Posted By Stephen D. Clarke Jo, As I undestand it a confined space means any place including a chamber, boiler, tank, vat, silo, pit, pipe, sewer, flue, well, trench or similar space in which by virtue of its enclosed nature, there is a foreseeable risk of any specified risk. Specified risk could be fire, explosion, loss of consciousness or asphyxiation arising from gas, fume, vapour or lack of oxygen, free flowing solid, or arising from high temperature. So for example a roof space with a gas supply could be a confined space, as could a small laboratory with a large liquid nitrogen dewar. Steve