Liquid fuel storage tanks shall be drained and refilled with fresh fuel at intervals not greater than 12 months
CAN/ CSA C282-05 Section 18.104.22.168(Interpretation of test Results)
The samples shall be clear and bright. The visual clarity shall be recorded as clear and bright or not clear and bright. It shall be recorded whether particulate matter or water was seen at the bottom of the vortex. Note: the term “clear and bright” has to relation to the natural fuel oil color. Fuel oil color varies from water white, to straw color, to amber, depending on the processing and/or crude source. Clear and bright fuel has no floating or suspended matter. Brightness is a quality independent of the sample color and refers to the lack of suspended or free water in the sample. Fuel brightness tends to sparkle.
4. Diesel fuel storage tank(s):The fuel oil in any storage tank (and day tank, if used) shall be tested in accordance with Clause 22.214.171.124, and if the fuel oil fails the test, it shall be
(a) Drained and refilled with fresh fuel in accordance with Article 126.96.36.199 of the National Fire Code of Canada; or
(b) Full filtered to remove water, scale, bacteria, and oxidized gums/resins in order to minimize filter clogging and ensure diesel start-up (see Clause B.22 for commentary)
When the fuel is filtered, it shall be treated with a suitable conditioner and stabilizer to minimize degradation while in storage.
NOTE: The bottom(s) of the tank(s) shall be also tested chemically for water.
Clause B.22 (table5, Item 4(b))
Diesel fuel has a limited storage life depending upon the initial fuel quality, contaminant levels, and storage conditions. To extend fuel life, it is recommended that periodic filtering and treatment of the fuel be conducted to remove water, scale and bacterial growth.
(a) The fuel should be filtered to a maximum particulate size of 20µ and the filter media should be capable of removing water.(b) The fuel (if it is being re-circulated in the same tank when being filtered) should be filtered for a period of time at least three times longer than the period necessary to process the volume of the fuel in the tank once. For example, if the volume of fuel is X and the filter unit will process X volume in 30 min, the filter unit should be run for at least 1.5 hours. This will achieve a reasonably good level of filtration. At the same time, an effort needs to be made to agitate the fuel and any contamination at the bottom of the tank to ensure treatment.
(c) Provision should be made by the designers and installers of the fuel tank(s) for easy access to the fuel by the filter unit suction and return probes, with sufficient overhead clearance above the tank(s) and also suitable blank plugs or similar devices in the top(s) of the tank(s) for the probes to be easily inserted without extensive work.