Instrumentasi Industri dan Kontrol Proses, oleh Ir. Sutarno, M.Sc. Hak Cipta © 2014 pada penulis GRAHA ILMU Ruko Jambusari 7A Yogyakarta 55283 Telp: 0274-882262; 0274-889398; Fax: 0274-889057 E-mail:
[email protected] Hak Cipta dilindungi undang-undang. Dilarang memperbanyak atau memindahkan sebagian atau seluruh isi buku ini dalam bentuk apa pun, secara elektronis maupun mekanis, termasuk memfotokopi, merekam, atau dengan teknik perekaman lainnya, tanpa izin tertulis dari penerbit. ISBN: 978-602-262-228-4 Cetakan ke I, tahun 2014
KATA PENGANTAR
P
uji dan syukur ke hadirat Allah SWT atas limpahan rahmat dan hidayah-Nya sehingga buku ini dapat terselesaikan.
Instrumentasi dan kontrol proses melibatkan berbagai teknologi dan disiplin ilmu, dan mereka digunakan dalam jumlah yang belum pernah terjadi dalam aplikasi sebelumnya. Contohnya menjangkau mulai dari kontrol pemanasan, pendinginan, dan sistem pemanas air di rumah tangga dan kantor untuk instrumentasi dan proses kimia dan kontrol otomotif. Buku ini dirancang untuk mencakup semua aspek instrumentasi industri, seperti penginderaan berbagai variabel, transmisi dan pencatatan sinyal penginderaan, pengendali untuk evaluasi sinyal, dan pengendalian proses manufaktur untuk kualitas dan penyeragaman produk. Bab 1 memberikan pengantar untuk instrumentasi industri. Bab 2 dan Bab 3 menyegarkan pengetahuan pembaca tentang dasar-dasar listrik dan memperkenalkan rangkaian listrik untuk digunakan dalam instrumentasi. Sensor dan penggunaannya dalam pengukuran berbagai variabel seperti pengukuran suhu, tekanan, ketinggian permukaan fluida (lvel), aliran, dan kelembaban, dibahas dalam Bab 3 sampai 8. Akhirnya, dalam Bab 9, dibahas mengenai proses kontrol dengan beberapa metode dan peralatan yang biasa digunakan di industri. Dalam setiap bab beberapa contoh soal dan soal-soal latihan berkaitan dengan topik bahasan. Diharapkan buku ini dapat membantu setiap pembaca dalam memahami Instrumentasi dan Proses Kontrol dan dijadikan sarana untuk memperluas cakrawala dalam bidang Instrumentasi industri.
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Instrumentasi Industri dan Kontrol Proses
Kami menyadari bahwa buku ini sangat jauh dari kesempurnaan, sehingga masih terdapat kekurangan-kekurangan baik dari segi penyajian maupun isinya. Oleh karena itu kritik maupun saran dari semua pihak sangat diharapkan. Terima kasih kepada semua pihak yang telah membantu penyusunan buku ini. Semoga Tuhan Yang Maha Kuasa memberikan rahmat dan hidayah-Nya kepada kita semua.
Yogyakarta, Mei 2014 Penyusun
Sutarno
DAFTAR ISI
KATA PENGANTAR .............................................................................................................................
v
DAFTAR ISI ..........................................................................................................................................
vii
BAB I.
PENDAHULUAN ..................................................................................................................
1
1.1 Pengertian dan Fungsi Instrumentasi ...............................................................................
1
1.2 Standar dan Satuan Pengukuran ......................................................................................
2
1.3 Definisi dan Konsep Pengukuran ....................................................................................
4
1.3.1
BAB II.
Pengukuran.........................................................................................................
4
1.4 Karakteristik Instrumentasi ..............................................................................................
9
1.4.1
Karakteristik Statis ...............................................................................................
9
1.4.2
Karakteristik Dinamis ..........................................................................................
9
1.4.3
Respons Dinamik Instrumen Order Nol ..............................................................
9
1.4.4
Respons Dinamik Instrumen Order Satu..............................................................
10
1.4.5
Respons Dinamik Instrumen Order Dua .............................................................
10
KOMPONEN DASAR LISTRIK ................................................................................................
15
2.1 Arus Listrik......................................................................................................................
15
2.2 Tegangan Listrik..............................................................................................................
16
2.3 Tahanan Listrik ...............................................................................................................
17
2.3.1
Resistor ...............................................................................................................
17
2.3.2
Tahanan Kombinasi ............................................................................................
20
2.3.3
Sensor Resistif .....................................................................................................
25
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Instrumentasi Industri dan Kontrol Proses
2.4 Kapasitansi......................................................................................................................
25
2.4.1
Formula Capacitor ..............................................................................................
25
2.4.2
Kapasitor Kombinasi ...........................................................................................
27
2.5 Induktansi .......................................................................................................................
29
2.5.1
Formula Induktor ................................................................................................
29
2.5.2
Induktor Kombinasi.............................................................................................
30
BAB III. ELEKTRONIKA ANALOG .......................................................................................................
33
3.1 Pendahuluan...................................................................................................................
33
3.2 Rangkaian Analog...........................................................................................................
33
3.2.1
Penguat Operasional atau Operasional Amplifier (Op-Amp)................................
33
3.2.2
Pengertian Dasar Op-Amp ..................................................................................
34
3.2.3
Diagram Op-Amp ...............................................................................................
35
3.2.4
Penguatan Open-Loop ........................................................................................
36
3.2.5
Unity-Gain Frequency.........................................................................................
36
3.2.6
Slew Rate............................................................................................................
36
3.3 Parameter CMRR ............................................................................................................
37
3.3.1
Op-Amp Ideal .....................................................................................................
37
3.3.2
Penguat Inverter (Inverting Amplifier)..................................................................
38
3.3.3
Penguat Non-Inverter ..........................................................................................
39
3.3.4
Integrator ............................................................................................................
40
3.3.5
Differensiator ......................................................................................................
42
3.4 Aplikasi Op-Amp dalam Kontrol Proses ..........................................................................
43
BAB IV. PENGUKURAN SUHU...........................................................................................................
47
4.1 Pendahuluan...................................................................................................................
47
4.2 Definisi-definisi ..............................................................................................................
47
4.2.1
Definisi Suhu ......................................................................................................
47
4.2.2
Definisi Panas .....................................................................................................
48
4.2.3
Definisi Ekspansi Termal .....................................................................................
51
4.3 Suhu dan Rumus Panas...................................................................................................
51
4.3.1
Suhu ...................................................................................................................
51
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Daftar Isi
BAB V.
4.3.2
Perpindahan Panas..............................................................................................
52
4.3.3
Ekspansi (Pemuaian) Panas..................................................................................
53
4.4 Termometer Tekanan Spiral (Pressure-Spring Thermometers) ..........................................
54
4.5 Resistance Temperature Device (RTD) ............................................................................
55
4.6 Termistor ........................................................................................................................
56
4.7 Termokopel ....................................................................................................................
56
4.8 Instalasi...........................................................................................................................
61
4.9 Kalibrasi..........................................................................................................................
61
4.10 Pengamanan ...................................................................................................................
61
PENGUKURAN TEKANAN ....................................................................................................
63
5.1 Pendahuluan...................................................................................................................
63
5.2 Definisi-definisi...............................................................................................................
64
5.3 Pengukuran Tekanan ......................................................................................................
65
5.4 Formula Tekanan ............................................................................................................
66
5.5 Instrumen Pengukuran ....................................................................................................
69
5.5.1
Manometer .........................................................................................................
69
5.5.2
Diafragma, Kapsul, dan Bellow ...........................................................................
71
5.5.3
Tabung Bourdon .................................................................................................
73
5.5.4
Sensor Tekanan Lain ...........................................................................................
74
5.5.5
Instrumen Vacuum..............................................................................................
75
5.6 Pertimbangan Aplikasi ...................................................................................................
75
5.6.1
Seleksi ................................................................................................................
75
5.6.2
Instalasi...............................................................................................................
76
BAB VI. PENGUKURAN KETINGGIAN PERMUKAAN CAIRAN (LEVEL) ..............................................
79
6.1 Pendahuluan...................................................................................................................
79
6.2 Rumus Level ...................................................................................................................
79
6.3 Perangkat Pengenderaan Level........................................................................................
81
6.3.1
Pengukuran Level Langsung ................................................................................
81
6.3.2
Pengukuran Level Tidak Langsung ......................................................................
85
6.4 Pertimbangan Aplikasi ....................................................................................................
88
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Instrumentasi Industri dan Kontrol Proses
BAB VII. PENGUKURAN ALIRAN (FLOW) ...........................................................................................
91
7.1 Pendahuluan...................................................................................................................
91
7.2 Dasar Istilah....................................................................................................................
91
7.3 Formula Aliran................................................................................................................
93
7.3.1
Persamaan Kontinuitas ........................................................................................
93
7.3.2
Persamaan Bernoulli ...........................................................................................
95
7.3.3
Kerugian Aliran ...................................................................................................
97
Instrumen Pengukuran Aliran .......................................................................................
99
7.4.1
Laju Aliran ..........................................................................................................
99
7.4.2
Aliran Total .........................................................................................................
103
7.4.3
Aliran Massa .......................................................................................................
104
7.4.4
Laju Aliran Partikel Kering...................................................................................
104
7.4.5
Aliran Saluran Terbuka (Open Channel Flow) .....................................................
105
7.5 Pertimbangan Aplikasi ....................................................................................................
105
7.4
7.5.1
Seleksi ................................................................................................................
105
7.5.2
Instalasi...............................................................................................................
107
7.5.3
Kalibrasi..............................................................................................................
107
BAB VIII. PENGUKURAN KELEMBABAN, KERAPATAN (DENSITAS), VISKOSITAS, DAN pH ...............
109
8.1 Pendahuluan...................................................................................................................
109
8.2 Kelembaban....................................................................................................................
109
8.2.1
Definisi Kelembaban...........................................................................................
109
8.2.2
Grafik Psychrometrics .........................................................................................
110
8.3 Alat Ukur Kelembaban....................................................................................................
111
8.3.1
Higrometer .........................................................................................................
111
8.3.2
Psychrometers.....................................................................................................
113
8.3.3
Alat Ukur Titik Embun ........................................................................................
113
8.3.4
Pertimbangan Aplikasi Kelembaban ....................................................................
114
8.4 Kerapatan dan Berat Jenis................................................................................................
114
8.4.1
Dasar Istilah ........................................................................................................
114
8.4.2
Alat Ukur Kerapatan............................................................................................
115
