Pumps available

Depending on the pumps available in your manufacturing or process plant, you will experience ... 

In the pneumatic pumping system, the pressure (and not the flow rate) is maintained constant as variations in chromatographic conditions occur. Thus, a change in mobile phase viscosity (e.g. gradient elution) or column back pressure will result in a change in flow rate for these types of pumps. The gas displacement pump in which a solvent is delivered to the column by gas pressure is an example of such a pneumatic pump. The gas displacement system is among the least expensive pumps available and is found in several low cost instruments. While the pump is nonpulsating and hence, produces low noise levels with the detectors in current use, its flow stability and reproducibility are only adequate. In addition, its upper pressure limit is only 2000 psi which may be too low in certain applications. 

Positive displacement, reciprocating, pumps are normally used where a high head is required at a low flow-rate. Holland and Chapman (1966) review the various types of positive displacement pumps available and discuss their applications. 

When more than one pump is installed, they should be coordinated to start in sequence, since immediate start up of all pumps may not be necessary and could cause damage to the system. Depending on the number of pumps available, they can be set to startup on sequentially decreasing fire main set points. All fire water pumps should be able to be started from remote activation switches located in manned control rooms. 

Regarding OQ validation, if one has only an isocratic pump available, it is recommended that one does not perform a detector linearity test at this time. However, this test can be subsequently performed as part of either the PQ validation or individual method validation, both of which typically test the performance of the system as a whole (holistically). 

An efficient roughing line will have a net pumping speed as nearly equal to the normal pumping speed as possible, so that the roughing time is the shortest possible with the pump available. 

Almost never take a person s word for the water recirculation rate. Check the number of pumps available and the number operational, read the pump plate, use pump curves, read the pump manual, measure using pitot tubes (measures the total pressure and hence indirectly the velocity), orifice plates, V-notch weirs, and distribution deck levels, or calculate based on amperage draw and the discharge pressure, to confirm the volume of water actually circulating in the system. 

There are many open recirculating cooling systems that still do not have chemical dosing pumps available. This represents a serious risk, as the... 

A Little Giant" submersible pump (available from Little Giant Pump Co., Oklahoma City, OK) is used to circulate ice water through the immersion well. 

Electroosmotic pumps lack mechanical parts and specific localization in the manifold, producing an even electroosmotic flow. Besides, the flow in interconnected and branched channels can be controlled by switching voltages only. Just two decades ago electroosmotic pumps were attractive and feasible ways for mobile phase flow into microfluidic devices [13] but in the 1990s the conventional pumps available showed a major problem with the high pressures... 

Vacuum pumps, either singly or, more usually, as part of a pumping system, create and maintain the conditions appropriate to a required process. Each of the types of vacuum pump available has a characteristic working range in which it is effective. Outside that range, shortcomings in performance become apparent. 

Chapter 3 summarised initially the various types of vacuum pump available and the pressure ranges in which they normally operate. Subsequent sections dealt specifically with types of pump and, in some cases, to support calculations, reviewed the operating principles and characteristics. For example, aspects of oil-sealed rotary pump operation were discussed (Examples 3.1-3.5) and Roots pumps, widely used in applications where large gas loads at pressures in the rough-medium range have to be handled, were examined (Examples 3.7-3.9). 

The pump set on a vacuum system has to evacuate the system, starting from atmospheric pressure down to the required pressure, often in a given time. It must be able to maintain this pressure during operation of the vacuum process. Chapter 3 reviews the range of vacuum pumps available and the combinations that are used over the range from atmospheric pressure down to our current limits of measurement in the EHV range. 

In drug delivery, infusion pumps have achieved remarkable success in recent years. As of 1983, there were 18 different models of external pumps available (6). These battery-powered portable pumps are used to infuse insulin into diabetic patients. Although capable of variable delivery rates, they have a reservoir volume of less than 6 ml, which is unsuitable for fluid replenishment. Further, the cost of these small pumps is very high which limits the affordability to a few selected individuals. 

A 1-in-diameter tube is used to collect a stack sample from a stack in which air is flowing at a velocity of 30 ft/s. The sampling pump available can pump only at a rate of 1 ft3/min. Estimate the error in sampling for (a) 10-pm-diameter spheres with p = 2 g/cm3 and (6) 0.1 p.m-diameter spheres with p = 10 g/cm3. 

In the first part of this chapter, the different designs of LC pumps are dealt with, from the simple mechanical instruments which were used to pioneer the field, to the microprocessor-controlled pumps available today. Later, some other related topics ate considered, such as the problems associated with the introduction of samples, and the means available for connecting up the highly pressurised HPLC system. 

There are several different types of HPLC pump available. However, these all fall into two main classes those which deliver mobile phase at a constant pressure, and those that pump at constant flow rates. In the vast majority (almost 90%) of current analytical HPLC work, it is the latter type of pump that is used. However, both types of pump have their place in modern chromatography, as discussed in the following sections. 

Oil, used for lubricating the gears and bearings, is separated from the compressed airstream by labyrinth seals. Shown in Figure 3.31, the seals consist of two separate components, an air seal and an oil seal. In between the two, the seal is open to atmosphere. Any oil bypassing the oil seal leaks to atmosphere. The air seal is always at a higher pressure so that any leaks are always from air to atmosphere and oil cannot enter the process fluid. Oil is typically provided by a shaft-driven pump with a standby motor-driven pump available. 

For somewhat higher pressures, depending upon the size, and a more even flow rate, a fish aquarium pump, available at any pet store, can be used (Jacobson, B.M., J. Chem. Ed., 65 (5), 459, 1988). The air controller obtained there also will work well. 

An HPLC procedure required a pressure of 800 p.s.i. when using a 30 cm column packed with 50 pmbeads. A column packed with 10 pm beads was to be purchased. The pump available had a 6000 p.s.i. capacity. Could a 30 cm column be used ... 

The COMOSS column was estimated to be equivalent to a conventional 4 pm non-porous bead packing. In addition, the surfaces of the structures were functionalized with a silane to form a C18 reversed-phase monolayer. To obtain the nanoliter per minute flow rates required to operate the devices, the authors relied on electroosmotically-driven flow using an electric field of 770 V cm thus operating in CEC mode, since mechanical HPLC pumps available at the time were not capable of delivering such a small flow at the pressures required. However, the column efficiency obtained was remarkable, with some 35 000 plates (777 000 plate m ) in 110 s obtained for unretained Rhodamine 123 on a column... 

Although neither of the two types of pumps available—the constant pressure type and the constant volume type, meets all these criteria, constant volume pumps maintain a more accurate flow rate and give a more precise analysis. 

This completes our survey of the methods of achieving a vacumn, the types of vacuum pumps available and the techniques used to form thin films. We are now ready to continue our description of Devices which utilize phosphors in their operation. This was shown in 7.2.1. given above and includes displays that are not very prevalent at the present. 

The variety of reciprocating pumps is indicated by the specific applications for which pumps are used. Among the variety of pumps available can be included deep-well, boiler-feed, condensation, dry-vacuum, wet-vacuum, compound, filter-press, hydraulic-press, creamery, milk, oil, proportioning, fuel-oil, lime, and magma pumps. Some data on the... 

When the Nitrogen column is taken in / out of service with respeet to the LNG pumps availability / shut down. ( Bypassing N2 Reboiler)... 

Number of main condensate pumps required for full power - the number of condensate pumps that are normally in operation at the rated turbine power. It is usual for some of the condensate pumps available to be on standby in case an operating pump trips. The value should be entered in the same form as for the total number of condensate pumps. 

Production from the platform depended on having one condensate pump available, so the platform had two condensate pumps located in the gas compression module. Either pump could supply the required flowrate. Hence, to enable the maintenance on pump A, the standby pump (pump B) was operational, with suitably closed isolation valves for pump A. However, at 2145 hours on July 6, 1988, for reasons unknown, pump B stopped and could not be restarted. 

A plot of the time course of inhibition by q.d. dosing of a PPI, illustrating the decline in the number of pumps available for add secretion (red) with successive doses and the progressive increase in median intragastric pH. 

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