Flow maximum

The efficiency of separation of solvent from solute varies with their nature and the rate of flow of liquid from the HPLC into the interface. Volatile solvents like hexane can be evaporated quickly and tend not to form large clusters, and therefore rates of flow of about 1 ml/min can be accepted from the HPLC apparatus. For less-volatile solvents like water, evaporation is slower, clusters are less easily broken down, and maximum flow rates are about 0.1-0.5 ml/min. Because separation of solvent from solute depends on relative volatilities and rates of diffusion, the greater the molecular mass difference between them, the better is the efficiency of separation. Generally, HPLC is used for substances that are nonvolatile or are thermally labile, as they would otherwise be analyzed by the practically simpler GC method the nonvolatile substances usually have molecular masses considerably larger than those of commonly used HPLC solvents, so separation is good. 

The wisest fan choice is frequently not the cheapest fan. A small fan operates well on its curve but may not have adequate capacity for maximum flow control, future needs, or process upset conditions. It may be so lightly constmcted that it is operating near its peak speed with no provision for speed increases in the future, if needed. As fan size is increased, efficiency generally improves and wheel speed is lower. These factors decrease operating cost and provide reserve capacity for the future. However, it is also possible to oversize a fan and impair its performance. 

One proposed simplified theory (4) provides reasonably accurate predictions of the internal flow characteristics. In this analysis, conservation of mass as well as angular and total momentum of the Hquid is assumed. To determine the exit film velocity, size of the air core, and discharge coefficient, it is also necessary to assume that a maximum flow through the orifice is attained. 

The separation parameters have been calculated for a centrifuge in which the behavior of the circulating gas is described by Martin s equation. The flow pattern efficiency is shown in Figure 15(b) as a function of the dimensionless parameter M, where M is equal to (ME /2RT). In this case the maximum flow pattern efficiency attainable is 0.956. 

The mean residence time T (defined as H JF) is the most important parameter, since it determines the time over which particles are exposed to grinding. Measurements on several industrial mills (Weller, Automation in Mining Mineral and Metal Processing, 3d IFAC Symposium, 303-309, 1980) (measured on the water, not the ore) showed that the maximum mill filhng was about 40 percent, and the maximum flow velocity through the mill is 40 m/h. 

Grit Chambers Industries with sand or hard, inert particles in their wastewaters have found aerated grit chambers useful for the rapid separation of these inert particles. Aerated grit chambers are relatively small, with total volume based on 3-min retention at maximum flow. Diffused air is normally used to create the mixing pattern shown in Fig. 25-44, with the heavy, inert particles removed by centrifugal action and friction against the tank walls. The air flow rate is adjusted for the specific particles to be removed. Floatable solids are removed in the aerated grit chamber. It is important to provide for... 

The initial gas temperature in a tank can reach a value of 55°C (131°F) as a result of strong solar radiation. Ambient rainfall is assumed to be 15°C (59°F). The maximum flow rate of air into the... 

Experimental data in small equipment has shown that condensation of water vapor causes a twofold increase in the maximum flow rate compared to dry air, and a fourfold increase in condensation of methanol vapor. 

Generally, maximum flow velocities for brass are between 3 and 5 ft/s (0.9 and 1.5 m/s) depending on environmental conditions. In this case, sand and silt entrained in the river water contributed to the erosiveness of the fluid. 

Sometimes you hear people say that the pump is operating off its cw. t velocity, the impeller diameter and design are correct, if the pump installed and functioning correctly, including the mechanical seal and impossible to operate off the curve. The pump will be somewhere on between shut-off head and maximum flow a zero elevation. 

What must be done is establish the maximum flow, and the minimum flow, and implement controls. Regarding filters, you ve got to establish the flow and pressure (resistance) that corresponds to the new, clean filter, and determine the flow and resistance that represents the dirty filter and its moment for replacement. These points must be predetermined. The visual graph of the system eurve with its dynamie resistances are seen in this example filtering and recirculating a liquid in a tank. Consider the following graphs (Figures 8-18 and 8-19). 

Pumps are usually over-designed. From the initial specification stages, future needs are taken into consideration, maximum flow is overrated and operating conditions are uncertain. Design engineers following a... 

The machine control system was set in accordance with the parameters determined during simulation prior to delivery to the site. Following re-routing and hook-up of the piping, the compressors were run to a maximum flow at 2.71 bar (absolute) and 480°C. The generator was disconnected from the grid and the expander tripped accordingly. 

The NPSH requirement must be met for all anticipated flows. Maximum flow will usually have a higher NPSH than normal flow. For some pumps, extremely low flows can also require higher NPSH. 

Collect contaminants in an impinger at a maximum flow rate of 1.0 1pm. 

Hot water basins are used to distribute water in crossflow towers. Here, water is pumped to an open pan over the wet deck fill. The bottom of the pan has holes through which water is distributed. Manufacturers will fit specially shaped plastic drip orifices into the holes to give the water an umbrella shape for more uniform distribution. Different size orifices are used for different flow rates. Ideally, the basin will be almost full at maximum flow. This way, sufficient depth is retained for good water distribution as turn down occurs. The turn down ratio can be extended by the addition of hot water basin weirs- a pattern of baffles perhaps 2... 

Maximum Flow to be Handled - The flare system must be sized to handle... 

Flare stack sizing and pressure drop is included with considerations of pressure drop through the safety valve headers, blowdown drums, flare headers, seal drum, etc. Elevated flare tips incorporating various steam injection nozzle configurations are normally sized for a velocity of 120 m/s at maximum flow, as limited by excessive noise and the ability of manufacturers to design tips which will insure flame stability. This velocity is based on the inclusion of steam flow if injected internally, but the steam is not included if added through jets external to the main tip. 

Normally an overcapacity line to an elevated flare is provided to handle the excess flow when the flaring rate exceeds the capacity of the multijet flare. The overcapacity flare is usually not equipped with steam injection, and smoke formation is accepted during infrequent operations. The overcapacity line and flare is designed to handle the entire maximum flow so that it can spare the multijet flare when the latter is shut down for maintenance. 

A butterfly valve in the line to the first stage seal drum limits the maximum flow to the first stage burner. The valve is set by observing the burners while flaring at design capacity. Once adjusted, the valve should be locked in position. 

The flare system shall be designed for zero flow to maximum flow. 

Permeate pressure = 1.013 x 10 N/m. The flowrate per module is bounded by the following minimum and maximum flows ... 

A maximum flow rate of 1.27 s m - tank sutface is considered... 

Wide-open volume The maximum flow volume a fan is capable of delivering with no resistance on the outlet side. 

---