This, however, is a misconception and can lead to severe issues in a hydraulic system unless the effects of viscosity are well understood, and the system designer properly communicates the information to the pump engineers. Select a pump model above the intersection (3). Nevertheless, avoiding cavitation is crucial to reliable fluid delivery. With that said, the published correction charts that will be discussed momentarily indicate centrifugal pump material handling applications where the fluid viscosity may range upward to 3,300 centistokes. Obviously, if there is changing viscosity in the application the PD pump is the best choice. To properly analyze brake horsepower, you must look at work horsepower versus viscous horsepower. Simple ingenious design coupled with precision Swiss manufacturing makes the DPP Precision Series pumps the most accurate in their class. As can be seen from the charts, viscosity has a major impact on the centrifugals performance. Found inside – Page 374... Pump effciencyð%Þ If a viscosity correction is required: Fig 7.7.14 Pump performance positive displacement vs. dynamic lube oil application A comparison ... Maintaining pump capacity at various viscosities requires meeting horsepower minimums, as shown in Fig. Low viscosity products (i.e. In some cases-as in the case of Reciprocation Pumps- NPSH is expressed as a pressure increment Δ P above the vapour pressure of the liquid. How Positive Displacement Pumps Handle Viscosity, U.S. Oil & Gas, Wasted Money & Strategies to Address Global Warming, Using Piston-Actuated Diaphragm Pumps in Mine Dewatering, Data Science as a Way to Extract Value From the Industrial Internet, 8 Tips States Can Borrow From Northern Neighbors for Future Storms, Peristaltic Hose Pump Technology in Precious Metal Mining, Unlock System Efficiency With Clean Power VFDs, Troubleshooting Fault in Stator of Rewound Motor, In-depth articles on pump industry issues, Expert insights into important topics in the field. Next is a description of a diagnostic experiment conducted to acquire a matrix of vibration . Locate the product viscosity on the horizontal axis (1). 1. The Hydraulic Institute (HI) is the global authority on pumps and pumping systems.HI is a pump association of positive displacement and rotodynamic, centrifugal pump manufacturers and suppliers whose mission is to be a value-adding resource to member companies, engineering consulting firms, and pump users worldwide. It is therefore essential that one is aware of how the fluid viscosity affects both the system (such as properly sizing tubes) and the pump. This can lead to cavitation and excess vibration. 4. The Hydraulic Institute (HI) is the global authority on pumps and pumping is a pump association of positive displacement and rotodynamic, centrifugal pump manufacturers and suppliers whose mission is to be a value-adding resource to member companies, engineering consulting firms, and pump users worldwide. The amount of slip in a PD pump is affected by the system discharge pressure requirement and the fluid viscosity. Positive displacement pumps move fixed volumes of fluid mechanically through a system. Resonance is never an easy problem to deal with—in particular, structural resonance. Simple ingenious design coupled Swiss manufacturing makes DPP gear pumps the most accurate, long-life continuous flow pumps available on the market. Found inside – Page 2638.2.5.2 Viscosity Viscosity is the measure of a material's resistance to flow . ... With positive - displacement pumps , most adjustments are to the speed ... QL Series - Positive displacement pumps QL Series Model QL15 Where: p = pressure (psi or bar) v = viscosity correction factor (from graph) n = speed (RPM) c = displacement (G/rev. Found inside – Page 5The technique for extracting the shear viscosity as a function of shear ... Alternatively, positive displacement pump systems allow the flow rates to be ... The Acrotec Group is a team of entrepreneurs and talents with a single ambition: to continuously push the boundaries of precision micromechanics and everything associated with it. Positive displacement pumps are all affected by internal leakage. Net Positive Suction Head Available (NPSHa), is determined by the process piping. 2.1.3.1 Positive displacement pumps. Static Lift is the height the water will rise before arriving at the suction side of the pump. Self-priming horizontal centrifugal pumps are available, but they are special-purpose pumps and not normally used with irrigation systems. The viscosity of shear-sensitive substances through a process line does change, however. 3. This allows the manufacturer to record detailed performance data at different operating conditions to develop a data set at this known viscosity. But with such a large variety of pumps, motors, and applications, picking the right pump can be difficult.That's where we come in!CSI is known as the experts in the specification, sizing, and supplying of pumping technology for hygienic industry processes. Interested in working with us?Send an email to jobs@dpp.swiss. They deliver a nearly constant volume of liquid over a range of discharge pressures. Viscosity correction curve When selecting an air operated double diaphragm pump one needs to pay attention to the viscosity of the fluid being pumped. Centrifugal Pump Water. 1. VHP is sometimes called internal horsepower. or L/rev from table below) x x x 1000 x (English units) Total Power (HP) = (.0007 x p + .0051 v) n c (Metric units) Total Power (Kw) = (2 p + v) n c A Guide to Choosing the Right Pump for Hygienic Applications. A positive displacement pump decreases the volume containing the liquid until the resulting liquid pressure equals the pressure in the discharge system. Turbulent flow is dependent on density much more than viscosity and is not worth considering in this article. The following comparison shows the difference in density between water and corn syrup in kilograms per cubic meter: Shear-sensitive liquids change viscosity when under stress, such as when they are hit by an impeller inside a pump. Its positive displacement principles ensure that it The Blagdon range of Air Operated Double Diaphragm Pumps is well suited to pumping viscous fluids. Friction Loss (or Head Loss) are the losses due to friction in the pipe at a given flow rate. Viscosity Viscosity is a measurement of a product's resistance to flow. Dynamic viscosity is a measure of a fluid’s resistance to flow. In Fig. Work horsepower (WHP) is the horsepower required for the selected PD pump to achieve the desired flow rate considering the anticipated pressure drop from system components. Realization of complex assembly machines of microcomponents, Roch MΓ©canique de prΓ©cision : Machining of small and medium series focused on the aeronautics industry, Tectri : CNC turning for the micromotor sector, Vardeco : High-speed bar turning of electronic components. How these pumps are able to operate at higher efficiencies and pressures. © Copyright Cahaba Media Group, Inc. All Rights Reserved. Low flow may lead to reduced output in a crude oil pipeline, which translates into lower throughput per day, and ultimately a financial loss. Thinking in terms of system efficiency instead of device efficiency offers opportunities. Determine the intersection between the flow rate and product viscosity (3). The viscosity of the product must be always taken into consideration for the design and selection of the pump type. This can have a major impact on the pump, the system or both. Static Height is the maximum height reached by the pipe on the discharge side of the pump). All the experience of the research team from one of the world's foremost pump manufacturers - Sulzer, featuring the lastest in pump design and construction. A PD pump produces the same flow at a given speed (in revolutions per minute--RPM) no matter what the discharge pressure. Found inside – Page 440( iv ) Using the water head figure and the corrected ( oil ) head figure ... With positive displacement pumps , viscosity effects are more specific . A positive displacement pump has a phenomenon known as "slip", which is the recirculation of the pumped fluid from the discharge side of the pump back to the suction side of the pump. Low viscosity products (i.e. QL Series - Positive displacement pumps QL Series Model QL15 Where: p = pressure (psi or bar) v = viscosity correction factor (from graph) n = speed (RPM) c = displacement (G/rev. Whether the specific fluid properties are proprietary, variable or just not known, this information must be determined and relayed to the manufacturer to ensure provision of a pump that will perform as desired in the specific application. An example would be trying to stir a bowl of water vs. trying to stir a bowl of honey. With changes in viscosity and pressure, slip correction indicates that flow capacity drops from a high of about 7 GPM to a low of about 3.5 GPM. It is important to check the Reynolds number is less than 2320 to ensure it is laminar. DPP is a member of the Acrotec Group, For a user to ensure that they will receive a pump that will perform as desired in their application, specific detail on viscosity is critical. 2700 N Partnership Blvd For pumps, this term generally relates to sealless canned motor pump (CMP) or magnetic drive pump (MDP) types. or L/rev from table below) x x x 1000 x (English units) Total Power (HP) = (.0007 x p + .0051 v) n c (Metric units) Total Power (Kw) = (2 p + v) n c Found inside – Page 333This data was prepared by using the viscosity correction graphs shown in Figures ... In rotary positive displacement pumps the increase in viscosity reduces ... 2, a positive displacement pump curve shows the influence of viscosity on slip with a correction chart. It is key to positive pump sizing and operation because it affects slip within the pump as well as the pressure required to over- In a lubricating system, the consequences of lower flow than . With fluid sampling and calibration, along with temperature measurements, the viscosity of this test fluid is known. Timothy Jones is a senior design engineer at CIRCOR. Call 08048605685 85 . With changes in viscosity and pressure, slip correction indicates that flow capacity drops from a high of about 7 GPM to a low of about 3.5 GPM. In some states, such as Minnesota, you have no choice; water-lubricated pumps are required in all new irrigation wells. Once viscosity is over 1000 cPs, slip basically doesn’t occur in liquid sanitary pumps. Thus the higher the viscosity, the less sensitive the displacement will be to pressure differential. Found inside – Page 55This is usually accomplished using a positive displacement pump ... this purpose are reciprocating piston-type pumps for low to medium viscosity products or ... Because PD pumps generate flow to transport relatively high viscosity fluids, PD pump selection requires analysis of three key influences on fluid transfer: The fluid’s dynamic viscosity, density, and response to shear. 4. Fluid can flow between thin gaps, between sliding components or through micro-gaps in internal seals. The flow rate is constant. The viscosity of water changes 3x over the same temperature range. Determine the intersection between the flow rate and product viscosity (3). Found inside – Page 13For positive - displacement pumps , protection against excessive pump pressure must be ... Based on the Viscous Liquid Performance Correction Chart from the ... One of the widely accepted methods used in determining a fluid’s viscosity is ASTM D445: Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids. Found insideThe book covers plant layout and the use of spreadsheet programs and key drawings produced by professional engineers as aids to design; subjects that are usually learned on the job rather than in education. This book tackles all these aspects in a readable manner, drawing on the authors' long experience of lecturing and writing on centrifugal pumps for industrial audiences. Continuing with the ketchup processing example, the next section discusses additional important information on pump curves: work horsepower (WHP), viscous horsepower (VHP), and Net Positive Suction Head required (NPSHr). Higher viscosity fluids are less prone to flow through internal gaps. Once viscosity is over 1000 cPs, slip basically doesn't occur in liquid sanitary pumps. Found inside – Page 196Fixed speed positive displacement compressors and pumps are the easiest. ... correction (non-dimensional) Kv = viscous correction (non-dimensional) p = set ... Illustrates, the lower the speed of a PD pump, the lower the NPSHr. Learn what can happen when you get viscosity calculations wrong. Found inside – Page 3-263 - Liquid Handling E Viscosity Correction For Centrifugal Pump Performance 1.1 ... Since diaphragm pumps are positive displacement , the effect of TDH and ... However the viscosity of the fluid Found inside – Page 432The resultant time measurement is directly proportional to the viscosity of the ... As illustrated in Figure 60i, a positive displacement pump (other flow ... Fluid can flow between thin gaps, between sliding components or through micro-gaps in internal seals. water) have little resistance to flow, while higher viscosity products have a greater resistance to flow. 27AAIHA8443B1ZJ. Found inside – Page 183Very little information is available to predict the effect of viscosity on ... pump for the application, or whether a positive displacement pump should be ... It may not be evident from the raw test data how the pump will perform in a specific application, but this information can then be corrected to user conditions, including the user’s fluid viscosity, and operating speeds and pressures. Recall the required RPM was a result of flow required coupled with slip correction, if any. head of liquid. These paths can create the same affect as the external pressure drops discussed in the previous section. It must be noted that extremely viscous fluid handling applications are best left to positive displacement, rather than centrifugal pumps. A positive displacement pump has a phenomenon known as "slip", which is the recirculation of the pumped fluid from the discharge side of the pump back to the suction side of the pump. It is always important to discuss the details of the application with the pump engineering team to ensure there are no unintended consequences. In some cases-as in the case of Reciprocation Pumps- NPSH is expressed as a pressure increment Δ P above the vapour pressure of the liquid. A positive displacement pump designed or selected for a fluid where the viscosity is lower than predicted will produce less flow than expected. The viscosity of a fluid is a key element in sizing and developing any pump, and the effects of viscosity on a positive displacement pump are much different than those on a centrifugal pump. A positive displacement pump decreases the volume containing the liquid until the resulting liquid pressure equals the pressure in the discharge system. Figure 2 Viscosity correction chart (source: Hydraulic Institute, www.pumps.org). The flow rate is constant. On the other hand, a pump that is selected for a fluid where viscosity is higher than predicted could also have negative impacts on a system. Common shear-sensitive substances include ketchup, shampoos, and polymers; as shear increases during ketchup processing, ketchup’s viscosity decreases. With that said, the published correction charts that will be discussed momentarily indicate centrifugal pump material handling applications where the fluid viscosity may range upward to 3,300 centistokes. The Hydraulic Institute (HI) is the global authority on pumps and pumping systems.HI is a pump association of positive displacement and rotodynamic, centrifugal pump manufacturers and suppliers whose mission is to be a value-adding resource to member companies, engineering consulting firms, and pump users worldwide. As a volumetric fluid handling technology, two- and three-screw rotary positive displacement pumps create flow and are insensitive to system pressure changes. Head is defined as the height to which a pump can raise water straight up. The groups strong technical expertise combined with the vertical integration of many production processes offers a qualitative and competitive service to our partners. We measure internal resistance to flow as absolute viscosity (also referred to as dynamic viscosity). More information can be found at www.csidesigns.com. 4. Optimize plant asset safety and reliability while minimizing operating costs with this invaluable guide to the engineering, operation and maintenance of rotating equipment Based upon his multi-volume Rotating Equipment Handbooks, ... PLEASE NOTE: This correction formula should be used as a guide only as there is no proven empirical formula for double diaphragm pumps viz a viz viscosity correction. 3. Positive displacement (PD) pump technologies vary, as do the curves for these pumps.
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