Confined Space Rescue Operations

Fred Endrikat continues his series on confined space rescues and knowing about your environment.


The federal Occupational Safety and Health Administration (OSHA) requires a written permit entry program to be established for confined space operations. What effect does this have on fire departments? Photo by Bob Stella Operating 250 feet under Boston Harbor during a tunnel...


To access the remainder of this piece of premium content, you must be registered with Firehouse. Already have an account? Login

Register in seconds by connecting with your preferred Social Network.

OR

Complete the registration form.

Required
Required
Required
Required
Required
Required
Required
Required
Required
Required

ATMOSPHERIC HAZARDS

Some of the most commonly encountered atmospheric hazards within confined spaces are made up of these five chemicals:

HYDROGEN SULFIDE (H2S)

  • Colorless gas with the odor of rotten eggs
  • Widely used in industry
  • Irritant and asphyxiant
  • Dangerously flammable in high concentrations
  • Vapor density of 1.2
  • Will collect in depressions and at the bottom of a confined space
  • LEL of 4%

METHANE (CH4)

  • Formed by decomposition of organic materials (also known as marsh gas)
  • Colorless, odorless and tasteless
  • Likely to be found in sewer waste water and treatment systems
  • Considered a simple asphyxiant
  • Can displace oxygen if present in high concentrations
  • Vapor density of 0.5
  • Will be trapped in the upper levels of manholes, sewage-related and other confined spaces
  • Will explode when the gas/air mixture is 5% to 15% methane
  • LEL of 5%

CARBON MONOXIDE (CO)

  • Colorless, odorless and tasteless gas
  • Produced during the combustion of any carbon-based material
  • Chemical asphyxiant will combine with hemoglobin in blood and make the blood incapable of transporting oxygen through the body
  • Vapor density of 1.25
  • Will accumulate at the bottom of a confined space
  • LEL of 12%

CARBON DIOXIDE (CO2)

  • Colorless, odorless and non-combustible gas
  • Produced during the combustion of any carbon-based material
  • Sometimes used as an "inerting" gas in confined space work
  • Introduced into the confined space in the form of "dry ice" to displace flammable gases and vapors
  • Vapor density of 1.5
  • Will collect at the bottom of a confined space
  • IDLH of 5%

NITROGEN DIOXIDE (NO2)

  • Dark brown fuming liquid or vapor
  • Product of diesel engines, blasting and high-temperature welding
  • Will not burn but is an oxidizer
  • Vapor density of 1.6
  • Vapor will collect at the bottom of a confined space
  • IDLH of .005%

Fred Endrikat, a Firehouse® contributing editor, is a lieutenant and 22-year veteran of the Philadelphia, PA, Fire Department, assigned to Rescue Company 1. The first part of this series was published in the October 1996 issue.