Coupled design

Various coupling designs are available to transmit torque from the driver, eg, electric motor, to a pump. In order to contain the pumped fluid inside the pump and prevent the pumpage from leaking, several types of sealing methods are used. A few options are described herein. 

Kramer, K., New Coupling Applications or Applications of New Coupling Designs, Proceedings of the 2nd Turbomachinery Symposium, Texas A M University, pp. 103-115, October 1973. 

McCormick. Doug, Finding the Right Flexible Coupling, Design Enyi-neering, October 1981, pp. 61-66. 

It is impossible to specify a completely foolproof coupling, particularly by manufacturer and model number. Still, in the interest of reliability, the specification should cover the subject of couplings. This requires the use of plant feedback and a lot of research on the part of the specification writer to determine the latest developments in coupling design. Unfortunately, when a vendor furnishes a coupling, it often becomes just another outside purchased item that he may purchase with a minimum specification and strictly on low price. 

The rules for potential nucleobases have become better defined by synthetic biologists.27 It is appropriate to couple design to experimental and theoretical considerations related to heterocycles that might be generated under prebiotic conditions. NASA should place high priority on Earth-based experiments that define what heterocycles might have been formed, especially in cometary bodies and on early Earth. 

The independence axiom asserts that all FRs and their associated DPs remain independently attached therefore, if you adjust a DP to satisfy an FR, you do this without affecting other FRs. Designs that don t satisfy the independence axiom are called coupled. Designs that do satisfy the independence axiom are called uncoupled or decoupled. 

EXHIBIT 31.2 A coupled design is one in which all functional requirennents cannot be achieved independently by adjusting design paranneters without affecting other functional requirements. 

A decoupled design is preferred over a coupled design. Looking at Exhibit 31.3, we see two simple FRs and DPs in a pulley-and-belt design for using the power generated from a car s crankshaft to run its air conditioner. The belt cannot slip sideways (FRl) and cannot slip forward or backward (FR2) as the system operates. In a decoupled design, both FRl and FR2 are influenced by... 

An uncoupled design is preferred over a decoupled or coupled design. Looking at Exhibit 31.4, we see two FRs and two DPs involved in a faucet design, where the flow rate valve (DPI) influences water flow (FRl), and the hot/cold mixing valve (D2) influences water temperature (FR2). The DPl/FRl combination is totally uncoupled from the DP2/FR2 combination, thereby ensuring that each FR/DP combination can stand alone. 

Thermally coupled design 1 and 2 should be considered as alternatives to two-column design, if less than half of the feed is middle product. 

Fig. 3 Bathroom faucets, getting the right flow rate (FRI) and temperature (FR2) coupled design left) and uncoupled design (right)...

Coupling due to insufficient number of DPs When the number of DPs is less than that of FRs, a coupled design is resulted always. To avoid this, the number of FRs should be equal to the number of DPs. 

Functionally coupled design to make a physical integration Many designers often misunderstand the Independence Axiom by confusing functional independence with physical independence. The physical integration is desirable as long as their functional requirements are independent and uncoupled. 

LRVPs in closed coupled design with variable pressure ports for covering the entire pressure ranging from approximately 40 to 1013 mbar represent at present the most frequently used design with new installations due to their good price-performance ratio. But even these vacuum pumps do not meet all the requirements. Thus, deposits in the dead spaces and drUHngs as well as defects of the valves ofthe variable pressure ports rank among the most frequent causes of failure. 

Figure 3.21 Section of a two-stage vacuum pump in closed coupled design.

Best suited for these applications are optimised two-stage LRVPs in closed coupled design. They combine the advantages of the traditional two-stage vacuum pumps with those of the closed coupled machines and set new standards with regard to noise emission as well as in the price—performance ratio (Figures 3.20-3.22). 

Many spectroscopists have contributed to the analysis of Pd I. The first regularities in that spectrum were recognized by Kayser [5], Snyder [6], and Paulson [7]. With the aid of the Zeeman effect, Beals identified all the low even levels [1]. The analysis was extended by Bechert and Catalan [8], McLennan and Smith [9], and mainly by Shenstone [2, 10] (see Tables 2/7 and 2/8, pp. 166/7) who assigned LS designations to most levels. Jl-coupling designations are also given in [11]. 

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