A ventilation apparatus includes a plurality of tubular conduit sections, each conduit section including a first semi-tubular section and a second semi-tubular section, each semi-tubular section having a cross-sectional profile generally in the form of an open semi-circular annular element, when viewed along a longitudinal axis. Each tubular conduit includes a first engagement formation located at an end of the tubular conduit, and a second engagement formation located at an opposing end of the tubular conduit.

A ventilation apparatus includes a plurality of tubular conduit sections, each conduit section including a first semi-tubular section and a second semi-tubular section, each semi-tubular section having a cross-sectional profile generally in the form of an open semi-circular annular element, when viewed along a longitudinal axis. Each tubular conduit includes a first engagement formation located at an end of the tubular conduit, and a second engagement formation located at an opposing end of the tubular conduit.

A ventilation apparatus includes a plurality of tubular conduit sections, each conduit section including a first semi-tubular section and a second semi-tubular section, each semi-tubular section having a cross-sectional profile generally in the form of an open semi-circular annular element, when viewed along a longitudinal axis. Each tubular conduit includes a first engagement formation located at an end of the tubular conduit, and a second engagement formation located at an opposing end of the tubular conduit.

A ventilation apparatus includes a plurality of tubular conduit sections, each conduit section including a first semi-tubular section and a second semi-tubular section, each semi-tubular section having a cross-sectional profile generally in the form of an open semi-circular annular element, when viewed along a longitudinal axis. Each tubular conduit includes a first engagement formation located at an end of the tubular conduit, and a second engagement formation located at an opposing end of the tubular conduit.

Apparatus and process for securing a grating over an atmospheric opening of a ventilation shaft fluidly communicating through the ventilation shaft to an underground ventilation duct. A vertically extending support for arrangement in the shaft has horizontal flanges for projecting across a top of at least two opposing sides of said shaft to hang said support in said shaft for over topping by said grating. An anchoring member is supported in the support at a level below the flanges and proximate the atmospheric opening. A hold-down connects to the anchoring member to secure the hold-down and the grating to the anchoring member.

Apparatus and process for securing a grating over an atmospheric opening of a ventilation shaft fluidly communicating through the ventilation shaft to an underground ventilation duct. A vertically extending support for arrangement in the shaft has horizontal flanges for projecting across a top of at least two opposing sides of said shaft to hang said support in said shaft for over topping by said grating. An anchoring member is supported in the support at a level below the flanges and proximate the atmospheric opening. A hold-down connects to the anchoring member to secure the hold-down and the grating to the anchoring member.

Apparatus and process for securing a grating over an atmospheric opening of a ventilation shaft fluidly communicating through the ventilation shaft to an underground ventilation duct. A vertically extending support for arrangement in the shaft has horizontal flanges for projecting across a top of at least two opposing sides of said shaft to hang said support in said shaft for over topping by said grating. An anchoring member is supported in the support at a level below the flanges and proximate the atmospheric opening. A hold-down connects to the anchoring member to secure the hold-down and the grating to the anchoring member.