A respirator is a device designed to protect the wearer from inhaling harmful dusts, fumes, vapors, and/or gases. Respirators come in a wide range of types and sizes used by the military, private industry, and the public. Respirators range from cheaper, single-use, disposable masks to reusable models with replaceable cartridges.
There are two main categories: the air-purifying respirator , which forces contaminated air through a filtering element, and the air-supplied respirator , in which an alternate supply of fresh air is delivered. Within each category, different techniques are employed to reduce or eliminate noxious airborne contents.
Early development of respirators
The history of protective respiratory equipment can be traced back as far as the 16th century, when Leonardo da Vinci suggested that a finely woven cloth dipped in water could protect sailors from a toxic weapon made of powder that he had designed. Alexander von Humboldt introduced a primitive respirator in 1799 when he was working in Prussia as a mining engineer.
Practically all the early respirators consisted of a bag placed completely over the head, fastened around the throat with windows through which the wearer could see. Some were rubber, some were made of rubberized fabric, and still others of impregnated fabric, but in most cases a tank of compressed air or a reservoir of air under slight pressure was carried by the wearer to supply the necessary breathing air. In some devices certain means were provided for the adsorption of carbon dioxide in exhaled air and the rebreathing of the same air many times; in other cases valves were provided for exhalation of used air.
The first US patent for an air purifying respirator was granted to Lewis P. Haslett in 1848 for his 'Haslett's Lung Protector,' which filtered dust from the air using one-way clapper valves and a filter made of moistened wool or a similar porous substance. Following Haslett, a long string of patents were issued for air purifying devices, including patents for the use of cotton fibers as a filtering medium, for charcoal and lime absorption of poisonous vapors, and for improvements on the eyepiece and eyepiece assembly. Hutson Hurd patented a cup-shaped mask in 1879 that became widespread in industrial use, and Hurd's H.S. Cover Company was still in business in the 1970s.
Inventors were also developing air purifying devices across the Atlantic. John Stenhouse, a Scottish chemist, was investigating the power of charcoal, in its various forms, to capture and hold large volumes of gas. He put his science to work in building one of the first respirators able to remove toxic gases from the air, paving the way for activated charcoal to become the most widely used filter for respirators. British physicist John Tyndall took Stenhouse's mask, added a filter of cotton wool saturated with lime, glycerin, and charcoal, and invented a 'fireman's respirator,' a hood that filtered smoke and gas from air, in 1871; Tyndall exhibited this respirator at a meeting of the Royal Society in London in 1874. Also in 1874, Samuel Barton patented a device that 'permitted respiration in places where the atmosphere is charged with noxious gases, or vapors, smoke, or other impurities.' German Bernhard Loeb patented several inventions to 'purify foul or vitiated air,' and counted among his customers the Brooklyn Fire Department.
Chemical warfare
The Second Battle of Ypres was the first time Germany used chemical weapons on a large scale on the Western Front in World War I. 168 tons of chlorine gas was released on 22 April over a four mile (6 km) front. Around 6,000 troops died within ten minutes from asphyxiation. The gas affects the lungs and the eyes causing respiration problems and blindness. Being denser than air it flowed downwards forcing the troops to climb out of trenches.
Eventually reserve Canadian troops held the front, being away from the attack, using urine-soaked cloths as primitive respirators. A Canadian soldier had discovered that the ammonia in urine would react with the chlorine, neutralizing it, and that the water would dissolve the chlorine, allowing the soldiers to breathe through the gas. This is the first recorded response and defense against chemical attacks using respirators.
Modern respirator technology
All respirators have some type of facepiece held to the wearer's head with straps, a cloth harness, or some other method. The facepiece of the respirator covers either the entire face or the bottom half of the face including the nose and mouth. Half-face respirators can only be worn in environments where the contaminants are not toxic to the eyes or facial area. For example, someone who is painting an object with spray paint could wear a half-face respirator, but someone who works with chlorine gas would have to wear a full-face respirator. Facepieces come in many different styles and sizes, to accommodate all types of face shapes, and there are many books and references available for determining which kind of hazard requires what type of respirator.
Air-purifying respirators
Air-purifying respirators are used against particulates (such as smoke or fumes), gases, and vapors that are at atmospheric concentrations less than immediately dangerous to life and health. The air-purifying respirator class includes:
- negative-pressure respirators, using mechanical filters and chemical media
- positive-pressure units such as powered air-purifying respirators (PAPRs)
- Escape Only respirators or hoods such as Air-Purifying Escape Respirators (APER) for use by the general public for Chemical, Biological, Radiological, and Nuclear (CBRN) terrorism incidents.
Full hood, half- or full-facepiece designs of this type are marketed in many varieties depending on the hazard of concern. They use a filter which acts passively on air inhaled by the wearer. Some common examples of this type of respirator are single-use escape hoods and filter masks. The latter are typically simple, light, single-piece, half-face masks and employ the first three mechanical mechanisms in the list below to remove particulates from the air stream. The most common of these is the disposable white N95 variety. The entire unit is discarded after some extended period or a single use, depending on the contaminant. Filter masks also come in replaceable-cartridge, multiple-use models. Typically one or two cartridges attach securely to a mask which has built into it a corresponding number of valves for inhalation and one for exhalation.
The American National Standard for Air-Purifying Respiratory Protective Smoke Escape Devices was established to define both test criteria and approval methods for fire/smoke escape hoods. ANSI/ISEA 110 provides design guidance to Respiratory Protective Smoke Escape Devices (RPED) manufacturers in the form of a detailed set of performance requirements and testing procedures. Key sections of the standard cover certification, labeling, design, performance, conditioning and testing requirements.
ANSI/ISEA 110 was prepared by members of the ISEA RPED Group, in consultation with testing laboratories and was reviewed by a consensus panel representing users, health and safety professionals and government representatives.
ANSI/ISEA Standard 110 contains general requirements for certification – including ISO registration for the manufacturer, independent process and quality control audits and follow-up inspection programs – and a comprehensive schedule of performance requirements and associated test methods.
The U.S. Consumer Product Safety Commission is using ANSI/ISEA 110 as the benchmark in their testing of fire escape masks, stating on their website, “Emergency escape masks have the potential to reduce consumer-related deaths and injuries by assisting in egress from fires, provided they perform effectively and reliably."
The Safety Equipment Institute (SEI) is a private, non-profit organization that administers a non-governmental, third-party certification program and tests and certifies a broad range of safety and protective products used occupationally and recreationally. SEI certification programs are voluntary and available to any manufacturer of safety and protective equipment seeking to have product models certified by SEI.
Mechanical filter respirators
Mechanical filter respirators retain particulate matter when contaminated air is passed through the filter material. This was the method used by early inventors such as Haslett and Tyndall. Wool is still used today as a filter, along with other substances such as plastic, glass, cellulose, and combinations of two or more of these materials. Since the filters cannot be cleaned and reused and therefore have a limited lifespan, cost and disposability are key factors. Single-use, disposable as well as replaceable cartridge models are common.
Mechanical filters remove contaminants from air in the following ways:
- by particles w
Party Kiosk :: Glitter Face Mask with Wig in Black Pink ...
Glitter Face Mask with Wig Plastic face mask with glitter detailing around eyes Mouth remains uncovered These masks come with long wavy hair
Masquerade Masks | Venetian Masquerade Masks | Ball ...
... masquerade masks, Venetian masquerade masks, masquerade ball masks, masquerade party masks ... ball masks - Which we import directly from Venice & include the Volto full face ...
Celebrity Face Masks | partydomain.co.uk
Celebrity Masks | Face Masks of Famous Characters and Celebrities including Politicians, Royalty, Rock Stars, Movie Stars and Famous Faces from the world of TV.
Masks, Face Masks, Eye Masks, Masquerade Masks, Party ...
Huge selection of masks from Face Masks, Eye Masks, Masquerade Masks, Party Masks, Domino Masks, Feather Masks, Masks with Sticks - Partyware from Party Delights, delivered direct ...
Face Masks : Fancy Dress Costumes & Ideas Shop, Outfits ...
Fancy Dress Costumes & Ideas Shop, Outfits, Hire : Face Masks - Fancy Dress Costumes Childrens Fancy Dress Plus Size Fancy Dress St.Patricks Day Shoes & Boots Beards And Moustaches ...
Party Kiosk :: Evil Clown Latex Halloween Face Mask and ...
Evil Clown Latex Halloween Face Mask Fun Halloween face mask of Evil Clown Has curly red yellow hair Holes for eyes nose mouth etc Latex mask
Rock | Movie | TV Star Face Masks | partydomain.co.uk
Celebrity Masks | Dress as your favourite Star with our Celebrity facemasks. Celebrity Fancy Dress made easy with our range of Rock, Movie and TV Celebrity Face Masks.
SillyJokes Halloween Face masks cover just your face ...
Halloween masks for the face, ... Halloween Face Masks. Check out our Halloween Party Guide to help you make the most of spooky event.
Face Masks Party Supplies Online - Face Masks Party ...
, Barack Obama Mask, Kids Iron Man Face Mask - Single, Official Deluxe Danger Mouse Mask - Please order this item 7 - 10 Working Days In Advance., Living Dead Latex Face Mask ...
Party Masks - The party mask is a great way to disguise ...
Cover your face to hide who you are or become spider man for the night! If you want to be original why not paint a white party mask with your own design.