Pump control

Thermal Dispersion. Thermal dispersion level switches are used on appHcations where multiple shifts inhquid characteristics are present. The unit is responsive only to a change in the thermal conductivity of the Hquid and ignores shifts in specific gravity, dielectric, density, temperature, and pressure. Units are used for alarm signal however, pump control maybe obtained using two units with a latching relay. 

In air conditioning circles, the tower normally represents the final heat sink in a turnkey package which would include compressors/condensers, pipework, ducting, fans, pumps, control gear, etc. Where consultants and experienced contractors are concerned, the tower specification is well defined and the purchases based upon economics related to efficiency. 

Each solvent passes from its reservoir directly to a pump and from the pump to a mixing manifold. After mixing, the solvents pass to the sample valve and column. The pumps control the actual program and are usually driven by stepping motors. The volume delivery of each solvent is controlled by the speed of the respective pump. In turn, the speed of each motor is precisely determined by the frequency of its power supply which can be either generated by external oscillators or, if the chromatograph is computer controlled, directly from the computer itself. 

Figure 2. Schematic representation of the reactor system computer-controlled pumps (PI, P2) pump controllers (fc) reactor (CSTR) reception vessel valves (S1-S4) monomer and initiator storage vessels (Tl, T2). (a) Digital input from GPC injection valve (b) analogue output from GPC (c, d) digital outputs to recorder chart drive and event marker (e, f) analogue outputs for pump set-point adjustment (g,h) reactor feeds (i) reactor output (j-m) digital outputs to reception system valves (n) manual sampling of products by GPC,...

Superior hardware to the traditional apparatus is readily available and in some cases microprocessor intelligence is being built into dedicated modules for say temperature or pumping control. Integration of such units has the potential of full automation. 

ShimadzuLC-lOAD VP HPLC Pumps (2) with 250-p.L high-pressure mixer and SCL-lOA VP pump controller... 

The acid and alkali wastes are pumped from the acid-alkali wastewater sump [T-30] into the acid-alkali treatment module [T-31], Metering pumps controlled by pH instruments feed either acid or caustic to the module as required to maintain an acceptable alkalinity for the formation of metal hydroxides prior to discharge to the precipitator consisting of a mixing tank [T-98], a surge tank [T-99], and a sedimentation clarifier [T-101], The pH is adjusted to a value of 8.5 for optimum metal hydroxide formation and removal. 

Quench waste recirculation requires installation of a cooling tower to lower the temperature of the quench wastewater stream. The multimedia filter system for the final polishing of effluent includes a backwash mechanism, pumps, control media, and the filter structure. 

FIGURE 7.11 Schematic of double-diaphragm pump controls. 

The proportioning pump controls the rate of advancement, viz 10 inch/minute, of each sample through the analysis stream. Hence, a fixed length of tubing is equivalent to a fixed amount of time. Each analysis stream is made of transparent plastic flexible tubing, and each patient-sample is separated from one another by an air-bubble. 

The major cost factors of an evaporation pond include pond liners, land preparation, excavation and clearing, site surveying, bank construction, pumps, control systems, disposal of precipitated solids, maintenance and geotechnical investigation of the site (Singh and Christen 2000). Of these, pond liners typically represent the greatest cost (Nicot et al. 2009). 

The recommended location for the diesel fuel tank is outdoors, just outside of the building. Where location of the diesel fuel storage tank outside of the fire water pump building is not appropriate (cold weather), sprinkler protection of the fire-water pump house is recommended. Pump controllers should be sealed and splash resistant. 

A controller should be provided for each fire water pump. The controller should be designed and installed in accordance with NFPA 20 specifications. An example fire water pump controller is shown in Figure 7-16. 

SGX-CAT uses a unique system based on a small liquid nitrogen pump for a similar purpose. The pump controls delivery of a gentle stream of liquid nitrogen that is directed onto the surface of the sample after it has been positioned within the gaseous cryostream by the sample-changing robot. A phase... 

All major functions of a plant, such as glass transport, control of the sputter processes and pump control, are carried out fully automatically. This is the only way to ensure high productivity along w/ith high product quality. 

API Standard 675, Positive Displacement Pumps—Controlled Volume, March 2000... 

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