Insulation Manufacturing Research Articles

DISSOLUTION OF FIBERS INHALED BY RATS

This article provides an analysis and an interpretation of the results of an inhalation study of the durability of several man-made vitreous fiber (MMVF) insulation wool samples in rats. The study was sponsored by the Thermal Insulation Manufacturers Association and was conducted by the Research and Consulting Company in Geneva with fiber size measurements made by Schuller Mountain Technical Center in Denver, CO. In this study, rats were exposed for 5 days to 4 types of airborne, respirable-sized MMVF and to crocidolite asbestos fibers. The MMVF included two compositions of glass wool, and one each of rock and slag wool. After exposure, animals were sacrificed at intervals up to 18 mo, and the number, length, and diameter of a representative sample of fibers in their lungs were measured. These data show that the long fibers (>20 μm) are eliminated from the rats' lungs at a rate that is predicted from the dissolution rate measured in vitro for these fiber compositions. In particular, the long MMVF were nearly completely eliminated in several months, whereas the long crocidolite asbestos fibers remained in significant numbers at the end of the study. The number, length, and diameter distributions of fibers remaining in the rats' lungs agreed well with a computer simulation of fiber clearance. This simulation assumed that the long fibers dissolved at the rate measured for each fiber in vitro, and that the short fibers of every type were removed at the same rate as short crocidolite asbestos. The results are strong evidence that long MMVF are cleared by complete dissolution at the rate measured in vitro and that short fibers do not dissolve but are cleared by macrophage-mediated physical removal.

A Comparison between Actual and Published k-Values for Saudi Insulation Materials

The objective of this technical note is to compare the tested results of the k-values of Saudi manufacturers' insulation materials with the same manufactur ers published values. The test insulation materials include expanded polystyrene, polyurethane, extruded polystyrene, light weight concrete (Siporex), polyiso cyanurate, glass fiber, and perlite from different Saudi manufacturers. The ASTM test for "Steady-State Thermal Transmission Properties by Means of the Guarded-Hot-Plate" (C-177) was utilized for testing the insulation samples. A guarded-hot-plate thermal conductance measuring system was utilized for conduct ing the tests. Insulation material samples from over 14 Saudi insulation manufacturers were ob tained. The results indicate that published thermal conductivity values do not necessarily represent the proper values for Saudi climatic conditions.

Characterization of china Clay Waste and its Utilization in the Manufacture of Tower Packing Materials and Low Tension Insulators

Physico-chemical and mineralogical characteristics of “china clay waste” from a china clay washing plant in Kachchh district in Gujarat State were studied with the object of determining its suitability in the manufacture of low cost industrial ceramic items like tower packing materials and low tension insulators. The results showed that the “china clay waste” was essentially a mixture of kaolin and quartz associated with impurities like haematite, rutile, orthoclase, albite, calcite etc. The study also revealed that the material could be used even up to 50 wt % in complete replacements of both china clay and quartz in the stoneware composition for the development of tower packing materials and low tension insulators. The products developed also conformed to the respective BIS Specifications as required for commercial utilization.

A case-control study of malignant and non-malignant disease among employees of a fiberglass manufacturing facility.

A case-control study was conducted to determine the influence of non-workplace factors on risk of respiratory disease among workers at the Owens-Corning Fiberglas plant in Newark, Ohio. Cases and controls were drawn from a historical cohort mortality study conducted on behalf of the Thermal Insulation Manufacturers Association (TIMA) of workers employed at Newark for at least one year between 1 January 1940 and 31 December 1963 and followed up to the end of 1982. The TIMA study reported a statistically significant increase in respiratory cancer (compared with national death rates). Interviews were completed for 144 lung cancer cases and 299 matching controls and 102 non-malignant respiratory disease cases and 201 matching controls. Unadjusted odds ratios (ORs) were used to assess the association between lung cancer or non-malignant respiratory disease and birthplace, education, income, marital state, smoking with a duration of six months or more, age at which smoking first started, and duration of smoking. Only the smoking variables were statistically significant. For lung cancer, of the variables entered into a conditional logistic regression model, only the smoking OR of 23.4 (95% CI 3.2-172.9) was statistically significant. For non-malignant respiratory disease no variables entered into the final model were statistically significant. Results of the interview portion of our case-control study clearly indicate that smoking is the most important non-workplace factor for risk of lung cancer in this group of workers. Smoking does not seem to play as important a part, however, for non-malignant respiratory disease. Prevalence of cigarette smoking at the Newark plant was estimated for birth cohorts by calendar year. Corresponding data for the United States were compiled from national smoking surveys. Prevalence of cigarette smoking for Newark in 1955 appears to be sufficiently greater than the corresponding United States data in 1955 to suggest that some of the previously reported excess of lung cancer for Newark based on United States mortality may be accounted for by differences in the prevalence of cigarette smoking between white men in Newark and those in the United States as a whole.

Recent studies of man-made vitreous fibers. Chronic animal inhalation studies.

The history of asbestos use and asbestos-related disease is replete with comments that the public health would have been better protected if the results of laboratory investigation, epidemiologic surveys, and clinical studies were made available at appropriate intervals during the ongoing research, rather than in the generally accepted method of awaiting completion of studies prior to reporting medical and scientific findings. No substantive evidence of long-term adverse effects has been published in workers exposed to man-made vitreous fibers. Nevertheless, in an effort to preclude a repetition of this error of omission that occurred with asbestos exposure and use, the Thermal Insulation Manufacturers Association is regularly reporting interim and final data from ongoing animal studies. A significant segment of man-made vitreous fibers have now been tested in state-of-the-art chronic studies. This paper includes the recently completed animal inhalation studies on refractory ceramic fibers and fibrous glass. It also reviews interim data on mineral wool studies.

Manufacture, solar transmission, and heat transfer characteristics of large-celled honeycomb transparent insulation

A method for manufacturing thin-walled (about 20 μm wall thickness), large-celled (about 10 mm hydraulic diameter of cell) honeycomb from FEP plastic is described. The honeycomb manufacturing method uses heat-sealing to join adjacent strips of plastic along thin lines. The honeycomb is sized to be just small enough to suppress convection, but in itself it provides little radiant suppression, so it is intended to be used in conjunction with low emissivity surfaces at one or both of its bounding faces to provide the necessary radiant reduction. In addition to the method for manufacture, measurements of the honeycomb's thermal conductance and solar transmittance are also reported. Mounted adjacent to a face with a thermal emittance of 0.1, a 40 mm deep honeycomb achieved thermal conductance values ranging from 1.4 to 2.4 W/m 2 K when the temperature difference ranged from 10 to 80 K and the mean temperature from 290 to 360 K. At an angle of incidence of 45°, the honeycomb achieved a solar transmittance of 92%.

A case-control study of malignant and non-malignant respiratory disease among employees of a fiberglass manufacturing facility.

A case-control study was conducted to determine the influence of non-workplace factors on risk of respiratory disease among workers at the Owens-Corning Fiberglas plant in Newark, Ohio. Cases and controls were drawn from a historical cohort mortality study conducted on behalf of the Thermal Insulation Manufacturers Association (TIMA) of workers employed at Newark for at least one year between 1 January 1940 and 31 December 1963 and followed up to the end of 1982. The TIMA study reported a statistically significant increase in respiratory cancer (compared with national death rates). Interviews were completed for 144 lung cancer cases and 299 matching controls and 102 non-malignant respiratory disease cases and 201 matching controls. Unadjusted odds ratios (ORs) were used to assess the association between lung cancer or non-malignant respiratory disease and birthplace, education, income, marital state, smoking with a duration of six months or more, age at which smoking first started, and duration of smoking. Only the smoking variables were statistically significant. For lung cancer, of the variables entered into a conditional logistic regression model, only the smoking OR of 23.4 (95% CI 3.2-172.9) was statistically significant. For non-malignant respiratory disease no variables entered into the final model were statistically significant. Results of the interview portion of our case-control study clearly indicate that smoking is the most important non-workplace factor for risk of lung cancer in this group of workers. Smoking does not seem to play as important a part, however, for non-malignant respiratory disease. Prevalence of cigarette smoking at the Newark plant was estimated for birth cohorts by calendar year. Corresponding data for the United States were compiled from national smoking surveys. Prevalence of cigarette smoking for Newark in 1955 appears to be sufficiently greater than the corresponding United States data in 1955 to suggest that some of the previously reported excess of lung cancer for Newark based on United States mortality may be accounted for by differences in the prevalence of cigarette smoking between white men in Newark and those in the United States as a whole.

Old Newspapers: Opportunities and Challenges in Using a Fiber Resource

AbstractNewsprint represents a readily identifiable and valuable fiber source. Although the use of old newspapers fibers to make new newsprint is increasing, this activity must compete with the export market and other established usages like paperboard, insulation and speciality product manufacturing.

Aged Thermal Resistance of Extruded Polystyrene Foams An Approach of a Small, Newer Manufacturer

New plastic foam insulation manufacturers or products encounter the problem that long age thermal performance data cannot be available, such as 5 years old. A method for estimating long-term thermal performance of extruded polystyrene foams based on computer curve fitting against a menu of classic techmcal equations is presented and compared with actual measurements at 5 years after insu lation manufacture. The effect of closed cell content, deviation of the foam from ideal uniformity, and foam density is discussed. The method permits estimation of long age thermal performance using relatively short age measurements without detailed and accurate knowledge of gas permeabilities, foam cell morphology, and deviations from ideal foam uniformity.

Thermal Insulation Manufacturers

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A world‐wide Champion solution

The Champion Sparking Plug company has designed a robot spark‐plug insulator manufacturing cell, of which 50 are now operating in the USA and UK. Brian Rooks went to see the latest UK installation.

Vacuum outgassing rates of plastics and composites for electrical insulators

Vacuum outgassing rates have been measured on several plastics and epoxies, some of which were filled with inorganic materials. The materials examined were chosen as possible candidates for the manufacture of vacuum insulators for large accelerators where good vacuum is a necessity. Generally, all the materials had similar vacuum outgassing rates so that in most applications, the choice of the material would be made after thorough examination and comparison of all the material properties including mechanical strength, ease of manufacture, and electrical breakdown strength in vacuum.

Electrical Insulation Reliability [Dakin's Corner

Most of us who are in the field of electrical insulation research, development, manufacture, or application are probably impressed with the value of what we do; but we may not always recognize the numerous, critical characteristics of our insulation that can adversely affect their reliability in service-and, ultimately, the reliability of the apparatus of which the insulation is a part. This column and some succeeding ones will attempt to point out more important insulation characteristics which, if inadequate, can result in insulation failure. This topic divides itself into two principal categories: 1) Initial insulation characteristics which may be marginal or inadequate to meet the demands of the initial test prior to service or the manufacturing application. 2) Characteristics that develop after aging in service for some period of time. If these characteristics are inadequate and unreliable, they can lead to equipment failure and repairs which could be more costly than the original price of the insulation.

Long-Term Characteristics of Fiber-Reinforced Plastic Under Mechanical Stress and an Acidic Environment

Glass fiber-reinforced plastic (GRP) rods are used in the manufacture of composite insulators for high voltage transmission lines. Should they come in contact with an acid solution their strength can be drastically reduced and the insulator may be unable to perform. Bending and tension tests are used to evaluate the long-term performance of GRP in contact with dilute sulfuric acid. The crack propagation velocity da/dt depends on the stress intensity factor KI. In both bending and tension tests the crack growth velocity is a linear function of KIn where the exponent n = 3.1. In both bending and tension tests, the total fracture time may be separated into an incubation time t1 and a propagation time t2 given by tf = t1 + t2 = (C1/pm) + [C2H( )/pn] where p is applied load, C1, C2, m, and n are constants, and H( ) is a constant that can be calculated from the initial crack length and the critical crack length.

Vibration damage testing of thermal barrier fibrous blanket insulation

GA Technologies is engaged in a long-term, multiphase program to determine the vibration characteristics of thermal barrier components leading to qualification of assemblies for High Temperature Gas-Cooled Reactor (HTGR) service. The phase of primary emphasis described herein is the third in a series of acoustic tests and uses as background the more elemental tests preceding it. Two sizes of thermal barrier coverplates with one fibrous blanket insulation type were tested in an acoustic environment at sound pressure levels up to 160 dB. Three tests were conducted using sinusoidal and random noise for up to 200 h duration at room temperature. Frequent inspections were made to determine the progression of degradation using definition of stages from a prior test program. Initially the insulation surface adjacent to the metallic seal sheets (noise side) assumed a chafed or polished appearance. This was followed by flattening of the as-received pillowed surface. This stage was followed by a depression being formed in the vicinity of the free edge of the coverplate. Next, loose powder from within the blanket and from fiber erosion accumulated in the depression. Prior experience showed that the next stage of deterioration exhibited a consolidation of the powder to form a local crust. In this test series, this last stage generally failed to materialize. Instead, surface holes generated by solid ceramic particulates (commonly referred to as ‘shot’) constituted the stage following powdering. With the exception of some manufacturing-induced anomalies, the final stage, namely, gross fiber breakup, did not occur. It is this last stage that must be prevented for the thermal barrier to maintain its integrity. Most of the damage done to the insulation was caused by small beads of shot that vibrated sufficiently to enlarge holes up several times the particle diameter. None of the holes caused by ‘normal’ shot was sufficiently damaging to render the insulation ineffective. Apparent anomalies in the insulation manufacturing process caused large clusters and layers of shot to be deposited within some blankets. The clusters were potentially damaging to the insulation's thermal performance. Tests were conducted to determine coverplate mode shapes. The frequency of maximum plate response correlated closely with the frequency predicted for the third (umbrella) mode. Considerable variation in the response data was found for both coverplates and the underlying seal sheets.

Current and Potential Uses for Mining and Mineral Processing Wastes in Canada: Standards

Abstract Mining and mineral processing operations in Canada produce about 650 × 106 metric tons of mineral waste annually. This waste is composed of broken rock from open pits and underground mines, coarse mill rejects from screening and heavy media separation processes, and fine mill tailings from screening, magnetic separation, and flotation processes. Most wastes have limited potential for reuse because of their high impurity content or remote location. However, some are favorably located and of interest because of contained metals and minerals or inherent physical and chemical characteristics. Waste utilization is an attractive alternative to disposal because disposal costs and potential pollution problems are reduced or even eliminated and resources are conserved. Waste rock could be used as landfill, in roadbed and dam construction, as railroad ballast, as aggregate in concrete and asphalt mixes, and, for the finer sizes of waste, as construction sand, as an additive to concrete and asphalt mixes, in brick and block manufacture, in the manufacture of thermal insulation, for the recovery of valuable metals or minerals, and as mineral fillers. Examples of the commercial utilization of a number of such wastes are noted.

The importance of lead and cadmium stabilizers to the vinyl compounder

AbstractThe inorganic salts of lead were the first materials proposed for use as vinyl stabilizers, and even though newer families of materials have been developed, lead salts continue to fill an important role in vinyl stabilization. They are irreplaceable in the manufacture of electrical insulation for high‐temperature use and are still considered among the most powerful of stabilizer types. Cadmium organic salts, as part of complex barium‐cadmium‐zinc systems, have proven indispensible in the manufacture of vinyl compounds requiring a combination of outstanding heat and light stability. The move in Detroit towards the manufacture of lighter, more fuel‐efficient automobiles would be difficult without the use of plastics, including some of the more sophisticated vinyl compounds stabilized with barium cadmium‐zinc combinations.

Loft insulation and condensation in roof spaces

A discussion meeting attended by an invited audience of some thirty people was held at the Chartered Institution of Building Services on 15 July 1981. The audience comprised researchers, consulting engineers, architects, insulation manufacturers and contractors and management personnel from both the public and private sectors of housing. The object of the discussion was to ascertain the extent of the problem of condensation in roof spaces of dwellings insulated to higher than traditional standards as evident now, to discuss the mechanisms resulting in condensation and to evaluate possible solutions. In addition, an attempt was to be made to assess the consequences in, say, ten years' time of the trends.

Mineral Wool Production from Copper Reverberatory Slag

Abstract Rapidly increasing energy costs and the introduction of government assistance programmes have stimulated consumer demand for home insulation products in Canada; in recent years, Canadian mineral wool production has increased at an average annual rate of about 20 %. Based on a preliminary economic assessment, which indicated that the manufacture of mineral wool insulation from copper reverberatory furnace slag could be viable ifan acceptable product could be produced using a high percentage of the copper slag in the charge, full-scale tests were conducted at the plant of a major mineral wool producer. The tests were carried out on blowing wool lines equipped with cupola melting furnaces, using charges containing variable amounts of copper reverberatory furnace slag from the Noranda Smelter.The technology of mineral wool production is reviewed, the plant tests are described, and the test results are presented. In all tests, a product fibre with satisfactory physical properties (fibre length, diamet...

Minimum Test Requirements for Non-Ceramic Insulators

This document* combines the experience and expertise of electric power utilities, manufacturers, and research laboratories into a single report that provides minimum test requirements for non-ceramic transmission insulators. The requirements are divided into material tests and insulator design tests that are needed to assess the relative merits of a variety of possible materials and insulator designs. The paper is intended for use by electric power utility engineers and insulator manufacturers to establish minimum material and design specifications for non-ceramic insulators. Insulators failing to meet the minimum test requirements should not be considered for long term use because of unsatisfactory materials, design, or both.