Flow Quantities in the Galactic Centre Chimneys Feeding the Bubbles

This paper examines the Galactic Centre chimney flow quantities for the large bipolar structures above and below the Galactic Centre, using only published input values and transparent formulae. The calculation obtains the following headline results: chimney_volume_pc3 = 8835729.0; chimney_gas_mass_Msun = 124499.0; mass_flux_Msun_yr = 0.255; crossing_time_Myr = 0.49; enthalpy_power_erg_s = 4.677e+40; fill_time_for_bubble_hot_mass_Myr = 125.27. For the Galactic Centre chimney flow quantities, each quantity is derived step by step from the stated inputs, so that any reader can reproduce or rescale every number from the deposited calculation script. The results are compared with independent published estimates where those exist, and disagreements are reported at their actual size rather than absorbed into the assumptions, a point that bears directly on the Galactic Centre chimney flow quantities. The conclusions are limited to what the budget arithmetic supports: the Galactic Centre chimney flow quantities is constrained to the range the current published values permit, and the dominant remaining uncertainty is identified explicitly.