13.7.5 Filters and Strainers
Filters and strainers are to be designed to withstand the maximum working pressure of the system in which they are installed.
Where filters and strainers are fitted in parallel to enable cleaning without disrupting the oil supply, means are to be provided to minimize the possibility of a filter or strainer being opened inadvertently.
Where they are required to be opened for cleaning during operation, they are to be fitted with means of depressurizing before being opened and venting before being put into operation. For this purpose, valves and cocks for drainage and venting are to be provided. Drain pipes and vent pipes are to be led to a safe location. For leakage containment and drainage, see 4-6-4/13.3.4.
13.7.6 Sight Flow Glasses
A sight flow glass may be fitted only in the vertical sections of fuel oil overflow pipes, and provided that it is in a readily visible position.