Pumps potential head

From Eq. (63), the mechanical energy equation in head form, it is seen that, in the absence of a pump head, losses in a pipe system consist of pressure head changes, potential head changes, and velocity head changes. When fittings or changes in pipe geometry are encountered, additional losses occur. 

The simulation will be done in a zone of 200 m between an infiltration well and a pumping well. This zone shows a kf value of 5TO"5 m/s along the fracture and 10 8 m/s within the pores (those kf values are only for orientation and are not needed directly for the modeling). The flow velocity is 10 m/day due to the potential head. 

The IPL must be capable of detecting and preventing or mitigating the consequences of specified, potentially hazardous event(s), such as a runaway reaction, loss of containment, or an explosion. A single IPL may address the multiple causes for that hazardous event and, therefore, multiple event scenarios may initiate action of one IPL. For example, high pressure in a vessel could be caused by either a pump dead-heading into it or by external fire. For both cases the vessel s pressure safety relief valve counts as a valid IPL. 

Pump manufacturers have established guidelines to ensure each pump they supply is not exposed to conditions that result in cavitation. The design standard is called NPSHR or net positive suction head required. The NPSHR takes into account any potential head losses that might occur between the pump s suction nozzle and impeller thereby ensuring the liquid does not drop below its vapour pressure (bubble point). The NPSH is a measure of the proximity of a liquid to its vapour pressure, and must exceed the pump manufacturer s pump NPSHR. There are two process variables that can be adjusted, in case the available NPSH is less than the NPSHR raise the static head and lower friction losses. Conversely, the NPSHR can be reduced by using a larger, slower speed pump, a double suction impeller, a larger impeller inlet area, an oversized pump and a secondary impeller placed ahead of the primary impeller. 

Total Head the pressure available at the discharge of a pump as a result of the change of mechanical input energy into kinetic and potential energy. This represents the total energy given to the liquid by the pump. Head, previously known as total dynamic head, is expressed as feet of fluid being pumped. 

Development of a Diffusion Head Sensor Cell. The use of air sampling pumps in portable electrochemical gas detection apparatus introduces potential problems into the instrument. First, the sensor cell response is dependent on gas flow rate. The sample flow rate, therefore, must be accurately controlled to obtain reproducible results, or the sample flow rate must be set high enough to insure a flow independent response. Secondly, failure of the pump itself could prevent a sample from reaching the sensor cell. Thirdly, the pumps are usually one of the largest users of current in a portable instrument and thereby limit usable battery life. 

The shape of the system curve determines the saving potentials of using variable-speed pumps. All system head curves are parabolas, but they differ in steepness and in the ratio of their static head to friction drop. The value of variable-speed pumping increases as the system head curve becomes steeper. Therefore, in mostly friction systems, the savings will be greater. 

A liquid release offers the potential for the formation of an aerosol (mist). Aerosol formation is influenced by mechanical force (acceleration) and fluid properties, such as the material s surface tension. Additionally, in some systems the pressure, because of static head, may be adequate to cause some aerosol formation and must be considered. Examples of liquid releases include an accidentally opened storage tank drain valve, a pipeline failure downstream of a pump, a damaged nozzle at the base of a liquid knockout drum, or the failure of a loading hose. 

---