Activity levels

Although a single project manager may direct activities throughout a project life, he or she will normally be supported by a project team whose oomposition should reflect the type of project and the experience levels of both company and contractor personnel. The make up and size of the team may change over the life of a project to match the prevailing activity levels in each particular section of the project. 

Recent experiments (4) have shown that there are no significant age or gender-related differences in thermal environment preference when all other factors such as weight of clothing and activity level are the same. Whereas people often accept thermal environments outside of their comfort range, there is no evidence that they adapt to these other conditions. Their environmental preference does not change. Similarly there is no evidence that there is any seasonal or circadian rhythm influence on a person s thermal preference. 

In research environments where the configuration and activity level of a sample can be made to conform to the desires of the experimenter, it is now possible to measure the energies of many y-rays to 0.01 keV and their emission rates to an uncertainty of about 0.5%. As the measurement conditions vary from the optimum, the uncertainty of the measured value increases. In most cases where the counting rate is high enough to allow collection of sufficient counts in the spectmm, the y-ray energies can stih be deterrnined to about 0.5 keV. If the configuration of the sample is not one for which the detector efficiency has been direcdy measured, however, the uncertainty in the y-ray emission rate may increase to 5 or 10%. 

The guarded hot-plate method can be modified to perform dry and wet heat transfer testing (sweating skin model). Some plates contain simulated sweat glands and use a pumping mechanism to deUver water to the plate surface. Thermal comfort properties that can be deterrnined from this test are do, permeabihty index (/ ), and comfort limits. PermeabiUty index indicates moisture—heat permeabiUty through the fabric on a scale of 0 (completely impermeable) to 1 (completely permeable). This parameter indicates the effect of skin moisture on heat loss. Comfort limits are the predicted metaboHc activity levels that may be sustained while maintaining body thermal comfort in the test environment. 

A fluidi2ed-bed catalytic reactor system developed by C. E. Lummus (323) offers several advantages over fixed-bed systems ia temperature control, heat and mass transfer, and continuity of operation. Higher catalyst activity levels and higher ethylene yields (99% compared to 94—96% with fixed-bed systems) are accompHshed by continuous circulation of catalyst between reactor and regenerator for carbon bum-off and continuous replacement of catalyst through attrition. 

Inert gas is used to blanket certain fixed-roof tanks for safet. Here is how to determine the inert gas requirements. Inert gas is lost in two ways breathing losses from day/night temperature differential, and working losses to displaee changes in active level. 

FIGURE 5.S Clothing imulation necessary for neutral thermal sensation of sedentary persons (I met) In a thermally unifonri still-air envrronment with 50% relative hurnidity. For higher activity levels the temperature at a do level can be reduced about 1.4 °C per met increase. ... 

Optimum comfort would be in the center of each zone. Moving away from the center, some people would be expected to have thermal sensations approaching - 0.5 and -i-0.5 at the cooler and warmer ET borders. The zones of Fig. 5.7b are for sedentary or slightly active ( M 1.2 met) people. If the activity level is higher than that, then the ET" line borders can be shifted about 1.4 K lower per met of increased activity. Similarly, if the clothing is different than the 0.9 and 0.5 do vales of Fig. 5.7a, the temperature boundaries can be decreased about 0.6 K for each 0.1 do increase in clothing insulation. Another, similar way to adjust the comfort zone for both different activity levels and do values is to shift the zone centered on the optimum temperature at... 

The main standards for comfortable thermal environment are ISO EN 7730 and ASHRAE 55-92. The research that forms the basis for these two standards is mainly performed under environmental conditions similar to those for commercial and residential buildings, with activity levels of 1 to 2 met, normal indoor clothing (0.5 to 1.0 do), and a limited range of environmental parameters. 

Aside from the general thermal state of the body, a person may find the thermal environment unacceptable if local influences on the body from asymmetric temperature radiation, draft, vertical air temperature differences, or contact with hot or cold surfaces (floors, machinery, tools, etc.) are experienced. The data for local thermal discomfort is mainly based on studies of people under low activity levels (1.2 met). For higher activities it can be expected that people are less sensitive to local thermal discomfort. The relations between dissatisfaction and local discomfort parameters are found in CR 1752. 

One of the most critical factors is draft. Many people at low activity levels (seated/standing) are very sensitive to air velocities, and therefore draft is a very common cause for occupant complaints in ventilated and air-conditioned spaces. Fluctuations of the air velocity have a significant influence on a person s sensation of draft. The fluctuations may be ex-... 

TABLE 6.9 Required Sweat Rate Index SW q W/m, and Wettedness (w q) as a Function of Clothing, Temperature, Air Speed, and Humidity at an Activity Level M Equal to 70 W/m ... 

The relationship between activity level, operative temperature, and may be calculated with this new method however, it has not been widely used, and little experience is available. Therefore, the method has been proposed in the form of a technical report, w hich in the future may be published as an ISO standard. 

Table 6.18 shows the effect of adding or removing garments on the preferred operative temperature. By individual adaption of clothing it is prrssible to compensate for individual differences in preferred temperature or for differences in activity level. The table is based on ISO EN 7730 and ISO EN 9920. 

Target values for thermal conditions at different design stages must also be considered. One example, for a scenario similar to regular office work, is shown in Table 8.2. The activity level and clothing insulation of the workers must always be taken into consideration when target values are chosen. Different target values other than the ones used in this table could be required, for example, for very cold and very hot and humid environments. 

Demand for worker involvement in every part of the industrial process must be outlined. Then zones of occupancy, the related activity level and clothing, and how that is expected to vary over a typical day and year should be described. 

At a later stage in the design process, when more detailed information is available, the following parameters should be described as a function of time for each worker breathing zone position, activity level, and clothing value. 

One example of how such information can be presented is shown in Table 8.3. Breathing zone location and activity level for one specific worker during a typical workday are listed. 

Time period (h) Accumulated time (h) Work description Breathing zone position Activity level (met) Pulm V. rate (kg/h)... 

Can activity level be adjusted by changing working routines ... 

Pollutant load Room height Heat load Human activity level Common air supply methods Type of process... 

Optimum operative The temperature that satisfies the greatest possible number of people at a given clothing and activity level. 

Activation level install alarm system for indicating valve left open. Observation level provide checklist to operators make valve more accessible or remotely operable. 

Figure 51.1 Typical activity levels during outage...

An activity of 20 picocuries (20 X 10-12 Ci) of radon-222 per liter of air in a house constitutes a health hazard to anyone living there. The half-life of radon-222 is 3.82 days. Calculate the concentration of radon in air (moles per liter) that corresponds to a 20-picocurie activity level. 

Flocculation Where dispersants are present at too high an active level in a boiler (say, when the actives exceed 80-100 ppm or possibly up to 120 ppm), the dispersant may exhibit flocculating properties normally dispersed sludges then settle out on boiler surfaces. 

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