Million fiber

The market for optical fiber worldwide in 1992 was 2.8 billion corresponding to 10 million fiber kilometers (Mfk) (38). This can be broken down into the U.S. market (3.7 Mfk), the rest of North America (0.4 Mfk), northern Europe (4.1 Mfk), eastern Europe (2.6 Mfk), the Pacific Rim (2.8 Mfk), and elsewhere (0.3 Mfk). Most of the optical fiber is manufactured by only a few companies, the largest of which are AT T and Coming. Other producers include Alcatel, Eujikura, Eurakawa, Northern Telecom, Pirelli, and Sumitomo. The market for optical fibers is projected to reach 3.5 biUion by 1998. In addition, according to ElectroniCast (San Mateo, Ca.), the total market for passive optical components, optical electronics, connectors, and fiber-optic cable is predicted to increase from 1.76 billion (U.S.) in 1992 to over 4 billion in 1997, and 10 billion by 2002. 

Asbestos fiber > 10 micrometer 7 million fibers per liter 7MFL Increased risk of developing benign intestinal polyps Decay of asbestos cement in water mains erosion of natural deposits... 

Hollow fiber membranes are primarily homogeneous. In use, their lower permeability is compensated for by large surface per unit volume of vessel. Fibers are 25-250 pm outside dia, wall thickness 5-50 pm. The cross section of a vessel for reverse osmosis may have 20-35 million fibers/sqft and a surface of 5500-9000 sqft/cuft of vessel. Recently developed hollow fibers for gas permeation processes have anisotropic structures. 

Figure 19.5. The Permasep hollow fiber module for reverse osmosis, (a) Cutaway of a DuPont Permasep hollow fiber membrane module for reverse osmosis a unit 1 ft dia and 7 ft active length contains 15-30 million fibers with a surface area of 50,000-80,000 sqft fibers are 25-250 pm outside dia with wall thickness of 5-50pm (DuPont Co.), (b) The countercurrent flow pattern of a Permasep module.

The results are expressed as million fibers per liter (MFL) or million structures per liter (MSL). 

OSHA PEL TWA 2 milUon fibers/m CL 10 million fibers/m Cancer Hazard ACGIH TLV TWA 0.1 fibers/cc Confirmed Human Carcinogen... 

L/day, this would yield a dose of about 2-200 million fibers per day. 

Million fibers per liter (fibers over 10 micron). 

FLOW PATTERNS IN MEMBRANE SEPARATORS. There are several ways of arranging the surface area in a gas separator, and some of these are illustrated in Fig. 26.5 for hollow-fiber membranes with an external skin. Only a few fibers are shown, and their si2S is greatly exaggerated for clarity. A commercial separator has up to a million fibers in a shell several inches in diameter. The fibers are sealed... 

REGULATORY STATUS MCLG 7 million fibers/L (fibers >10p in length) MCL (7 million fibers/L) HAL (child) none Criterion to protect freshwater aquatic life insufficient data Criterion to protect saltwater aquatic life insufficient data Criterion to protect human health preferably 0 the concentration to keep the lifetime cancer risk level of 1x10 lO , and 10 is 300,000, 30,000, and 3,000 fibers/L respectively a maximum level in drinking water proposed by EPA is 7 million fibers/L Kansas and Minnesota have set guidelines in drinking water... 

Asbestos 7 MX. (million fibers per liter) 7M.L. asbestos products, chlorine, asphalt felts and coating, auto parts, petroleum refining, plastic pipes... 

MFL = million fibers per liter greater than 10 //. in length. (P) = Provisional. 

Asbestos From dissolution of mineral/industrial waste and deterioration of cement water mains DS U 7 million fibers per liter TEM... 

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