The workers often install metal ducts in new buildings.
These were: the original fitting of the cross-feed duct, in 1969; the addition of the supplementary cooling pact duct, in about 1979; and the fitting of the permanent air-to-air refuelling modification, in about 1989.
But regulators have approved them only for helping to drain digestive fluids from the bile duct in cancer patients.
There are no plumbing pipes or heating ducts in the exterior walls to minimize heat and cooling loss.
Another set of fires rage through elevator shafts and air ducts in the core, spreading the blaze to higher floors.
The function of this duct in utero is to shunt blood away from the lungs.
Homeless people lived in heating ducts in the ceiling, phone card scammers targeted the hapless, and roving gangs had set up shop in the men's rooms.
In a forced-hot-air system, the air is heated by the boiler and delivered through ducts in the floor or ceiling like central air-conditioning.
The third is the tilt duct, in which propellers shrouded in ducts are rotated from one flight mode to the other.
Mr. Pearman's system calls for the placement of inflatable bags -- much like automobile airbags -- at strategic points throughout the air ducts in a building.
