19/02/2026
Ive been asked to test a very old site in a rural town so I added this to the quote, and they still came back with " when can you be there" . -----------The tank test is an acoustic test ,an ultrasonic sonde is installed in the tank, fittings are capped off, the tank is pressurized or vacuumed +/- 2psi max, and a computer determines the sound signature of a leak.
These tanks are under the foot path on council land.
The 25mm vent indicates the age of the tanks-- 25mm vent 60s-70s, 40mm vent 70s-80s, 50mm vent from 80s to current, this is based on the filling pipe size, the vent is half the filling size,
As delivery trucks got bigger so did vent sizes, most service stations now have 100mm fill and 50mm vents
As the tanks are likely installed in the 70s ( over 50 years), the construction practices were to make the tanks with a permanent drop tube down the dip and fill, (with no compensation hole) this means test equipment cannot access the ullage space of the tank and therefore the test is inconclusive.
When this happens the next stage (stage 2 testing ) is to remove the concrete above the tanks and locate a fitting that can be used for testing.( small tanks do not always have a spare fitting.)
This is when I usually find corrosion pitting and\ or holes in the top of the tank. And the tanks then need to be removed as per worksafe requirements,
Product lines are pressure tested from the pumps back to tank valves, older tanks only have a brass valve, this allows test pressure to get past and reenter the tank and the line is determined as failed, this can happen even if the line is not leaking.
Older suction lines such as these which will be 40mm have a very high percentage fail rate, underground steel fuel lines generally last 20-30 years,
This was the exact scenario that happened at the ###x service Station in 2017, and the tanks at this store in the same town are surprisingly similar and roughly the same age, (note the servo tanks failed tests 9 years ago, they already had holes) and probably installed by the same old grey fitter.
I have have come across this situation many times.
I have known other test companies to not fully explain the process, and just test, charge and fail, then dig up, retest, charge and fail.
You cannot test down the vent, this is not how any of the test systems work, it is not a pressure test, and a test like that will be inconclusive ( even if they say it passed)
If the site wishes to continue, please continue the booking a deposit will be required
The site needs to be aware, stage two testing will cost more than stage one testing , and may still result in failed tanks.