The proper choice of respiratory protective equipment is important for confined space activity. Often, if a confined space is properly prepared respiratory equipment is not needed for safe entry. However, if levels of toxic chemicals are expected and/or determined to be present or if the atmosphere within the confined space has <19.5% oxygen and cannot be controlled via alternate methods(i.e. ventilation) then it is required that respiratory equipment be used.
What follows is a basic discussion on the various types of equipment available.
There are two basic types of respiratory devices. Those that supply air on their own and those that purify air.
Air Purifying Respirators rely on mechanical cartriges and filters. The contaminant must be known in order to make a proper selection of cannister or cartridge type. THESE
TYPES OF RESPIRATORS CANNOT BE USED
IN AN OXYGEN DEFICIENT ATMOSPHERE.
Supplied Air Respirators are used when chemical contamination exceeds the levels for a cartridge unit or if the chemical contaminant is unknown.
The most frequently used of this type is known as a SCBA or self contained breathing appartatus. Air is carried in a pressurized cylinder and passes through at regulator and hose as it is supplied to a full facemask. Usually only 30-60 minute supply is available with SCBAs. Sometimes connections for air-line from an alternate cylinder is provided which can extend the usefull working time to 4-5 hours. All SCBA's should be operated in a pressure-demand mode in which the air supplied is at a pressure slightly greater than outside. In this way any leakage around the facemask will result in an outward flow keeping contaminants out.
Here are some guidelines for respiratory cleaning and care:
To assist in making cleaning of full face respirators convenient it is necessary to provide a good cleaning station or area for cleaning. The required equipment should include at least a bench about 4' x 2.5' with a double stainless steel sink. Hot and cold running water should be available. Above the bench a row of hooks for hanging
masks to dry, or perhaps a stainless steel wire mesh shelf to set masks on. Either under the bench or on the wall nearby a cabinet for cleaning supplies such as brush, cleaning/sanitizer solution and other supplies for maintenance. Having a conveniently located cleaning station with good stock of supplies is key element to successful respirator cleaning and maintenance compliance.
Mask Cleaning
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The following procedure is general in nature however the basics apply to equipment for most manufacturers. Always consult with the manufacturer of your equipment to obtain the specific cleaning and inspection requirements.
1) Scrub the mask thoroughly with a soft brush using warm water and a commercially available cleaning solution for masks. Remove nosecup and clean seperately.
2) Dip the entire mask into the solution making sure the hose is submerged both inside and out. You may dissasemble the hose from the
mask if you like. However this is not required.
3) Rinse the entire mask with fresh water and hang to dry.
Mask Inspection
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1) Inspect the mask edges around the facial seal area. Check for cracking of the rubber. All edge areas should be soft and pliable.
2) Stretch the breathing hose and inspect for cracks or other signs of excessive wear.
3) Examine hose connection to canister or regulator. It should be round with no irregularities or deformities.
4) Confirm that the appropriate washers are in place at both ends of the breathing hose. Especially important with SCBA units. Without washers SCBA tank may leak contents at connection.
5) Examine straps for cracking, cut off ends, etc. Stretch straps to expose any signs of excess wear.
6) Confirm that the mask lens is not excessively scrathed and is held firmly in place and properly seated. Do not remove or dissasemble lens unless maintenance is required.
7) Inspect the exhaust valve, remove exhaust valve cover and inspect exhaust valve for signs of wear or cracking. The exhaust valve should be very pliable. If it is stiff, replace it. Make sure it is properly seated then replace the cover.
Discard/Replace any mask or component which does not pass the inspection. Do not attempt makeshift repairs with duct tape/glue/ etc.
Purchase certified replacement parts from the manufacturer or replace the entire facemask.
The above guidelines cover only the cleaning and inspection of full face respirator mask equipment and do not cover inspections of regulators,SCBA tanks and canister equipment. Adequate inspections of SCBA units include inspections of regulators and pressure tests of tanks are also required for safe use. Also, canisters should be inspected before use to make sure they are fresh. Canisters "out-of-date" should be discarded. Consult with the manufacturer of your equipment to obtain the appropriate testing and inspection requirements specific to your equipment. You should become thoroughly familiar with the manufacturers specific instructions for use of any Canister or SCBA style respirator equipment before attempting to use in a potentially hazardous environment.
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