There are many advantages of flexible impeller pumps in handling viscous fluids over centrifugal pumps. Martin Ruse, Jabsco's pioneer in flexible impeller technology, discusses the fundamentals of flexible vane pump operation and its many advantages in terms of installation, maintenance and use. Positive displacement pumps such as flexible vane pumps are used as a replacement for centrifugal pumps in many industrial applications. The flexible impeller pump was invented by Jabsco Corporation (now part of the ITT Industries Group for Momentum and Flow Control) about 60 years ago and has the obvious advantage of handling viscous fluids compared to centrifugal pumps. After the impeller turns the eccentric cam, the volume of the cavity per unit decreases. As the cell volume increases through the inlet tube, a partial vacuum is created and the atmosphere forces the fluid into the cavity. As the volume decreases through the outlet tube, the fluid is forced out of the cavity into the outlet tube. The key to flexible viscometer delivery of viscous fluids is that the flow rate is proportional to pump speed. There are two important things to consider here. The first is the friction loss inside the pump itself and the second is the frictional loss between the fluid and the pump inlet wall. Loss of pump friction increases fluid viscosity and results in a drastic drop in centrifugal pump performance. Although viscous friction can be reduced by reducing pump speed, decreasing centrifugal speed can result in a drastic reduction in pump performance, as centrifugal pump performance relies primarily on the speed at which the fluid passes through the impeller. Practical applications of fluid viscosity are limited up to 200-300cP. The flexible impeller pump can reduce the internal friction loss caused by the viscosity by reducing the pump speed. The pump impeller blades can automatically adjust to speed, fluid viscosity and different pressures. How to get fluid into the pump is a major issue when transporting fluids. The pressure drop caused by the friction loss inside the inlet pipe is an important factor that prevents the fluid from entering the pump. To reduce friction losses, the size of the inlet pipe must increase with increasing viscosity. In addition, the inlet pipe should be as short as possible and not be bent. The harder the fluid is, the more difficult it is for the pump to lift the fluid. If the viscosity is too high, a supply tank with an overflow hopper should be installed above the pump position to provide a positive pressure head for the fluid. The Advantages of Installation The main advantage of a flexible impeller pump is that it can be installed in the most convenient locations for some special applications. Unlike centrifugal pumps, they do not have to be limited to the overflow side when installed below the liquid level. They can therefore be installed in a safe place above the ground, thus avoiding the possibility of the pump or pipe being tripped or damaged by the vehicle. Another advantage is the reservoir configuration, which may not have a matching bottom outlet flange or valve if the reservoir (typically a barrel and can) is provided by an outside supplier. Some containers, such as rubber-lined reservoirs, can not open at the bottom; flexible pump can solve this problem by using a simple hose connection at the top of the reservoir. This tank can be installed either on the ground can also be installed under the ground, and do not set overflow inlet. Easy to use for the first time is also an important advantage of a flexible impeller pump, especially if there are unskilled operators during start-up. The start-up and subsequent operation of the flexible impeller pump only requires switching without a complicated start-up procedure. Advantages when Servicing Pumps are carefully arranged to simplify maintenance. The flexible impeller pump is installed above the liquid level to allow for emptying during maintenance, no longer having to be connected to the pipe, or full of fluid in the pump during service, resulting in fluid spillage when the end cap is opened. In contrast, the submersible pump is generally immersed in liquid easily forgotten until failure! Immersed in viscous, repulsive or corrosive liquids when they need to be repaired. It is therefore almost impossible to repair such a sealed pump, at least more than to repair a flexible impeller pump. Factors that affect the self-priming performance of flexible impeller pumps are baffles, air leaks and internal leaks. The normally closed valves and baffles on the outlet side prevent the inlet side from forming a partial vacuum. Leakage of air on the inlet side and internal leakage of the impeller to the inlet side will prevent the formation of a partial vacuum (ensuring that the inlet fittings are sealed). For example, long-term conveyor belt abrasive particles cause severe scraping of the pump body Injury caused by the leak. However, if the impeller is made of rubber, it adapts to the worn pump body shape because the rubber material is not significantly worn and flexible. Therefore, flexible pump impeller than other types of pumps (such as gear pumps) to maintain its long-term self-priming performance and volumetric efficiency must be retained between the rigid parts of a fixed gap. Jabsco's Flexible Impeller Pump Provides Easy Removal of End Caps and Old End Plates When Servicing is Needed. In addition to replace the most worn pump in addition to the impeller can enter the maximum efficiency of the working state. These pumps can also be easily disassembled for cleaning in accordance with the In-Place Cleansing Program (CIP), which is designed to ensure that the cleaning fluid reaches all areas of the pump during cleaning. The actual use case Filling the cake with cream and jam is one of the most viscous materials in practical use. Pumps must be run at 70-100 RPM in order to successfully process them. The cream filling the cake has thick and thin. These types of materials usually require loading pressure plates in the hopper to press them into the pump. A jam of the same viscosity does not require such an aid because its own weight is sufficient to allow it to reach the pump through the inlet tube. A typical application example is to send the jams from the container to the hopper of the filling machine. The filling machine then places the jams on the conveyor belt with the cake and pie, or squeezes a strip directly underneath the filling machine Cake and pie. The hopper is located above the pump delivering the jam. Connect the hopper to the top of the filling machine with a hose and connect the inside of the filling machine. For too viscous jams that can not flow by their own weight, start with a very low pump speed (20 rpm) and then gradually increase until the optimum speed to avoid jam emulsification. The choice of pump speed depends very much on the actual situation and the material delivered. For example, low speed for jams, 500 rpm for syrup, and 1000 rpm for double milk cream. Pumps are both hygienic and easy to clean during batch processing and rotation. Jabsco's 28 Series Hygienic Flexible Impeller Pumps are made of 316 austenitic stainless steel and the impeller is made from a hygienic rubber material that contains EPDM to meet the recent Standard 0209 by the U.S. Sanitary Standards Institute. Flexible impeller pumps also have a number of other features that make them ideal for use in the processing industry. Such as being able to deliver liquid with abrasive properties without damage and delivering fluids containing hard or soft particles without damage.