What is the difference between permit required v non permit required confined spaces?

Permit Required Versus Non Permit Required Confined Spaces. What precautions must workers keep when entering permit required confined spaces?   

As per the OSHA definition, there are three important characteristics of confined spaces.

• The confined spaces are sufficiently large to allow the workers to enter and do their work.
• The space for entry and exit is limited.
• Cannot be occupied continuously as its design does not allow.

Workers come across such spaces on a daily basis. Some of the common examples of tanks, vessels, silos, storage bins, hoppers, vaults, pits, manholes, tunnels, equipment housings, ductwork, pipelines, etc.

 This definition can also be used to identify the non-permit required confined spaces from the permit required confined spaces. However, apart from the above mentioned characteristics the confined spaces also contain an additional characteristics out of these four. Those confined spaces which do not contain any of the below mentioned four characteristics.

1. An atmosphere that can be potentially hazardous for the person entering it.
2. Contains a substance that has the potential to engulf or suffocate the entering employee.
3. Walls that converge inwards  or a floor that slopes downward into a cross section
4. The space contains any other kind of serious hazard like exposed live wires, unguarded machinery or even heat stress.

Any of the confined spaces that contain one of the above mentioned hazards must be marked as dangerous by the employer. The employers must mark such places with the help of a sign or any other means that effectively communicates the hazard.  Apart from it training materials and instructions must be provided to the workers who have to enter these spaces and work there. Employers must develop proper procedures for working in and around these spaces.  

OSHA provides the following guidance for the workers who have to work inside such confined spaces.

• Workers must not enter a permit required confined space without having the training and entry permit.
• Workers must review and understand the employer procedures before they enter the permit required confined spaces. Workers must have a proper understanding of entry and exit from confined spaces.
• Workers must identify any type of physical hazards that may be inside such spaces.
• Workers must test and monitor the oxygen content of these spaces before entering. They should also test for inflammability, toxicity and for hazardous chemicals just as necessary.
• Moreover, the workers must use employer’s fall protection, rescue, air-monitoring, ventilation, lighting and communication equipment per the entry procedures.
• Workers must maintain contact with an attendant all the while through a two way phone, any other visual or telephonic means. Such monitoring systems allow the attendants to conduct appropriate evacuation if necessary.