Transcript Slide 1
Exercise Problem No. 5
Figure below shows a diagram of fluid power system for a hydraulic press used to
extrude rubber patrs. The following data are known :
1. The fluid is oil (sg =0,93), Volume flow rate is 175 gal/min
2. Power input to the pump is 28.4 hp, Pump efficiency is 80 %
3. Energy loss from point 1 to 2 is 2.80 lb-ft/lb, from point 3 to 4 is 28.50 lb-ft/lb and
from point 5 to 6 is 3.50 lb-ft/lb
a). Compute the power removed from the fluid by the press
b). Compute the pressure at point 3 at the pump outlet
c). Compute the pressure at point 5 at the press outlet
Answer :
a). 21.16 hp
b). 219,1 psig
c). 1.01 psig
Jawab :
m
0,3048m
3,281ft
m
h L h L1 2 h L 3 4 h L 56 (2,80 28,50 3,50) 34,8 ft
10,61m
3,281ft
N
g 0,93(1000)(9,81) 9123,3 3
m
p6
V62
V62
p1
V12
z1
hA hR hL
z6
h R h A h L z6
2g
2g
2g
p1 Po
p 6 Po
z1 0 V1 0 z 6 1 ft
m3
gal
m3
1
s
Q 175
0,011 D 6 2 in A 6 3,090x103 m 2
min 15850gal
s
2
745,7 W
P
16942,3
PA 0,8(28,4 ) 22,72 hp
16942,3W h A Q h A A
168,82 m
hp
Q 9123,3(0,011)
V62
Q
0,011
m
5,562
V6
5,56
1,576m
3
A 3,090x10
s
2g 2(9,81)
h R 168,82 10,61 0,3048 1,576 156,329m PR h R Q 9123,3(156,329)(0,011) 15668,6 W
PA 15668,6 W
hp
21,012hp
745,7 W
b).
h L1 2
m
m
2,80 ft
0,853m z 3 4 ft
1,219m
3,281
3,281
V32 V62
1,576m
2g 2 g
p3
V32
p1
V12
z1
h A h R h L z3
2g
2g
p 3 p1
V32
h A h L1 2 z 3
168,82 1,219 0,853 1,576 165,172m
2g
psig
p 3 p1 165,172(9123,3) 1506913Pa
218,6 psig
6895P a
c).
h L56 3,50 ft
m
m
1,067m z 5 2 ft
0,61m z 6 0,3048 V5 V6
3,281
3,281
p5
V52
p6
V62
z5
h A h R h L z6
2g
2g
p5 p6
z 6 h L56 z 5 0,3048 1,067 0,61 0,762m
psig
p 5 p 6 0,762(9123,3) 6950Pa
1,01psig
6895P a
p6 po
Soal Kuis 2
Gambar di bawah ini adalah suatu bagian dari sistem pemadam kebakaran dimana
pompa menarik air pada 50oFdengan debit 1500 gal/min dari suatu reservoir dan
mengeluarkannya ke titik B. Kehilangan energi antara reservoir dan titik A adalah 0,65
lblb.ft/lb.
a). Tentukan kedalaman h untuk mempertahankan tekanan paling sedikit 5 psig pada
titik A. [12,8 ft]
b). Bila titik A tekanannya 5 psig tentukan daya pompa yang diperlukan agar tekanan di
B adalah 85 psig. Kehilangan energi antara pompa dan titik B adalah 28 lb.ft/lb
[90 hp]
N
3
lb
N
m
62,4 3
9803 3
lb
ft
m
3
ft
m3
gal
m3
s
Q 1500
0,0946
min 15850 gal
s
min
D 10in A A 5,090x10 2
157,1
1
2
D 8 in A B 3,226x10 2
VA
Q
0,0946
m
1
,
859
A A 5,090x10 2
s
m
0,198m
3,281
6895P a
p A p o 5psig
34475P a
psig
h L1 0,65ft
p1
V12
pA
VA2
z1
h L1
zA
2g
2g
p1 p o
V1 0 z A 0 z1 h
pA po
VA2
h
h L1
2g
34475
1,8592
3,281ft
0,198
3,517 0,198 0,176 3,891m
12,8 ft
9803
2(9,81)
m
N
9803 3
m
m3
Q 0,0946
s
m
8,534m
3,281
6895P a
p A p o 5psig
34,475x103 P a
psig
h L 2 28ft
p A 34,475x103 101,3x103 1,358x105 P a
m
7,62m
3,281ft
6895P a
p B p 0 85psig
586,075x103 P a
psig
z B 25ft
p B 586,075x103 101,3x103 687,375x103 P a
p2
V22
pB
VB2
z2
h L2
zB
2g
2g
z 2 0 V2 VB
p 2 p B (h L 2 z B ) 9803(8,534 7,62) 1,583x105 P a
p 2 1,583x105 687,375x103 8,45x105 P a
p 2 p A 8,45x105 1,358x105
hA
72,345m
9803
hp
PA h A Q 9803(72,345)(0,0946) 6,709x104 W
90hp
745,7 W
pA
p
hA 2
Exercise Problem No. 6
Professor Crocker is building a cabin on a hillside and has proposed the water system
shown in figure below. The distribution tank in the cabin maintain a pressure of 30 psig
above the water. There is an energy loss of 15.5 lb-ft/lb in the piping. The pump is
delivering 40 gal/min of water.
If the pump has an efficiency of 72%, what size motor is required to drive the pump ?
Answer : 42,8 hp