Chum pressure

Types of Pumps. The two major type pumps are vertical turbine and horizontal split case. The horizontal fire pumps are designed to take suction from an above-ground reservoir or be used as booster pumps. It is important that these pumps not be used for suction under lift. Horizontal fire pumps are traditionally designed to chum at 120% of rated capacity. They will have a rated capacity for volume and pressure and they will provide 150% of the rated volume at 65% of rated pressure. Present codes now allow the chum pressure to reach 140% of rated pressure. 

Many plants consider using ordinary domestic water pumps. The domestic water pumps will differ from UL listed pumps and should not be used. The chum pressure is usually much greater than the design pressure. When you exceed the designed flow of a domestic water pump, the pressure drops off very rapidly and the pump does not work efficiently. If you compared the curves of a domestic pump and a UL listed fire pump, a 1,000 gpm at 125 psi fire pump would have a similar curve to a 1,500 gpm at 81 psi domestic water pump. 

At high flowrates when chum flow sets in, the pressure drop undergoes a sudden increase and the coefficient in equation 8.57 increases ... 

Figure 5.3-8. Details of the chum-turbulent flow regime of BSCR according to Inga [1], (db)0-gas bubble size at atmospheric conditions in the absence of solid particles, (d, )ps- bubble size at the operating pressure and catalyst concentration. Column height = 2.8 m, internal diameter = 0.316 m. P < 8 bars. Organic media, catalyst diameter < 100 pm.

Only some scattered information on the influence of pressure and gas density on k a is available. Recently, Dewes et al. [51] reported results from a 0.115m diameter column operated in all but the chum-turbulent regime, both at 1 bar and 8 bar, with 2 vol% of solids. The influence of solids was negligible (see Fig. 8), but, as expected from Wilkinson s findings on the influence of pCl on r< [44], A Ltf increased substantially with pressure. Dewes et al. [51] were able to show that the pressure affected a only, with A l- remaining independent of both pressure and the presence of solids. 

Oral administration of hydrolysates (doses of 500 and 2000mg/kg of body weight) from upstream chum salmon muscle prepared with thermolysin resulted in significant reductions in the blood pressure of SHRs in comparison with control rats. Blood pressure in SHRs remained significantly lower than control rats for up to 8h, with the maximum reduction occurring 4h after administration, and levels returning to normal after 24h (Ono et al., 2003). This trend implies that the key constituents of the hypotensive effect were likely short-chain peptides from protein hydrolysates. In contrast, if the main... 

Three-phase fluidized beds and slurry reactors (see Figs. 30g-l) in which the solid catalyst is suspended in the liquid usually operate under conditions of homogeneous bubbly flow or chum turbulent flow (see regime map in Fig. 33). The presence of solids alters the bubble hydrodynamics to a significant extent. In recent years there has been considerable research effort on the study of the hydrodynamics of such systems (see, e.g., Fan, 1989). However, the scale-up aspects of such reactors are still a mater of some uncertainty, especially for systems with high solids concentration and operations at increased pressures it is for this reason that the Shell Middle Distillate Synthesis process adopts the multi-tubular trickle bed reactor concept (cf. Fig. 30e). The even distribution of liquid to thousands of tubes packed with catalyst, however poses problems of a different engineering nature. 

Two-phase valve flow can he caused either by entrainment or because the vessel becomes two-phase full. In the entrained case, mist/droplet flow usually results. If the vessel becomes two-phase full, chum-turbulent, bubbly two-phase flow through the valve may occur. In any case, the choke pressure for such flows is greater, and the choke velocity substantially less, than those for any prior superheated vapor flow. The pressure-relieving capacity of the valve can now become compromised as the two-phase fluid exits with a much lower enthalpy. 

The vertical turbine pumps appear to be used for suction under lift. In reality, they are also under head because the impeller is below the water level. This can be used for suction from wells and below grade reservoirs, and are sometimes configured into can pumps. These pumps will chum at 140% of rated pressure. They can also provide 150% of volume at 65% of rated pressure. 

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