Glossary of NR-7

ATA: Abbreviation for Absolute Pressure Atmosphere. A unit of pressure that considers both the gauge pressure and the ambient atmospheric pressure.

Critical Activities: Those that require a specific medical evaluation to determine the employee’s fitness.

Hyperbaric Treatment Chamber: A chamber that, independent of the work chamber, is used for treating individuals who develop decompression sickness or embolism and is directly supervised by a qualified physician. It constitutes a Human Occupation Pressure Vessel (VPOH), of the multipatient type (for more than one person).

Surface Chamber: A hyperbaric chamber specifically designed for use in decompressing divers, required by the operation or hyperbaric treatment. Work

Chamber: A space or compartment with pressure higher than atmospheric pressure where the work is performed.

Submersible Atmospheric Pressure Chamber: A chamber resistant to external pressure, specially designed for underwater use, where its occupants remain at atmospheric pressure.

Bell: A chamber through which the worker passes from the open air to the work chamber of the caisson and vice versa. The term is used in caisson work with compressed air and defines the chamber where the worker waits while the pressure is increased at the start of the work activity, and where the pressure is decreased at the end of the work activity.

Decompression: The set of procedures through which a diver eliminates from their body the excess inert gases absorbed during certain hyperbaric conditions. These procedures are absolutely necessary when returning to atmospheric pressure.

Personnel Airlock: A chamber through which the worker passes from the open air to the work chamber in pressurized tunnels and vice versa. The term is used in tunnel drilling operations, also known as “Shield,” which refers to the brand name of the tunnel drilling equipment, which has a hyperbaric chamber for compression. It is the chamber where the worker waits while the pressure is increased at the start of the work activity, and where the pressure is decreased at the end of the work activity.

Compressed Air Supervisor: A trained professional knowledgeable in the techniques used in hyperbaric work conditions, designated by the organization as the immediate responsible person for employees and the entire compressed air operation, including personnel and equipment.

Internal Guide: A health professional or professional diver who is pressurized together with the patient.

Qualified Physician: A physician with qualification in hyperbaric medicine.

Diver: A worker qualified to use diving equipment with a supply of respiratory gas in a submerged environment.

Artificial Respiratory Mixtures: Mixtures of oxygen, helium, or other gases suitable for breathing during underwater work when natural air is not indicated.

Airlock or Bell Operator: A worker previously trained in the compression and decompression maneuvers of airlocks or bells, responsible for pressure control within them, both in the caisson and in the personnel airlock.

Diving Operation: Any operation that involves underwater work, extending from the initial preparation procedures to the end of the observation period, as determined by the qualified physician responsible for the dive.

Work Period: The time during which the worker remains under hyperbaric conditions, excluding the decompression time. In diving activities, it is called “bottom time”.

Dust Containing Insoluble or Slightly Soluble Particles of Low Toxicity Not Otherwise Classified: Also known as “nuisance dust,” “biologically inert dust,” or “particles not otherwise classified” (PNOC), which, when inhaled in excessive quantities, can contribute to lung diseases.

Maximum Working Pressure – MWP: The highest air pressure to which the worker is exposed during their work shift. This pressure must be considered in the decompression schedule.

Compressed Air Work: Work performed in environments where the worker is required to withstand pressures greater than atmospheric pressure, and where careful decompression is required, according to established technical standards.

Recompressive Treatment: Emergency treatment in a multipatient hyperbaric chamber, performed or supervised exclusively by a qualified physician and directly accompanied by an internal guide with the patient.

Compressed Air Caisson: Equipment for foundations with a vertical structure that extends below the surface of the water or soil, inside which workers must enter through the bell to a pressure greater than atmospheric. The pressurized atmosphere opposes the water pressure and allows work inside.

Pressurized Tunnel: Excavation below the surface of the soil, whose main axis forms an angle not exceeding 45 degrees with the horizontal, closed at both ends, with internal pressure higher than one atmosphere.