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Pertemuan 21 Pompa. Matakuliah : S0634/Hidrologi dan Sumber Daya Air Tahun : 2006 Versi : <<versi/revisi>>. Learning Outcomes. Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : Mahasiswa dapat menghubungkan antara aliran dalam pipa dan jaringannya yang menggunakan sistem pompa.
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Pertemuan 21Pompa Matakuliah : S0634/Hidrologi dan Sumber Daya Air Tahun : 2006 Versi : <<versi/revisi>>
Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : • Mahasiswa dapat menghubungkan antara aliran dalam pipa dan jaringannya yang menggunakan sistem pompa
Outline Materi • Materi 1: Sistem Pompa
Pompa Daya dari suatu pompa Daya = kilowatt = T = γQh(satuan internasioanal) Q= debit , h= tinggi hisap bersih Specipic speed Pump performance parameters (vary from to pump) Rotational speed Discharge capacity Pumping head Power applied Efficiency Kombinasi dari 3 parameter diatas merupakan kecepatan spesifik Specific speed is the same for geometrically similar pumps (homologous) Ns= NQ0,5/H3/4,Ns = kecepatan spesifik, N=kecepatan putaran (rpm), H=tinggi total Nilai kecepatan spesifik daapat berubah dibawah kondisi operasi. For classification we use the specific speed at maximum efficiency Features of specific speed: Efficiency drops for Ns < 1000 Efficiency is low for Ns > 5000 Efficiency is high for medium range Ns
Geometrically simillar pumps • Q2 /Q1 = (N2/N1)(D2/D1)2 • H2 /H1 = (N2/N1)2(D2/D1)2 • P2 /P1 = (N2/N1)3(D2/D1)5 • Q=kapasitas • H=Tinggi • D=diameter • N=Kecepatan putaran • P= Daya
Istilah tinggi dalam pompa • Tinggi isap statis (static suction lift) : Jarak vertikal dari muka air dalam tanki air sampai pusat pompa. • Tinggi debit statis (static discharge head) : Jarak vertikal dari pusat pompa sampai muka air tanki keluar (discharge tank) • Total static head: sum of total static suction lift and static discharge head • Total dinamic head: sum of total static head and friction and minor losses: • Hp = Δz + hloss • Hp = Δz + f(L/D)(V2/2g) + ΣK(V2/2g) • Hp = Δz + (0.81/g){(fLQ2/D5 )+ΣK(Q2/D4 )}
Pump characteristic curves Derived from actual test (pump factory): • Pumping Head vs. Discharge • Brake HorsePower vs. Discharge • Efficiency vs. Discharge Curve shape varies with pump size, speed,design. Increase in head reuces capacity. There is capacity where efficiency is MAX There is capacity where HP is MAX • γQH • HP=--------- • 550h • Q(cfs) • H(ft) • γ =62,4 • h =efficiency
Single pump and pipeline system • SUITABILITY OF PUMP:Superimpose System Head Curve (Piping System) on the Head-Capacity Curve (pump). • Intersectin is operating point. • Check efficiency at this point. If too low consider another pump
Multiple pump system • Single pump: Suitable for narrow range of head and discharge. • Multiple pumps: Fluctuations of operating conditions are considerable or Head or Capacity requirement is too high for a single pump.
