Pumps minimum flow

Imposing a minimum density is justified by the need to obtain sufficient maximum power for the engine, by means of an injection pump whose flow is controlled by regulating the volume. 

Pump is operated Match pump capacity to the service at a fraction of, Install minimum flow recirculation line to heat capacity. Possihil- ensure adequate cooling of the pump ities of excessive internal interlock to shutdown pump on mini-recirculation, fre- indication quent seal and Implement procedural controls to avoid operat-bearing failure ing at too low a flow resulting in loss of, Provide deadhead protection containment. CCPS G-23 CCPS G-29... 

Most pumps need minimum flow protection to protect them against shutoff. At shutoff, practically all of a... 

This approach will provide a number aecurate enough for initial planning. For detailed design, the proeess engineer should work elosely with the meehanieal engineer and/or vendor representative involved to set exact requirements, ineluding orifice type and size for the minimum flow line. Also, a eooler may be required in the minimum flow line or it may need to be routed to a vessel. For boiler feedwater pumps, a special stepped type orifice is often used to eontrol flashing. 

The maximum and minimum flow rate available from the solvent pump may also, under certain circumstances, determine the minimum or maximum column diameter that can be employed. As a consequence, limits will be placed on the mass sensitivity of the chromatographic system as well as the solvent consumption. Almost all commercially available LC solvent pumps, however, have a flow rate range that will include all optimum flow rates that are likely to be required in analytical chromatography... 

The minimum flow simply means that this flow must circulate through the pump casing (not recirculate with no cooling) back to at least the initial temperature of the feed, if excessive temperatures are not to dev elop. The best practice is to request the manufacturer to state tliis value for the... 

In some situations it is very important to be able to increase the flow rate above the design conditions (for example, the cooling water to an exothermic reactor may have to be doubled or tripled to handle dynamic upsets). In other cases this is not as important (for example, the feed flow rate to a unit). Therefore it is logical to base the design of the control valve and the pump on having a process that can attain both the maximum and the minimum flow conditions. The design flow conditions are only used to get the pressure drop over the heat exchanger (or fixed resistance part of the process). 

The designer must specify the maximum flow rate that is required under the worst conditions and the minimum flow rate that is required. Then the valve flow equations for the maximum and minimum conditions give two equations and two unknowns the pressure head of the centrifugal pump APj> and the control valve size C . 

Design the control valve and pump so that both the maximum and minimum flow rates can be handled with the valve never less than 10 percent open. 

Eire water pumping capacity (flow rate) should be sufficient to provide the required amount of water at required pressure to the fire areas having the greatest demand. At least 50% of the pumping capacity should be from diesel-driven pumps. Eire water pumps should have a minimum capacity of 1,500 gpm (5,700 Ipm) and can range up to 5,000 gpm (18,930 Ipm). Earger pumps... 

When a zone is within the comfort gap, its reheat coil is turned off and its VAV box is closed to the minimum flow required for air refreshment (Figure 2.6). When all the zones are inside the ZEB, HW (hot water), CHW (chilled water), and STM supplies to the airhandler are all closed and the fan is operated at minimum flow. When all other airhandlers are also within the ZEB, the pumping stations, chillers, cooling towers, and HW generators are also turned off. 

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