Standard Interpretations - Table of Contents|
| Standard Number:||1926|
|OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.|
(1)(i) Fresh air shall be supplied to all underground work areas in sufficient quantities to prevent dangerous or harmful accumulation of dusts, fumes, mists, vapors or gases.Section 1926.800(k)(2)-(13) contains a number of specification requirements. Among these are §1926.800(k)(4), which state:
(ii) Mechanical ventilation shall be provided in all underground work areas except when the employer can demonstrate that natural ventilation provides the necessary air quality through sufficient air volume and air flow.
(4) The direction of mechanical air flow shall be reversible.Irrespective of the location of the fan, a flexible bag line may be used only if it will not collapse when the air flow is reversed (only some bag lines are so designed). If reversing the air flow would collapse the bag line, the ventilation system would not meet the §1926.800(k)(4) requirement for reversibility.(1)
(11) Potentially gassy or gassy operations shall have ventilation systems installed which shall:Specifically requiring the controls to be on the surface for gassy operations indicates that the Agency assumed that at least some fan equipment would be located underground. This is reflected in the rulemaking, in which a commenter objected to a proposed requirement for surface controls in all instances:
(i) Be constructed of fire-resistant materials; and
(ii) Have acceptable electrical systems, including fan motors.
(12) Gassy operations shall be provided with controls located above ground for reversing the air flow of ventilation systems. [Emphasis added.]
Kenny Construction argued that connecting the in-line booster fans to a central above-ground control will require the installation of a burdensome wiring and switch system which is unjustified, absent some compelling need for surface control . . .[54 FR 23837].Although rejecting the concept of requiring above-ground controls in all circumstances, OSHA found that above-ground controls were necessary to deal with emergencies associated with gassy operations:
In light of . . . testimony about the value of above-ground controls for control from the surface after evacuation and during rescue work . . . OSHA believes that the record does support a decision to require above-ground controls in operations where such events are most likely to occur, that is, in 'gassy' operations. [54 FR 23837].Nonetheless, a requirement to place the main fan above ground was not included in the standard.
(13) In potentially gassy or gassy operations, wherever mine-type ventilation systems using an offset main fan installed on the surface are used, they shall be equipped with explosion-doors or a weak-wall having an area at least equivalent to the cross-sectional area of the airway. [Emphasis added].However, unlike the underground coal mine standard, this requirement is not coupled with a requirement that the main fan be located at the surface.
|Standard Interpretations - Table of Contents|