High pressure pump

Capillary Electrochromatography Another approach to separating neutral species is capillary electrochromatography (CEC). In this technique the capillary tubing is packed with 1.5-3-pm silica particles coated with a bonded, nonpolar stationary phase. Neutral species separate based on their ability to partition between the stationary phase and the buffer solution (which, due to electroosmotic flow, is the mobile phase). Separations are similar to the analogous HPLC separation, but without the need for high-pressure pumps, furthermore, efficiency in CEC is better than in HPLC, with shorter analysis times. 

Reverse Osmosis. Membranes are used for the separation of smaller components (<500 daltons). They have smaller pore space and are tighter than those used for ultrafiltration. High pressure pumps, usually of the positive piston or multistage centrifugal type, provide pressures up to 4.14 MPa (600 psi). 

Measurable Process Parameters. The RO process is relatively simple ia design. It consists of a feed water source, feed pretreatment, high pressure pump, RO membrane modules, and ia some cases, post-treatment steps. A schematic of the RO process is shown ia Figure 2a. 

Figure 6.2 Schematic diagram showing the basic components of (a) SFE and (b) SFC instruments 1, carbon dioxide 2, high pressure pump 3, oven 4, exti action cell (SFE) or column (SFC) 5, collection vial (SFE) or data system (SEC).

In general, rotary pumps with discharge pressure of up to 100 psi are considered low-pressure pumps. Rotary pumps with pressure between 100 and 500 psi are considered moderate-pressure pumps. Pumps with pressure beyond 500 psi are considered to be high-pressure pumps. 

Over the years the performance standards of hydraulic equipment have risen. Whereas a pressure of about 1000 psi used to be adequate for industrial hydraulic systems, nowadays systems operating with pressures of 2000-3500psi are common. Pressures above 5000psi are to be found in applications such as large presses for which suitable high-pressure pumps have been developed. Additionally, systems have to provide increased power densities, more accurate response, better reliability and increased safety. Their use in numerically controlled machine tools and other advanced control systems creates the need for enhanced filtration. Full flow filters as fine as 1-10 micron retention capabilities are now to be found in many hydraulic systems. 

High-pressure pumps operating at up to 6000 psi are required to force solvent through a tightly packed HPLC column, and electronic detectors are used to monitor the appearance of material eluting from the column. Alternatively, the column can be interfaced to a mass spectrometer to determine the mass spectrum of every substance as it elutes. Figure 12.18 shows the results of HPLC analysis of a mixture of 10 fat-soluble vitamins on 5 jam silica spheres with acetonitrile as solvent. 

Some OEMs produce many of the individual components required for their systems totally in-house, although there are also a large number of specialist equipment manufacturers for pressure vessel (PV) housings, high pressure pumps, and the like. World-class membrane manufacturers include Trisep, Koch, Fluid Systems, Hydranautics, Du Pont, Osmonics, and Dow. 

A hydraulic press is powered by a remote high pressure pump. The gage pressure at the pump is 20 MPa, and the pressure required to operate the press is 19 MPa (gage) at a flow rate of 0.032 m3/min. The press and pump are to be connected by 50 m of drawn stainless steel tubing. The fluid properties are those of SAE 10 lube oil at 40°C. What is the minimum tubing diameter that can be used ... 

A compressor may be thought of as a high pressure pump for a compressible fluid. By high pressure is meant conditions under which the compressible properties of the fluid (gas) must be considered, which normally occur when the pressure changes by as much as 30% or more. For low pressures (i.e., smaller pressure changes), a fan or blower may be an appropriate pump ... 

Speed Useful for a variety of samples Selective and efficient columns High flow rate Fast data output Variety of detectors and stationary phases Low dead-volume fittings High-pressure pumps Fast-response recorders and automatic data handling... 

High-pressure pumps used in SFC can come in a variety of types most of them are modifications of pumps used in LC. Piston, diaphragm and syringe pumps are used. 

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