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A Guide Used to Assist in Equipment Selection for Aboveground Storage Tanks VEN

A Guide Used to Assist in Equipment Selection for Aboveground Storage Tanks VENTING GUIDE This guide is intended for reference use only. All ﬁ nal 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. September 2011 for aboveground storage tanks Page ii Morrison Bros. Co. Changes to this edition of the Morrison Venting Guide include... Reference Updates • UL 142 references updated according to 9th edition. • NFPA 30 references updated from 2003 edition to 2008 edition. • Addition of ULC S601-07 reference. Product Updates EMERGENCY VENTS • Vents with brass seats obsoleted • All 244Os now UL and ULC listed • Updated CFH capacities • Added CFH capacities for vents with screens • Added Enhanced Vapor Recovery (EVR) models • Added 2" 16 oz. brass vents - New Product! • Added 2" 16 oz. aluminum vents - New Product! • Added 3" 16 oz. vents - New Product! • Added 4" ﬂ anged vents - New Product! • Added 5" male and female threaded vents - New Product! OVERFILL PREVENTION VALVES • Added 9095SS valve - New Product! • Added 9095DS valve - New Product! • Added 9095C valve - New Product! • Added Enhanced Vapor Recovery (EVR) models - New Product! SPILL CONTAINERS/FILL PORTS • Added 515OEM - New Product! • Added 516 - New Product! • Added Enhanced Vapor Recovery (EVR) models - New Product! • Added 715 remote ﬁ ll box - New Product! PRESSURE/VACUUM VENTS • Added 3" 749 vent - New Product! TANK GAUGES • Added 1018 series Morrison Bros. Co. is continuously adding new products, receiving third party approvals, and making product improvements where possible. To view the most current version of this document or speciﬁ c product speciﬁ cation sheets describing our products, visit our website at www.morbros.com or contact Morrison Customer Service at custserv@morbros.com. Page 1 Venting Guide Contents I. Background Information Page Introduction 2 Deﬁ nitions 2 II. Example Calculations for Vent Selection Horizontal Cylindrical Storage Tank 3 Vertical Cylindrical Storage Tank 4 Horizontal Rectangular Storage Tank 5 III. Calculation Tables Precalculated-Horizontal Cylindrical Tanks 6 Precalculated-Vertical Cylindrical Storage Tanks 7 Precalculated-Horizontal Rectangular Storage Tanks 8 Wetted Areas for Horizontal Cylindrical Tanks 9 Wetted Areas for Vertical Cylindrical Tanks 10 Emergency Venting Capacity 11 Gallon Capacity per Foot of Length 12 IV. Vent Selection Vent Capacity 13 Vent Combination Examples 14 Morrison Equipment 15 V. Aboveground Fuel Storage Diagrams Pressure Systems 28 Suction Systems 30 Bulk Storage 32 References NFPA 30 “Flammable and Combustible Liquids Code” 2008 Edition National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02269 UL 142 “Steel Aboveground Tanks” 9th Edition, December 28, 2006 UL Standards for Safety—UL Publication Stock, 333 Pﬁ ngsten Road, Northbrook, IL 60062, Tel (847) 272-8800 ULC S601-07 Standard for Shop Fabricated Steel Aboveground Tanks for Flammable and Combustible Liquids, December 2007, Underwriters’ Laboratories of Canada 7 Underwriters Rd., Toronto, ON M1R 3B4, (514) 757-3611 API Std 2000 “Venting Atmospheric & Low Pressure Storage Tanks” American Petroleum Institute—Fifth Edition, April 1998 1120 L Street, Northwest, Washington, DC 20005 Order #822-20000 PEI RP200 “Recommended Practices for Installation of Aboveground Storage Systems for Motor Vehicle Fueling” Petroleum Equipment Institute, 2003 Edition, P.O. Box 2380. Tulsa, OK, 74101 Tel (918) 494-9696 Morrison Bros. Co. 507 East 7th Street, Dubuque, Iowa 52001. Tel (563) 583-5701 Page 2 Morrison Bros. Co. Background Information The Morrison Bros. Co. Venting Guide was created to assist in equipment selection for aboveground storage tanks. Examples on the next two pages illustrate a vent selection process. It is best to work through the examples before attempting to use any of the tables in this book. Tables include examples for standard sized tanks. The venting capacity charts and wetted area tables were taken directly from NFPA 30 and UL 142. The vent selection chapter includes venting capacities of speciﬁ c Morrison vents. This data was obtained from results of laboratory testing and engineering calculations. Catalog pages of the Morrison equipment follow the vent capacity chart. Deﬁ nitions Emergency Venting — Venting sufﬁ cient to relieve excessive internal pressure in storage tanks caused by exposure ﬁ res. Venting rate may exceed requirements of normal atmo- spheric and product transfer effects. In such cases, the construction of the tank will deter- mine if additional venting capacity must be provided. Atmospheric Tank — A storage tank that has been designed to operate at pressures from atmospheric through 1.0 PSIG (760 mm Hg through 812 mm Hg) measured at the top of the tank (NFPA 30 Pg. 30-13). Pressure not to exceed 1.0 PSIG under normal operation, and 2.5 PSIG under emergency conditions (PEI RP-200). Pressure Relieving Devices — Deﬁ ned in NFPA 30 4.2.5.2.3, where entire depen- dence for emergency relief is placed upon pressure relieving devices, the total venting capacity of both normal and emergency vents shall be enough to prevent rupture of the shell or bottom of the tank if vertical, or of the shell or heads if horizontal. Wetted Area — Exposed surface or shell area of a tank used in determining the vent- ing requirements needed for that size tank in event of an exposure ﬁ re. In a horizontal tank, the wetted area is calculated as 75% of the exposed surface area. In a vertical tank, the wetted area is calculated as the ﬁ rst 30 ft. above grade of the exposed shell area of the tank. CFH — Abbreviation for Cubic Feet per Hour used to quantify or measure the airﬂ ow and degree of pressure relief for venting calculations. Vent Capacity — The maximum rate of air- ﬂ ow (CFH) recorded under test conditions at a maximum pressure of 2.5 PSI for speciﬁ c sized emergency vents. This capacity rating is often required to be indicated on the vent itself. Page 3 Venting Guide STEP 1 Precalculated Data for Common Sizes Find tank size on Table A which can be found on page 6. Table lists wetted area and CFH for common sized horizon- tal tanks. For a 10’ x 17’ tank – wetted area = 518 sq. ft. and required vent capacity = 360,840 CFH. Proceed to Step 5. STEP 2 Wetted Area Table If tank size is NOT listed on Table A, page 6, wetted area can also be found on Table D, page 9. Follow grid for this example – 10’ diameter x 17’ length = 518 sq. ft. Proceed to Step 4. STEP 3 Calculate Wetted Area If the tank size is NOT on either chart, wetted area can be calculated. For Horizontal Tanks, wetted area = 75% of the total exposed surface area. For a 10’ x 17’ tank: 0.75[2(area of each end) + (area of shell)] = wetted area π = 3.14, d = diameter, L = length, WA = wetted area WA = 0.75[(πd 2 ÷ 2) +(πdL)] 0.75[((3.14)(10 2) ÷ 2) + (3.14)(10)(17)] WA = 518 sq. ft. STEP 4 Determine CFH Requirement Use Table F: Venting Capacity Chart on page 11. Wetted area must be known (518 sq. ft.). Since 518 is between 500 and 600 on the chart, interpolation is needed and is done as follows: 600 sq. ft. 392,000 CFH 500 sq. ft. 354,000 CFH Difference = 100 sq. ft. 38,000 CFH 38,000 = x 100 (518-500) x = 6,840 CFH Total CFH Required: (6,840 + 354,000) = 360,840 CFH Vent Selection/Capacity Example 1 STEP 5 Vent Selection Options based on size of piping, type of product, ﬂ ow requirements, required venting capacity and mounting. For the sake of this example, use 2” piping, Class 1B liquid. The normal vent size should be no smaller than the system piping, so a Morrison 2” Fig. 548 (20,200 CFH) is selected. Total required venting capacity for this tank example was determined to be 360,840 CFH. Normal venting and emergency venting may be combined to reach this total. Morrison Vent Capacities are listed on Table H, page 13. Since the 6” Emergency Vent (278,660 CFH) can not pro- vide enough additional capacity to meet the requirement, an 8” Emergency Vent (504,818 CFH) is selected. In specify- ing pressure settings, it is recommended that the Emergency Vent NOT be less than the normal vent. Therefore, the vent speciﬁ cation for this example is as follows: Normal Vent - 2” Fig 548 20,200 CFH (8 oz pressure - 1 oz vacuum) Emergency Vent - 8” Fig 244O 504,818 CFH (16 oz pressure) Total Venting Provided 525,018 CFH STEP 6 Veriﬁ cation Refer to Table I on page 14 showing vent combinations and verify the total CFH ﬁ gure. Also refer to the product illustra- tions on pages 15-19 and verify the selection for correct option on material compatibility and mounting requirements. Horizontal Cylindrical Storage Tank TANK CAPACITY 10,000 gallons TANK SIZE 10 ft. dia uploads/Geographie/ venting-guide.pdf