llr~ FIBERGLASS \B) TANK & PIPE INSTITUTE 

Sullivan D. Curran, P.E., Executive Director Internet: www.fiberglasstankandpipe.com 

11150 S. Wilcrest Dr., Suite 101 • Houston, Texas 77099-4343 • Telephone (281) 568-4100 • Facsimile (281) 568-9998 

Aprt/ F~l5,2013 

Ms. Carolyn Loomis Hoskinson 

Environmental Protection Agency 

Director, Office of Underground Storage Tanks 

1200 Pennsylvania Avenue, N.W. 

MC: 5401P 

Washington, D.C. 20460-000 I 

RE:- September 23, 1988 EPA UST Over fill Prevention Rule §280.20 (c)(3), and 

- November 18, 2012 EPA proposed rev ision under Subpart B - UST Systems overfill prevention rule 

§280.20 (c)(3) " Flow restrictors used in vent lines may not be used to comp ly with paragraph 

(c)(l)(ii) ofthis section when overfi ll prevention is insta lled or replaced after [effective date of rule)." 

Dear Ms. Hoskinson: 

We appreciate your letter of March 19, 20 13 to consider add ition comments after the public comments on 

proposed amendments to 40 CFR Parts 280 and 28 1 that were due on or before April 16, 20 12. While, we 

do not want to be taking advantage of the opportunity to submit supplemental comments to EPA after the 

c lose of the comment period, the Institute has become aware of ball float vent valve eq uipped USTs that 

have been over pressurized and damaged in these past twelve months such that the risk of existing ball 

tloat vent va lves should be considered in the upcoming EPA final rule. Specifica lly, we are addressing 

EPA's proposed §280.20(c)(3) "Flow restrictors used in vent lines may not be used to comply with 

paragraph (c)( I )(ii) of this sectio n when overfi ll prevention is insta lled or replaced after [effective date of 

rule). We believe that the EPA has an opportunity with the upcoming revisions to the 1988 UST Rule to 

implement a scheduled removal of ball float valves via the extractor valve and installing inexpensive fi ll 

pipe shutoff valves to reduce known environmental contamination and fire safety risks. 

Attached is the Institute paper that reinforces the EPA proposed rule §280.20(c)(3) statement " EPA 

identified vent line tlow restrictors as a significant concern for operability and safety." Further, EPA 

implementation of a scheduled ball tloat valve (BFV) removal program is historica lly supported by the 

following implementing agencies that have limited authority: 

I. 1995 LUSTLine articles c iting disadvantages of BFV's and advantages of Fill Pipe Valves 

2. 1995 Long Island, Suffolk County disallowed BFY's 

3. 1997 CA State Water Resources Gu idance to discourage BFY's & encourage their remova l 

4. 2003 N FPA 30A prohibition of BFV's (NFPA can only grandfather existing eq uipment) 

We appreciate the opportunity to provide EPA OUST with our recommendation for the li nal rule to 

implement a scheduled removal of ball tloat valves and replace with alternative proven methods. 

Sincerely, 

Sullivan D. 

~~~ Curran P.E. 

CC: Institute board members 

Mr. Jeffrey Leiter, Leiter & Cramer 

1 
Kn FIBERGLASS \.\._\V/) TANK & PIPE INSTITUTE 

11150 S. Wilcrest Dr., Suite 101, Houston, Texas 77099-4343 

www.fiberglasstankandpipe.com"' tel: 281 568 4100 

Overfill Prevention of Petroleum Underground Storage Tanks 

and Adverse Unintended Consequences 

I. Introduction 

EPA UST Overfill Prevention Rule: The September 23, 1988 Environmental Protection Agency 

(EPA} 40CFR Parts 280 and 281 Technical Requirements for regulated Underground Storage 

Tanks (USTs) required equipment that is capable of preventing an UST overfill. Subpart B - UST 

Systems: Design, Construction, Installation and Notification §280.20 (c) Spill and overfill 

prevention equipment, except where exempted, owners and operators must use overfill 

prevention equipment that will automatically shut off flow into the tank when the tank is no 

more than 95% full or alert the t ransfer operator when the tank is no more than 90 % full by 

restricting the flow into the tank or triggering a high level alarm. Later, the EPA revised the rule 

to permit restricting the flow into the tank at 95% of capacity in response to comments that 

excess top of the tank ullage was requiring more frequent deliveries and associated spill risks. 

EPA Must for USTs publication: In September 1988 EPA published a summary of the new 

regulations with compliance suggestions. Page 16 addressed Spill/Overfill Prevention and listed 

three options for tank overfill prevention namely, (a) Automatic Shutoff Devices; (b) Overfill 

Alarms or (c) Ball Float Valves. The unintended consequence was to specifically identify Ball 

Float Valve equipment as an EPA approved "automatic shut off device" which unfortunately, 

has resulted in ball float valves being the most common overfill prevention device in use today. 

This paper describes why the Ball Float Valve usage is not the best available control technology 

(BACT) and is contributing to spills, overfills and tank ruptures. 

II. Table of Contents 

I. Introduction 

II. Table of Content s 

Ill. UST Overfill Prevention Options 

IV. Ball Float Vent Valve Operation 

V. Fill Pipe Shutoff Valve Operation 

VI. UL Listed Atmospheric USTs 

VII. Tank Rupture Releases from Pressurized Deliveries 

VIII.NFPA 30A 2003 Prohibition of Ball Float Vent Valves 

IX. State & County Ball Float Vent Valve Restrictions/Prohibitions 

X. Fill Pipe Positive Shutoff versus Ball Float Vent Valve 

XI. November 18, 2012 EPA Proposed Revisions to 1988 UST Rule 

XII. Summary of Unintended Consequence Leaks, Spills & Releases 

Exhibit A: OPW Ball Float Valve Fuel Rates at Various Head Pressures 

Exhibit B: Ball Float Valves & Fill Pipe Valves in Open and Closed Positions 

References 
Ill. UST Overfill Prevention Options 

Since the 1988 EPA Rule went into effect some 20+ years ago, and based on user experience 

with new electronic or mechanical devices, the UST equipment market has essentially evolved 

into one electronic and the two mechanical overfill prevention devices described below: 

A. Electronic Automatic Tank Gauge (ATG): The ATG has evolved as a state-of-art 

electronic device that provides monitoring functions including fuel management, 

with low and high product alarms. ATG's may be programmed to determine the 95% 

ullage level (i.e., amount of product that is required to make the tank 100% full) and 

to alarm when the product tank exceeds that 95% level. The alarm may consist of a 

warning light and/or an audible alarm at the ATG Console. The ATG Console is 

located in the equipment room of the refueling facility and the alarm does not "alert 

the transfer operator" who is located outside of the building. Thus, the audible 

alarm may be supplemented by an outdoor alarm loud enough to overcome traffic 

noise. However, the location of outdoor alarms is critical. The audible alarm must be 

located in the vicinity of the transfer operator, clearly visible from where the 

operator is likely to be standing and clearly labeled as an overfill protection device. 

Since the alarm does not slow down the flow of product to the UST, the transfer 

operator has only some 60 seconds to shut off the truck delivery valve to allow for 

the time it will take to drain the hose contents (14 gallons for a 20 foot 4 inch 

diameter hose) into the tank. As a result, installing an audible alarm near the 

transfer operator has not proven to be a practical option for public retail refueling 

facilities. 

B. Mechanical Ball Float Vent Valves: These are also known as float-vent valves, they 

are fitted on the bottom of the vent line inside the tank. When the product level is 

below the cage, the ball rests at the bottom of the cage and the vent line is open 

(see attached Exhibit A for illustrations). As the level of the product rises above the 

bottom of the cage, the ball floats on the product and rises in the cage. As the 

delivery continues, the ball eventually seats in the vent line opening and restricts 

vapor flowing out the vent line before the tank is full. Flow restrictors must begin 

restricting flow when the tank is 95 percent full or 30 minutes before overfilling. If 

the tank top is tight, the ball float valve is intended to create enough back pressure 

to restrict product flow into the tank. When a ball float valve closes, the vapor in the 

tank ullage compresses gradually and acts as a cushion, thus there is little movement 

of the product delivery hose to signal the transfer operator that product has stopped 

flowing. However, if the UST has loose fittings or other non-tight tank top 

components, flow will not be restricted and an overfill will occur. 

C. Mechanical Fill Pipe Shutoff Valve: The fill pipe prevention valve is integral to or may 

be retrofitted into the four inch drop tube used for submerged filling of USTs. When 

the tank liquid level rises to 95% of tank capacity, the valve closes automatically into 

the path of the product flow and reduces flow to approximately 5 gallons per 

minute through a bypass valve. The transfer operator may then stop the filling 

process and disconnect and drain the delivery hose. As long as the liquid exceeds the 

95% level, the valve will close automatically each time a delivery is attempted. If the 

delivery attempts are not stopped, and the liquid rises to about 98% of tank 

2 
capacity, the bypass valve closes completely (see Exhibit A for illustrations). No 

additional liquid can flow into the tank until the level drops below a reset point. 

IV. Ball Float Vent Valve Operation 

The EPA web site as of 09/24/12 (http://www.epa.gov/oust/ustsystm/balfloat.htm) 

provides a description of how ball float valves are designed to operate. The EPA illustrations, 

shown on attached Exhibit A, do not explain how the ball float valve continues to allow fuel to 

be added to the tank at a reduced rate. However, this is normally accomplished with a 1/16" or 

1/8" diameter vent hole in the pipe above the closure point inside the tank. This vent hole in 

the pipe is designed to relieve the hydraulic pressure from the liquid above the tank and the air 

space in the ullage when flow into the tanks is reduced. 

The following unintended adverse consequences occur when: 

A. Fuel rises until the ball float valve closes. Once closed, the tank ullage is compressed, 

the delivery flow into the tank is reduced gradually, the transfer operator does not 

see a "hose jump" from hydraulic shock and does not know that the float-vent valve 

has closed. This requires the transfer operator to periodically feel the hose for fluid 

flow vibration and/or look at the sight glass to see bubbles in the product flow. 

B. The pressure will equal the fuel head pressure from the fuel level in the delivery 

truck to the ball float closure point. This pressure can be as high as 6.3 psig 

depending on the truck fuel level, the tank burial depth, the position of the ball float 

and cause a seepage spill from worn hose connection gaskets. 

C. At the point the ball float valve actuates, the transfer operator can close and then 

"crack open" the truck tank valve (permitting air in) to drain the hose into the tank. 

As the vapor slowly vents, the escaping vapor is replaced with fuel from the delivery 

truck. The pressure in the ullage is maintained since fuel flows into the tank at the 

same rate that the vapor escapes. But, the rate fuel being delivered is significantly 

lower than the delivery rate before the ball float valve closes and it may take up to 

30 minutes for the ullage pressure to be relieved through the vent hole. 

Truck drivers are paid by the load and typically do not want to 

lose 30 minutes of productive time. Thus, an experienced transfer operator knows 

that propping open the drain mechanism on the spill containment manhole will 

increase the release of the tank ullage vapors to the atmosphere at ground level and 

risk the potential of vapor ignition and a fire. 

V. Fill Pipe Shutoff Valve Operation 

The EPA site provides the following information concerning automatic shutoff devices: 

An automatic shutoff device installed in an underground storage tank (UST) fill pipe will 

slow down and then stop the flow of product to the tank when the product has reached a 

certain level in the tank. Federal regulations require that shutoff occurs when the tank is 95 

percent full or before any fittings located on top of the tank are exposed to product. This device 

has the option of one or two valves that are operated by a float mechanism. The illustration in 

Exhibit A shows one type of automatic shutoff device. Note that the float is down and the fill 

3 
valve is open. The illustration on the right side in Exhibit A shows the same shutoff device with 

the float up and the fill valve closed. 

Automatic shutoff devices should operate in two stages. The first stage drastically reduces 

the flow of product to alert the transfer operator that the UST is nearly full. The operator can 

then close the delivery valve and still have room in the UST for the product left in the delivery 

hose. If the transfer operator does not pay attention, and the liquid level rises higher, the valve 

closes completely and no additional liquid can be delivered into the UST, leaving the operator 

with a delivery hose full of product. 

The OPW 6150 is a two-stage shut-off valve. When the liquid level rises to about 95% of 

tank capacity the valve mechanism is released, closing automatically with the flow. This reduces 

the flow rate to approximately 5 gpm through a bypass valve. The operator may then stop the 

filling process and disconnect and drain the delivery hose. As long as the liquid exceeds the 95% 

level, the valve will close automatically each time delivery is attempted. If the delivery is not 

stopped and the liquid rises to about 98% of tank capacity, the bypass valve closes completely, 

and no additional liquid can flow into the tank until the level drops below a reset point. 

VI. UL Listed Atmospheric USTs 

Underwriters Laboratories List horizontal cylindrical fiberglass (UL 1316) and steel (UL 58 & 

UL 1746) atmospheric tanks that are designed for atmospheric venting. The Listed USTs "shall 

have a fitting of a size no less than that specified .. .for the attachment of a vent pipe." Thus, it is 

clear that the UL Listed tanks are properly vented atmospheric tanks and not designed to be 

pressure vessels. However, every time a ball float valve is used to stop the fuel delivery, the 

tank is being pressurized, even whi le the ball float valve is still venting through the vent hole. 

The following table shows the pressure that will be developed for various configurations: 

Pressure in Ullage With Ball Float Valve Closed 

and Fuel Drop Still Connected (ball float 10" below tank top) 

Gasoline (S.G. 0.74) Diesel (S.G. 0.82) 

Tank Bury Depth Tank Bury Depth 

Truck Fuel Level above Grade 3ft 7ft 3ft 7ft 

7ft 3.5 psig 4.8 psig 3.9 psig 5.3 psig 

lOft 4.4 psig 5.7 psig 4.9 psig 6.3 psig 

It should also be noted that when the ball float valve closes, it shuts down the fuel flow 

rate. Depending on how quickly the valve closes, the momentum of the fuel into the tank 

causes a spike in the tank ullage pressure (in plumbing this is called water hammer). If the 

ullage is large enough, it acts as a pressure dampener and the spike in the ullage pressure is 

minimized. However, if the ullage is small, the spike can be significant. Some studies show 

pressures in excess of 50 psig. 

The EPA site provides two options for setting the ball float valve in order to provide a 

minimum tank ullage volume: 

1. Begin restricting flow when the tank is 95 percent full (e.g. OPW Model 53VML intended 

for setting at 90% of full. This model has a 1/8" vent hole.) or 

4 
2. Begin restricting flow 30 minutes before overfilling (e.g., Model 30MV intended for 

setting at a point that provides 30 minutes of flow after the valve closes. This model is 

actually the same as the 53VML except that the vent hole is modified down to 1/16".) 

The Table of OPW Ball Float Valve Fuel Flow Rates at Various Head Pressures in Exhibit A 

shows what fuel flow rates to expect with the two OPW ball float valves closed at various head 

pressures. The Table includes the resulting 30 minute flow volume based on OPW data which 

includes the OPW recommended 73% pressurization factor and the OPW 1.5 safety factor. The 

Table shows that actuation of ball float valves repeatedly pressurize atmospheric UL Listed USTs 

at pressures up to 6.5 psig many of which are beyond the Underwriters Laboratory design 

strength and over time risks weakening tank or bulkhead seams and fitting penetrations that 

may lead to underground leakage. 

VII. Tank Rupture Releases from Pressurized Deliveries 

Ball float valve equipped tanks are vulnerable to rupture failures when deliveries are made 

with pump equipped tank trucks. It is a common practice to use tank trucks up to 5,000 gallon 

capacity range to make fuel deliveries in urban areas where street access is limited. These dual 

purpose trucks are typically equipped with positive-displacement pumps for delivery into home 

and commercial fuel oil tanks. These pumps are capable of pumping at pressures of 50 to 125 

psig and, when used to fill tanks with ball float valves, the pumps wi ll rupture the tanks when 

the valves are actuated and close off the tank vent to atmosphere. Thus, there is no room for 

error (i.e., shut off flow and drain the hose as in a gravity delivery) and the transfer operator 

must ensure that the tank ullage will accommodate the delivered quantity or the tank will likely 

rupture. Unfortunately, there is documented history of such tank ruptures in areas such as 

Washington DC, NYC, Long Island, Philadelphia, California and likely elsewhere. 

An automatic shutoff device installed in an underground storage tank fill pipe will slow 

down and then stop the flow of product to the tank and then stop the flow of product to the 

tank when the product has reached a predetermined level. When the product flow is slowed 

down in a pressurized pump actuated delivery, the product will back up the fill pipe and result 

in a visible surface spill rather than a ruptured underground tank release. 

VIII. NFPA 30A 2003 Prohibition of Ball Float Vent Valves 

NFPA 30A Code for Motor Fuel Dispensing Facilities and Repair Garages is approved as an 

American National Standard and is the model fire code referenced in the International Fire 

Code and adopted as a model code in the majority of US fire jurisdictions. The Institute is a 

voting committee member of NFPA 30A which recognized that, as a means of overfill 

protection, ball float valves were a fire safety hazard. Thus, the 2003 edition of NFPA 30A 

included a prohibition for the use of ball float valves. The 2008 edition also included a 

prohibition and the yet to be published 2013 edition will also include the prohibition. The 2008 

§4.3.4.5.3 reads: "An approved means of overfill protection shall be provided for tanks. The use 

of ball float valves shall be prohibited." However, NFPA model codes are not retroactive and 

existing ball float installations are "grandfathered." 

5 
IX. State and County Ball Float Vent Valve Restrictions/Prohibitions 

Certain implementing agencies have had adverse experience with ball float vent valves and 

either recommend against or prohibit the application of ball float valves as an overfill 

prevention device. Following is one agency that has recommended against the application of 

ball vent valves and another that has banned their use. 

A. On September 5, 1997 the California State Water Resources Board wrote local 

implementing agencies to provide reasons for discouraging the use of ball float 

valves as an overfill protection device. Its letter listed the following: 

a. Advantages of fi ll tube valves: 

-They are easily installed and maintained 

- They prevent overfills without pressurizing the tank 

-They exempt pipe risers from additional CA regulations 

b. Disadvantages of Vent valves 

- blow back when the delivery hose is disconnected 

-vapors forced into the atmosphere through small holes, or 

the drain valve of the spill bucket 

-a ruptured tank release 

- pipe risers are subject to CA regulations 

c. State of California Advice 

- Do not approve installation plans that show both overfill prevention devices 

- If an installation plan shows a vent valve, encourage the owner to replace it 

with a fill tube valve. If the owner insists on use of vent valves, secondary 

containment and interstitial monitoring for all the riser pipes is required. 

- At double wall facilities where both devices have already been installed, 

require removal of the vent valve if the pipe risers are not secondarily 

contained and monitored, share this information with the owner and 

recommend removal of the vent valve. 

- At single walled facilities, pipe riser are regulated and require corrosion 

protection if a vent valve is used. To avoid the requirement to retrofit with 

corrosion protection, suggest the use of a fill tube valve instead of the vent 

valve. 

-Share this information with tank owners, operators, and contractors in your 

jurisdiction. 

B. Since 1995 Long Island in Suffolk County, no longer allows float vent valves. 

X. Fill Pipe Positive Shutoff Valve versus Ball Float Vent Valve 

A. Advantages of Fill Pipe Positive Shutoff Overfill Prevention Device: 

a. Less costly installation 

-Simple and quick installation 

- Integral part of drop tube 

- No excavation, vent piping or additional manholes required 

- Exempt pipe risers from secondary containment where regulated 

b. Completely automatic operation: no tank quantity pre-check to perform 

c. Automatic and quicker hose drain for transfer operator convenience 

d. Keeps top of UST "dry" eliminating loose bung leaks 

6 
e. Shuts off product flow 

f. Does not rely on pressure in the UST to stop flow 

g. Does not subject atmospheric tank to repeated high pressure spikes 

B. Disadvantages of Ball-Float Valve 

a. Requires extracting the Ball Float Valve to "tightness test" tank 

b. Does not shut off product flow 

c. Subjects atmospheric tank to high pressure spikes when activated 

d. Will risk a tank rupture in a pumper truck pressurized delivery 

e. Hydrocarbon vapors vented to the atmosphere 

XI. November 18, 2012 EPA Proposed Revisions to 1988 UST Rule 

On November 18, 2011 the EPA proposed revisions to the 1988 underground storage tank 

(UST) technical standards under Subpart B - UST Systems: Design, Construction, Installation and 

Notification section §280.20(c)(3) "Flow restrictors used in vent lines may not be used to 

comply with paragraph (c)(1)(ii) of this section when overfill prevention is installed or replaced 

after [effective date of rule]." [underline added] 

In the Preamble [see FR Vol. 76, No.223/Friday, November 18, 2011/Proposed Rules, page 

71737] the EPA is proposing to eliminate flow restrictors (also called ball float valves) in vent 

lines as an overfill prevention either as an overfill prevention option either when a UST system 

is installed or when a UST system is installed or when an UST system's overfill prevention 

equipment is replaced." "EPA identified vent line flow restrictors as a significant concern for 

operability and safety. To reduce the frequency of UST releases due to operability and to 

address system safety and personnel safety concerns, EPA is proposing to eliminate vent line 

flow restrictors for new installations and replacements." [underline added] 

XII. Summary Of Unintended Adverse Consequences 

Following is a summary of unintended adverse environmental consequences that have 

resulted from the 1988 EPA publication approval of ball float valve equipment as the best 

available technology (BACT) to meet the EPA tank overfill prevention rule: 

1. Ball float vent valve actuation repeatedly pressurizes atmospheric USTs at internal 

pressures not intended for UL Listed atmospheric tanks, and over time risk 

weakening tank seams and fitting penetrations which may cause product or vapor 

releases. 

2. Since 1997 state and other UST Rule implementing jurisdictions followed EPA 

publications and as a result have experienced hydrocarbon vapor and liquid releases 

from ball float vent valves. 

3. Since 2003 the National Fire Protection Association recognized that ball float vent 

valves were a fire and safety ri sk and prohibited their use in new/replaced USTs. 

4. Uncontrolled hydrocarbon vapor releases occur every time a ball float vent valve is 

actuated in the USA. 

5. Significant underground releases have occurred from pressurized deliveries into 

USTs equipped with ball float vent valves. 

6. The November 18, 2012 EPA proposed UST Rule revisions, while agreeing "vent line 

flow restrictors are a significant concern for operability and safety," will permit the 

7 
continued operation of USTs with ball float vent valves with their associated fire 

safety and environmental risks. 

Recommendation: The EPA has an opportunity with the upcoming revisions to the 1988 UST 

Rule to implement a scheduled removal of ball float vent valves via the extractor valve and 

installing inexpensive fill pipe shutoff valves to reduce known environmental contamination and 

fire safety risks. 

References: 

1. September 23, 1988 EPA 40CFR Parts 280 and 281 Technical Requirements for 

regulated USTs 

2. November 18, 2012 EPA proposed revisions to the 1988 UST Standards, Subpart B -

UST Systems: Design, Construction, Installation and Notification §280.20{c)(3) 

3. September 1988 EPA Musts for USTs publication 

4. Veeder-Root TLS-350 Monitoring System Operator's Manual 

5. OPW Dover Resources Company Service Station products manual: Ball Float Vent 

Valves; Overfill Prevention Valves 

6. National Fire Protection Association NFPA 30A 2003, 2008 & proposed 2013 

Code for Motor Fuel Dispensing Facilities and Repair Garages 

7. September 5, 1997 California State Water Resources Control Board Local Guidance 

Letter 

8. LUSTLine Bulletin 18 Overfill Prevention 

9. LUSTLine Bulletin Summer 1995 What every Tank Owner should know about Overfill 

Prevention 

10. OPW Table of Orifice Flow Rates with Various Head Pressures 

11. Calculations of Ullage Vapor Space Pressures with Fuel Delivery Head Pressures 

ws-sdc/4/10/13 rev.4/15/13 

8 
Exhibit A 

Overfill Prevention of Petroleum Underground Storage Tanks 

and Adverse Unintended Consequences 

OPW Ball Float Valve Fuel Flow Rates at Various Head Pressures 

Note: The minimum ullage volumes are not provided in the OPW literature for 

each condition. However, one example with the flow at 5 gpm is provided. 

53V (1/8" Orifice) 30MV (1/16" Orifice) 

Gasoline 30 Gasoline 

Ullage Head Flow Minutes Ullage Head Flow 

Pressure Pressure Rate of Flow Pressure Pressure Rate 

(psig) (ft) (gpm) (gal) (psig) (ft) (gpm) 

0.5 1.6 6.1 373 0.5 1.6 2.35 

1.0 3.1 10.7 658 1.0 3.1 2.73 

1.5 4.7 15.0 926 1.5 4.7 3.12 

2.0 6.2 19.1 1178 2.0 6.2 3.50 

2.5 7.8 22.9 1413 2.5 7.8 3.88 

3.0 9.3 26.5 1632 3.0 9.3 4.27 

3.5 10.9 29.7 1834 3.5 10.9 4.65 

4.0 12.5 32.8 2019 4.0 12.5 5.03 

4.5 14.0 35.5 2188 4.5 14.0 5.42 

5.0 15.6 38.0 2341 5.0 15.6 5.80 

5.5 17.1 40.2 2477 5.5 17.1 6.18 

6.0 18.7 42.1 2596 6.0 18.7 6.57 

6.5 20.3 43.8 2699 6.5 20.3 6.95 

The gasoline head pressure is feet of gasoline head above the fuel level with 

the ball float valve closed. 

30 

Minutes 

of Flow 

(gal) 

145 

168 

192 

216 

239 

263 

287 

310 

334 

358 

381 

405 

429 

9 
Exhibit B 

Overfill Prevention of Petroleum Underground Storage Tanks 

and Adverse Unintended Consequences 

Ball Float Valves in Open and Closed Positions 

Frtted to 

Ven't L1roe 

Bnll Ftoflt Vftlvc ,..,(th the b~ll ;,t the bott om 

cl tho caoe •nd the vent line open. This indAc.;ates th• produe1 iii b~tow the c.aoe .1-nd 

the vent lin• Is open. 

Frtted to 

Vo?nt lin& 

Bull Floal 

Ball Floot Vehtc rls@"s as th~ product rts~. 

The b•ll event\Jilly seats m the vet' t line and restricts ViPO-r flovvln(J out of the v•nt b~ore 

the ~rtk l.s full. 

Fill Pipe Valves in Open and Closed Positions 

Fill Pipe 

Float 

Automatic Shutoff Oevlce Vllth The l="loon Down And 

The F•ll Valve Open 

Automatic Shutoff Oe•JIC@ With The rloat up .1nd 

The Fill Valve Closed