Issue Date: December 17, 2019

Core Engineered Solutions

SafeSite Vacuum Interstitial Monitoring System


Leak rate of 0.1 gph with PD=95.0% and PFA=<5.0% Evaluation Protocol for Vacuum-Wrapped Pressurized Portions of a Fuel Containment and Dispensing System. Revision 3A, Jairus D. Flora, Jr., Ph.D., December 15, 2006

Operating Principle:
System uses vacuum generated by a vacuum pump or submersible pump to continuously maintain a partial vacuum of a 7.5 psig, equivalent to 207.6” water column for a period of 60 minutes, and maintain vacuum for 30 seconds prior to testing.
System is designed to activate a visual and acoustic alarm, and optional submersible pump shutdown before stored product can escape to the environment.
System was evaluated for detecting breaches within the interstitial space of 1/8” or greater of a double-walled tank or double-walled piping.

Alarm Condition:
System alarms when a liquid or air leak occurs which causes the interstitial vacuum to decrease (pressure to increase) and the system is unable to maintain a vacuum pressure of 1.0 psi per hour for three consecutive failures based upon the rate of vacuum decay. The system incorporates a minimum detectable pressure change of 0.028 psi.
System will also alarm if liquid is detected in the interstitial space, or if the vacuum level in the interstitial space decreases at a rate exceeding 0.1 gallons per minute in 15 minutes.

Double-walled piping or double-walled tank (underground or aboveground) with an interstitial space of 1/8” or greater, storing gasoline, gasohol, diesel, heating oil #2, kerosene, aviation fuel, motor oil, water. Storage of biodiesel blends B6-B20 meeting ASTM D7467 and biodiesel B100 meeting ASTM D6751 would also produce a system alarm if the system threshold is exceeded. Responses to these fuels were not determined, but would be expected to be very similar to the system's response when storing diesel.

Manufacturer’s Specifications:
Alarm will activate when interstitial vacuum decreases 1.0 psi for three consecutive tests. Default maximum vacuum level (pump-off pressure) is 7.5 psi vacuum (207.6” water column), Volume of monitored interstitial space must not exceed 270 gallons or 5,120 feet of piping.

The system must be programmed by a factory trained technician or under the direction of the manufacturer. Programmed parameters include: system type (pressure or vacuum), test target pressure or vacuum (PSI or inH2O), test duration, maximum allowable loss, number of failed tests required to activate leak alarm, and optional disabling of the fuel pump.

The System described herein was tested only with open interstitial spaces of 1/8” or greater, and therefore it cannot be concluded that it would operate satisfactorily with restricted interstitial spaces. This system may not be compatible with all secondarily contained tanks and/or piping. Always consult with the tank and/or piping manufacturer and the manufacturer’s applicable recommended installation practices before installing this system, or damage may be caused to the tank or piping by its use.

Core Engineered Solutions

Evaluator: Dennis Eryou, PhD, P.E.

620 Herndon Parkway, Suite 120

5501 Castello Drive

Herndon, VA 20170

Naples, FL 34103

Tel: (703) 563-0320

Tel: (239) 530-4301

URL: Dates of Evaluation: January 22, 2019

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