Service time

The next graph (Figure 10-1) indicates the expected eontinuous running time of rotating equipment with inereasing misalignment. As you soon. see, the alignment improves and so does the service time. 

Oxide, hydroxide and basic salts of aluminum are less soluble at pH values of about 7 than those of zinc [17], which explains the easy passivatability. Galvanic anodes of aluminum alloys are primarily employed in the area of offshore technology. The anodes work in relatively pure seawater flowing with a high velocity so that by using suitable alloys, passivation phenomena are rare. Their low weight is particularly favorable in view of a service time of 20 to 30 years. 

Anodes are designed to last 4 years so that ballast times for (a) are 40% of the service time and for (b) 25%, which corresponds to 146 and 91 days per year, respectively. The shortest filling time should amount to 5 days per ballast journey. Protection current densities are given in Table 17-3. 

It is not known to what extent each of the previous mechanisms contributes to turbine blade degradation during service. It is also probable that each alloy will respond differently to a particular temperature/stress combination. Figure 21-12 shows the typical variation in stress/rupture life determined at 1350°F (375 °C) with service time for forged Inconel X-750 blades. 

Service (times in minutes) 14 Full (Reference 1) Lhl to Lu. (minimum) Reference 2 ) ) Full (Ref- Miscel-erence 3) laneous ... 

Adsorption for gas purification comes under the category of dynamic adsorption. Where a high separation efficiency is required, the adsorption would be stopped when the breakthrough point is reached. The relationship between adsorbate concentration in the gas stream and the solid may be determined experimentally and plotted in the form of isotherms. These are usually determined under static equilibrium conditions but dynamic adsorption conditions operating in gas purification bear little relationship to these results. Isotherms indicate the affinity of the adsorbent for the adsorbate but do not relate the contact time or the amount of adsorbent required to reduce the adsorbate from one concentration to another. Factors which influence the service time of an adsorbent bed include the grain size of the adsorbent depth of adsorbent bed gas velocity temperature of gas and adsorbent pressure of the gas stream concentration of the adsorbates concentration of other gas constituents which may be adsorbed at the same time moisture content of the gas and adsorbent concentration of substances which may polymerize or react with the adsorbent adsorptive capacity of the adsorbent for the adsorbate over the concentration range applicable over the filter or carbon bed efficiency of adsorbate removal required. 

Soufc. No. of failures No. of demands or service time Test interval No. of maintenances No. of dependent failures Failure rate Failures/ demand Repair lime... 

In common parlance, there is no difference between a standby boiler and an idle boiler, but where any distinction is drawn, it usually is based on the out-of-service time involved. Where the shutdown period is short, perhaps 2 to 3 days or less, boilers may be described as on standby whereas idle boilers are shut down for prolonged periods. 

It is a fact of life that the cost of providing water treatment services increases with the size and complexity of boiler plant. This cost may be recovered with larger boiler plants by the higher volumes of chemical treatments sold, as often the chemical selling prices will include an allowance for all the anticipated (and expensive) technical service time requirements. 

For smaller chemical volume consumers, especially those with little in the way of in-house BW treatment technical skills, the overall program costs can be relatively high. This typically is due to the disproportionately high requirement for on-site technical service time (including the travel time to and from a customer s site) compared to the volumes of chemical treatment sold. Travel and on-site time is expensive. Typically, the cost of labor and technical service is two to three times the cost of the chemical raw materials used to provide treatments. 

As a result of the high costs of technical services, most water treatment vendors employ a variety of methods that allows them to charge an economic rate for the programs they sell. They will negotiate a price with the customer based on providing the most suitable balance of on-site service time and chemical/equipment requirements, that anticipates and resolves problems, meets the customers needs, and relieves his or her pain. ... 

The maximum service temperatures depend on the duration of service time and the possible simultaneous application of mechanical stresses. 

Polyamide-imides are appreciated for good mechanical and electrical properties high service temperatures (up to 220°C with possible long service times at 260°C) rigidity good creep behaviour fatigue endurance low shrinkage and moisture uptake inherent flame retardancy chemical resistance usability down to -196°C. 

Exclusive products/services Time-based bottom-up Volume-based bottom-up... 

Figure 17.4 enlarges the breakthrough parts at X<0.1 that is below 10% of the feed. If we choose a given percentage of the feed, we can see that the models foresee different service times. Thus the model choice is of primary importance for calculating service time of cartridges. 

The choice of the appropriate flow rate depends on the wastewater volume to be treated and on the desired service time, and as presented in a following section, on the degree of utilization of the fixed-bed material. 

In upflow operation, a low flow rate could be used, for example, 0.5 BV/h and in this case, as much as 188 m3 of the wastewater could be treated in 157 days. On the other hand, if the bed is operated under the highest flow rate of 6.66 BV/h, the treated volume is 48 m3 and the service time 73 h. It should be noted that in downflow operation the volume that can be treated is between 48 and 72 m3, due to the limits on the relative flow rate, as analyzed in a previous section. 

Low utilization means that at the breakpoint, i.e. when the operation of the bed is stopped, the portion of the solid material in the bed used during the service time is low, which is undesirable. Especially, if the material cannot be regenerated, low utilization means that the unused material is lost. 

However, conventional antioxidants exhibit certain disadvantages, including their inherent volatility and the possibility of being leached by water or organic solvents. If the antioxidants are removed from the polymer during ordinary service time, a serious... 

Several factors will conceivably influence the retention. Not all poisons will be retained to the same extent. Retention of any given element might depend on its amount in the fuel and oil on the composition of fuel and oil on the operation variables of the engine on the design of the exhaust system on temperature, shape, size, position of the catalyst, and the atmosphere to which it is exposed the service time of the system etc. It may, or may not, vary linearly with any of these parameters. 

Hydrocarbon oxidation on base metal catalysts is also susceptible to lead poisoning, especially if the catalysts are exposed to relatively high temperatures, for at least part of their service time. It was noted above that lead retention, especially on base metal catalysts, also increases with temperature up to a certain point. This behavior is shown by the results of Yao and Kummer (81) in Fig. 18. One should note that the hydrocarbon used for testing catalyst activity, namely propylene, was quite reactive. With a less reactive test hydrocarbon one could expect a still sharper effect. The comparison with a reference production noble metal catalyst, given in Fig. 18, is quite instructive. 

Buyers should further understand that in most marketplaces, and for most types of cooling water program sold, the labor and technical services element is a higher cost item than the chemical component. Thus, if the prices charged, or the prices sought, are too low, this may also result in the service company seeking to reduce additional expenditure by cutting down on the provision of service time to site. 

Pricing of cooling water programs by water treatment vendors will almost always take into account the amount of service time expected to be spent on-site during the life of the contract or for each fiscal year for routine analytical inspection and advisory work. 

The cost of the service time charged to the contract varies considerably, depending on the size and nature of the water treatment vendor and the country in which the work takes place. And so it is common for water treatment companies to issue internal instructions to their representatives governing the amount of routine service time that may be spent on a customer s site as a ratio of the cooling water account value. 

Products for small cooling systems tend to become progressively more dilute. This practice is often necessary to ensure adequate profitability at low revenue-generating sites (because smaller sites require proportionately more service time than larger sites, and technical service time is expensive). Also, where only a limited amount of actives is required to be injected per day, the addition of a more dilute product ensures better chemical dosing control and minimizes the risk of under- or overdosing. 

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