RULE 212 STORAGE OF ORGANIC LIQUIDS

 Adopted 5-24-77 

(Amended 6-19-79, 9-25-90, 10-19-93, 11-03-94, 6-08-95, 6-19-97) 

CONTENTS

100 GENERAL

101 PURPOSE 

102 APPLICABILITY 

200 DEFINITIONS

201 EFFICIENCY 

202 EXEMPT COMPOUNDS 

203 EXTERNAL FLOATING ROOF 

204 INTERNAL FLOATING ROOF 

205 METALLIC-SHOE-SEAL 

206 ORGANIC LIQUID 

207 PRESSURE TANK 

208 RESILIENT-TOROID-SEAL 

209 STORAGE TANK 

210 VAPOR PRESSURE 

211 VAPOR RECOVERY SYSTEM 

212 VAPOR TIGHT 

213 VOLATILE ORGANIC COMPOUNDS (VOC) 

300 STANDARDS

301 STORAGE TANKS WITH A CAPACITY GREATER THAN 40,000 GALLONS 

302 STORAGE TANKS WITH A CAPACITY LESS THAN OR EQUAL TO 40,000 GALLONS 

303 STORAGE TANKS WITH A CAPACITY GREATER THAN 20,000 GALLONS AND LESS 

THAN OR EQUAL TO 40,000 GALLONS 

304 ABOVE GROUND STORAGE TANKS WITH A CAPACITY GREATER THAN 10,000 

GALLONS AND LESS THAN OR EQUAL TO 20,000 GALLONS 

305 ANY STORAGE TANK CONTAINING ORGANIC LIQUIDS WITH A VAPOR 

PRESSURE GREATER THAN 569 MM Hg (11 PSIA) 

306 EXTERNAL FLOATING ROOF 

307 INTERNAL FLOATING ROOF 

308 VAPOR RECOVERY SYSTEM 

309 CRITERIA FOR METALLIC-SHOE-SEAL CLOSURES 

310 CRITERIA FOR WELDED TANKS WITH METALLIC-SHOE-SEALS 

311 CRITERIA FOR RIVETED TANKS WITH METALLIC-SHOE-SEALS 

312 CRITERIA FOR RESILIENT-TOROID-SEAL 

313 CRITERIA FOR WELDED TANKS WITH ZERO GAP SECONDARY SEALS 

400 ADMINISTRATIVE REQUIREMENTS

401 PRIMARY SEAL INSPECTION 

500 MONITORING AND RECORDS

501 RECORDKEEPING 

502 TEST METHODS 

June 19, 1997

Placer County APCD 212 - 1 Rules and Regulations 
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June 19, 1997 

Rules and Regulations 212 - 2 Placer County APCD 
100 GENERAL

101 PURPOSE: To limit emissions from storage tanks for organic liquids. 

102 APPLICABILITY:

102.1 Geographic: The provisions of this rule apply to all of Placer County. 

102.2 Business Function: This rule applies to any facility where organic liquids having 

a vapor pressure greater than 25.8 mm Hg (0.5 psia) are placed, stored, or held 

in any stationary tank, reservoir or other bulk container. 

200 DEFINITIONS

201 EFFICIENCY: A comparison of controlled emissions to those uncontrolled emissions 

which would occur from a fixed or cone roof tank in the same product service without a 

vapor control system. Baseline emissions shall be calculated using the criteria in API 

Bulletin 2518. 

202 EXEMPT COMPOUNDS: Exempt Compounds are defined in Rule 102, Definitions.

203 EXTERNAL FLOATING ROOF: A vapor loss control device, consisting of a pontoontype or double-deck-type cover that rests on the surface of the liquid contents and which 

is equipped with an approved closure device between the tank shell and roof edge.

204 INTERNAL FLOATING ROOF: A vapor loss control device consisting of a fixed roof 

with an internal-floating-type cover which prevents the release or emission to the 

atmosphere of organic vapors or gases at an efficiency equivalent to an approved 

external floating roof closure device. 

205 METALLIC-SHOE-SEAL: A type of seal used to minimize evaporative losses of organic 

liquids from a storage tank equipped with an external floating roof. It serves a primary 

seal, and is constructed with vertical metal plates or "shoes", connected by braces or 

other devices to the circumference of the floating roof. They are partially immersed in 

the liquid being stored, and are suspended in such a way that they are forced outward 

against the inner tank wall. 

206 ORGANIC LIQUID: Any volatile organic compound which contains hydrogen and which 

would exist as a liquid at actual conditions of use or storage. 

207 PRESSURE TANK: A closed storage tank designed and constructed to (1) operate at 

internal pressures above one atmosphere, (2) be able to withstand the vapor pressure of 

the stored liquid under all storage conditions and (3) prevent at all times the loss of such 

material or its vapor to the atmosphere.

208 RESILIENT-TOROID-SEAL: A type of seal used to minimize evaporative losses of 

organic liquids from a storage tank equipped with an external floating roof. It is a toroidal 

tube, or "donut", made of fabric or other resilient material, that rests on the surface of the 

stored liquid. It serves as primary seal that minimizes evaporative losses from the tank. 

The toroid seal may be filled with air, foam, or other resilient material.

209 STORAGE TANK: Any stationary container, reservoir, or tank used for the storage of 

organic liquids. 

210 VAPOR PRESSURE: The vapor pressure under actual storage conditions as 

determined by the test methods specified in Section 502.1. 

June 19, 1997

Placer County APCD 212 - 3 Rules and Regulations 
211 VAPOR RECOVERY SYSTEM: A California Air Resources Board (CARB) - certified 

system that collects organic vapors and gases from a storage tank and either returns 

them to the tank or otherwise processes them to prevent or reduce emissions to the 

atmosphere. 

212 VAPOR TIGHT: A condition when the concentration of total hydrocarbons does not 

exceed 10,000 ppm (expressed as methane) above background, as determined by EPA 

Reference Method 21. Background shall be defined as the ambient concentration of 

organic compounds determined at least three (3) meters upwind of the potential source 

and not influenced by any specific emissions source. 

213 VOLATILE ORGANIC COMPOUNDS (VOC): Compounds which contain at least one 

atom of carbon, except for the Exempt Compounds. 

300 STANDARDS

301 STORAGE TANKS WITH A CAPACITY GREATER THAN 40,000 GALLONS: A person 

shall not store any organic liquid having a vapor pressure greater than 25.8 mm Hg (0.5 

psia), in any storage tank with a capacity greater than 40,000 gallons, unless such tank is 

(1) a pressure tank maintaining working pressures sufficient at all times to prevent 

organic vapor or gas loss to the atmosphere, or (2) designed and equipped with one of 

the vapor loss control devices as specified in Sections 306, 307, and 308 of this rule.

302 STORAGE TANKS WITH A CAPACITY LESS THAN OR EQUAL TO 40,000 

GALLONS: A person shall not store any organic liquid having a vapor pressure greater 

than 25.8 mm Hg (0.5 psia), in any storage tank with a capacity less than or equal to 

40,000 gallons, unless such tank is equipped with one of the following: 

302.1 A submerged fill pipe. 

302.2 An apparatus of efficiency equal to a submerged fill pipe and which has been 

approved by the Air Pollution Control Officer. 

302.3 One of the vapor loss control devices that complies with the applicable 

requirements of Sections 306 through 313 of this rule. 

303 STORAGE TANKS WITH A CAPACITY GREATER THAN 20,000 GALLONS AND 

LESS THAN OR EQUAL TO 40,000 GALLONS: A person shall not store any organic 

liquid having a vapor pressure greater than 77.5 mm Hg (1.5 psia) in any storage tank 

with a capacity greater than 20,000 gallons, but less than or equal to 40,000 gallons, 

unless such tank is (1) a pressure tank maintaining working pressures sufficient at all 

times to prevent organic vapor or gas loss to the atmosphere, or (2) designed and 

equipped with one of the vapor loss control devices as specified in Sections 306 through 

313 of this rule. 

304 ABOVE GROUND STORAGE TANKS WITH A CAPACITY GREATER THAN 10,000 

GALLONS AND LESS THAN OR EQUAL TO 20,000 GALLONS: A person shall not 

store any organic liquid having a vapor pressure greater than 77.5 mm Hg (1.5 psia) in 

any above ground storage tank with a capacity greater than 10,000 gallons, but less than 

or equal to 20,000 gallons capacity, unless such tank is (1) equipped with a pressurevacuum valve which is set to operate at a pressure within 10% of the maximum allowable 

working pressure of the tank, or at a pressure of at least 25.8 mm Hg (0.5 psia), or (2) 

equipped with a vapor loss control device as specified in Sections 306 through 313 of this 

rule. 

June 19, 1997 

Rules and Regulations 212 - 4 Placer County APCD 
305 ANY STORAGE TANK CONTAINING ORGANIC LIQUIDS WITH A VAPOR 

PRESSURE GREATER THAN 569 mm Hg (11 psia): A person shall not store organic 

liquid with a vapor pressure greater than 569 mm Hg (11 psia) in any storage tank 

unless such tank is (1) a pressure tank maintaining working pressures sufficient at all 

times to prevent organic vapor or gas loss to the atmosphere, or (2) designed and 

equipped with a vapor recovery system which meets the requirements of Section 308 of 

this rule. 

306 EXTERNAL FLOATING ROOF: This vapor loss control device, as defined in Section 

203, shall be equipped with a closure device that consists of two seals, one above the 

other; the one below shall be referred to as the primary seal and the one above shall be 

referred to as the secondary seal. Seal designs shall be submitted to the Air Pollution 

Control Officer and shall not be installed or used unless they are approved by the Air 

Pollution Control Officer as meeting the criteria set forth within this section and the 

applicable closure requirements of Sections 309 through 313 of this rule. 

307 INTERNAL FLOATING ROOF: This vapor loss control device with a fixed external roof, 

as defined in Section 205, shall prevent the release or emission to the atmosphere of 

organic vapors or gases at an efficiency equivalent to a floating roof closure device which 

meets the applicable requirements of Sections 309 through 313 of this rule. 

308 VAPOR RECOVERY SYSTEM:

308.1 Any installed vapor recovery system shall be a CARB certified vapor recovery 

system capable of collecting organic vapors and gases, and shall include a vapor 

return or disposal system capable of processing such vapors and gases to 

prevent their emission to the atmosphere, at an efficiency of at least 95 percent 

by weight, determined in accordance with the applicable test method of Section 

502.2. 

308.2 Any tank gauging or sampling device on a tank vented to the vapor recovery 

system shall be equipped with a vapor-tight cover which shall be closed at all 

times except during gauging or sampling. 

308.3 All piping, valves and fittings shall be constructed and maintained in a vapor-tight 

condition, as defined in Section 212. 

309 CRITERIA FOR METALLIC-SHOE-SEAL CLOSURES: 

309.1 Metallic-shoe-type seals shall be installed so that one end of the shoe extends 

into the stored liquid and the other end extends a minimum vertical distance of 61 

cm (24 inches) above the stored liquid surface. 

309.2 The geometry of the shoe shall be such that the maximum gap between the shoe 

and the tank shell is no greater than double the gap allowed by the seal gap 

criteria for a length of at least 46 cm (18 inches) in the vertical plane above the 

liquid surface. 

309.3 There shall be no holes or tears in, or openings through the secondary seal or in 

the primary seal envelope surrounding the annular vapor space enclosed by the 

roof edge, stored liquid surface, shoe, and seal fabric. 

309.4 The secondary seal shall extend from the roof to the tank shell and shall not be 

attached to the primary seal. 

June 19, 1997

Placer County APCD 212 - 5 Rules and Regulations 
309.5 Any roof drain which opens directly into the organic liquid content in the tank 

shall be provided with a slotted membrane fabric cover, or equivalent, that covers 

at least 90% of the area of the opening. 

309.6 All openings in the roof, except pressure-vacuum valves, shall provide a 

projection below the liquid surface to prevent belching of liquid and to prevent 

entrained or formed organic vapor from escaping from the liquid contents of the 

tank and shall be equipped with a cover, seal or lid. The cover, seal, or lid shall at 

all times be in a closed position, with no measurable gap exceeding 0.32 cm (1/8 

in.), except when the device or appurtenance is in use. Pressure-vacuum valves 

located in the roof shall be set to within ten percent of the maximum allowable 

working pressure of the roof. 

310 CRITERIA FOR WELDED TANKS WITH METALLIC-SHOE-SEALS: Any welded tank 

shell which uses a metallic-shoe-type seal shall meet the following conditions: 

310.1 No gap between the tank shell and the primary seal shall exceed 3.8 cm (1-1/2 

inches). The cumulative length of all primary seal gaps exceeding 1.3 cm (2 inch) 

shall be not more than 10% of the circumference; the cumulative length of all 

primary seal gaps exceeding 0.32 cm (1/8 inch) shall not be more than 40 

percent of the circumference. No continuous gap greater than 0.32 cm (1/8 inch) 

shall exceed 10% of the circumference of the tank. 

310.2 No gap between the tank shell and the secondary seal shall exceed 1.3 cm (2

inch). The cumulative length of all secondary seal gaps exceeding 0.32 cm (1/8 

inch) shall not exceed 5 percent of the circumference of the tank. 

310.3 The secondary seal shall allow easy insertion of probes up to 3.8 cm (1-1/2 

inches) in width in order to measure gaps in the primary seal. 

311 CRITERIA FOR RIVETED TANKS WITH METALLIC-SHOE-SEALS: Any riveted tank 

shell which uses a metallic-shoe-seal shall meet the following conditions: 

311.1 No gap between the tank shell and the primary seal shall exceed 6.4 cm (2-1/2 

in.). The cumulative length of all primary seal gaps exceeding 3.8 cm (1-1/2 in.) 

shall not be more than 10% of the circumference. 

311.2 The secondary seal shall consist of at least two sealing surfaces, such that the 

sealing surfaces prevent the emission of organic compounds around the rivets. 

Serrated sealing surfaces are allowable if the length of serration does not exceed 

15.2 cm (6 in.). No gap between the tank shell and the secondary seal shall 

exceed 1.3 cm (2 in.). The cumulative length of all secondary seal gaps 

exceeding 0.32 cm (1/8 in.) shall not be more than 5% of the circumference. 

311.3 The secondary seal shall allow easy insertion of probes up to 3.8 cm (1-1/2 

inches) in width in order to measure gaps in the primary seal. 

312 CRITERIA FOR RESILIENT-TOROID-SEAL: Any storage tank which uses a resilienttoroid-type seal shall meet the following conditions: 

312.1 No gap between the tank shell and the primary seal shall exceed 1.3 cm (2 inch). 

The cumulative length of all gaps exceeding 0.32 cm (1/8 inch) shall not be more 

than 5% of the circumference. 

June 19, 1997 

Rules and Regulations 212 - 6 Placer County APCD 
312.2 No gap between the tank shell and the secondary seal shall exceed 1.3 cm (2

inch). The cumulative length of all gaps exceeding 0.32 cm (1/8 inch) shall not be 

more than 5% of the circumference. 

312.3 The secondary seal shall allow easy insertion of probes up to 1.3 cm (2 inch) in 

width in order to measure gaps in the primary seal. 

312.4 There shall be no holes or tears in, or openings through the secondary seal or in 

the primary seal envelope surrounding the annular vapor space enclosed by the 

roof edge, stored liquid surface, shoe, and seal fabric. 

313 CRITERIA FOR WELDED TANKS WITH ZERO GAP SECONDARY SEALS: Any 

welded tank shell which uses a zero gap secondary seal must meet the following 

conditions: 

313.1 No gap between the tank shell and the primary seal shall exceed 3.8 cm (1-1/2 

inches). The cumulative length of all primary seal gaps exceeding 1.3 cm (2 inch) 

shall be not more than 10% of the circumference and the cumulative length of all 

primary seal gaps exceeding 0.32 cm (1/8 inch) shall not be more than 40% of 

the circumference. No continuous gap greater than 0.32 cm (1/8 inch) shall 

exceed 10% of the circumference of the tank. 

313.2 No gap between the tank shell and the secondary seal shall exceed 1.5 mm 

(0.06 in.). The cumulative length of all secondary seal gaps exceeding 0.5 mm 

(0.02 inch) shall not exceed 5% of the circumference of the tank, excluding gaps 

less than 5 cm (1.79 in.) from vertical weld seams. 

313.3 The secondary seal must exert a positive pressure against the tank shell such 

that the seal surface in contact with the tank shell does not pull away from the 

tank shell more than the gaps allowed in Section 313.2. 

400 ADMINISTRATIVE REQUIREMENTS

401 PRIMARY SEAL INSPECTION:

401.1 The primary seal envelope shall be made available for unobstructed inspection 

by the District on an annual basis at four locations selected along its 

circumference at random by the APCO. If the District detects one or more 

violations as a result of any such inspection, the District may require such further 

unobstructed inspection of the primary seal as may be necessary to determine 

the seal condition for its entire circumference. The District shall also have the 

authority to require more inspection locations if the inspector suspects the 

possibility of a cumulative gap criteria violation. 

401.2 In addition, for tanks with secondary seals the primary seal envelope shall be 

made available for inspection by the District prior to the installation of the 

secondary seal. For tanks with secondary seals installed before June 19, 1979, 

the primary seal envelope shall be made available for unobstructed inspection by 

the District for its full length every 5 years after June 19, 1979, except that if the 

secondary seal is voluntarily removed by the owner or operator prior thereto, it 

shall be made available for such inspection at that time. The owner or operator 

shall provide notification to the District no less than 7 working days prior to 

voluntary removal of the secondary seal. 

June 19, 1997

Placer County APCD 212 - 7 Rules and Regulations 
500 MONITORING AND RECORDS

501 RECORDKEEPING:

501.1 A person whose tanks are subject to this Rule shall keep an accurate record of 

liquids stored in such containers and the vapor pressure ranges of such liquids. 

501.2 Accurate records of throughput and stock temperature shall also be maintained. 

501.3 Records shall include the number of organic liquid storage tanks serviced and 

their respective capacities in gallons. 

501.4 Records shall be retained for a period of at least 2 years, and shall be retained at 

least 5 years by sources subject to the requirements of Rule 507, Federal 

Operating Permit Program, and made available to the Air Pollution Control 

Officer on request. 

501.5 In addition to the recordkeeping requirements specified herein, all applicable 

provisions of Rule 410, Recordkeeping for Volatile Organic Compounds 

Emissions, shall be met. 

502 TEST METHODS 

502.1 Vapor Pressure Determination: The vapor pressure under actual storage 

conditions is determined by ASTM method D-2879-83 or ASTM method D-323-

82. 

502.2 Vapor Recovery System Testing: The determination of the overall vapor 

recovery system efficiency required in Section 308 shall be made using the 

following test procedures, as applicable: 

502.2.1 California Air Resources Board Test Method TP 202.1, ADetermination of 

Emission Factor of Vapor Recovery Systems at Gasoline Bulk Plants@. 

502.2.2 California Air Resources Board Test Method TP 203.1, ADetermination of 

Emission Factor of Vapor Recovery Systems at Gasoline Terminals@. 

502.3 Vapor-Tight Condition Testing: EPA Reference Method 21 shall be used to test 

for vapor-tight condition.

June 19, 1997 

Rules and Regulations 212 - 8 Placer County APCD