出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/04/09 15:25:11」(JST)
|
A hard hat is a type of helmet predominantly used in workplace environments, such as construction sites, to protect the head from injury by falling objects, impact with other objects, debris, bad weather and electric shock. Inside the helmet is a suspension that spreads the helmet's weight over the top of the head. It also provides a space of approximately 30 mm (1.2 inch) between the helmet's shell and the wearer's head so that if an object strikes the shell, the impact is less likely to be transmitted directly to the skull. Sometimes the helmet shell has a mid-line reinforcement ridge, which strengthens it against impact.
Blue-collar workers, especially union shop construction workers, engaged in occupations that require protective equipment are sometimes metonymically referred to as "hard hats".
A bump cap is a lightweight kind of hard hat with simplified suspension or padding in lieu of suspension and having only a chin strap. It is used where there is a possibility of scraping or bumping one's head on equipment or structure projections, but is not strong enough to absorb large impacts, such as from a tool dropped several stories.
Early on in the ship building industry workers would cover their hats with pitch (tar), and set them in the sun to cure. This was common practice for dock workers who were in constant danger of being hit on the head by objects being dropped from the deck of ships. There were also occasional items falling from the beaks of sea birds, who would pick up just about any item then drop it realizing that the object was inedible.
Management professor Peter Drucker credited writer Franz Kafka with developing the first civilian hard hat when he was employed at the Worker's Accident Insurance Institute for the Kingdom of Bohemia (1912), but this is not supported by any document from his employer.[1]
In the United States, the E.D. Bullard Company was a mining equipment firm in California, created by Edward Dickinson Bullard in 1898, who was in the industrial safety business for 20 years. The company sold protective hats, but they were only made of leather. His son, E. W. Bullard, arrived home from World War I with a steel helmet, which provided him with an idea to improve industrial safety. In 1919 Bullard patented a "Hard-Boiled Hat", made of steamed canvas, glue and black paint. That same year the U.S. Navy commissioned Bullard to create a shipyard protective cap, which began the widespread use of hard hats. Not long after, Bullard developed an internal suspension that would provide a more effective hat. These early designs bore a resemblance to the military M1917 "Brodie" helmet, which served as their inspiration.
In 1933 construction began on the Golden Gate Bridge in San Francisco California.[2] This was the second construction site in history where construction workers were required to wear hard hats (the first being the Hoover Dam project in 1931, as mandated by Six Companies, Inc), by order of Joseph Strauss, the project chief engineer. He wanted the workplace to be as safe as possible; hence, he installed safety nets and required hard hats while on the job site. Strauss also asked Bullard to create a hard hat to protect workers who performed sandblasting. Bullard produced a design that covered the worker's face, provided a window for vision and a supply of fresh air via a hose connected to the air compressor.
Aluminum became a standard for hard hats around 1938, except in electrical applications.
Fiberglass came into use in the 1940s.
Thermoplastics took over in the 1950s, because they were easy to mold and shape with heat and cost less to manufacture. Today, most hard hats are made from high-density polyethylene (HDPE) or advanced engineering resins, such as Ultem.
In 1997 ANSI allowed the development of a ventilated hard hat to keep wearers cooler. To it could be added accessories like face shields, sun visors, earmuffs, and perspiration-absorbing cloths which line the hats. Today, attachments include radios, walkie-talkies, pagers, and cameras.
Because hard hats are intended to protect the wearer's head from impacts where heavy labor is being performed, they are made from durable materials, originally from metal, then fiberglass, and most-commonly (from the 1950s onward) rigid plastic.
Some contemporary cap-style hard hats feature a rolled edge that acts like a rain gutter to channel rainwater to the front, allowing it to drain off the bill, instead of letting the water run down the wearer's neck. A cowboy hard hat is a hard hat shaped like a wide rimmed cowboy hat,[3] although some organizations disallow their use.
Organizations issuing hard hats often include their names and/or logos (or some other message) on the front of each hard hat.
Hard hats may also be fitted with:
Hard hat colors can signify different roles on construction sites. These color designations will vary from company to company and work site to work site. Government agencies, such as the U.S. Navy, and DOT have their own color scheme for hard hats, which they may apply to subcontractors. On very large projects involving a number of companies, it is sometimes the practice for all the employees of a company to wear the same color hat.
Regardless of who decides on a color scheme, the scheme is not always strictly enforced on every project. Older workers will often bring their personal hard hats with them from another project, new workers may buy a hard hat of their own before showing up, and some of the office staff may purchase a hard hat with a custom design. Some companies will insist that the workers take a hard hat of the correct color. Other companies will ignore these variations in order to save money.
The most common color scheme is white for managers, engineers, foremen or supervisors. Derogatory references to "shiny white hard hats" are common on many sites. Other hard hats may be required for a job. Brown fiberglass hard hats are worn by welders, and some other workers because plastic would melt. All other hard hat colors vary significantly by company. Green often signifies a safety inspector, but it is also occasionally used for new workers. General laborers and earthmoving operators often wear yellow. Carpenters, technical advisors, and temps may wear blue. Orange is sometimes used for road crews, new employees, or visitors. Women often purchase pink hard hats to keep other workers from accidentally stealing their hard hat. Some companies also offer loaner hard hats in pink for workers who forget their hard hat. At one time, blasters traditionally wore red.
Supervisors often are not very familiar with all the workers on a construction site. Often, stickers, labels, and markers are used to mark hard hats so that important information can be shared. Note that permanent markers can actually degrade the plastic in hard hats. Label makers or masking tape is often put on a hard hat with the worker's name written on it. Stickers with company logos are very common, especially with smaller companies that send their workers to many larger job sites. Stickers that indicate some of a worker's training or qualifications are also very common. Many companies specialize in ready made stickers to indicate that someone has been trained in electrical safety, confined space safety, excavation trench safety, or how to operate particular pieces of equipment. Environmental monitors often make stickers to indicate that the worker has been educated on the risk of unexploded ordinance, or the archaeological, or biological sensitivity of an area. Some projects have stickers just to indicate who is authorized to be present on the site. Unions also tend to make their presence known by offering free stickers for hard hats and other objects. All of these stickers are of course made in fairly small runs, which tend to get used up before the end of the project, and therefore a new design must usually be ordered to handle new workers who arrived late. With so many possible stickers, a hard hat becomes a sort of informal resume.
A hard hat also gives a worker a distinctive profile, readily identifiable even in peripheral vision, for safety around equipment or traffic. Peripheral vision registers shapes, but not colors. The obvious shape of a hard hat is therefore easier for machine operators to recognize and avoid. Some companies also require reflective tape to be put on hard hats, in order to increase visibility of workers at night.
In 1997, the American National Standards Institute revised its performance Z89.1 standards for hard hats[4] which has been harmonized with the CSA Z94.1 standard. Conformity to these standards and regulation are not necessary but almost all manufactures comply.
Each hard hat is specified by both a Type and Class. The types are:
The classes are:
A Hardhat is specified by both its Type and Class, for example, Class I Type G.[5]
ANSI standards for hard hats set combustibility or flammability criteria. The ANSI Z89 standard was significantly revised in 1986, 1997 and 2003. The current American standard for hard hats is ISEA Z89.1-2009, by the International Safety Equipment Association, which took over publication of the Z89 standard from ANSI. The ISO standard for industrial protective headgear is ISO 3873, first published in 1977.
In the UK, the Personal Protective Equipment (PPE) Regulations 1992 specifies that hard hats are a component of PPE and, by law, all those working on a construction site or within a hazardous environment are required to a wear one[6]
Full-brimmed hard hat
Workman's safety helmet with visor and chinstrap
Hard hat with a helmet light mount
Suspension system inside a typical hard hat
| Wikimedia Commons has media related to Hard hats. |
|
||||||||||||||||||||||||||||||||
全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.
| 関連記事 | 「hard」「HAT」 |