Third-Party Evaluations & EPA Certifications

Issue Date:  August 23, 1999
Revision Date:  May 28, 2008

Mass Technology Corp.

Precision Mass Measurement Systems SIM-1000 and CBU-1000 (24 hour test)

BULK UNDERGROUND STORAGE TANK LEAK DETECTION METHOD (50,000 gallons or greater)

Certification

Leak rate is proportional to product surface area (PSA). 
For tanks with PSA of 1,257 ft² or less, leak rate is 0.1 gph with PD = 97.9% and PFA = 2.1%. 
For tanks with larger PSA, leak rate equals [(PSA in ft² ÷ 1,257 ft²) x 0.1 gph]. 
Example:
For a tank with PSA = 2,000 ft²; leak rate = [(2,000 ft² ÷ 1,257 ft²) x 0.1 gph] = 0.16 gph. 
Calculated minimum detectable leak rate is 0.078 gph with PD = 95% and PFA = 5%. 
Leak rate may not be scaled below 0.1 gph.
Leak Threshold Leak threshold is proportional to product surface area (PSA). 
For tanks with PSA of 1,257 ft² or less, leak threshold is 0.05 gph. 
For tanks with larger PSA, leak threshold equals [(PSA in ft² ÷ 1,257 ft²) x 0.05 gph]. 
Example:
For a tank with PSA = 2,000 ft²; leak threshold = [(2,000 ft² ÷ 1,257 ft²) x 0.05 gph] = 0.08 gph. 
A tank system should not be declared tight if the test result indicates a loss or gain that equals or exceeds the calculated leak threshold.
Applicability Gasoline, diesel, aviation fuel, fuel oil #4. 
Other liquids may be tested after consultation with the manufacturer.
Tank Capacity Use limited to single field-constructed vertical tanks. 
Maximum product surface area (PSA) is 3,143 ft² (approximately 63 ft diameter). 
Performance not sensitive to product level.
Waiting Time Minimum of 1 hour, 6 minutes after delivery or dispensing. 
Valve leaks and pump drain-back may mask a leak. 
Allow sufficient waiting time to minimize these effects. 
Waiting times during evaluation ranged from 62 minutes to 31 hours.
Test Period Minimum of 24 hours. 
There must be no dispensing or delivery during test.
Temperature Measurement not required by this system.
Water Sensor None. 
Water leaks are measured as increase in mass inside tank.
Calibration Differential pressure sensor must be checked regularly in accordance with manufacturer's instructions.
Comments Tests only portion of tank containing product. 
As product level is lowered, leak rate in a leaking tank decreases (due to lower head pressure). 
Consistent testing at low levels could allow a leak to remain undetected. 
Evaluated in a nominal 120,000 gallon, vertical underground tank with product surface area (PSA) of 1,257 ft².

 

 

Issue Date: August 23, 1999
Revision Date:  May 28, 2008

Mass Technology Corp.

Precision Mass Measurement Systems SIM-1000 and CBU-1000 (48 hour test)

BULK UNDERGROUND STORAGE TANK LEAK DETECTION METHOD (50,000 gallons or greater)

Certification Leak rate is proportional to product surface area (PSA). 
For tanks with PSA of 6,082 ft², leak rate is 0.294 gph with PD = 95% and PFA = 5%. 
For other tank sizes, leak rate equals [(PSA in ft² ÷ 6,082 ft²) x 0.294 gph]. 
Example:
For a tank with PSA = 4,000 ft²; leak rate = [(4,000 ft² ÷ 6,082 ft²) x 0.294 gph] = 0.19 gph.
Leak rate may not be scaled below 0.2 gph.
Leak Threshold Leak threshold is proportional to product surface area (PSA). 
For tanks with PSA of 6,082 ft², leak threshold is 0.147 gph. 
For other tank sizes, leak threshold equals [(PSA in ft² ÷ 6,082 ft²) x 0.147 gph].
Example:
For a tank with PSA = 4,000 ft²; leak threshold = [(4,000 ft² ÷ 6,082 ft²) x 0.147 gph] = 0.1gph. 
A tank system should not be declared tight if the test result indicates a loss or gain that equals or exceeds the calculated leak threshold.
Applicability Gasoline, diesel, aviation fuel, fuel oil #4. 
Other liquids may be tested after consultation with the manufacturer.
Tank Capacity Use limited to single field-constructed vertical tanks. 
Maximum product surface area (PSA) is 6,082 ft² (approximately 88 ft diameter). 
Performance not sensitive to product level.
Waiting Time Minimum of 1 hour, 6 minutes after delivery or dispensing. 
Valve leaks and pump drain-back may mask a leak.
Allow sufficient waiting time to minimize these effects. 
Waiting times during evaluation ranged from 62 minutes to 31 hours.
Test Period Minimum of 48 hours. 
There must be no dispensing or delivery during test.
Temperature Measurement not required by this system.
Water Sensor None. Water leaks are measured as increase in mass inside tank.
Calibration Differential pressure sensor must be checked regularly in accordance with manufacturer's instructions.
Comments Tests only portion of tank containing product. 
As product level is lowered, leak rate in a leaking tank decreases (due to lower head pressure). 
Consistent testing at low levels could allow a leak to remain undetected. 
Evaluated in a nominal 600,000 gallon, vertical underground tank with product surface area (PSA) of 6,082 ft².

 

Issue: August 23, 1999
Revision Date:  May 28, 2008

Mass Technology Corp.

Precision Mass Measurement Systems SIM-1000 and CBU-1000 (72 hour test)

BULK UNDERGROUND STORAGE TANK LEAK DETECTION METHOD (50,000 gallons or greater)

Certification Leak rate is proportional to product surface area (PSA). 
For tanks with PSA of 14,200 ft², leak rate is 0.638 gph with PD = 95% and PFA = 5%. 
For other tank sizes, leak rate equals [(PSA in ft² ÷ 14,200 ft²) x 0.638 gph]. 
Example:
For a tank with PSA = 20,000 ft²; leak rate = [(20,000 ft² ÷ 14,200 ft²) x 0.638 gph] = 0.898 gph.
Leak rate may not be scaled below 0.2 gph.
Leak Threshold Leak threshold is proportional to product surface area (PSA). 
For tanks with PSA of 14,200 ft², leak threshold is 0.319 gph. 
For other tank sizes, leak threshold equals [(PSA in ft² ÷ 14,200 ft²) x 0.319 gph].
Example:
For a tank with PSA = 20,000 ft²; leak threshold = [(20,000 ft² ÷ 14,200 ft²) x 0.319 gph] = 0.449 gph.
A tank system should not be declared tight if the test result indicates a loss or gain that equals or exceeds the calculated leak threshold.
Applicability Gasoline, diesel, aviation fuel, fuel oil #4. 
Other liquids may be tested after consultation with the manufacturer.
Tank Capacity Use limited to single field-constructed vertical tanks larger than 50,000 gallons. 
Maximum product surface area (PSA) is 35,500 ft² (approximately 213 ft diameter). 
Performance not sensitive to product level.
Waiting Time Minimum of 1 hour, 6 minutes after delivery or dispensing. 
Valve leaks and pump drain-back may mask a leak. 
Allow sufficient waiting time to minimize these effects. 
Waiting times during evaluation ranged from 8 minutes to 42.5 hours.
Test Period Minimum of 72 hours.
There must be no dispensing or delivery during test.
Temperature Measurement not required by this system.
Water Sensor None. Water leaks are measured as increase in mass inside tank.
Calibration Differential pressure sensor must be checked regularly in accordance with manufacturer's instructions.
Comments Tests only portion of tank containing product. 
As product level is lowered, leak rate in a leaking tank decreases (due to lower head pressure). 
Consistent testing at low levels could allow a leak to remain undetected. 
Evaluated in a nominal 2,000,000 gallon, vertical underground tank with product surface area (PSA) of 14,200 ft².

 

 

Issue Date:  July 13, 2007
Revision Date:  May 28, 2008

Mass Technology Corp.

Precision Mass Measurement Systems SIM-1000 and CBU-1000

ABOVEGROUND STORAGE TANK LEAK DETECTION METHOD 

Certification

Leak rate of 1.717 gph with PD = 95% and PFA = 5%.
The US EPA has not set a minimum detectable leak rate for aboveground storage tank systems at the time of this evaluation.

Leak Threshold

0.859 gph.
A tank system should not be declared tight if the test result indicates a loss or gain that equals or exceeds this threshold.

Applicability

Gasoline, diesel, jet fuel, fuel oil up to #6.
Other liquids may be tested after consultation with the manufacturer.

Tank Capacity

AST's with surface areas from 7,854 to 30,172 sq. ft. and diameter's from 100 to 196 feet.
Tank must be 20% full.

Waiting Time

Minimum of 20 minutes.

Test Period

Minimum of 20 hours.
There must be no delivery, transfer, or dispensing during test.

Temperature

One Resistance Temperature Detector (RTD) attached to the bubbler unit.

System Features

This system uses nitrogen under pressure conveyed to the bottom of the tank via a hose to generate (bubbler unit) and release small bubbles at the tank bottom.
The pressure required to produce the bubbles is equal to the hydrostatic head pressure produced by the fluid in the tank plus one atmosphere.  This pressure is measured by a pressure transducer.
The measured differential pressure is a direct measurement of the mass of the fluid in the tank.

Calibration

The differential pressure transducer is benchmark calibrated by the manufacturer.
Annual calibration is performed by the CBU/SIM unit and returned to the manufacturer if results fall outside the benchmark calibration values.
RTDs are calibrated annually.
Barometer is replaced every five years.

Comments

Data set is filtered to extract only night time data to eliminate the effects of radiant solar heating.
The CBU/SIM control unit is not rated for installation in areas where an explosive ignition risk may exist.
Method may be applied to steel, concrete, aluminum, or fiberglass tanks with either fixed or floating roofs.
Bubbler test pressure must not exceed 18 psig.

 

Issue Date:  April 19, 2011
Mass Technology Corp.

Precision Mass Measurement Systems CBU-1000D

VOLUMETRIC TANK TIGHTNESS TEST METHOD (Underfill)

Certification Leak rate of 0.1 gph with PD > 95% and PFA < 5%.
Leak Threshold

0.55 gph.

A tank system should not be declared tight if the test result indicates a loss or gain that equals or exceeds this threshold.
Applicability

Gasoline, diesel, aviation fuel, fuel oil #4.
Other liquids may be tested after consultation with the manufacturer.
Tank Capacity Maximum of 76,500 gallons.
Waiting Time

Minimum of 1.5 hours after delivery or dispensing.

Waiting times during evaluation ranged from 20 minutes to 1.5 hours.
Test Period

Minimum of 13 hours.
There must be no dispensing or delivery during test.
Temperature

Measurement not required by this system.
Groundwater

Tank may not be tested unless the groundwater level is known to be below the tank bottom.
Calibration

Differential pressure sensor must be checked regularly in accordance with manufacturer's instructions..
Comments

This method was not evaluated with groundwater taken into account.  Test results are not valid when it is not demonstrated that the groundwater level is below the bottom of the tank during the test.

Tests only portion of tank containing product.

The tank must be at least 90% full.

Evaluated in a nominal 51,000 gallon, horizontal cylindrical steel tank with a diameter of 13 feet and a length of 54 feet containing JP-5 jet fuel.

 

Evaluator:  Ken Wilcox Associates, Inc.
P.O. Box 1578
Tel:  (816) 443-2494
Kilgore, TX 75663
Date of Evaluation:  08/19/09