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Questions and Answers
What is the median popliteal height for American men?
What is the median popliteal height for American men?
- 15.0 inches
- 16.3 inches (correct)
- 17.0 inches
- 18.0 inches
What type of chair is specified by ISO 6875?
What type of chair is specified by ISO 6875?
- Office chairs
- Dining chairs
- Plastic lawn chairs
- Dental chairs (correct)
What is the purpose of armrests on chairs?
What is the purpose of armrests on chairs?
- To make entry and exit from the chair easier (correct)
- To reduce the load on the occupant's back muscles
- To provide back and head support
- To provide padding
What is the purpose of footrests on chairs?
What is the purpose of footrests on chairs?
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What is the purpose of the BIFMA standard ANSI/BIFMA X5.1?
What is the purpose of the BIFMA standard ANSI/BIFMA X5.1?
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Study Notes
- The chair has been used since antiquity, although for many centuries it was a symbolic article of state and dignity rather than an article for ordinary use.
- Until the 16th century, people sat on chests, benches, and stools, which were the ordinary seats of everyday life.
- The chair was in existence since at least the Early Dynastic Period of Egypt (c. 3100 BC).
- It was not until the 16th century that chairs became common.
- In Europe, it was owing in great measure to the Renaissance that the chair ceased to be a privilege of state and became a standard item of furniture for anyone who could afford to buy it.
- Once the idea of privilege faded the chair speedily came into general use.
- The chair began to change every few years to reflect the fashions of the day.
- Chairs can be made from a variety of materials, including wood, metal, and other strong materials.
- Chairs can have hard surfaces of wood, metal, plastic, or other materials, or some or all of these hard surfaces may be covered with upholstery or padding.
- The design may be made of porous materials, or be drilled with holes for decoration; a low back or gaps can provide ventilation.
- Chairs can also be made from more creative materials, such as recycled materials like cutlery and wooden play bricks, pencils, plumbing tubes, rope, corrugated cardboard, and PVC pipe.
- In rare cases, chairs are made out of unusual materials, especially as a form of art or experimentation.
- Seat height can be adjusted to help distribute the weight of the occupant to various parts of the body.
- Foot rests are common, and around 15% of women and 2% of men need them.
- Chairs can be purchased in a variety of sizes and styles, and can be used for a variety of purposes.
- Chair design is based on measurements of the human body or anthropometric measurements.
- The two most relevant anthropometric measurement for chair design are the popliteal height and buttock popliteal length.
- For someone seated, the popliteal height is the distance from the underside of the foot to the underside of the thigh at the knees.
- The term "sitting height" is reserved for the height to the top of the head when seated.
- For American men, the median popliteal height is 16.3 inches (41Â cm) and for American women it is 15.0 inches (38Â cm).
- The popliteal height, after adjusting for heels, clothing and other issues, is used to determine the height of the chair seat.
- Mass-produced chairs are typically 17 inches (43Â cm) high.
- Researchers such as Mary Blade and Galen Cranz found that sitting on the edge of a high stool with feet on the floor is less harmful for the lower back than sitting up straight on a conventional chair.
- Reclining angle
- Different types of chairs can have a variety of seating positions, depending on the intended task.
- Chairs intended for people completing work or dining can only recline very slightly (otherwise the occupant is too far away from the desk or table).
- Dental chairs are necessarily reclined.
- In order to recline, the back-rest may be independently adjustable.
- A reclining seat and back will reduce the load on the occupant's back muscles.
- Back and head support
- Padding
- Armrests
- Seat size and legroom
- Armrests further have the function of making entry and exit from the chair easier (but from the side it becomes more difficult).
- ISO 9241 specifies the requirements for chairs used in offices.
- Dental chairs are specified by ISO 6875.
- Bean bag chairs are specified by ANSI standard ASTM F1912-98.
- ISO 7174 specifies stability of rocking and tilting chairs.
- ASTM F1858-98 specifies plastic lawn chairs.
- ASTM E1822-02b defines the combustibility of chairs when they are stacked.
- BIFMA defines ANSI/BIFMA X5.1 for testing commercial-grade chairs.
- Large institutions will reference these standards within their own detailed criteria for purchase.
- Governments will often make bulk purchases of chairs that meet these standards.
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