Losses ratings

The amount of energy lost in unit time, the energy-loss frequency, is Vgg = kpN (t). The energy-loss rate coefficient for two-temperature Maxwellian distributions is... 

Vacuum Outgassing and Permeability. Under vacuum, modified ethylene—tetrafluoroethylene copolymers give off Htde gas at elevated temperatures. The loss rate is about one-tenth of the acceptable maximum rates for spacecraft uses. Exposing 750-pm specimens for 24 h at 149°C to a high vacuum results ia a maximum weight loss of 0.12% volatile condensible material is less than 0.02%. 

Dielectric Strength. Dielectric failure may be thermal or dismptive. In thermal breakdown, appHed voltage heats the sample and thus lowers its electrical resistance. The lower resistance causes still greater heating and a vicious circle, leading to dielectric failure, occurs. However, if appHed voltage is below a critical value, a stabilized condition may exist where heat iaput rate equals heat loss rate. In dismptive dielectric failure, the sample temperature does not iacrease. This type of failure is usually associated with voids and defects ia the materials. 

Each of the endoscopic imaging procedures is relatively risk free and painless when performed by competent and weU-trained individuals using a local anesthetic. Eetoscopy has the highest risk. There is a 10% increased probabiUty of premature deUvery and 10% higher fetal loss rate. 

Fig. 3. Time dependence per unit of area for a silica—gel, where the shaded area represents an opaque ministage (a) loss rate (b) absolute loss rate and (c)...

Much effort has been made by catalyst manufacturers to improve catalyst atttition resistance and thus reduce the formation of fines (see Catalysts, supported). In the 10-year petiod from 1980 to 1990, most catalyst manufacturers improved the atttition resistance of their catalyst by a factor of at least 3—4. This improvement was achieved even though the catalyst zeoHte content duting this petiod was continually increasing, a factor that makes achieving catalyst hardness more difficult. As an example of the type of atttition improvement that has been achieved, the catalyst atttition index, which is directiy related to catalyst loss rate in a laboratory attrition test, decreased from 1.0 to 0.35 for one constant catalyst grade during 1989—1990 (37). 

The protection potential can be evaluated kinetically for such cases [10,21]. It is assumed that the concentration of metal ions on the metal surface is Cq. The weight loss rate follows from the first law of diffusion ... 

Protection potentials are usually determined experimentally because of the possibilities of error. Figure 2-9 shows experimental results for the potential dependence of weight loss rates for carbon steel [29,30]. Four curves are plotted at 25°C for the following media ... 

Figure 2-11 shows weight loss rate-potential curves for aluminum in neutral saline solution under cathodic protection [36,39]. Aluminum and its alloys are passive in neutral waters but can suffer pitting corrosion in the presence of chloride ions which can be prevented by cathodic protection [10, 40-42]. In alkaline media which arise by cathodic polarization according to Eq. (2-19), the passivating oxide films are soluble ... 

Anodes for boilers can be tested by such methods. Good-quality magnesium anodes have a mass loss rate per unit area < 30 g m d", corresponding to a current yield of >18% under galvanostatic anode loading of 50 /xA cm" in 10 M NaCl at 60°C. In 10 M NaCl at 60°C, the potential should not be more positive than t/jj = -0.9 V for the same polarization conditions [27],... 

Six iron anodes are required for corrosion protection of each condenser, each weighing 13 kg. Every outflow chamber contains 14 titanium rod anodes, with a platinum coating 5 /tm thick and weighing 0.73 g. The mass loss rate for the anodes is 10 kg A a for Fe (see Table 7-1) and 10 mg A a for Pt (see Table 7-3). A protection current density of 0.1 A m is assumed for the coated condenser surfaces and 1 A m for the copper alloy tubes. This corresponds to a protection current of 27 A. An automatic potential-control transformer-rectifier with a capacity of 125 A/10 V is installed for each main condenser. Potential control and monitoring are provided by fixed zinc reference electrodes. Figure 21-2 shows the anode arrangement in the inlet chamber [9]. 

Power switch. The power switeh is going to be a P-ehannel power MOSFET. The maximum input voltage is 18VDC. Therefore, a Loss rating of -I-30VDC or higher will be satisfaetory. The peak eurrent is 2.8 A. It is also desired to keep the heat dissipation less than 1 watt so the estimated RDS(on) should be less than ... 

FIRAC is a computer code designed to estimate radioactive and chemical source-terms as.sociaied with a fire and predict fire-induced flows and thermal and material transport within facilities, especially transport through a ventilation system. It includes a fire compartment module based on the FIRIN computer code, which calculates fuel mass loss rates and energy generation rates within the fire compartment. A second fire module, FIRAC2, based on the CFAST computer code, is in the code to model fire growth and smoke transport in multicompartment stmetures. 

For distribution transformers, a voluntary standard assembled by the trade association NEMA (National Electrical Manufacturers Association) achieves substantial savings, particularly in standby energy, with a payback period typically of three years. The loss rate from the transformers is small, but the throughput of electricity accounts for a large fraction of total energy use in buildings, particularly when utility-owned transformers are considered. 

This method can also be used to calculate the catalyst retention factor. The above equations assume steady-state operation, constant unit inventory, and constant addition and loss rate. 

Soil resistivity The role of soil in the electrical circuitry of corrosion is now apparent. Thus the conductivity of the soil represents an important parameter. Soil resistivity has probably been more widely used than any other test procedure. Opinions of experts vary somewhat as to the actual values in terms of ohm centimetres which relate to metal-loss rates. The extended study of the US Bureau of Standards presents a mass of data with soil-resistivity values given. A weakness of the resistivity procedure is that it neither indicates variations in aeration and pH of the soil, nor microbial activity in terms of coating deterioration or corrosion under anaerobic conditions. Furthermore, as shown by Costanzo rainfall fluctuations markedly affect readings. Despite its short comings, however, this procedure represents a valuable survey method. Scott points out the value of multiple data and the statistical nature of the resistivity readings as related to corrosion rates (see also Chapter 10). 

Steel thickness. Loss rate (mm/year) (average minimum and maximum rates)... 

Attenuation zone (decreasing loss rate to a steady-state value). 

Steady-state zone (loss rate at a constant value). 

Batteries with a high operating temperature, of about 300 °C, require high-efficiency insulating jackets to maintain the temperature within an acceptable range. Especially in non operating periods, the battery should not cool down. It was requested that batteries should keep their operating temperature window for at lest four days. This requires heat loss rates of less than 200 W for a 40 kWh battery. 

When moisture loss was to be determined, each packet was weighed initially and at intervals of 2-4 weeks through the holding time. Moisture loss rates were calculated on the basis of grams/100 sq. in./24 hours (excluding the first 24 hours which constitutes a packaging material conditioning time). 

Mustard. Mustard has been packaged in PVDC-coated cellophane/ polyethylene pouch material which was recognized to have a 3-6 month shelf life. In this case, the moisture loss rate was diminished by using the PVDC-coated cellophane. The main drawback of this package was the moisture loss, since the flavor was not markedly changed by the oxygen traces allowed by the PVDC cellophane coating. 

In low pressure flames, however, the situation is less clear cut (9). For example, in stoichiometric acetylene-oxygen flames at 1.0 torr (T = 2500°K.) the value of k required to explain the experimental data can be calculated by equating the rate of OH - formation at the steady state to the appropriate loss rate, which must include diffusion ... 

The total energy-loss rate dEjdx can be expressed as ... 

The hydrodynamic forces acting on the suspended colloids determine the rate of cake buildup and therefore the fluid loss rate. A simple model has been proposed in literature [907] that predicts a power law relationship between the filtration rate and the shear stress at the cake surface. The model shows that the cake formed will be inhomogeneous with smaller and smaller particles being deposited as the filtration proceeds. An equilibrium cake thickness is achieved when no particles small enough to be deposited are available in the suspension. The cake thickness as a function of time can be computed from the model. 

During the first period, the slurry flow is eroding the filter-cake as it is growing thus a steady state, in which the filtration occurs through a cake of constant thickness, is rapidly reached. At the same time, because the slurry is losing water but no solid particles, its density is increasing in line with the fluid loss rate. 

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