Asbestos Pad Research Articles

Experimental analysis of the heat transfer generated during the operation of an automotive disc brake

ABSTRACT This experimental mathematical work aims to analyse the results obtained from the heat transfer of a typical automotive disc brake and thus compare the behaviour of heat dissipation of this mechanical element under different operating conditions. The results demonstrate that the disc brakes can be used effectively in severe operational conditions with a speed of 36 km/h and an ambient temperature of 25°C, without affecting the safety of the occupants or the braking system. The use of semi-metallic pads increases the temperature over the wear track superficial temperature by around 20% more than the asbestos pad, but the material removal during sliding is around ~2.5 times more for the asbestos pad due to the coupling in the tribosystem (pad and disc brake). The heat dissipation in the disc brakes depends on the geometry of the disc, the material from which it is manufactured, the material of the pad, the weight of the vehicle, and the operating conditions, as it could be verified with the mathematical and experimental results, thus validating the contribution of the effectiveness of the braking process during its real operation.

ANALISIS KEAUSAN DAN WAKTU PENGEREMAN KAMPAS CAKRAM ASBESTOS DAN NON ASBESTOS DENGAN VARIASI BEBAN PENGEREMAN DAN BERAT PENGENDARA PADA SEPEDA MOTOR HONDA SUPRA X 125 CC

Brake system is an important thing of vehicle. Many kinds of brake pads presents by each factory. Brake pads made of asbestos and non asbestos material. Each of them have excess and lack. This research aims to know the performance of each type of brake pads so that it can show the excess and lack of each type of product. As user, we have to choose a product which will be used in our vehicle cleverly.The research be done by giving variations in load of brake and weight of rider at a constant speed. The load of brake used spring with the variation are 2 kg, 3 kg and 4kg. While, weight rider are varied with 54 kg and 111 kg.Research result shows that increasing load of pull brake led to increasing the value of worn out and a decline in the braking time, while increasing weight of the rider causes an increase in the value of worn out and braking time at all types of brake pad products. In dry condition, the lowest wear is 1,37x10-4 mm/second in non asbestos pads and the highest wear is 3,088x10-5 mm/second in asbestos pads. While, the smallest braking time is 28,79 seconds in asbestos pads and the biggest is 64,26 seconds in non asbestos pads. In wet condition, the lowest wear is 2,422x10-5 mm/second in asbestos pads and the highest wear is 7,716x10-5mm/second in non asbestos pads. While, the smallest braking time is 29,46 seconds in non asbestos pads and the biggest is 62,71 seconds in asbestos pads.

Conjugate heat transfer analysis of an ultrasonic molten metal treatment system

In piezoceramic ultrasonic devices, the piezoceramic stacks may fail permanently or function improperly if their working temperatures overstep the Curie temperature of the piezoceramic material. While the end of the horn usually serves near the melting point of the molten metal and is enclosed in an airtight chamber, so that it is difficult to experimentally measure the temperature of the transducer and its variation with time, which bring heavy difficulty to the design of the ultrasonic molten metal treatment system. To find a way out, conjugate heat transfer analysis of an ultrasonic molten metal treatment system is performed with coupled fluid and heat transfer finite element method. In modeling of the system, the RNG model and the SIMPLE algorithm are adopted for turbulence and nonlinear coupling between the momentum equation and the energy equation. Forced air cooling as well as natural air cooling is analyzed to compare the difference of temperature evolution. Numerical results show that, after about 350 s of working time, temperatures in the surface of the ceramic stacks in forced air cooling drop about 7 K compared with that in natural cooling. At 240 s, The molten metal surface emits heat radiation with a maximum rate of about 19 036 W/m2, while the heat insulation disc absorbs heat radiation at a maximum rate of about 7922 W/m2, which indicates the effectiveness of heat insulation of the asbestos pad. Transient heat transfer film coefficient and its distribution, which are difficult to be measured experimentally are also obtained through numerical simulation. At 240 s, the heat transfer film coefficient in the surface of the transducer ranges from −17.86 to 20.17 W/(m2 · K). Compared with the trial and error method based on the test, the proposed research provides a more effective way in the design and analysis of the temperature control of the molten metal treatment system.

A Computational Study on the Use of an Aluminium Metal Matrix Composite and Aramid as Alternative Brake Disc and Brake Pad Material

A computational model for the heat generation and dissipation in a disk brake during braking and the following release period has been formulated. The model simulates the braking action by investigating the thermal behaviour occurring on the disc and pad surfaces during this period. A comparative study was made between grey cast iron (GCI), asbestos, Aluminium metal matrix composite (AMC), and aramid as brake pad and disc materials. The braking process and following release period were simulated for four material combinations, GCI disc and Asbestos pad, GCI disc and Aramid pad, AMC disc and Asbestos pad, AMC disc and Aramid pad using COMSOL Multiphysics software. The results show similarity in thermal behaviour at the contact surface for the asbestos and aramid brake pad materials with a temperature difference of 1.8 K after 10 seconds. For the brake disc materials, the thermal behaviour was close, with the highest temperature difference being 9.6 K. The GCI had a peak temperature of 489 K at 1.2 seconds and AMC was 465.5 K but cooling to 406.4 K at 10 seconds, while the GCI was 394.7 K.

Moisture and seed carbonization

In recent years the multidisciplinary approach of modem archeology has involved an increasing number of botanists in the recovery, identification, and interpretation of seeds from archeological excavations. These seeds are frequently carbonized. This is particularly true of tell archeology of the Middle East, where usually the concern is the origin and early development of agriculture. In many reports and discussions that treat this subject, the size of carbonized grains from various sites is used to support species or wild from cultivated form determinations. Also carbonized modem forms have been used as reference collections. Concern about relatively small size differences being given appreciable weight in such diagnosis has led to this study of the effect of moisture percentage at carbonization on the size of carbonized grain. Two lots of 10 seeds each of Triticum dicoccum Schrank., T. manococcum L., T. aestivum L., Hordeum vulgare L., and H. distichon L. were adjusted to 11 and 15 per cent moisture.2 Test seeds were carbonized by heating on an asbestos pad for ten minutes. This is thought to be a rough equivalent to grains accidentally dropped into an open fire by site occupants. It was apparent that the lower moisture percentage resulted in carbonized grains more representative of unaltered grain. Table I shows that in every case the length of the grain was shortened, but at 11 per cent moisture the grains were wider following carbonization whereas at 15 per cent they were narrowed. Although more tests with other moisture percentages and other methods of carbonization could

Particulate material as a prerequisite for rapid cell multiplication in Tetrahymena cultures

1. 1. Tetrahymena pyriformis GL, cultivated axenically in 2 % proteose peptone in slanted test tubes at 28°C, had a population doubling time of more than 40 h when the medium was sterilized by asbestos pad or membrane filtration. Under these conditions the cultures could not be propagated successfully. 2. 2. The doubling time was reduced to 5 h or less when the medium was sterilized in the autoclave instead of by filtration. 3. 3. Various additives improved the growth potential of the sterile-filtered proteose peptone. These included both insoluble materials such as talcum, quartz, clay and calcium carbonate, and water-soluble compounds which through hydrolytic decomposition readily produce insoluble particles in aqueous solution, as, for example, ferrous ammonium sulphate, ferrous sulphate and potassium aluminium sulphate. Other water-soluble compounds such as amino acids, purines, pyrimidines, vitamins and glucose, added either singly or in combination to the sterile-filtered broth, did not significantly improve the rate of cell multiplication. 4. 4. The average number of food vacuoles present in the cells of a culture was observed to be correlated with the growth potential of the medium. 5. 5. On the basis of these observations it is suggested that formation of food vacuoles in Tetrahymena induced by the presence of particulate material is a condition for rapid multiplication of the cells.

Certification of probability of sterilization of liquid by filtration.

Four types of hydrosol filters, two reusable (diatomaceous cylinder and fritted-glass funnel) and two disposable (asbestos pad and membrane filter) were challenged with a heavy bacterial suspension to assess their ability to produce sterile filtrates. Two of the four diatomaceous earth filters, the four fritted-glass funnels, and all of the asbestos pads tested generally gave sterile filtrates. However, only one type of filter, one of the membranes in its manufacturer's own holder, consistently gave sterile filtrates. The two other types of membranes usually gave sterile filtrates if tested in one manufacturer's holder, but all types invariably gave contaminated filtrates when tested in another manufacturer's holder. Contaminated filtrates were generally attributed to a poor reusable filter or to a faulty holder used with a disposable filter. If a high degree of certainty is required for sterile heat-labile filtrate, it is suggested that the liquid be passed through two or more filters in a previously tested and proven system.

Certification of Probability of Sterilization of Liquid by Filtration

Four types of hydrosol filters, two reusable (diatomaceous cylinder and fritted-glass funnel) and two disposable (asbestos pad and membrane filter) were challenged with a heavy bacterial suspension to assess their ability to produce sterile filtrates. Two of the four diatomaceous earth filters, the four fritted-glass funnels, and all of the asbestos pads tested generally gave sterile filtrates. However, only one type of filter, one of the membranes in its manufacturer's own holder, consistently gave sterile filtrates. The two other types of membranes usually gave sterile filtrates if tested in one manufacturer's holder, but all types invariably gave contaminated filtrates when tested in another manufacturer's holder. Contaminated filtrates were generally attributed to a poor reusable filter or to a faulty holder used with a disposable filter. If a high degree of certainty is required for sterile heat-labile filtrate, it is suggested that the liquid be passed through two or more filters in a previously tested and proven system.

Determination of Submicrogram Quantities of Mercury by Cold Vapor Atomic Absorption Photometry

Abstract One gram samples are burned in oxygen in a modified Schöniger flask, and the combustion products are absorbed into 1.2N HCl. After neutralization of this solution to pH 6–7, the mercury is collected as HgS on CdS-impregnated asbestos pads. The pads are pyrolyzed at 650°C, and the vapors are swept by nitrogen gas into a cold vapor atomic absorption cell where the absorption by mercury is measured. Interferences that may absorb are removed by a series of traps before they reach the absorption cell. Mercury recoveries from wheat at levels between 0.01 and 2.00 ppm averaged 86%. Wheat samples treated with organic mercurials as well as untreated samples were analyzed.

INHIBITION OF VIRUS GROWTH BY A TOXIC FACTOR FROM ASBESTOS PAD AND CELLULOSE ACETATE MEMBRANE FILTERS.

Inhibition of Virus Growth by a Toxic Factor from Asbestos Pad and Cellulose Acetate Membrane Filters

TOXICITY OF CELL CULTURE MEDIUM DUE TO FILTRATION THROUGH ASBESTOS PADS.

DURING investigations of tissue culture cells under various conditions of storage, it was observed that the viability of a single cell batch varied when tested with different batches of the same medium. This variation was found to be related to the order in which the medium batch was collected during filtration using standard asbestos pads.

Bacteria-Excluding Filters for Oils

Various unglazed porcelain and diatomaceous earth candles, sintered glass filters, and asbestos pad filters were studied under prolonged contact with corn oil to determine whether or not such filters were effective. Tests of their physical properties and, especially, of their ability to retain bacteria and spores before and after prolonged contact with the corn oil were performed. The results of these tests are presented.

Occupational leucoderma from rubber dust and debris.

OLIVER, Schwartz, and Warren¹were the first to report their observation that leucoderma may occur as a result of occupation. In their patients areas of depigmentation developed after contact with rubber containing the antioxidant monobenzyl ether of hydroquinone. Since then, W. D. McNally²presented a number of similar cases of depigmentation in Negro workers. Peck and Sobotka³discussed in great detail the experimental and physiochemical aspects of this pigmentary disturbance. Spencer⁴later recorded additional cases of leucoderma due to "agarite alba," the trade name of the antioxidant monobenzyl ether of hydroquinone. Recently we have encountered nine cases of leucoderma in white workers who came in contact with dust and debris containing "agarite alba." These workers are machine operators who sew thin rubber strips onto asbestos pads. In the course of this operation a heavy alkaline oily dust is created, which settles down upon the face, hands,

Changes in the Properties of the Coagulase-Reacting Factor of Plasma After Separation from Prothrombin by Seitz Filtration

Summary Successive filtration of plasma through Seitz asbestos pads separates coagulase-reacting factor (C.R.F.) and prothrombin by differential adsorption. Although both substances are adsorbed, repeated filtration essentially eliminates demonstrable prothrombin activity from the filtrate, but allows the recovery of 50% or more of the C.R.F. Seitz filtration of plasma significantly alters the properties of C.R.F. in that it becomes more heat labile, adsorption on alumina is reduced, and precipitation by the Mellanby technique markedly impaired.

LOCAL TREATMENT OF PSORIASIS BY CHOLINE CHLORIDE

Feeding of lecithin in the treatment of psoriasis has been favorably described. Results in a recent controlled hospital study 1 by my colleagues and me justified continued study. In place of lecithin supplied orally over a period, the supposed active fraction, choline chloride, was prepared in pure form and directed into the lesions by iontophoresis. The technical application of the iontophoresis was by procedures in common use, with the positive pole as the active pole and the negative pole as the inactive. Pure choline chloride in powder state was made up to a 1 per cent solution in water, and an asbestos pad 6 by 6 cm. was soaked with the solution at the positive pole. Isotonic solution of sodium chloride was used to moisten the large asbestos negative pole. Areas of equally severe involvement were used, and the upper extremities found entirely suitable in these cases. The maximum

A Study of the Fever-Producing Principle in the Typhoid Vaccine.

Conclusions1. The fever-producing principle in typhoid vaccine and in broth in which B. typhosus has grown for 48 hours is not removed by Berkefeld filtration. The principle is, therefore, not bound to the bacterial bodies.2. The principle is removed by a 200-second Zsigmondy filter and is, therefore, of approximately the same size as the principle previously found in reactive inulin and infusion-fluids.3. Like “pyrogen” found in inulin and in infusion-fluids, it is removed by filtration through asbestos pads of the types of Seitz and Ertel.4. On the basis of the clinical response provoked by intravenous injection, and the filtration characteristics, it is submitted that the fever-producing principle associated with B. typhosus and the “pyrogen” found in infusion-fluids and inulin are closely related substances.