Issue Date: November 22, 1995
Revision Date: February 6, 2015 

Purpora Engineering, Inc.
(originally listed by Alert Technologies, Inc.)

Alert Model 2000 In-Tank Mass Measurement Probe System
(Mass Buoyancy Probe)


Certification Leak rate of 0.2 gph with PD = 95.4% and PFA = 4.6% (calculated based on a 1-hour test).
Leak Threshold 0.1 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, waste oil. 
Tank Capacity Maximum of 15,000 gallons. 
Tank must be between 50 and 95% full.
Waiting Time Minimum of 15 hours between delivery and testing. 
There must be no delivery during waiting time.
Test Period Minimum of 2 hours. 
Test data are acquired and recorded by system's computer. 
Leak rate is calculated from data determined to be valid by statistical analysis. 
There must be no dispensing or delivery during test.
Temperature Product measurement not required. 
System measures product mass (which is not affected by temperature) instead of product volume.
Water Sensor Must be used to detect water ingress. 
Minimum detectable water level in the tank is 0.175 inch (0.27 inch for waste oil). 
Minimum detectable change in water level is 0.088 inch (0.031 inch for waste oil).
Calibration Mass measurement probe and water sensor must be checked and, if necessary, calibrated in accordance with manufacturer's instructions.

Not evaluated using manifolded tank systems. Therefore, this certification is only applicable when there is a probe used in each tank and the siphon is broken during testing. 
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.
EPA leak detection regulations require testing of the portion of the tank system which routinely contains product. 
System is battery operated and does not automatically generate a hard copy of the leak test result. However, a hard copy of the results can be obtained by transfer of data to another unit (see manufacturer's instructions for further details). 
System is not equipped with any alarms (e.g. high water alarm, or failed leak test alarm).

The manufacturer does not support test results if the technician does not hold a current Alert Technologies certification when the test is performed.  Recertification is required by the manufacturer every two years.


Purpora Engineering Inc.

Evaluator:  Midwest Research Institute

658 North Progress Drive

Tel:  (816) 753-7600

Saukville, WI 53080

Date of Evaluation:  03/11/91

Tel:  (262) 536-4081








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