This material is for training purposes only to inform the reader of occupational safety and health best practices and general compliance requirements and is not a substitute for provisions of the OSH Act of 1970 or any governmental regulatory agency.
MODULE 6: CONTROLLING CONFINED SPACE HAZARDS
Introduction Once hazards are identified, it is critical to institute appropriate control measures to eliminate or, if not possible, reduce and control confined space hazards. Remember, acceptable entry conditions must be attained before entry and those safe conditions must be maintained throughout the duration of an entry. This module explains some of the procedures and precautions that should be in place to safeguard entrants while they are working in the confined space. Confined space engineering controls Engineering controls are those controls which eliminate or reduce the hazard through implementation of sound engineering practices.
Ventilation is one of the most common engineering controls used in confined spaces. When ventilation is used to remove atmospheric contaminants from
the confined space, the space should be ventilated until the atmosphere is within the acceptable ranges. Ventilation should be maintained during the occupancy if there is a potential for the atmospheric conditions to move out of the acceptable range.
When ventilation is not possible or feasible, alternate protective measures or methods to remove air contaminants and
protect occupants should be determined by the qualified person prior to
authorizing entry. Conditions regarding continuous forced air ventilation
should be used as follows:
- Employees should not enter the space until the forced air ventilation has eliminated any hazardous atmosphere,
- Forced air ventilation should be so directed as to ventilate the immediate areas where an employee is or will be present within the space,
- Continuous ventilation is maintained until all employees have left the space, and
- Air supply for forced air ventilation should be from a clean source.
- Provide adequate oxygen to the air in the space.
- Control atmospheric contaminants.
- Prevent fire and explosion hazards.
- Control heat and humidity.
- Number and size of openings.
- Volume and configuration of the space to be entered.
- Capacity and positioning of the ventilation equipment to be used.
- Existing and potential atmospheric hazards.
- Routinely test the confined space until levels stabilize at acceptable entry conditions.
- Continue ventilation and frequent atmospheric testing for the entire duration of entry.
- Consider atmospheric hazards created by work in the space.
Respiratory protection
Respiratory protection is needed whenever:
- An emergency exists and entry cannot be delayed. Assume that an IDLH atmosphere exists.
- There is an inert atmosphere or testing shows that an IDLH exists and additional ventilation cannot reduce concentrations to safe levels.
- Current testing indicates atmosphere to be safe, but unsafe conditions could reasonably be expected to develop at any time.
- _____ Are confined spaces thoroughly emptied of any corrosive or hazardous substances, such as acids or caustics, before entry?
- _____ Are all lines to a confined space, containing inert, toxic, flammable, or corrosive materials valved off and blanked or disconnected and separated before entry?
- _____ Are all impellers, agitators, or other moving parts and equipment inside confined spaces locked-out if they present a hazard?
- _____ Is either natural or mechanical ventilation provided prior to confined space entry?
- _____ Are appropriate atmospheric tests performed to check for oxygen deficiency, toxic substances and explosive concentrations in the confined space before entry?
- _____ Is adequate illumination provided for the work to be performed in the confined space?
- _____ Is the atmosphere inside the confined space frequently tested or continuously monitored during conduct of work?
- _____ Is there an assigned safety standby employee outside of the confined space when required, whose sole responsibility is to watch the work in progress, sound an alarm if necessary, and render assistance?
- _____ Is the standby employee appropriately trained and equipped to handle an emergency?
- _____ Is the standby employee or other employees prohibited from entering the confined space without lifelines and respiratory equipment if there is any question as to the cause of an emergency?
- _____ Is approved respiratory equipment required if the atmosphere inside the confined space cannot be made acceptable?
- _____ Is all portable electrical equipment used inside confined spaces either grounded and insulated, or equipped with ground fault protection?
- _____ Before gas welding or burning is started in a confined space, are hoses checked for leaks?
- _____ Are compressed gas bottles forbidden inside of the confined space?
- _____ Is the confined area tested for a flammable/explosive atmosphere prior to using electrical equipment/lights within the confined space?
- _____ If the confined space may contain a potentially flammable/explosive atmosphere, are only intrinsically safe equipment and lights used within the confined space?
- _____ If employees will be using oxygen-consuming equipment-such as salamanders, torches, and furnaces, in a confined space, is sufficient air provided to assure combustion without reducing the oxygen concentration of the atmosphere below 19.5 percent by volume?
- _____ Whenever combustion-type equipment is used in a confined space, are provisions made to ensure the exhaust gases are vented outside of the enclosure?
- _____ Is each confined space checked for decaying vegetation or animal matter which may produce methane?
- _____ Is the confined space checked for possible industrial waste which could contain toxic properties?
- _____ If the confined space is below the ground and near areas where motor vehicles will be operating, is it possible for vehicle exhaust or carbon monoxide to enter the space?