155479 ⎘
Steam boilers of fire-box type, i.e. the combustion of fuel being performed in a chamber or fire-box with subsequent flue(s) or fire tube(s), both chamber or fire-box and flues or fire tubes being built-in in the boiler body mounted in fixed position with the boiler body disposed upright with auxiliary water tubes inside the fire-box, e.g. vertical tubes the tubes being in substantially horizontal arrangement