Dowels

The earliest ball and stick models were exactly that wooden balls in which holes were drilled to ac commodate dowels that connected the atoms Plastic versions including relatively inexpensive student sets became available in the 1960s and proved to be a valuable learning aid Precisely scaled stainless steel framework and plastic space filling models although relatively expensive were standard equipment in most research laboratories... 

Process Hazard Analysis (PHA) (Dowell, 1994, pp. 30-34.) The OSHA rule for Process Safety Management (PSM) of Highly Toxic Hazardous Chemicals, 29 CFR 1910.119, part (e), reqmres an initial PHA and an update every five years for processes that handle listed chemicals or contain over 10,000 lb (4356 kg) of flammable material. The PHA must be done by a team, must include employees such as operators and mechanics, and must have at least one person skilled in the methodology employed. Suggested methodologies from Process Safety Management are listed in Table 26-1. 

Documentation is important. Everything considered should be documented. If it is not documented, then you didn t do it. (Dowell, 1994, pp. 30-34.) The key to PHA documentation is to do it right away before it gets cold. Periodic follow-up is needed by management and safety professionals to confirm that all recommendations have been addressed. 

Inspect gasket surfaces for knots and irregularities. Look for bent dowel pins and misaligned jack bolts, dirt and any other factor that might lead to misalignment. 

The bearing housings and supports required extensive repair. All of the housing bores were pounded out, partieularly the bearing bores, whieh were pounded out up to one-quarter ineh. Ninety pereent of the threaded fasteners had been ripped out of their respeetive threaded holes and the dowel holes were all oval. The sealing steam ehamber of tlie bearing support was ripped away from the main support struemre. 

Expander-compressor shafts are preferably designed to operate below the first lateral critical speed and torsional resonance. A flame-plated band of aluminum alloy or similarly suitable material is generally applied to the shaft in the area sensed by the vibration probes to preclude erroneous electrical runout readings. This technique has been used on hundreds of expanders, steam turbines, and other turbomachines with complete success. Unless integral with the shaft, expander wheels (disks) are often attached to the shaft on a special tapered profile, with dowel-type keys and keyways. The latter design attempts to avoid the stress concentrations occasionally associated with splines and conventional keyways. It also reduces the cost of manufacture. When used, wheels are sometimes secured to the tapered ends of the shaft by a common center stretch rod which is pre-stressed during assembly. This results in a constant preload on each wheel to ensure proper contact between wheels and shaft at the anticipated extremes of temperature and speed. 

The horizontally split types have easings split horizontally at the mid-seetion and the top. The bottom halves are bolted and doweled together as shown in Figure 6-45. This design type is preferred for large multistage units. 

Pin or dowel used to eject molded articles from a mold. 

Dowel Pin that maintains alignment between the various sections of a... 

Carrithers, G. W., A. M. Dowell, and D. C. Hendershot (1996). It s Never Too Late for Inherent Safety. International Conference and Workshop on Process Safety Management and Inherently Safer Processes, October 8-11,1996, Orlando, PL, New York American Institute of Chemical Engineers. 

Green, D. L., and A. M. Dowell (1996). Cookbook Safety Shutdown System Design. i996 Process Plant Safety Symposium, Volume 1, April 1-2,1996, Houston, TX, ed. H. Cullingford, 552-565. Houston, TX South Texas Section of the American Institute of Chemical Engineers. 

Arthur M. Dowell, III (Co-Chair), Rohm and Haas Texas Inc. 

A. M. Dowell, Regulations Build a System or Add Layers , presented at the AIChE... 

Figure 4-391. Cementing of large-diameter casing with and inner drillpipe string. (Courtesy Dowell Schlumberger.)...

Two-plug method is a rather new method and requires the use of the telltale catcher sub (Dowell Schlumberger) to set a cement plug in a well at a rather precise location with minimum contamination. The tell-tale catcher sub is made up to the lower end of a drillpipe string. The sub also has an aluminum tail pipe, a bottom wiper plug (which carries a dart) and a top wiper plug. The sub on the drillpipe is lowered to the depth desired for... 

KEITH McHENRY Chairman), Amoco Oil Company LESLIE BURRIS, Argonne National Laboratory ELTON J. CAIRNS, Lawrence Berkeley Laboratory NOEL JARRETT, Alcoa Laboratories FREDERIC LEDER, Dowell Schlnmberger JOHN SHINN, Chevron Research Company REUEL SHINNAR, City College of New York PAUL B. WEISZ, University of Peimsylvania... 

A lattice model of uniaxial smectics, formed by molecules with flexible tails, was recently suggested by Dowell [29]. It was shown that differences in the steric (hard-repulsive) packing of rigid cores and flexible tails - as a function of tail chain flexibility - can stabilize different types of smectic A phases. These results explain the fact that virtually all molecules that form smectic phases (with only a few exceptions [la, 4]) have one or more flexible tail chains. Furthermore, as the chain tails are shortened, the smectic phase disappears, replaced by the nematic phase (Fig. 1). 

Winter J, LH Moore, VR Dowell, VD Bokkenheuser (1989) C-ring cleavage of flavonoids by human intestinal bacteria. Appl Environ Microbiol 55 1203-1208. 

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