utilitas (pak sudarminto)
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Utilitas
Dr. Ir. Sudarminto Setyo Yuwono, M.App.Sc
UTILITAS
• Utilitas merupakan unit pokok dalam prasarana produksi.
• Air
• Steam
• Listrik
• Bahan bakar
Air
• Sumber air
• Air tanah : sanitasi pekerja, air ketel, air cadangan
• Air PDAM : proses produksi, sanitasi peralatan
• Persyaratan air
Kebutuhan daya pompa
• Digunakan untuk:
– Menggerak air (energi kinetik) = (v2/2) x faktor kehilangan energi pada tikungan dan sambungan
– Mengangkat air (energi potensial) = gh
– Mengatasi hambatan (gesekan) = (4ƒv2/2) x (L/D)
TABLE 3.1RELATIVE ROUGHNESS FACTORS FOR PIPES
MaterialRoughness factor
(e) Material
Roughness factor
(e)
Riveted steel 0.001- 0.01Galvanized
iron0.0002
Concrete 0.0003 - 0.003Asphalted
cast iron0.001
Wood staves 0.0002 - 0.003Commercial
steel0.00005
Cast iron 0.0003 Drawn tubing Smooth
Friction factors in pipe
TABLE 3.2FRICTION LOSS FACTORS IN FITTINGS
k
Valves, fully open:
gate 0.13
globe 6.0
angle 3.0
Elbows:
90° standard 0.74
medium sweep 0.5
long radius 0.25
square 1.5
Tee, used as elbow 1.5
Tee, straight through 0.5
Entrance, large tank to pipe:
sharp 0.5
rounded 0.05
Contoh
• Pompa untuk menaikkan air setinggi 22 m dengan debit 1,2 m3/menit. Pipa dari galvanis berdiameter 15 cm dengan panjang 120m. Jika ada 8 tikungan berapa kebutuhan daya pompa.
Reynold number
• Assume properties of water at 20°C are density 998 kg m-3, and viscosity 0.001 N s m-2
• Cross-sectional area of pipe A = (π/4)D2
= π /4 x (0.15)2= 0.0177 m-2
Volume of flow V = 1.2 m3 min-1= 1.2/60 m3 s-1= 0.02 m3 s-1.
• Velocity in the pipe = V/A= (0.02)/(0.0177) = 1.13 ms-1
• Now (Re) = Dvρ/µ• = (0.15 x 1.13 x 998)/0.001
= 1.7 x 105
so the flow is clearly turbulent.
friction loss of energy
From Table 3.1, the roughness factor ε is 0.0002 for
galvanized iron
and so
roughness ratio ε /D = 0.0002/0.15 = 0.001
So from Fig. 3.8,
ƒ = 0.0053
Therefore the friction loss of energy
= (4ƒv2/2) x (L/D)
= [4ƒv2L/2D]
= [4 x 0.0053 x (1.13)2 x 120]/(2 x 0.15)
= 10.8 J.
TABLE 3.1RELATIVE ROUGHNESS FACTORS FOR PIPES
MaterialRoughness factor
(e) Material
Roughness factor
(e)
Riveted steel 0.001- 0.01Galvanized
iron0.0002
Concrete 0.0003 - 0.003Asphalted
cast iron0.001
Wood staves 0.0002 - 0.003Commercial
steel0.00005
Cast iron 0.0003 Drawn tubing Smooth
Friction factors in pipe
TABLE 3.2FRICTION LOSS FACTORS IN FITTINGS
k
Valves, fully open:
gate 0.13
globe 6.0
angle 3.0
Elbows:
90° standard 0.74
medium sweep 0.5
long radius 0.25
square 1.5
Tee, used as elbow 1.5
Tee, straight through 0.5
Entrance, large tank to pipe:
sharp 0.5
rounded 0.05
• For the eight right-angled bends, from Table 3.2 we would expect a loss of 0.74 velocity energies at each, making (8 x 0.74) = 6 in all.
velocity energy = v2/2= (1.13)2/2= 0.64 J
• So total loss from bends and discharge energy= (6 + 1) x 0.64 = 4.5 J
There would be one additional velocity energy loss because of the unrecovered flow energy discharged into the reservoir.
Energy loss from bends and discharge
Energy to move 1 kg water
• Energy to move 1 kg water against a head of 22 m of water is
E = Zg= 22 x 9.81= 215.8 J.
• Total energy requirement per kg:Etot = 10.8 + 4.5 + 215.8
= 231.1 J
energy requirement of pump
• and theoretical power requirement= Energy x volume flow x density= (Energy/kg) x kgs-1= 231.1 x 0.02 x 998= 4613 J s-1.
• Now the head equivalent to the energy requirement= Etot/g= 231.1/9.81= 23.5 m of water,
•
TABLE 3.2FRICTION LOSS FACTORS IN FITTINGS
k
Valves, fully open:
gate 0.13
globe 6.0
angle 3.0
Elbows:
90° standard 0.74
medium sweep 0.5
long radius 0.25
square 1.5
Tee, used as elbow 1.5
Tee, straight through 0.5
Entrance, large tank to pipe:
sharp 0.5
rounded 0.05
TABLE 3.1RELATIVE ROUGHNESS FACTORS FOR PIPES
MaterialRoughness factor
(e) Material
Roughness factor
(e)
Riveted steel 0.001- 0.01Galvanized
iron0.0002
Concrete 0.0003 - 0.003Asphalted
cast iron0.001
Wood staves 0.0002 - 0.003Commercial
steel0.00005
Cast iron 0.0003 Drawn tubing Smooth
Friction factors in pipe
Listrik
LOKASI LUAS (m2) CANDL
E
LUMEN
Taman
Kantin
Mushola
Laboratorium
Perkantoran dan TU
Toilet
Area penyimpanan
produk
Area Proses
Area Penerimaan dan
Pengeluaran Bahan Baku
30,4
13,57
50,53
20
129,50
10
30
130
36
5
6
9
15
34
2
25
36
10
152
81,42
454,77
300
4403
20
750
4680
360
PERHITUNGAN JUMLAH LAMPU
• N= (E.A)/Qlampu.Cu.LLF
• KETERANGAN:
• N = JUMLAH LAMPU
• E =KEKUATAN PENERANGAN(LUX)
• A =LUAS AREA
• QLAMPU =BESAR LUMEN DARI LAMPU
• Cu =KOEFESIEN OF UTILITYè 0.5(STANDART)
• LLF =LIGHT LOST FILTER è 0.7(STANDAR)
• Untuk sistem penerangan langsung dengan warna plafon dan dinding terang, CU ( coeffesien of utilization ) –nya 50-65 %. Light loss factor ( LLF ) = 0,7-0,8. LLF tergantung ; kebersihan sumber cahaya, tipe kap lampu, penyusutan cahaya dari permukaan lampu, dll.
• Suatu ruang laboratorium di pabrik berukuran 20 x 20 m. Direncanakan dipasang lampu TL 36 watt. Berapa buah lampu TL yang dbutuhkan?
• E= 500 LUX
• A=20 x 20 METER= 400 METER2
• QLAMPUè 1 WATT = 75 LUMEN
• 36 WATT = 2700 LUMEN
• Cu = 0.5 (STANDART UNTUK Cu)
• LLF = 0.7
• N= (E.A)/Qlampu.Cu.LLF
• N= (500.400)/(2700.0.5.0.7)
• = 211,64
• DIBUTUHKAN 212 LAMPU PADA RUANGAN TERSEBUT
• Contoh perhitungan : ruangan kantor berukuran 20 x 10 x 3 m direncanakan memakai TL 4 x 40 watt dengan penerangan E = 300 lux. Hitung, jumlah lampu dan daya listrik yang dibutuhkan.
• Penyelesaian : dari tabel,
• Untuk 1 bh TL 40 watt, jumlah lumen = 40 x 75 = 3000 lumen. Untuk 4 TL 40 watt, jumlah lumen = 4 x 3000 = 12.000 lumen.
• Dipilih CU 60 % dan LLF 0,8
• Jumlah lampu yang dibutuhkan ( N ) = E x A dibagi lampu x CU x LLF = 300 x 200 dibagi 12000 x 0,6 x 0,8 = 10,4
• Jadi N = 11 buah 4 x TL 40 watt. Pemakaian watt untuk lampu TL 40 watt termasuk ballast = 50 watt. Jumlah beban dari lampu = 11 x 4 x 50 watt = 2200 watt. Untuk stop kontak peralatan kantor diperhitungkan 20 % dari beban lampu = 20 % x 2200 watt = 440 watt. Total kebutuhan watt = 2640 watt, atau watt/m2 = 13, 4.
RUANG FC LUAS RUANG(ft²)
LUMEN
(FCxLUAS)
KANTOR 30 1184,07 35522,1
PROSES 20 10764,26 215285,2
TOILET 10 775,03 7750,3
LABORATORIUM 30 322,93 9687,9
GUDANG 10
BAHAN BAKU 1614,64 16146,4
BAHAN TAMBAHAN 645,86 6458,6
COOL STORAGE 4305,71 43057,1
MUSHOLA 10 258,34 2853,4
PARKIR 10
RODA 2 430,57 4305,7
MOBIL 645,86 6458,6
RUANG GANTI 10 322,93 3229,3
JALAN+HALAMAN 5 3229,28 16146,4
PEMBUANGAN LIMBAH 5 322,93 1614,65
TOTAL 368245,65
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