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Open AccessArticle

Ventilation of an Isolated Subsurface Structure Induced by Natural Forces

1
NorthWest Occupational Health & Safety, North Vancouver, BC V7K1P3, Canada
2
Programa de Pós-Graduação, Universidade Federal Fluminense, Niterói 24210-240, Brazil
3
Escola Politécnica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972, Brazil
*
Author to whom correspondence should be addressed.
Infrastructures 2019, 4(2), 33; https://doi.org/10.3390/infrastructures4020033
Received: 9 May 2019 / Revised: 27 May 2019 / Accepted: 1 June 2019 / Published: 5 June 2019
The subsurface infrastructure comprises many types of isolated structures, a type of confined space. This study reports on the effect of engine operating time, number/area and spacing of openings in the manhole cover, and operation during different seasons on ventilation of a subsurface, isolated, pre-cast concrete chamber through opening(s) in the manhole cover. Carbon monoxide (CO) emitted by a small gasoline engine reached 800 ppm in 30 s at the start of testing. Ventilation occurred continuously. Generally, the concentration of CO reported by instruments located at different heights was the same for the same moment in time, suggestive of a rapidly well-mixed atmosphere. Mathematical modelling suggested that ventilation occurred through a zero-order kinetic process. Statistical testing suggested that optimization of ventilation is possible through design modifications such as change in the number/area/shape/spacing/geometric arrangement of openings in the manhole cover. Optimizing the rate of ventilation induced by natural forces during the interval between entries will reduce the risk of explosion of the confined atmosphere and overexposure of workers when opening the manhole cover to prepare for entry. This improvement will have immense implications to safety worldwide. View Full-Text
Keywords: carbon monoxide; CO; exhaust gases; gasoline engine; natural forces; subsurface structure; ventilation carbon monoxide; CO; exhaust gases; gasoline engine; natural forces; subsurface structure; ventilation
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MDPI and ACS Style

McManus, T.N.; Haddad, A. Ventilation of an Isolated Subsurface Structure Induced by Natural Forces. Infrastructures 2019, 4, 33.

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