Tag Archives: flow

Tech Tip: Pump Cavitation

Centrifugal pump cavitation can be described as the formation and eventual collapse or implosion of vapor bubbles inside a pump.

A primary cause for cavitation is inadequate net positive suction head available (NPSHa). Poor NPSH leads to lower liquid pressure in the pump and if pressure in the eye of the impeller falls below the vapor pressure of the fluid, then cavitation can begin. When this takes place, the following can occur:

  • Pitting on impeller blades
  • Bearing failure
  • Mechanical seal failure
  • Shaft breakage
  • Poor efficiency

Preventing this type of pump cavitation may require several changes in system design or operations. Increasing pressure at the suction of the pump, decreasing the temperature of the liquid being pumped, and reducing head losses in the pump suction piping can increase the NPSH.

Implosion of vapor bubbles that form within the liquid inside a pump is what causes cavitation. Determining if this abnormal condition is taking place and how to correct will be vital to the longevity of your pump.

Sources: Engineers Edge, Enggcyclopedia

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Pumps & Valves 101

1000709Pumps and valves are the hearts and lungs of a dairy processing plant. They control the flow of fluid milk, cheese curds, ice cream mix, and other dairy products through a facility. Pumps move ingredients from vats to fillers and valves direct liquids to a line and allow for cleaning. Choosing the right equipment for a given application is critical for a plant to lower waste and increase production.

downloadAny pump or valve considered for a processing system should bear a 3-A symbol. 3-A Sanitary Standards Inc. is an independent, non-profit corporation dedicated to advancing hygienic equipment design for the food, beverage, and pharmaceutical industries. The 3-A symbol assures that the equipment is configured and built to exacting sanitary standards.

A well designed pump or valve allows for complete and efficient CIP (Cleaning in Place). The pump or valve would have minimal dead zones, no sharp corners, or other places where product entrapment could occur. Product entrapment may result in cross contamination and loss of product.

Unique Mixproof changed

Along with an easy to clean design, it is important to use proper seal materials and elastomers. Seal materials should be compatible with all product ranges. Choose the seal material that stands up to the most demanding application. EPDM is often the standard elastomer for pumps and valves because the material is resistant to most fluids used in a dairy processing plant. However, high temperatures and product compatibility may require different types, such as Viton, Buna, Silicone, etc….

Proper design coupled with the correct seals and elastomers will allow for an efficient, clean, and productive pump or valve. Here at Nelson-Jameson are in the unique position of offering these products to our customers, and possessing baseline knowledge will help us provide the service they have come to expect. Pumps and valves are critical in the day to day operations of a dairy plant. For more information on pumps and valves, contact our Process Systems Department at 800-826-8302 or see our website.

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Tech Tip: Hose Maintenance

Prevent premature washdown hose wear and failure. Washdown hoses are often subjected to physical abuse while in service. Select a hose that meets or exceeds the application it is intended for. Consider temperature, pressure, and environmental concerns such as abrasion and chemical resistance. Every plant should have a maintenance/inspection plan in place to ensure the longest possible life of the hose.

Be sure to consider these steps in your plan:

  • Store hose properly when not in use.  Hose racks or reels are highly recommended to keep hoses off the floor and out of harms way. Pay attention to humidity, temperature, ozone and sunlight. Storing out of direct sunlight, in a room with moderate humidity and a temperature range of 50 to 75°F is recommended.
  • Always shut off the water supply to the hose when not in use and open the nozzle to relieve the pressure before storing.  Leaving water in the hose subjects it to constant pressure and will shorten the life of the hose.
  • Don’t pull the hose by the nozzle – this puts undo stress on the connection point.
  • Avoid exceeding the hose’s rated bend radius. Kinking of the hose can create weak spots in the hose wall. Consider using hoses with internal springs or kink guards to prevent kinking directly behind the coupler.
  • Never exceed the rated temperature and working pressure of a hose assembly.
  • Routinely inspect hose for wear and damage. Look for external damage – stiffness, discoloration, cuts, cracks, kinks, blisters, excessive abrasion and exposed or broken wires.
  • Regularly inspect fittings.  A hose should be removed from service if any fitting movement or damage is found that could prevent it from operating as intended.

Giving careful consideration to hose selection, care, maintenance and storage can provide optimum return on your investment. For more information contact our Process & Flow Control department at 800-826-8302.

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Tech Tip: Pump Maintenance

Time is critical when equipment goes down. When a pump seal breaks, the pump is frequently opened on the floor and the parts are replaced. Although this practice can work when combined with thorough, regularly scheduled full maintenance programs, the workload can get so large that regular maintenance can slide. And then there are always fires to put out to add to the distractions.

When maintaining a pump, it is critical to remove it from the line and fully disassemble. Check parts for excessive wear and replace all of the parts in the kits. Not only on the wet end, but inspect the motor shaft and motor as well. If the bearings and shaft are not checked, the runout could be out of spec and the hundreds of dollars of new parts that are put in the wet end can be ruined within minutes – not to mention that those parts could end up in the product!

Also be sure to remove all rust from cast iron or carbon steel backplates and pump adapters. The rusting/oxidation process creates swelling that can impact the runout and create the same issues.

We recommend stainless steel pump adapters, as they are available for many pumps and motors, and will not rust.

Call our technical sales department for more information on pump maintenance at 800-826-8302.

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