Pump restriction

Separator. Fat is normally separated from the milk before the HTST however, ia one system the airtight separator is placed after the FDV, foUowiag pasteurization. A restricting device and several control combiaations are placed ia the line after the FDV to ensure that constant flow is maintained, that vacuum does not develop ia the line, that the timing pump stops if the separator stops, and that the legal holding time is met. 

Whereas the total dynamic head developed by a centrifugal, mixed-flow, or axial-flow pump is uniquely determined for any given flow by the speed at whicdi it rotates, positive-displacement pumps and those which approach positive displacement will ideally produce whatever head is impressed upon them by the system restrictions to flow. Actually with slippage neglecTed, the maximum head attainable is determined by the power available in the drive and the strength of the pump parts. An automatic relief valve set to open at a safe pressure... 

Lubricity. In any mechanical seal design, there is rubbing motion between the dynamic seal faces. This rubbing motion is often lubricated by the fluid being pumped. Most seal mauufac turers hmit the speed of their seals to 90 ft/sec (30 m/sec). This is primarily due to centrifugal forces acting on the seal, which tends to restrict the seal s axial flexibihty. 

At design head, on the other hand, capacity does not change markedly with speed, so that once the design point has been passed the pump-turbine acts as a restriction in the hue. Since most or these units operate on a relatively fixed pressure differential, they then tend to act Eke an orifice to limit flow, and little or no benefit can be realized from any overcapacity in terms of fluid flow available to the unit in the actual iustaUatiou. 

Gas pressurized Monitor tank level and provide interlock for feed feed shut-off overpressurizes, alternate fluid delivery system (e.g., pump) centrifuge system when feed vessel delivery gas pressure to maximum safe empties working pressure of downstream system (e.g., pressure regulation) Restrict feed flow rate to be consistent with vent capacity Ensure adequate vent capacity for maximum possible gas flow ... 

Low pump head Increase pressure at source pressure., Verify pump design will achieve needed pressure Check for restrictions in suction and discharge lines CCPS G-23... 

Overflows cause by pump failure or restrictions in discharge piping... 

This is a low flow condition where the discharge flow of the pump is restricted and the product cannot leave the pump. The liquid is forced to re-circulate from high-pressure zones in the pump into low-pressure zones across the impeller. 

This condition cannot be corrected on pumps with an enclosed impeller. You need to relax the restricted discharge flow on the pump. The problem could be a clogged downstream filter, a closed discharge valve, an over-pressurized header (back-pressurizing the pump), or a... 

In the third e.vample, the line terminates at 53%. This means DO NOT run this pump at less than 53% of the BEP. 53% of 4500 gpm is 2385 gpm. Because this is a firewater pump and because firemen need to throttle the nozzles on their fire hoses, then we need to install a pressure relief valve on this system with a discharge bypass line so that the pump dumps the restricted water (less than 2400 gpm) back into the suction tank or lake. If not, this firewater pump is likely to suffer bearing failure during an emergency. 

The scratch marks on the circumference of these close tolerance rotary parts will correspond to. scratch marks on close tolerance stationary parts at approximately 60 around the volute from the cutwater. These marks will be vi.sible on the back plate with open impellers, or on the wear rings of pumps with enclosed impellers, or the ID bore of the restriction bushing at the bottom of the seal chamber where the shaft pa.sses through, or the ID of the seal chamber bore at the back end of the mechanical seal (Figure 9-6 and Figure 9-7, next page). 

This would be induced or caused by operation, if the plant operators strangle valves to control production tlow. Any other discharge flow restriction (clogged filter, pipe obstruction, or tin-calibrated automatic valve) would produce the same evidence. Talk with the plant engineer about this situation and show him the evidence on the pump. 

The pumps can be either centrifugal or positive displacement types. The centrifugal pumps should have a head curve continuously rising toward the shut-off point. The standby pump should be piped into the system in a manner that permits checking of the pump while the main pump is in operation. To achieve this, a restriction orifice is required with a test bleeder valve piped to the return oil line or the reservoir. 

Limit the total possible charge to a batch reactor by using a precharge or feed tank of limited capacity. Alternatively, limit the addition rate by selecting a pump with a maximum capacity lower than the safe maximum addition rate for the process, or by using restriction orifices. 

Use physical limits of pipe size, restrictive orifices, and pump sizing to limit excessive flow rates. 

Positive pumps are normally fitted with relief valves. These are not usually fitted to centrifugal pumps unless the process material is likely to explode if it gets too hot. As an alternative to a relief valve, such pumps may be fitted with a high-temperature trip. This isolates the power supply. Or a kick-back, a small-diameter line (or a line with a restrietion orifice plate) leading from the delivery line baek to the suction vessel, may be used. The line or orifice plate is sized so that it will pass just enough liquid to prevent the pump from overheating. Small-diameter tines are better than restriction orifice plates as they are less easily removed. 

Failure modes vary in degree of magnitude, for example, a pump may have no output or may have its output restricted. Consequently, failure modes have been divided into three categories of severity, which are defined as follows ... 

Electrodriven separation techniques are destined to be included in many future multidimensional systems, as CE is increasingly accepted in the analytical laboratory. The combination of LC and CE should become easier as vendors work towards providing enhanced microscale pumps, injectors, and detectors (18). Detection is often a problem in capillary techniques due to the short path length that is inherent in the capillary. The work by Jorgenson s group mainly involved fluorescence detection to overcome this limit in the sensitivity of detection, although UV-VIS would be less restrictive in the types of analytes detected. Increasingly sensitive detectors of many types will make the use of all kinds of capillary electrophoretic techniques more popular. 

A SMB, whatever the number of zones, consist of 4 to 24 columns with 3 to 5 pumps and a number of valves, which allow the columns to be connected to different lines. Further discussions are restricted to the classical 4-zone SMB. There are different ways to connect columns in order to build a SMB. An important option is linked to the presence or absence of a recycling pump in order to build a SMB. The examples are shown in Fig. 10.3. 

The tool generates at bottom positive pulses by restricting momentarily the flow of mud each time that the mud flow (pumps) is started. The pulses are detected at surface on the stand pipe and recorded as a function of time. 

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