Issue Date: January 11, 2001 

Ronan Engineering Co.

X76CTM Series Monitoring System (MTS UST Series Magnetostrictive Probe)



Leak rate of 0.2 gph with PD = 99.9% and PFA = 0.1% for Precision Test. 
Leak rate of 0.2 gph with PD = 95.0% and PFA = 0.1% for Quick Test. 
Leak rate of 0.1 gph with PD = 95.2% and PFA = 2.5% for 0.1 gph Test

Leak Threshold

0.124 gph for leak rate of 0.2 gph, Precision Test. 
0.168 gph for leak rate of 0.2 gph, Quick Test. 
0.067 gph for leak rate of 0.1 gph, 0.1 gph Test. 
A tank system should not be declared tight if the test result indicates a loss that equals or exceeds this threshold.


Gasoline, diesel, aviation fuel, fuel oil #4. 

Tank Capacity

Maximum of 20,000 gallons. 
Tanks less than 95% full may be tested. 
Minimum product level required based on test mode as follows:
For Quick Test, the minimum product level is computed as probe length multiplied by 0.12 plus 5 inches.
For Precision Test and 0.1 gph Test, the minimum product level is 50% of tank capacity.

Waiting Time

Minimum of 1 hour between delivery and testing for Quick Test. 
Minimum of 6 hours between delivery and testing for Precision Test and 0.1 gph Test. 
There must be no delivery during waiting time.

Test Period

Minimum of 2 hours for all tests. 
Test data are acquired and recorded by system's computer. 
Leak rate is calculated from data determined to be statistically valid. 
There must be no dispensing or delivery during test.


Average for product is determined by a probe with 5 resistance temperature detectors (RTDs). 
The bottom RTD must be submerged in at least 5 inches of product during test.

Water Sensor

Must be used to detect water ingress. 
Minimum detectable water level in the tank is 0.874 inch. 
Minimum detectable water level change is 0.011 inch. 
System is default programmed to report a water depth only when it exceeds 3.5 inches. 
System can be programmed to report a water depth of 0.874 inch and above.


System 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.


Ronan Engineering Co.

Evaluator:  Ken Wilcox Associates

21200 Oxnard St.

Tel:  (816) 443-2494

Woodland Hills, CA  91367

Date of Evaluation:  08/15/99

Tel: (800) 327-6626



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