1. Water flows through an orifice of 25 mm diameter situated in a 75 mm diameter pipe, at a rate of 300 cm3/s. What will be the difference in level on a water manometer connected across the meter? The viscosity of water is 1 mN.s/m2.
2. Sulphuric acid of density 1300 kg/m3 is flowing through a pipe of 50 mm, internal diameter. A thin-lipped orifice, 10 mm in diameter is fitted in the pipe and the differential pressure shown on a mercury manometer is 0.1 m. Assuming that the leads to the anometer are filled with the acid, calculate (a) the mass flow rate of acid and (b) the approximate drop in pressure caused by the orifice in kN/m2. The coefficient of discharge of the orifice may be taken as 0.61, the density of mercury as 13,550 kg/m3 and the density of the water as 1000 kg/m3.
3. The rate of flow of water in a 150 mm diameter pipe is measured with a venturi meter with a 50 mm diameter throat. When the pressure drop over the converging section is 121 mm of water, the flowrate is 2.91 kg/s. What is the coefficient for the converging cone of the meter at this flowrate?
4. A rotameter tube is 0.3 m long with an internal diameter of 25 mm at the top and 20 mm at the bottom. The diameter of the float is 20 mm, its density is 4800 kg/m3 and its volume is 6.0 cm3. If the coefficient of discharge is 0.7, what is the flowrate of water (density 1000 kg/m3) when the float is halfway up the tube?
5. Water leaves the 25 mm diameter nozzle of a fire hose at a velocity of 25 m/s. What will be the reaction force at the nozzle which the fireman will need to counterbalance?
6. Water flows from a tap at a pressure of 250 kN/m2 above atmospheric. What is the velocity of the jet if frictional effects are neglected?
7. Ninety-eight per cent sulphuric acid is pumped at 4.5 tonne/h (1.25 kg/s) through a 25 mm diameter pipe, 30 m long, to a reservoir 12 m higher than the feed point. Calculate the pressure drop in the pipeline. Viscosity of acid = 25 mNs/m2 or 25 x 10-3 Ns/m2 Density of acid = 1840 kg/m3
8. Water flows in a 50 mm pipe, 100 m long, whose roughness e is equal to 0.013 mm. If the pressure drop across this length of pipe is not to exceed 50 kN/m2, what is the maximum allowable water velocity? The density and viscosity of water may be taken as 1000 kg/m3 and 1.0 mN s/m2 respectively.
9. (Exsample 3.6) Water flows at 7.2 m3/h through a sudden enlargement from a 40 mm to a 50 mm diameter pipe. What is the loss in head?
10. 2.27 m3/h water at 320 K is pumped in a 40 mm i.d. pipe through a distance of 150 m in a horizontal direction and then up through a vertical height of 10m. In the pipe there is a control valve for which the friction loss may be taken as equivalent to 200 pipe diameters and also other pipe fittings equivalent to 60 pipe diameters. Also in the line is a heat exchanger across which there is a loss in head of 1.5 m of water. If the main pipe has a roughness of 0.2 mm, what power must be supplied to the pump if it is 60 per cent efficient?
11. A simple U-tube manometer is installed across an orifice meter. The manometer is filled with mecury (specific gravity 13,6) and the liquid above the mecury is carbon tetrachloride (specific gravity 1,6). The manometer reads 200mm. What is pressure difference over the manometer in newton per square meter?
12. The temperature of the earth’s atmosphere drops 5oC for every 1000m of elevation above the earth’s surface. If the air temperature at ground level is 15oC and the pressure is 760 mmHg, at what elevation is the pressure 380 mmHg? Assume that the air behaves as an ideal gas?
13. How much error would be introduced in the answer to Prob.2.2 if the equation for hydrostatic equilibrium [Eq.(2.5)] were used, with the density evaluated at 0oC and an arithmetic average pressure?
14. A continuous gravity decanter is to separate chlorobenzene, with a density of 1109 kg/m3, from an aqueous wash liquid having a density of 1020 kg/m3. If the total depth in the height affect the position of the interface?
15. What should be the volume of the separetor in Prob.2.4 to separate 1600 kg/h chlorobenzene from 2100 kg/h of wash liquid? The wash liquid is to be the continuous phase; its viscovery is the same as that at that water at the operating temperature of 35oC.
16. A centrifuge bowl 250mm ID (interael diameter) is turning at 4000 r/min. It contains a layer of chlorobenzene 50 mm thick. If the density of the chlorobenzene is 1109 kg/m3 and the pressure at the liquid surface is atmospheric, what gauge pressure is exerted on the wall of the centrifuge bowl?
17. (Example 4.1) Crude oil, speccific gravity 60oF/60oF =0,887, flows through the piping shown in Fig. 4.2. Pipe A is 2-in. (50mm) Schedule 40, pipe B is 3-in. (75mm) Schedule 40, and each of pipes C is1,5-in. (38mm) Schedule 40. An equal quality of liquid flows through each of the pipes C. The flow through pipe A is 30gal/min (6,65 m3/h). Calculate (a) the mass flow rate in each pipe, (b) the average linear velocity in each pipe, and (c) the mass velocity in each pipe.
1. A single-acting (tác dụng đơn) reciprocating (kiểu pittong) pump has a cylinder (xy lanh) diameter of 110 mm and a stroke (khoảng chạy) of 230 mm. The suction line (ống hút) is 6 m long and 50 mm in diameter and the level of the water in the suction tank is 3 m below the cylinder of the pump. What is the aximum speed at which the pump can run without an air vessel if separation is not to occur in the suction line? The piston undergoes approximately simple harmonic motion. Atmospheric pressure is equivalent to a head of 10.36 m of water and separation occurs at an absolute pressure corresponding to a head of 1.20 m of water.
2. A centrifugal pump is required to circulate a liquid of density 800 kg/m3 and viscosity 0.5 x 10-3 Ns/m2 from the reboiler of a distillation column through a vaporiser at the rate of 0.004 m3/s, and to introduce the superheated vapour above the vapour space in the reboiler which contains a 0.07 m depth of liquid. If smooth-bore 25 mm diameter pipe is to be used, the pressure of vapour in the reboiler is 1 kN/m2 and the Net Positive Suction Head required by the pump is 2 m of liquid, what is the minimum height required between the liquid level in the reboiler and the pump?
3. 2.16 m3/h (600 x 10-6 m3/s) water at 320 K is pumped through a 40 mm i.d. pipe, through a length of 150 m in a horizontal direction, and up through a vertical height of 10 m. In the pipe there are a control valve, equivalent to 200 pipe diameters, and other pipe fittings equivalent to 60 pipe diameters. Also in the line is a heat exchanger across which the head lost is 2 m water. Assuming the main pipe has a roughness of 0.0002 m. what power must be supplied to the pump if it is 60 per cent efficient?
4. It is required to pump cooling water from a storage pond to a condenser in a process plant situated 10 in above the level of the pond. 200 m of 74.2 mm i.d. pipe is available and the pump has the characteristics given below. The head lost in the condenser is equivalent to 16 velocity heads based on the flow in the 74,2 mm pipe. If the friction factor 0 = 0.003, estimate the rate of flow and the power to be supplied to the pump assuming an efficiency of 50 per cent.
Discharge (m3/s) 0,0028 0,0039 0,005 0,0056 0,0059
Head developed (m) 23,2 21,3 18,9 15,2 11,0
5. In the equipment shown in Fig 4.6 (hình bên dưới), a pump draws a solution of specific gravity 1,84 from a storage tank through a 3-in. (75-mm) Schedule 40 steel pipe. The efficiency of the pump is 60 percent. The velocity in the suction line is 3 ft/s (1,194 m/s) The pump discharge a 2-in. (50-mm) Schedule 40 pipe to an overhead tank. The end of the discharge pipe is 50 ft (15,2m) above the level of the solution in the feed tank. Friction (ma sát) losses in the entire piping system are 10 ft-Ibs/Ib (29,9 J/kg). What pressure must the pump develop? What is the power of the pump?
6. (a) A water tank is 30 ft in diameter and the normol depth is 25 ft. The outlet is a 4-in. horizontal pipe at the bottom. If this pipe is sheared off close to the tank? (Neglect friction loss in the short stub of pipe).
(b) How long will it take for the tank to be empty?
(c) Calculate the average flow rate and compare it with the initial flow rate?
7. Water at 20oC is pumped at a constant rate of 9 m3/h from a large reservoir (bể chứa) resting (tựa) on the floor to the open top of an experimental absorption (hấp thụ) tower (đài, tháp). The point of discharge is 5 m above the floor, and frictional (ma sát) losses in the 50-mm pipe from the reservoir to the tower amount to 2,5 J/kg. At what height in the reservoir must the water level be kept if the pump can develop only 0,1 kW?
8. Water enters a 100-mm-ID 90o elbow (khuỷu), positioned in a horizontal plane (mặt phẳng nằm ngang) at a velocity of 6 m/s and a pressure of 70 kN/m2 gauge (áp kế). Neglecting (bỏ qua) friction (ma sát), what are the magnitude (độ lớn) and the direction (hướng) of the force that must be applied to the elbow to keep it in position without moving?