Document omdpx1Z60pwkExdL08vBoBvQw

Unfortunately, a knowledge of surface temperature is in itself not sufficient to predict the relative safe ty or hazard of human contact with a heated surface. It is well known, for example, that a metal surface is more likely to cause bums through its heat flow than a plastic surface, though both are of the same elevated temperature. Therefore there has been a need for a definitive instrument to mea sure and indicate the temperature that would be experienced by some one in contact with a heated sur face. Louis A. Marzetta, an electronics engineer with the National Bureau of Standards has recently developed such a device, called a "theimesthesiometer," which consists of a cylin drical measuring probe similar to a human finger. The probe is con nected to an electronic unit that gives a digital reading of the contact temperature in degrees C. The end of the probe, designed to be pressed against the heated test surface, is made of silicone robber; this materia! is resilient, as is human tissue; and its thermal properties also are close to those of human tis sue. A heated wire, wound around an inner core tube keeps the probe as sembly at 33 C--the temperature of a finger, and a resistance thermom eter transducer inside the core tube acts as the heat sensor. Obviously, damage to tissue from a heated surface is a function not only of the surface temperature, but also the length of time the tissue is in contact with the surface. To duplicate this time factor, the thermesthesiometer contains an adjust able circuit that allows measure ments for contact periods of 1, 2, 4, or S seconds. The measuring time is started automatically upon thermal contact, and "frozen*' at the interval end. Although no instrument maker, as yet, manufactures the thermesthesiometer, NBS officials report, a mar ket potential exists for it This mar ket should develop quickly if the unit is used by the Consumer Prod uct Safety Commission as a basis for safety criteria and regulation. keeping a sharp lookout on vinyl chloride South Norwalk, Conn.--Six months ago the New Year entered with a host of problems--most of which were expected. But one parti cular problem not only was unex pected, hut was deadly also. In January, officials at B.F. Good rich Chemical Co.'s Louisville, Ky. plant reported that four workers had died of an extremely rare liver cancer, angiosarcoma. All had been involved in the plant's main activity: converting vinyl chloride monomer to polyvinyl chloride--the industrial chemical widely used in plastic pipes, floor tiles, phonograph re cords, and countless other products. Then, in February, the company lost two more workers, again from angiosarcoma, bringing the total to six. Previously, the nationwide occurance was thought to be less than 30 cases a year. Thus, such regulatory agencies as the National Institute of Occupa tional Safety & Health (NIOSH) and the Occupational Safety & Health Administration (OSHA) quickly rushed into the picture. POINTING OUT A HEW WAY TO IMPROVE CUkN SAFETY finger-like temperature instrument puts blame on faulty designs as did the employes' unions, and many of the 23 U.S. VCM/PVC manufacturers, who employ some 6,500 persons at 37 plants. Much of the resulting debate cen tered around the limits set for safety. The previous level had been 500 ppm vinyl chloride in the atmos phere. Union officials urged an im mediate 95% emergency reduction to 50 ppm. Several firms, however, argued that more time should be taken to investigate the problem and that controls should be set by ordi nary (and sometimes lengthy) role making procedures. Nonetheless, under strong union pressure, NIOSH urged the Labor Dept, to quickly issue rules requir ing a "closed system" for VCM manufacture and processing, envi ronment monitoring around VCM/ PVC plants, as well as periodic em ploye medical tests. These proposals, however, included no mention of safe exposure limits.______________ Terre Haute, Ind.--A tank car con taining the controversial chemical vinyl chloride overturned here last March 17, allowing vapors to es cape through a 15 x 31-cm open ing. The tank car, owned by the Pennsylvania Central Railroad, was lined with lead wool and "Neo prene," and it was thought that none ol the liquid escaped. Nevertheless, residents were evacuated over a 15-block area as a "precautionary" measure, reports the Smithsonaln institution Center for Short-Lived Phenomena (Cam bridge, Mass.). The residents were allowed to return to their homes the following day. To their credit, B. F. Goodrich voluntarily limited their safe level to less than 50 ppm, as did several other manufacturers. (As of this writing, laboratory mice and rats have developed angiosarcoma from breathing VCM vapors in varying amounts from 200 to 2,500 ppm, but not yet at 50 ppm. Dr. Cesare Maltoni of the Instituto Di Oncologia, Bologna, Italy, is concentrating now on that 50-ppm level in MCAsponsored tests.) Not all firms were as concerned as B. F. Goodrich and others, who voluntarily limited exposure levels. In a March 1974 survey of five VCM and two PVC plants in the New Orleans-Baton Rouge, La., area, OSHA judged control measures to be "inadequate," and that actual exposure to the chemicals was gen erally unknown. Finally, in mid-April, OSHA pub lished in the Federal Register an emergency temporary ceiling of 50 R&S 104456 T* J 47INDUSTRIAL RESEARCH--JUNE 1174 mmm\ i ! <** R&S 104457 ppm affecting all companies making the monomer or polymerizing it And the permanent standard, it has been rumored, may be set as low as X ppm. To measure the actual concentra tion, NIOSH has reportedly urged OSHA to require usage of a gas chromatograph coupled with a sam ple-collecting tube. Industry spokes men, however, have criticized that method as being expensive and not providing real-time analysis. There are other techniques, it should be noted, that may be better suited for VCM monitoring. One of these is. infrared spectroscopy. Officials at Wilks Scientific Co. 1 Says Sinclair, "A major strength of the IR method is that, should there be interference from extran eous chemicals (such as Freon-113, which interferes slightly at 13.9 am), it would still be safe to do the analysis. Concentrations in excess of the ceiling limit will always give ab sorbances above the limit value, and once the contaminant is known, it is relatively easy to subtract its spec trum." Infrared gas spectroscopy is suit able, for area (atmosphere) surveys, leak detection, and general VCM compliance testing. In addition there are systems available to monitor 6, 12, 24, or more remote points, such as the MIRAN II, which can handle samples from distances approaching 80 meters (200 ft). !v . 'n L COSMOLOGY life on Mars may be underground McMubdo Station, Antartica-- A recent discovery that 10,000-year old frozen bacteria can be thawed 4 out and revived may have important implications in the search for life on Mars. This conclusion is based on re search performed by a U.S.-JapanNew Zealand drilling team studying the frozen continent's geologic his tory. The team members, being con- L cemed about the fragile antartic en>4 vironment, routinely made checks CLOSE WATCH ON VINYL CHLORIDE , no microorganisms from the infrared gas analyzer detects at 1 ppm 1 drilling team ended up in the rocks, 1 Biologists in the project took samples here discussed with Industrial Re- \ of deep rock cores drilled up, and search how typical low-level VCM I added them to nutrient solutions de monitoring can be handled with IR 1 signed to encourage bacteria growth, techniques. Says Terry F. Sinclair, I A solution prepared with rocks "Vinyl chloride concentrations less I drilled from a 120-meter depth here than 100 ppm con be analyzed l showed obvious signs of bacterial easily using our 'MIRAN I' Portable \ life. Frank Morelli of the Jet Pro- Gas Analyzer. This is a single-beam pulsion Laboratory (Pasadena, Cal.) spectrometer' equipped with a and the Darwin Research Institute unique variable-pathlength gas cell. The vinyl chloride absorption bands of Dana Point, Cal., initially sus pected that the bacteria represented at 6,15, 9.8, 10.9, and 13.9 Mm are the type of contamination that pro considered in quantitative analysis, ject scientists were trying to avoid. and minimum detectable concentra However, checks made of micro tions are usually found to be less organisms around the drilling site than 1 ppm." and laboratory showed the cultured The choice of bands depends bacteria from the deep cores were upon other chemicals present, as not from these sources. some 20 different chemicals are com Morelli then ran four extra checks monly found in VCM use or proces on the cores, each time producing sing. Thus, if the environment con the same unidentified bacteria. tains ethylene, Freon-11, perchloro- Then, deeper cores from the same ethylene, and vinylidine chloride, in site produced slightly different addition to vinyl chloride, the 13.9 jacteria strains--also unidentified-- Mm band will be found free from interference. and cores collected by Morelli's colleague, Roy Cameron, from another site 98-km away produced cultured bacteria colonies that act ually reproduced. The two scientists were thus forced to conclude that the bacteria were native to the cores, which are dated geologically as being be tween 10,000 and 1,000,000 years old. Plainly, the microorgan isms had survived in a freeze-dried form in the rocks all these years, and had then been revived by warmth and the nutrient solution. Among the factors that kept the bacteria alive for thousands of years longer than any creatures previously identified, suggests Cameron, were their small size and high concentra tion, and the low temperature of the ice-pocked antartic rocks. Cameron and Morelli point out that their discovery has important implications in the search for life on other planets, especially Mars, which in some ways resembles Antartica. If the Viking mission, designed to land instruments on the red planet in 1976, fails to detect life on the surface, Cameron notes, scientists may well speculate that "the surface permafrost of that planet may hold the key to ancient--and living--biota deep within it," MATERIALS depositing a cheap, superhard coating Los Angeles--A new material has been discovered that is second in hardness only to diamond--and it can be produced relatively easily and cheaply. The superhard material is made of titanium carbide, formed in thin layers through vapor deposition. De scribed as "easily the most startling material development in recent years," the new titanium carbide material promises to have a wide range of uses in cutting, grinding, and wear-resistant applications. Dr. Rointan F. Bunshah, inventor of the material and a UCLA engi neering professor, believes that ti tanium carbide can be produced at one-hundredth to one-thousandth the cost of various commercial grades of synthetic diamonds. In the forming process, titanium metal atoms are vaporized by an electric beam in a vacuum chamber. A hydrocarbon gas is then injected into the chamber and the reaction forms titanium carbide. The newly-formed vapor is then condensed and deposited at desired rates and degrees of hardness. De- Ctrel* 14T on InqUtly laid-if dlal-for-aata (trae): 800/621-0560 W INDUSTRIAL RESEARCH--JUNE 1ST4