Methodology
The tightness of fuel pipeline systems can be determined by applying the HCNA Pressure-Step tightness testing methodology. A pressure test is conducted and a tightness factor is determined by the evaluation of the measurement results. The tightness factor is the leaking liquid volume of fuel in gallons per hour of the checked volume usually based on 145 psi (10 bar).
“HCNA discovered a leak on our first project. Very professional and a great partner in our program.”Geoff LittleProgram Manager
HCNA LDS Features
The HCNA LDS tests the fuel pipeline or hydrant system in single or multiple sections. Multiple sections can be tested simultaneously during a given test cycle.
The testing time is a short 45 minutes, start to finish. Because of this short test time, HCNA LDS is able to prove the tightness of the entire fuel system on a daily basis if desired.
This provides customers with the highest degree of confidence in the integrity of their fuel piping.
All HCNA LDS applications operate in the same fashion and have a US EPA Third Party certified minimum detectable leak rate (MDLR) of 0.002% of the volume of the section tested. HCNA guarantees the US-EPA recognized certified capability of the HCNA-LDS to detect leaks of 0.002% of the volume at 145 psi with a detection probability of PD > 95% and a PFA < 5%. The HCNA LDS compensates for any fuel temperature changes that may occur during a test. Its performance is defined in relation to the size of the line that it is being tested, and this performance is expressed by a leak rate that is computed as a percent of the test segment line volume per hour. Because of these features, there are no test segment volume limitations and the size of the segment defines the accuracy. Additionally, each test section can have the leak rate validated and confirmed via a controlled simulated leak procedure.
The HCNA LDS pipeline testing of either aboveground or underground pipe is certified to function on both single-walled piping and double-walled containment piping systems.
Pressure Step Methodology
In any pressure based test, the determination of a leak is most influenced by temperature and pressure changes during testing. The Pressure-Step method is based on the physical fact that given a defined leak size, the leak rate would be proportionately larger at higher pressure than at lower pressure. Because the leak rate is directly related to a change in pressure, it can be determined from the pressure gradients during the test, whether the system is or is not tight.
The leak rate sensitivity is primarily determined by the volume of the test section. In special cases (e.g. air in the fuel system), the detection accuracy may be impacted if the volume of an air inclusion is significant relative to the test section volume.
The HCNA Pressure-Step program is able to determine the leak rate on the basis of the specific properties of the material and geometry of the piping system being tested. The evaluated tightness factors are recorded in a statistical database. The reliability of the HCNA Pressure-Step method can be proven anytime by means of controlled, manually created leaks.