| abstract |
A filter for an apparatus for delivering a flow of gas, the filter comprising: a filter body, wherein the filter body has a main compartment and a sub-compartment at least partly within the main compartment, wherein the main compartment is in fluid communication with a main compartment gases inlet and the sub-compartment is in fluid communication with a sub-compartment gases inlet; and a filter medium associated with both the main compartment and the sub-compartment, and that is arranged to filter gases in, or exiting, the main compartment and the sub-compartment. |