Calculation reciprocating pump

Mechanical vibration of pipe is handled in the same manner as for reciprocating pumps (Volume 1, Chapter 12). Normally, if the pipe support spacing is kept short, the pipe is securely tied down, the support spans are not unifoiTn in length, and fluid pulsations have been adequately dampened, mechanical pipe vibrations will not be a problem. It is good practice to ensure that the natural frequency of all pipe spans is higher than the calculated pulsation frequency. The pulsation frequency is given by ... 

Classifications 458. General Calculations 461. Reciprocating Pumps 463. Rotary Pumps 468. 

Related Calculations. Use this procedure for any type of reciprocating pump handling liquids falling within the range of Table 6.27. Such liquids include oil, kerosene, gasoline, brine, water, etc. 

In order to damp almost completely the pulses generated at high pressure in a dual-head, special-drive piston reciprocating pump, the electronic correction circuitry in the Altex Model 100 pump calculates the average back-pressure and then corrects the speed of the pump motor so as to maintain the actual pressure close to the average calculated pressure. The effect of this correction is to speed up the motor momentarily when pumping is switched from one piston to the... 

As is quite evident from interpreting the ehromatograms in Fig. 4.50, RP-HPLC columns have a finite lifetime It is good practice for the analyst to keep a record of N (as calculated using the above equation) versus either time or number of injected samples in an attempt to continuously monitor column performance. Because HPLC reciprocating pumps maintain constant flow rate, a continuous observation of the back-pressure or pressure buildup at the front on the HPLC column is an important parameter to monitor. Making sure that there are no leaks in an operating HPLC is also very important. 

The NPSHr of reciprocating pumps is usually calculated for incipient cavitation conditions from the maximum entry pressure losses [18, 19], which are largely dictated by the characteristics of the suction check valve. The manufacturer s NPSHr data are in general based on these fluid mechanical effects. Typical values for the NPSHr range between 1 and 3 m for liquid CO2 (this corresponds to a pressure requirement of between 0.1 and 0.3 bar). 

The pump parameters Up, Ap and bp can either be calculated or taken from manufacturers documentation. For reciprocating pumps, the losses Ha and //ja both vary in an oscillatory manner with time and are not in phase. 

The required NPSH (NPSHr) is specific to each individual pump design and can normally be taken from the pump specification or manufacturers documentation. The NPSHr values are normally based on the 3% AH criterion (Figure 9.29a). For reciprocating pumps they are usually calculated from the pressure drop A/ e required to actuate the entry check valve (Figure 9.29b) at the onset of cavitation... 

Avoidance of cavitation. As with reciprocating pumps, the criterion NPSHa > NPSHr should be obeyed. The available NPSH (NPSHa) for a centrifugal pump may be calculated using equations (9.14) and (9.15) developed in section 9.S.2.4 for reciprocating pumps. In this case however //ja = 0 and NPSHa usually falls with the square of the volume flow rate (Figure 9.28). 

Reciprocating pump capacity is calculated by following equation. 

As discussed in Section II1.2.1.2, for reciprocating pump, an additional head, acceleration head (Ha, in feet), is required for NPSHA calculation. Ha is calculated by following equation. 

There are several important calculations that are needed in order to properly evaluate and select the appropriate reciprocating piston pump [17]. These calculations are used in conjunction with Equations 3-32-3-37. 

Related Calculations. Use this procedure for any liquid-water, oil, chemical, sludge, etc.—whose specific gravity is known. When liquids other than water are being pumped, the specific gravity and viscosity of the liquid must be taken into consideration. The procedure given here can be used for any class of pump—centrifugal, rotary, or reciprocating. 

Related Calculations. Use the techniques given here for any type of pump—centrifugal, reciprocating, or rotary—handling any type of liquid—oil, water, chemicals, etc. The methods given here are the work of Melvin Mann, as reported in Chemical Engineering, and Peerless Pump Div. of FMC Corp. 

Figure 5.7 shows that positive-displacement compressors, like vacuum pumps, are divided into two main classes reciprocating and rotary. Table 5.4 lists characteristics of these compressors. Ludwig [14] discusses compression equipment and calculation methods in detail. 

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