|Definition:|| a reactor which is non-breathing, that is, so sealed that there can be no significant interchange between its contents and the external atmosphere
NOTE 1 – In the case of oil-immersed reactors, these may or may not have a cushion of air (or other gas).
NOTE 2 – Sealed reactors fall into two categories:
a) reactors in which the total volume of oil, together with air (or other gas), or any combination thereof, remains constant over the temperature range.
b) reactors in which the total volume of oil, air (or other gas), or any combination thereof, varies over the temperature range and this variation is accommodated by a sealed flexible container or a flexible membrane.