Intumescent Pack. The 2420.IP is an Intumescent Pack to be used with the Briton 2400 series Cam Action Door Closers. A significant amount of fire resisting doorset material is removed when concealed closers are mortised into the door leaf. The intumescent gasket set will provide the additional performance that is required to protect the door from integrity failure during fire conditions. It is particularly important with these closers to check that the details of the fire test certification are relevant to your intended door application.. To suit Briton 2400 series door closers. . .