Solutions for Problems Commonly Found By Pump Engineers

Solutions for Problems Commonly Found By Pump Engineers

An essential element in cooling and lubrication systems, hydraulic systems, heating systems, water and …

Solutions for Problems Commonly Found By Pump Engineers

An essential element in cooling and lubrication systems, hydraulic systems, heating systems, water and waste water transfer and treatment and for land drainage, pumps play are important for a wide range of fluid applications. Manufacturing, energy, commercial and municipalities sectors require pumping systems for daily operations. The pumping system requires maintenance and ease of handling for smooth operations.

Improper system design or pump sizing and inefficient pump operation can result in a plethora of problems for pumping systems. These can include wear and tear of pumps, cavitation, and leakage among other problems which call for sufficient skill and experience to be diagnosed and rectified. The conditions that highlight a troubled pump are quite few, and therefore it is important to understand how these work together to cause an underlying pump problem. Pump engineers and operating personnel should pay attention to the frequency of problem occurrence and require excellent observation skills to troubleshoot pump problems.

Here are a few commonly faced pumping problems by pump engineers and operations personnel and easy ways to solve them:

Physical Problems In Pumps

Leakage, valve failures and cracks in pipe supports can cause problems in pumping systems that can affect the efficiency of pumps.

Usually solid pipes or welded joints do not leak unless the pipe has been corroded. Leaks in pumps usually occur at mechanical joints because these undergo wear and tear or loosen over time. It is quite easy to identify such leaks by passing highly pressurized water through the pipes. Common causes of mechanical leakage include thermal strain, sagging pipes and vibrations. Pump engineers can simply repair mechanical joints by either tightening the fasteners or replacing the gaskets incase they are corroded.

Valves are prone to wear and leaks in a similar manner to mechanical joints. Pump engineers need to assess whether valve repairs are needed immediately or not. Considerations such as toxic fluids and steam systems are essential to figure out the need for valve packing repair. Caution must be carried out to prevent over tightening of valve packing because this might result in safety considerations.

Cavitation

When operating personnel or pump engineers notice rattling noises and high vibration levels along with pitting damage to the impeller, it might be as a result of cavitation. Cavitation is basically when the fluid’s pressure falls below the fluid’s vapor pressure at the centre of the impeller. When this happens, the liquid vaporizes and the tiny bubbles collapse fiercely causing a water spray to hit the impeller surfaces hard. This ultimately results in disintegration of the impeller and formation of tiny cavities which reduces the operating life as well as increases wear and tear of the seals and bearings.

Cavitation problems are usually caused by the wrong pump, and operating the system at higher temperatures or lower pressures. Cavitation is a serious problem because it heavily affects pumping system performance. In order to prevent cavitation, materials of high tensile strength can be used for the impeller as they can withstand the high energy bombardments. Bear in mind that whatever material is used for impeller, it should be compatible with system fluid. Moreover, the pumps should be operated at a certain amount of inflow pressure to prevent cavitation.

Packing and Sealing Issues

Leaks can occur at the point at which the shaft is inserted into the pump casing. Usually mechanical seals or packing are used to prevent leaks; the former being expensive and difficult to replace.

Although packing is cheaper and does not require much maintenance, it causes problems of improper installation and over tightening. When packing is being installed, deliberate space is left so that the excessive heat escapes the system which would prevent damages to the shaft. Over time, this packing wears down and it has to be again repacked tightly to bring down that leakage to the desired level. When the packing is improperly installed, excessive leaks can cause high moisture and contamination levels.

If strict sealing is required, mechanical seals can be used. Mechanical seals in pumping systems face deterioration as well as loss of spring. If any waste falls on the surface of the seal, it causes damage. Moreover, a force keeps the seals glued to each other which can be adversely affected by corrosive fluids and fatigue. To prevent this, the mechanical seal is placed as such that the spring movement is minimal.

NSK’s Pump Tough Case Study

Challenge:Increasing life span of pump and decreasing the operational costs.

Solution: NSK invested heavily in research and development and produced a process pump super bearing called the NKS Pump Tough. After thorough analysis and investigations regarding pump applications, NSK decided to use EP steel with advanced UR heat treatment with a high purity ratio. As a result of this material, the life span of bearing was increased significantly even under contaminated conditions.

Moreover, as compared to conventional pump bearing, the life was increased by five times on the tougher bearing of the same size. This means that lesser pump rebuilds and repairs were needed. Furthermore, no major design changes were required in the pump design. The pumping industry thus enjoyed the advantage of lower operating costs and reduced warranty.

NSK has invested much into testing this new piece of technology, the NSK bearing solution for the pumping industry. The Pump Tough is pretty reliable and demonstrates a high level of performance.

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