EPA’s Third Party Testing Results of Pipeline Leak Detectors

An EPA work group recently reviewed the third-party test data for more than 200 leak monitoring systems. How did the 89 pipeline leak detection systems tested measure up?

This article provides an overview of the testing results for 89 pipeline leak detectors listed in a recently published EPA report on third-party testing of line leak detection equipment. These detectors are:

• Automatic electronic pipeline leak detectors
• Automatic mechanical pipeline leak detectors
• large diameter pipeline leak detectors
• Line tightness test
• Trace chemical test

Column headings for each type of system vary, depending on the type of information provided in the listing. If all of the information in a column for a particular category is identical, the data is generally presented under “Common Characteristics.” Following is an explanation of the information in each column.

A. Manufacturer.
The name of the primary system manufacturer or, in cases of “private labeled” systems, the vendor. (For more information, circle the Reader Response number on PE&T’s postage-paid Reader Response postcard or contact the manufacturer directly.)

B. Model. 
Most automatic electronic leak detector models are listed more than once because they were evaluated to perform multiple EPA-prescribed tests (i.e., hourly, monthly, annual). Leak detectors with different model numbers may be combined in a listing if the model numbers indicate consoles and do not affect performance, or indicate optional manual or automatic operation.

C. Certified leak rate. 
Certified leak rates are the minimum standards established by the US EPA. These rates are: hourly test—3.0 gph; monthly test—0.2 gph; annual test—0.1. State requirements may be different.

D. Probability of Detection (Pd). 
Probability of detection is a measure of the reliability of a system to detect an existing leak. The detection system must be capable of doing so at least 95 percent or more of the time to be acceptable.

E. Probability of false alarm (Pfa). 
The probability of false alarm is the other side of the same coin; this is the probability that the system will erroneously detect a leak in a tight system. This value must be 5 percent or less for the equipment to qualify.

F. Leak threshold. 
The leak threshold is “the value used during the test to determine whether the piping passed or failed the test.” This value is set by each system manufacturer to meet EPA criteria. It requires a balance between (1) a high sensitivity to finding a leak at the risk of causing a false alarm (a low threshold) and (2) less sensitivity with less chance of causing a false alarm (a high threshold). A more complete definition involves delving into the statistical operations required in the evaluation process. (We will be addressing the test protocols and procedures in more depth in a future article for our mathematically inclined readers.)

G. Certified for. 
This column refers to the liquid products for which the systems are certified. Acceptable products are determined by the manufacturer and the third-party evaluator. The EPA considers any system meeting the other EPA criteria to be suitable for use with any regulated product. Industry standards of practice, manufacturers’ instructions and fire codes require that all equipment that is part of an UST or AST system be compatible with the product stored and handled.

H. Piping materials. 
Leak detection systems designed for use with steel and FRP piping may not work with flexible piping. Others have been modified specifically for flexible (hose-type) piping systems that “balloon,” or stretch, when pressurized. Ballooning may otherwise be misread as a leak, resulting in a false alarm. While FRP piping and systems using flexible connectors are somewhat flexible, they are not considered “flexible” in the EPA listings.

Piping materials are not specified by EPA. As far as the Agency is concerned, any system meeting its standard criteria is acceptable for use with any type of piping. Again, industry standards of practice require all equipment that is part of an UST or AST system be compatible with the product stored and handled.

I. Test pressure.
Most evaluation tests are performed at normal operating pressure. Since leak rates are a function of pressure, EPA standard protocols require testing at the following pressures:

Hourly test    3.0 gph @ 10 psi
Monthly test  0.2 gph @ normal pump operating pressure
Annual test   0.1 gph @ 1.5 times normal operating pressure

J. Maximum volume. 
EPA permits a leak detection system to be used in any application where the maximum volume to be monitored does not exceed twice the capacity at which the system was evaluated. This value is stated as the maximum volume of product in the piping to be monitored.

K. Waiting time after dispensing. 
Most systems do not require a delay between dispensing fuel and performing the line test. Some test immediately after each fueling operation. If a dispenser is turned on during a test period, the test is aborted. If a waiting time is required, operators must allow it for the test to be valid.   Tracer chemicals require four weeks between inoculation and testing of the surrounding soil to allow time for the chemical to migrate to the sampling points.

L. Testing durations. 
The length of a test is a factor in the size of the leak to be detected. The type of testing (hourly, monthly or annually) directly affects test time; the more sensitive the test, the longer the test period required. Mechanical leak detectors test before each fuel dispensing operation and require only 2 to 6 seconds. Other systems test continuously or intermittently until a result is determined.

M. Action if leak is declared. 
To satisfy hourly testing requirements, automatic mechanical leak detectors signal the user by slowing the delivery rate at the start of a fueling. After a short period, full flow resumes. The user is presumed to notify the operator of the “erratic” dispenser operation. Electronic systems may activate a warning light or horn, or may cause electrical power to pumps to be interrupted. Either is acceptable.

Monthly and annual tests permit audible or visible alarms, interruption of pump power or flow restriction. Manual test methods rely on the tester to inform the owner/operator of the facility of the test results.

There are other factors to consider in selecting equipment. For example, technical support, warranties, cost and product quality vary between manufacturers. These factors do not show up in the materials we are presenting. Some systems require a minimum amount of pressure to operate while others operate under all conditions. The listing confirms that the systems were evaluated according to standard evaluation procedures, but it is no guarantee that the systems will work properly in a particular application.

There may also some difficulty in applying the EPA standard test procedures to particular leak detection systems. More tests are customized somewhat to accommodate the nature of the system being tested. Some unique systems cannot be tested by using the standard way, and evaluating laboratories must develop alternative test procedures. While this is acceptable to EPA, these systems are not listed, since only systems that follow the standard EPA procedures were evaluated.

There are leak detection systems for unregulated piping applications that have not been evaluated or may not have been submitted for evaluation. While they may provide acceptable performance, they are not listed. The work group is currently evaluating systems that may or may not meet the criteria. There are also lists of approved leak detection methods prepared by state and local regulators and third-party evaluators.

Despite its limitations, the report provides a useful tool. When you have narrowed your selection, check with state or local regulators for their approval. Make certain you understand the principles employed or the system limitations of the systems selected, and confirm the appropriateness of the selected system for the particular application. Then look for a qualified vendor who can provide ongoing support. Keep in mind that this listing represents minimum acceptable standards.

Discuss