Pump Operation Safety

Operation of equipment away from its design point can produce stresses that lead to premature failure. Pumps are a good example. Many are able to operate well above design flow if the discharge head is reduced. This can happen when a pump is transferred to a new duty. The result often is surging and vibration. 

Use of a pump at a flow rate below design may seem innocuous. However, the resulting internal recirculation induces hydraulic vibrations. These have 

Operation of a pump with the discharge shut off forces all the frictional heat into a small volmne of liquid and can raise its temperature to dangerous levels. Note that provision of a minimmn-flow bypass around the pump may not prevent this situation if the fluid is returned directly to the suction of the pump. 

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The technique of the filtration of hot solutions has already been described in Section 11,28. The filtration of cold solutions will now be considered this operation is usually carried out when it is desired to separate a crystalline solid from the mother liquor in which it is suspended. When substantial quantities of a solid are to be handled, a Buchner funnel of convenient size is employed. The ordinary Buchner fimnel (Fig. 11,1, 7, a) consists of a cylindrical porcelain funnel carrying a fixed, flat, perforated porcelain plate. It is fitted by means of a rubber stopper or a good cork into the neck of a thick-walled filtering flask (also termed filter flask, Buchner flask or suction flask) (Fig. 11,1, 7, c), which is connected by means of thick-walled rubber tubing (rubber pressure tubing) to a similar flask or safety bottle, and the latter is attached by rubber pressure tubing to a filter pump the safety bottle or trap is essential since a sudden fall in water pressure may result in the water sucking back. The use of suction renders rapid filtration possihle... 

Clean up in such a way tliat the hazardous material is removed and does not produce a future danger. It may be necessary to pump out a hazardous liquid or to remove contaminated soil, etc. Decontamination procedures may be necessaiy. See EPA s Standard Operating Safety Guides for instructions for decontamination required following exposure to different danger levels of liazmds... 

New systems or processes may also need to be qualified from an operational safety perspective. This is particularly relevant in the case of chemical synthesis involving exothermic reactions. Critical safety aspects are usually identified using hazard operability or HAZOP assessments and studies. For example, a HAZOP analysis of an exothermic reaction vessel would involve consideration of the consequence of failure of the motors for mixers or circulation pumps for cooling water. Thus, the qualification of such a system would involve checks and assessment to ensure that the system/process can be operated safely and that pressure relief valves or other emergency measures are adequate and functional. 

Pratt, T.H., et al., Electrostatic Hazards in Liquid Pumping Operation, Paper 57-1,6th Int Symp. Loss Prevention and Safety Promotion in the Process Industries, Oslo, June 1989. 

Other elements especially designed to ensure a high efficiency and operational safety are devices that use bellow valves and diaphragm pumps that do not have primary moving parts in contact with the culture medium. More details regarding these and other devices are available in the technical literature (Krahe, 2003). 

The versatile drive system of the asynchronous canned motor has set fresh yardsticks for centrifugal pumps operating under high-pressure conditions. The operating limits for pressure, temperature and toxicity of the flow product have been extended by some orders of magnitude. This is the logical result of the response to heightened safety environment requirements, and means that technical processes can now be implemented for the manufacture of new products. 

In the United States, methods for several pesticides at occupational levels in air are given in the National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods (Eller, 1994). The NIOSH methods for organochlo-rines and organophosphates utilize small traps with a particle filter backed up by two Amberlite XAD-2 resin beds. They are designed to be used with personal sampling pumps operating at flow rates of 0.2 to 1 L/min for maximum sample volumes of 60 to 240 L. Detection limits are in the 5 ng/m to 600 ng/m range. 

The ICP source subsystem incorporates its own internal microcomputer and memory in order to execute the controller s commands. The RF power supply Is under computer control. Likewise, all of the argon flows, the ignitor, peristaltic pump and safety interlocks are directly controlled by the system computer. The RF power output Is stable to less than 0.01 over 1 h of operation. The nebulizer argon flow is controlled through a thermostated mass flow controller to ensure long-term stability. The uptake rate of the two-channel peristaltic pump Incorporated within the source subsystem Is variable by the system controller. 

The greater the amount of carbon dioxide injected, the more will return to the surface with the methane. This creates the need for a gas-separation plant of the type shown in Figure 3.2. The removal of carbon dioxide from oil is much simpler than from methane, which is why enhanced oil recovery is practised more widely than enhanced gas recovery. With an extensive coal seam, it will be necessary to drill injection and extraction wells every few hundred metres or so. These, together with the associated gas compressors, distribution pipes and pumps, access roads, etc., will turn a rural landscape into an industrial site. When the operational/safety issues and the extent of industrialization become fully appreciated, not to mention the impact on the ecological habitat, there may well be local opposition to the recovery of coal-bed methane - with or without carbon dioxide injection and storage. 

A safety expert who has a broad grasp of the issues to do with pump operations... 

Fire Similar to housekeeping audits, fire audits are focused on life safety issues that are applicable in the event of a fire. This can include the verification of fire pump operation, clearance of sprinkler heads from obstruction, and clear paths of egress in the event that an evacuation must occur. Also similar to housekeeping audits, fire audits can take place on a weekly or monthly basis in the span of a few hours. 

On French plants, cold overpressure protection is provided by pilot operated safety valves on the pressurizer when the RHR system is isolated. When the RHR system is operating, the protection is provided by pilot operated safety valves on the discharge lines from the RHR pumps. All these valves are qualified to operate in water conditions. In addition, specific requirements have been included in the Technical Specifications. 

Restart Test Identification Report (RTIR) No. 7 (Reference 11). RTIR No. 7 identifies the safety functions of the CURDS and the required restart testing that will demonstrate equipment operability. Safety functions to be tested include pump capacity, diversion valve function, and equipment control and monitoring functions. A direct linkage of safety function to test requirement is provided in the RTIR to ensure all safety functions are tested. Specific test procedures are identified in the RTIR, which will fulfill required testing. The staff considers the RTIR to adequately document the required equipment testing to demonstrate equipment operability. 

Detection of Bromine Vapor. Bromine vapor in air can be monitored by using an oxidant monitor instmment that sounds an alarm when a certain level is reached. An oxidant monitor operates on an amperometric principle. The bromine oxidizes potassium iodide in solution, producing an electrical output by depolarizing one sensor electrode. Detector tubes, usefiil for determining the level of respiratory protection required, contain (9-toluidine that produces a yellow-orange stain when reacted with bromine. These tubes and sample pumps are available through safety supply companies (54). The usefiil concentration range is 0.2—30 ppm. 

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