Pat BennettEngineering Evaluation SectionMonitoring and Laboratory DivisionCalifornia Air Resources Board

AST EVR WORKGROUP MEETINGJuly 23, 2002

Workgroup Agenda• Welcome & Sign-In• Overview of April 17th Meeting• AST Inventory Request• Status of AST Monitoring Effort• Estimating AST Fugitive Emissions• Efficiency Testing / Procedure

Development• Open Discussion and Schedule Next

Meeting• Close

April 17th Meeting Highlights

• AST Definition - Consensus to include requirement for emergency vent into AST definition found in ARB’s Interim AST Certification Guidelines

• AST Inventory - Current estimate of ASTs is very low. Recommend to contact AST manufacturers for more accurate number.

Revised AST Definition

A system that uses a gasoline storage tank that is intended for

fixed installation, without backfill, is located above or below grade and requires emergency relief venting.

AST Inventory Request

• Letter Sent to AST Manufacturers

– list included 279 manufacturers from UL Listed Storage Tanks Directory

– requested response by August 15th

– requested information on number of ASTs for agricultural and non-agricultural applications, and size distributions

Status of AST Monitoring Effort

• Monitoring 1,000 and 6,000 gallon balance, single dispenser AST systems

• Difficulty in maintaining vapor integrity on 1,000 gallon AST due to component leakages and loose drain valve and tank bung following Phase I deliveries.

Status of AST Monitoring Effort (continued)

• High throughput of ORVR vehicles on 6,000 gallon AST

• Will not conduct pressure integrity test on 6,000 gallon tank until long-bolt manway emergency vent is replaced with new vent.

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Pre

ssur

e (in

H2O

)

Tank Pressure

Pressure Decay Test #1 - Passed After

Replacing Fuel Gauge

Phase I Delivery

Loss of Vapor Integrity Following Phase I

Delivery

Vapor Integrity Maintained For Only 6 Days Following Successful Pressure Decay Test

1,000 Gallon Capacity Balance Tank3,000 Gallon/Month Throughput

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Pre

ssur

e (in

H2O

)

Pressure Decay Test #2 - Passed After Tightening 2" Tank Bung, Drain Valve,

and Cleaning Vapor Poppet

1,000 Gallon Capacity Balance Tank3,000 Gallon/Month Throughput

2nd Pressure Decay Test Conducted Within 3 Weeks Identifies Further Leaking Components

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6/25P

ress

ure

(in H

2O)

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10

30

50

70

90

110

Tem

pera

ture

(F

)

Tank Pressure

Ambient Temperature

High Throughput of ORVR Vehicles -Indicates Correlation Between Tank Pressure and

Ambient Temperature

6,000 Gallon Capacity Balance Tank20,000 Gallons/Month Throughput

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728

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Time

Pre

ssur

e (in

H2O

)

20

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110

Tem

pera

ture

(F

)

Tank Pressure

Ambient Temperature

High Throughput of ORVR Vehicles - One-Day Tank Pressure and Ambient Temperature

Tank Still Operates at Positive Pressures

6,000 Gallon Capacity Balance Tank20,000 Gallons/Month Throughput

Methodology for Estimating AST Fugitive Emissions

• Use vapor system pressure data and system leak data to establish a correlation between system leak flow over time.

• Determine fugitive emissions by calculating the area under the leak flow curve.

Example of Fugitive Emissions Estimate Over Time

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0 1 2 3 4 5 6 7 8 9 9.5

Time (hours)

Vap

or

Sys

tem

Lea

k R

ate

(ft3

/hr)

Area under curve is the total volume of vapors released from

the AST during the day

Efficiency Testing / Procedure Development

• Plan to conduct Phase I and Phase II efficiency testing on a small and large balance AST vapor recovery system and a processor type system.

• Purpose is to estimate in-use efficiencies of existing systems and update the current baseline Phase I and Phase II emissions estimate

Open Discussion

• Rupture Disk Emergency Vent (2000 Uniform Fire Code Section 7902.2.6.2)

• Existing Emergency Vents– Lubrication– Maintenance– UL Certification Requirements

• Tank Sticking– Dedicated stick port w/drop-tube

Open Discussion (cont)• Anti-Siphon Devices

– Top-fill (holes in drop tube, size and location requirements)

– Side or remote fills (check valves/anti-siphon devices, location requirements)

• Poppeted Fill Adapters (top fill application)

• Poppeted Fill Adapters w/Close Coupled Shut-Off Valves (side and remote fill applications)

• Operations and Maintenance Manuals– Minimal response from ARB request

ContactPat BennettEngineering Evaluation SectionMonitoring and Laboratory DivisionCalifornia Air Resources BoardP.O. Box 2815Sacramento, CA 95812

(916) 445-9308pbennett@arb.ca.gov