Maximum flow rate

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 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. 

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

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

Back-pressure can affect either the set pressure or the capacity of a relief valve. The set pressure is the pressure at which the relief valve begins to open. Capacity is the maximum flow rate that the relief valve will relieve. The set pressure for a conventional relief valve increases directly with back-pressure. Conventional valves can be compensated for constant back-pressure by lowering the set pressure. For self-imposed back-pressure—back-pressure due to the valve itself relieving—-there is no way to compensate. In production facility design, the back-pressure is usually not constant. It is due to the relief valve or other relief valves relieving into the header. Conventional relief valves should be limited to 10% back-pressure due to the effect of back-pressure on the set point. 

Description Particie size (/im) Minimum theoreticai piates/30 cm Exclusion limit (poiystyrene moiecuiar weight) Standard flow rate (ml/min) Maximum flow rate (ml/min) Maximum pressure drop/30 cm (bar)... 

In-column solvents Column size (mm) Theoretical plate number Exclusion limit Polystyrene" Particle size (/tm) Pore size (A) Maximum flow rate (ml/mln) Maximum pressure (kgf/cm ) Maximum temperature rc) Anaiyticai column... 

Fractogel EMD BioSEC (S) a Superformance column 600-26 packed with Fractogei EMD BioSEC (S) (V, 318.5 mi 600 mm bed height) was connected to an external pressure gauge (0.1 -6.0 bar), and a HPLC pump. The linear flow rate was increased successively from 10 up to 100 cm/hr and the pressure drop was measured. A pressure drop of I bar was reached at a linear flow rate of approximately 25 cm/hr. (B) The same experiment was performed using a Superformance 1000-200 preparative column (200 mm i.d.) with a bed volume of 20 liter (63 cm bed height) and a maximum flow rate of 50 cm/hr. A pressure drop of I bar was reached at a linear flow rate of approximately 17 cm/hr. 

Fji = friction pressure drop at maximum flow rate... 

APc = pressure drop across control valve F i = friction pressure drop at maximum flow rate, psi... 

At the maximum flow rate the friction drop will become ... 

Q = Flow rate, gallons per minute, gpm Qb = Flow rate, barrels/day Qd = Design flow rate, gpm, or ACFM Qm = Maximum flow rate, gpm, or ACFM q = Flow rate at flowing conditions, cu ft/sec... 

Gas pipework in a user s premises serves the function of transporting the gas from the meter to the point of use in a safe way and without incurring an avoidable pressure loss. For low-pressure installations, the permitted pressure loss is only 1 mbar from the meter to the plant manual isolating valve at maximum flow rate. The pipework must be sized adequately to allow for this. Boosters are sometimes used to overcome pressure losses, but the use of a booster should never be considered a satisfactory substitute for correct design of pipe sizes. Where gas is available at higher pressures it may be permissible to tolerate pressure losses of more than 1 mbar. 

Figure 26.3 shows the relationship between port diameter and fluid velocity at 4 and 7 m/s and highlights the nominal maximum velocities for various plates. As the flow through the machine increases, the entry and exit pressure losses also increase. The nominal maximum flow rate for a plate heat exchanger limits these losses to an acceptable proportion of the total pressure losses, and is therefore a function not only of the port diameter but... 

In the process industries hf is calculated for the maximum flow rate and the NPSH at normal flow allowed for by using the formula... 

For a given upstream pressure P] the maximum flow rate occurs when U2 = s/kPiih, the velocity of transmission of a pressure wave under these conditions (equation 4.38). 

The maximum flow rate that can be accommodated while still allowing the mass spectrometer to operate is in the range of 10-20 tilmin" Typical flow rates used in conventional HPLC separations are between 500 and 1000 tilmin and therefore only between 1 and 4% of the column eluate, and therefore ana-lyte(s), enter the mass spectrometer source. The sensitivity, or more accurately the lack of sensitivity, of the DLl interface is one of its major limitations. 

There is an interior optimum. For this particular numerical example, it occurs when 40% of the reactor volume is in the initial CSTR and 60% is in the downstream PFR. The model reaction is chemically unrealistic but illustrates behavior that can arise with real reactions. An excellent process for the bulk polymerization of styrene consists of a CSTR followed by a tubular post-reactor. The model reaction also demonstrates a phenomenon known as washout which is important in continuous cell culture. If kt is too small, a steady-state reaction cannot be sustained even with initial spiking of component B. A continuous fermentation process will have a maximum flow rate beyond which the initial inoculum of cells will be washed out of the system. At lower flow rates, the cells reproduce fast enough to achieve and hold a steady state. 

Peak expiratory flow The maximum flow rate of air leaving the lungs upon forced exhalation. 

Liquid chlorine is unloaded from rail tankers into a storage vessel. To provide the necessary NPSH, the transfer pump is placed in a pit below ground level. Given the following information, calculate the NPSH available at the inlet to the pump, at a maximum flow-rate of 16,000 kg/h. 

Design for a maximum flow-rate of 20 per cent above the average flow. 

If the maximum flow-rate required is 20,000 kg/h, calculate the pump motor rating (power) needed. Take the pump efficiency as 70 per cent and allow for a pressure drop of 0.5 bar across the control valve and a loss of 10 velocity heads across the orifice. 

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