Hose Mask Respirators. These consist of a
facepiece, breathing tube, harness, and large diameter,
thick wall, nonkinking, air supply hose. The air may be
supplied by a blower, either motor or hand driven.
Air-Line Respirators. These consist of a
facepiece, hood, helmet or suit, breathing tube,
regulator, and small diameter hose provided with some
means to attach the hose to the user. Air is provided by
a compressor, ambient air breathing apparatus (AABA),
or compressed air cylinders. There are three types of
Demand: Available only with a facepiece, it
supplies air to the user on demand (when he
Available only with a
facepiece, it maintains a continuous positive
pressure within the facepiece.
Continuous Flow: Available with facepiece,
hood, helmet, or suit, it provides a continuous
positive pressure and flow of air.
SELF-CONTAINED BREATHING APPARA-
TUSES. These consist of a facepiece, helmet or hood, a
breathing tube, and a source of air or oxygen, all of which
are carried by the wearer. SCBAs are divided into the
following closed- and open-circuit types:
Closed Circuit. In closed circuit, or rebreathing,
SCBAS, carbon dioxide (CO2) in the exhaled breath is
removed by a chemical canister, and the remaining air
is rebreathed. There are two types: In one type the
oxygen is provided by either high-pressure gaseous
oxygen or gaseous oxygen converted from liquid
oxygen. In the other type the water vapor in the exhaled
breath reacts with a chemical in the canister to release
oxygen. The Navy oxygen breathing apparatus (OBA)
is an example of the second type. The OBA is not
approved by NIOSH/MSHA for commercial use, and it
is only authorized for damage control and fire-fighting
operations aboard ship. OBAs MUST NOT be used in
flammable atmospheres because of the heat generated
by the canister.
Open Circuit. In this type of SCBA, the exhaled
air is expelled to the atmosphere, and air is provided to
the user from a compressed air cylinder. This type of
respirator is available in either a demand or
Emergency Escape Breathing Device
(EEBD). This a special type of SCBA developed
specifically for emergency escape from shipboard fires.
It has a short-duration air supply. IT MUST NEVER BE
USED TO ENTER A HAZARDOUS ATMOSPHERE;
IT IS FOR ESCAPE ONLY!
Use only respirators that are jointly approved by
NIOSH/MSHA. If there is any doubt as to the respirator
required to protect against a particular contaminant, ask
an industrial hygienist.
Different respirators protect against different
contaminants and concentrations of contaminants, so
you must select one that protects you from specific
contaminants. The industrial hygiene surveys will give
you information on how to match contaminants and
respirators. Or if you need new information, ask an
industrial hygienist for help. Before you select a
respirator, always ask the following questions about the
conditions where you plan to use it:
What are the warning properties of the
contaminant (smell, eye irritation, or respiratory
irritation)? Some contaminants do not have
enough warning properties to alert you to
respirator failure. Vapor- and gas-removing
respirators are not approved for some
contaminants that include carbon monoxide,
hydrogen cyanide, isocyanates, and methyl
Is the contaminant absorbed through the skin?
Are any of the contaminants IDLH, or will they
cause ill effects after prolonged exposure?
What is the concentration of the contaminant in
What are the NAVOSH standards for maximum
levels of contamination in a given environment?
Is the atmosphere oxygen deficient or oxygen
rich or will such conditions be created?
What is the nature, extent, and frequency of the
duties to be performed in the work area?
What degree of protection is provided by the
Before you may use a respirator, you must meet the
. Be certified by the MDR as medically qualified
to use each type of respirator required.