultinstructuraldamagetothetank,fuelspillage,propertydamage,fire,injury,anddeath.Monthlyinspection,andimmediateinspectionduringfreezingconditions,bysomeonefamiliarwiththeproperoperationofstoragetankvents,isrequiredtoinsureventingdevicesarefunctioningproperlybeforefillingorunloadingatank.NormalventssuchaspressurevacuumandupdraftventsforabovegroundstoragetanksshouldbesizedaccordingtoNFPA30(2008)21.4.3.
WARNING: DO NOT FILL OR UNLOAD FUEL FROM A STORAGE TANK UNLESS IT IS CERTAIN THAT THE TANK VENTS WILL OPERATE PROPERLY. MorrisontankventsaredesignedonlyforuseonshopfabricatedatmospherictankswhichhavebeenbuiltandtestedinaccordancewithUL142,NFPA30&30A,andAPI650andinaccordancewithallapplicablelocal,stateandfederallaws.Innormaloperation,dustanddebriscanaccumulateinventopeningsandblockairpassages.Certainatmosphericconditionssuchasasuddendropintemperature,belowfreezingtemperatures,andfreezingraincancausemoisturetoentertheventandfreezewhichcanrestrictinternalmovementofventmechanismsandblockairpassages.Allstoragetankventairpassagesmustbecompletelyfreeofrestrictionandallventmechanismsmusthavefreemovementinordertoinsureproperoperation.Anyrestrictionofairflowcancauseexcessivepressureorvacuumtobuildupinthestoragetank,whichcanresultinstructuraldamagetothetank,fuelspillage,propertydamage,fire,injury,anddeath.Monthlyinspection,andimmediateinspectionduringfreezingconditions,bysomeonefamiliarwiththeproperoperationofstoragetankvents,isrequiredtoinsureventingdevicesarefunctioningproperlybeforefillingorunloadingatank.NormalventssuchaspressurevacuumandupdraftventsforabovegroundstoragetanksshouldbesizedaccordingtoNFPA30(2008)21.4.3.
Construction DetailsBodyandcover...CastironArresterplates...StainlesssteelArrestergridhousing...Brass
351S
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Venting Guide
WARNING: DO NOT FILL OR UNLOAD FUEL FROM A STORAGE TANK UNLESS IT IS CERTAIN THAT THE TANK VENTS WILL OPERATE PROPERLY. MorrisontankventsaredesignedonlyforuseonshopfabricatedatmospherictankswhichhavebeenbuiltandtestedinaccordancewithUL142,NFPA30&30A,andAPI650andinaccordancewithallapplicablelocal,stateandfederallaws.Innormaloperation,dustanddebriscanaccumulateinventopeningsandblockairpassages.Certainatmosphericconditionssuchasasuddendropintemperature,belowfreezingtemperatures,andfreezingraincancausemoisturetoentertheventandfreezewhichcanrestrictinternalmovementofventmechanismsandblockairpassages.Allstoragetankventairpassagesmustbecompletelyfreeofrestrictionandallventmechanismsmusthavefreemovementinordertoinsureproperoperation.Anyrestrictionofairflowcancauseexcessivepressureorvacuumtobuildupinthestoragetank,whichcanresultinstructuraldamagetothetank,fuelspillage,propertydamage,fire,injury,anddeath.Monthlyinspection,andimmediateinspectionduringfreezingconditions,bysomeonefamiliarwiththeproperoperationofstoragetankvents,isrequiredtoinsureventingdevicesarefunctioningproperlybeforefillingorunloadingatank.NormalventssuchaspressurevacuumandupdraftventsforabovegroundstoragetanksshouldbesizedaccordingtoNFPA30(2008)21.4.3.