Pumps, problems

For many plants handling monomers and other hazardous materials, sealless pumps are the first choice. They can practically eliminate the pump problems that can occur due to se leaks, which can include product loss, flammabihty, waste disposal, and exposure of personnel to hazardous vapors. 

In a plant with a shaft-driven boiler feedwater pump, problems had historically occurred with failure of the bearing in the hydraulic coupling. There was no apparent cause, but throughout the 12-year life of the equipment, the failure occurred about once every 1 or 2 years and resulted in an outage of about 5 weeks. 

Pump problems vary over a large range depending on the type of pumps and the usage of the pumps. They can be classified in the following manner by the pump type and the service ... 

Positive-displacement pumps—reciprocating pumps problems can be classified into the following categories ... 

Pumping Problems with Residual Fuel and Marine Fuel Oils... 

Any time residual fuel or marine fuel pumping problems occur, the first place to begin looking for the source of the problem would be the viscosity of the fuel. Pumps are designed and rated to move fluids within a fixed viscosity range. When a fluid s viscosity is either above or below the recommended viscosity range, pumping problems will eventually result. 

Contamination of fuel with high-viscosity products or operation at excessively low temperatures can increase the viscosity of fuel and result in fuel pumping problems. Also, if diesel fuel viscosity at 0°F (-17.8°C) is greater than 45 cSt, fuel pumping problems are likely to occur. 

S. Yedidiah, Centrifugal Pump Problems, Petroleum Publishing, Tulsa, OK, 1980. 

Typically, organic antiscalents supplied for RO applications are 35% w/v active materials and dosed at 2.5 to 6 ppm chemical product (dependent on the composition of the source water analysis). Some chemical products are available at up to 50% w/v activity, but they require a proportionally lower dose rate. Higher strength chemicals are often extremely viscous, which may present pumping problems. 

Results obtained from the dynamic pulsed pumping problems will be compared to the optimum continuous pumping (M=l) policy, given the same period of active pumping (1260 days). This formulation does not, however, constrain the total time period of remediation, tR. Note that from a strict... 

I have had many people threaten to return whole HPLC systems because of bad pumps or bad detectors, who were simply suffering from dirty columns. It s always the detector first and then the pump that gets blamed. And, the poor service people who are hardware oriented, as they usually are, will make multiple trips without finding the problem. I encourage service people to carry a Ci8 column, used only with standards, and a vial containing four-standard mix in their service bag. The first thing they should do is remove the customer s column and run the four standards on their column. It s very embarrassing when the detector or pump problems go away, but it saves the company or the customer a lot of money. 

Solutions to these puzzling pump problems may help you to resolve some of the difficulties that you encounter with pumps. 

Yedidiah, S., Centrifugal Pump Problems, Causes and Cures. Penn-Well Book Co., Tulsa, Okla., 1980. 

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