Viscosity performance curve

Example 3-17 Corrected Performance Curves for Viscosity Effect... 

Unless specifically identified otherwise, the BHP values read from a manufacturers performance curve represent the power only for handling a fluid of viscosity about the same as water and a specific gravity the same as water, i.e., SpGr = LG. To obtain actual horsepower for liquids of specific gravity other than 1.0, the curve values must be multiplied by the gravity referenced to water. Viscosity corrections are discussed in another section. Good design must allow for variations in these physical properties. 

The vendor shall provide eomplete performance curves, ineluding differential head, typieal efficieney, water NPSHR, and power expressed as funetions of capacity. The curves shall be extended to at least 120 percent of capacity at peak efficiency, and the rated operating point shall be indicated. The head curve for maximum and minimum impeller diameters shall be ineluded. The eye area of the first-stage impeller and the impeller identification number shall be shown on the curves. If applieable, the curves shall indicate viscosity corrections. Minimum flow (both thermal and stable), preferred and allowable operating regions, and any limitations of operation shall be indicated. 

Standard k-s Simplest model to represent variation of turbulence length and velocity scales Robust and economical Excellent performance for many industrial flows The most widely validated model More expensive than zero equation models Assumes isotropic eddy viscosity Performs poorly for — some unconfined flows — rotating flows — non-circular ducts — curved boundary layers... 

Most SRIM resins have several characteristics in common their liquid reactants have room-temperature viscosity below 200 cps their viscosity-cure curves are sigmoidal in shape, the typical mold-fill time being 10-90 sec and their demold time is from 60 to 180 sec, varying with catalyst concentration. The low viscosity of SRIM resins and their relatively long fill times are crucial in allowing them to penetrate and flow through their reinforcing performs. 

Engineering factors include (a) contaminant characteristics such as physical and chemical properties - concentration, particulate shape, size distribution, chemical reactivity, corrosivity, abrasiveness, and toxicity (b) gas stream characteristics such as volume flow rate, dust loading, temperature, pressure, humidity, composition, viscosity, density, reactivity, combustibility, corrosivity, and toxicity and (c) design and performance characteristics of the control system such as pressure drop, reliability, dependability, compliance with utility and maintenance requirements, and temperature limitations, as well as size, weight, and fractional efficiency curves for particulates and mass transfer or contaminant destruction capability for gases or vapors. 

When a pump performance is defined for water, the corrected performance for a viscous fluid can be developed using Figure 3-56 or 3-57. In order to develop the curves for viscosity conditions of 100 SSU or 1,000 SSU as shown in Figure 3-58, the following general procedure is used [17]. 

Effects of performance changes, 201-203 Head curve for single pump, 198 Relations between head, horsepower, capacity and speed, 200 Temperature rise 207-209 Viscosity corrections, 203-207 Purging, flare stack systems, 535 Reciprocating pumps, 215—219 Flow patterns, 219 Specification form, 219 Relief areas, 437 External fires, 451, 453 Sizing, 434, 436... 

Studies of flow-induced coalescence are possible with the methods described here. Effects of flow conditions and emulsion properties, such as shear rate, initial droplet size, viscosity and type of surfactant can be investigated in detail. Recently developed, fast (3-10 s) [82, 83] PFG NMR methods of measuring droplet size distributions have provided nearly real-time droplet distribution curves during evolving flows such as emulsification [83], Studies of other destabilization mechanisms in emulsions such as creaming and flocculation can also be performed. 

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