Tanknology VacuTect
The TANKNOLOGY Tank Test Method works by the means of applying a slight vacuum to the underground storage tank system. The Tank Test System used is known as the VacuTect® System.
The VacuTect® system, works by applying the vacuum via the tank vent pipe. This means that the vent is also tested with the tank, as is the offset fill, if one is fitted.
A computer controls the whole test. The vacuum is controlled at two points for safety. One is on the probe, that is inserted into the tank and stands vertically on the tank bottom. The other, is at the vacuum pump measuring the ullage pressure, by measuring the vacuum at these two points. This allows us to make sure that at no time does the tank system have too much vacuum being applied at any point. Also, on the probe that is inserted into the tank, there is a water sensor and a hydrophone.
When the tank system has vacuum applied, it is understandable that should a leak exist at any point, whatever is surrounding the point of the leak (either air or water) shall be drawn into the system.
Air Ingress
When air is drawn into the system, an air ingress is detected by the sound it makes (detectable by the hydrophone) and by the loss of the applied vacuum (detectable by the two pressure transducers). Identifying the area of the leak is the responsibility of the Test Unit manager. Various processes apply when sourcing area’s of leakage. TANKNOLOGY prides itself in being able to correctly identify the area of the system that is leaking. In most cases this can be done without any further works being carried out.
Size of Leak
|
 Fuel Loss- Litres Per Annum
|
| 1-2 drops per minute |
 164 LPA |
1-2 drops per second |
1,964 LPA |
| Intermittent stream |
 35,841 LPA |
| 1.5mm(1/16") diameter hole |
 119,523 LPA |
3.0mm(1/8") diameter hole |
  406,371 LPA |
Water Ingress
When water is drawn into the tank system a water ingress is detected by the hydrophone and the water sensor. If water is drawn into the system above the product level we will be able to hear this as it falls onto the product within the tank. Also, as the water filters through the product and gathers at the tank bottom the level at the bottom will increase and be detected by the water sensor. This is how the water ingress is detected when the leak is below the product level within the tank.
Suction Lines
Lines are tested independently of the tank system, by a patented line test device, known as the TLD 1. The lines are tested by connecting the TLD 1 to beneath the pumping unit. The TLD 1 is then filled with the same fuel as that stored in the line. There is a calibrated cylinder with a sight glass built into the TLD 1 (0.000549 cm/gallon). Once the TLD 1 is connected and filled with fuel, nitrogen is applied by regulated pressure to the calibrated cylinder (15psi). When the fuel obtains a stable level within the cylinder (entrapped air in line is removed) the line test commences. Readings are taken every ten minutes and the line is tested for a minimum time of 30 minutes. Lines are passed when readings of 0.025 gph or lower are obtained.
Pressure Lines
These lines are tested in a similar way as the suction lines. The only differences are that instead of 15psi of pressure, 50psi is used. The connection point differs also. Normally the test line is connected directly to the submersible pump and all lines from the submersible pump are tested at once. The threshold of 0.01 gph is used for pressure lines.
Reporting
When reporting leaks to the Customer, TANKNOLOGY Technicians will identify the area of the leak. We will also, if applicable, be able to tell the Customer the height of the hole in the tank from the tank bottom. This information can be useful if the fuel within the tank needs to be pumped out (in accordance with the local legal regulations) to a point below the level of the leak. This then stops any further environmental damage, especially when resources to undertake such a task are limited.
Tank Test times are normally around the two-hour mark. This will alter depending on the tank capacity.
The VacuTect® tank test system is one of the most reliable test systems on the market. This system can test a tank at virtually any product level (5%-95%). This is a major benefit especially when it’s believed that there may be an integrity problem with the tank. The last thing you would want to do is put more fuel in the tank if it is leaking. The other major benefit is that you do not ever receive an inconclusive result, this I am afraid to say is all too common with other test methods.
For further information on LCM Tanknology services please contact us.