Causes of PTT Failures:
A failure of a PTT occurs only when a contaminant reacts with Potassium Permanganate. Such reactions are caused by all inhibited products and organic matter. Potassium Permanganate does not react with hydrocarbons.
By spraying, or recirculation washing, the tank with Potassium Permanganate you will pass the PTT time (just by pre-empting the surveyors medium). First, clean the tank has to a water-white standard before applying the Potassium Permanganate by spraying.
The different ways of spraying Potassium Permanganate with good results are:
1/ Put one tablespoon of Permanganate in a 200 litre drum with around 100-150 litres of fresh water. Use a high-pressure drum pump and spray gun and constantly replace the fresh water in the drum whilst spraying as this mixture is strong. Spray the tank for about 45-60 minutes.
2/ Mix six table spoons of Potassium Permanganate crystals in 2 m3 of water and recirculation wash for half an hour. If the mixture turns to a straw-like colour (indicating high contaminates are present) before the half-hour, then renew the mixture.
3/ Steam the tank, inserting a strong mixture of Potassium Permanganate, for about 60 minutes.
In all cases the tank must be thoroughly washed afterwards to remove the Potassium Permanganate/sludge. There are no known coating restrictions.