Clean room values

The average air flow velocity, or the average or total air flow volume, for the clean room or clean zone should be within 5% of the value specified for the clean room or clean zone, or within other standardized tolerance limits. 

The instrumental LoDs set forth in Table 3.1 shows that inductively coupled plasma-mass spectrometry (ICP-MS) is the technique that yields the best values. It should be considered that these limits are based on pure solutions analyzed under optimal conditions. Dealing with real foodstuffs will dramatically change the picture, owing to the complexity of the matrices and contamination phenomena in the laboratory. This means that in food laboratories without clean-room facilities (which is the vast majority) the practical difference in LoDs for ET-AAS and ICP-MS will be of minor importance. The relatively poor LoDs for inductively coupled plasma-atomic emission spectrometry (ICP-AES) when compared to those of ET-AAS implies that this technique is not fit for low-level determination of many elements, for example, Cd and Pb. 

In the absence of other guidance governing the cleanliness classification and acceptable levels of microbial contamination of the clean room, the values presented in Table 1 may be used. The room grades presented are from most critical (A) to least critical (E). The definition of criticality is left to the clean-room user organization. 

Particles settle by gravity on to settle plates. Large and heavy particles tend to settle out due to gravitational forces with increasing air movement only the very heaviest particles settle out. This limits the value of the method in laminar flow protected areas or other clean rooms where still air is not intended. Of course it can be argued that dead air is the main coiKcra in clean rooms, and... 

Regarding the workability the common constituents in ambient air are aerosols composed mainly of solid and liquid particulate matter which can cause serious contamination problems at trace and ultra trace levels. The values in Table 5 demonstrate the significance of clean room conditions for precise and accurate determinations at these levels.Thus, for prevention of foreign contamination through Pb, Cu, Zn the clean room technology is a must. ... 

Fig. 17.43 The concentrations of microscopic dust particles in ice cores from Antarctica and Greenland increase sharply at the Holocen-Wisconsinan boundary indicated by a steep decrease of values of the ice. The concentrations of dust particles having diameters greater than 0.6 pm are expressed by the number of particles per 500 pL of water. The concentrations were measured in a class 100 clean room by means of a Coulter counter...

Blanks of the air in a clean-room laboratory or other working area ( room blank ). These are collected in a petri dish of approximately 100 cm area that is left exposed on a surface for 1-2 weeks. Then, U and Pu are recovered with concentrated HNO3, spiked with tracers of 233u Pu, and subjected to bulk analysis by ICP-MS. Typical values in a Class 100/... 

Analysis of pure gases by LEAF is much less developed. Nevertheless, some very impressive results have been demonstrated. Traces of Pb and Tl in the air of a normal laboratory and a class-100 clean room were detected by LEAF. Air from the room was pumped through a tantalum jet, fixed in a hole inside a graphite tube. The heavy particles impacted onto the tube wall opposite the jet. After pumping a certain volume of ambient air in a particular time interval the impacted metal traces were detected by graphite furnace LEAF. LODs of 0.1 pg/m and 0.01 pg/m for Pb and Tl. re.spectively, were achieved. The Pb LOD is two orders of magnitude better than the LOD for graphite furnace AAS. The measured concentrations of Pb and Tl in laboratory air were 1.25 ng/m and 4.3 pg/m , respectively. The same values in clean-room air were about 0.3-0.6 ng/m and 0.9-1.0pg/m. The measured concentrations of the same metals inside a clean... 

The evaluation of detection limits (3s of the mean total blank values see also Chapter 1) for the elements discussed here have been achieved under clean room conditions and been... 

Performance, rather than cost, has been the primary driver for the adoption of COCs into industry. With applications in lenses for laser printers, LCD screens, cell phone cameras, and other high-value products, only a small amount of polymer is required to produce valuable parts. Accordingly, the market can accommodate a relatively high price per pound for these materials. Due to the stringent purity requirements for optical applications, much of the cost associated with COC manufacturing is in contaminant removal and clean room handling. Taken together, the impact of raw material and polymerization costs is relatively small compared to other polymeric materials. 

The detection limits were different for each laboratory and are situated between 10 and 40 Mg/g of nitrogen. In the micro-Kjeldahl method the detection limit is however as low as 1 Mg/g. To obtain accurate results using the Kjeldahl method it proved however to be necessary to control the blank value in a correct way and to avoid contamination from the laboratory environment. It was therefore recommended to determine the blank value with ultra pure aluminium and to carry out the analyses in a clean room with an atmosphere free of ammonia and nitric acid (64). These good results were confirmed in certification analyses carried out within BCR on candidate reference materials for nitrogen in titanium metal and TiA16V4 alloy (Table VI-12). 

The use of FTIR monitoring methods for HAP, VOC, PFC and HFC emissions for identification and quantification in process exhaust and in clean room air, is discussed. A summary is included of the various protocols, test methods and references for the use of FTIR spectroscopy to generate verifiable data. Results of field trials and laboratory study trials are presented, which demonstrate its value as a monitoring method in the semiconductor industry USA... 

Samples constructed from adherends which had been alkaline cleaned, lubricated or left untreated exhibited similar joint strength values and durability trends (Figure 10). Adhesive joints placed in the room temperature control environment or the 23 C water bath retained lOOZ and 92% of initial joint strength, respectively. Failure remained cohesive within the adhesive for all of the control samples and for the first 20 days of exposure in the 23 C water bath. After 20 days, some failure began to initiate at both the primer/steel and primer/topcoat interfaces. The adhesive/topcoat interface proved to be more durable than those found between the substrate/primer/topcoat layers. Samples exposed to the more severe salt fog, 60 C water bath and cycle tests were able to retain 70% to 50% of their initial strength over a 60-day exposure period. 

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