Issue Date: October 22, 2013


OPW Fuel Management Systems
Site Sentinel Nano
(Model 924B with 2 inch dia Floats)



Leak rate of 0.2 gph with PD = 98.18% and PFA = 1.82% using 924B probe with 2 dia float.

Leak Threshold

0.1 gph for leak rate of 0.2 gph using 924B probe with 2 dia floats. 
A tank system should not be declared tight if the test result indicates a loss or gain that equals or exceeds this threshold.


Gasoline, diesel, aviation fuel.

Tank Capacity

Maximum of 20,000 gallons. 
Tank must be minimum 50% full for leak rate of 0.2 gph using 924B probe.  

Waiting Time

Minimum of 6 hours between delivery and testing using 924B probe. 
There must be no delivery during waiting time.

Test Period

Average data collection time of 2 hours using 924B probe for leak rate of 0.2 gph.
Test data are acquired and recorded by system's computer.  
There must be no dispensing or delivery during test.


Average for product is determined by a probe containing 5 thermistors.

Water Sensor

Minimum detectable water level that can be detected by the 2 dia float is 0.75 inch.  

Minimum detectable change in water level that can be detected by the 2 dia float is 0.080 inch.


Thermistors (or RTDs) and probe 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.

2012 console comparison with OPW iSite; which was based on 2-26-2008 evaluation of OPW iSite.


OPW Fuel Management Systems

Evaluator:  Ken Wilcox Associates

6900 Santa Fe Dr.

Tel:  (816) 443-2494

Hodgkins, IL 60525-9909

Date of Evaluation:  08/03/2013

Tel:  (708) 485-4200






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