For each 10 litres of solution required first dissolve 1 kg of DS-10 in a small quantity of warm water then add to the remaining water. This should provide a solution of sufficient strength to clean adequately a lightly contaminated heat exchanger in a few minutes. For cases where severe contamination of combustion surfaces has occurred, several units are to be cleaned, or where a reduction in the cleaning time is required, the strength of the solution may be increased to 20% w/v (i.e. 2 kg of powder per 10 litres of water). Neutralise prior to disposal using Fernox System Neutraliser added at a rate of 5 L System Neutraliser to every 7 kg of DS-10 used. Note: Fernox DS-10 must not be used with boilers employing aluminium heat exchangers. Refer to manufacturer’s service literature for detailed instructions. Fernox DS-10 must not be mixed with products containing nitrite or with bleaching products.