Tugas Mekanika Fluida dari Lab CCIT Kukusan, 4 Maret 2023, Darell Jeremia Sitompul

Pada hari Sabtu, 4 Maret 2023 lalu, saya pergi ke Lab CCIT Kukusan untuk mempelajari lebih lanjut tentang alat-alat pengukuran tekanan.

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Ketika saya mengikuti kegiatan belajar di Lab CCIT Kukusan, saya mendapatkan banyak pelajaran yang menarik dan interaktif, disana kami mempelajari bahwa terdapat beragam jenis alat pengukuran tekanan.

Contoh dari alat pengukur tekanan adalah

1. Manometer analog,

2. Manometer tipe U, dan

3. Pressure transducer.

Manometer analog bekerja dengan prinsip menggerakkan jarum sesuai dengan besaran tekanan yang diukurnya.

Dalam sebuah manometer analog, terdapat sebuah fluida yang terjebak di bagian bawah tabung manometer, dan ketika terdapat udara berkecepatan tertentu maka udara tersebut akan mendorong fluida di dalam tabung manometer sehingga air di tabung manometer naik dan mendorong jarum manometer sejauh angka tekanan yang diindikasikan (diukur) oleh manometer tersebut.

Pencatatan data pengukuran dilakukan secara manual dengan melihat arah jarum manometer analog tersebut.

Manometer tipe U mengandalkan perhitungan menggunakan persamaan

P(gas) = P(udara bebas) + ρ.g.Δh

P(gas) - P(udara bebas) = ρ.g.Δh

ΔP = ρ.g.Δh

dimana hasil pengukuran perbedaan tekanan bergantung pada jenis fluida yang digunakan, percepatan gravitasi, dan perbedaan ketinggian fluida.

Pressure transducer memanfaatkan prinsip data acquisition, dimana tekanan yang diukur dicatat dalam bentuk data secara online atau real-time melalui sebuah program dan menyimpan data tersebut di perangkat komputer.

Selain macam-macam alat pengukur tekanan, kami juga mempelajari sistem penyaluran udara yang digunakan dan diperagakan Kakak pengajar di lab CCIT kukusan. Jika kita meletakkan alat pengukur di dekat alat peniup udara, tekanan yang diukur semakin besar, dan jika posisi pengukuran dilakukan di ujung sistem saluran udara (dekat ujung pipa yang berhubungan dengan udara bebas), maka pengukuran tekanan yang didapatkan sangat kecil (mendekati nol).

Hasil pengukuran yang mendekati nol disebabkan karena ujung saluran udara yang terhubung ke udara bebas terdapat tekanan udara bebas yang berusaha menekan masuk ke dalam pipa. Maka semakin dekat posisi pengukuran dengan udara bebas dibandingkan dengan posisi peniup udara, maka semakin kecil perbedaan tekanan yang diukur.

Alat pengukur tekanan dapat mengalami error atau kerusakan sehingga menyebabkan kesalahan pengukuran. Alat pengukuran yang rusak tersebut dapat diperbaiki dengan cara dikalibrasi (diperbaiki sesuai error yang dihasilkan alat tersebut), dan diverifikasi (memastikan bahwa seluruh hasil pengukurannya sudah sesuai standar).

Masing-masing alat ukur memiliki akurasi yang berbeda. Contohnya manometer analog memiliki skala terkecil sebesar 1.25 mbar, lalu pressure transducer memiliki skala yang detail dan range yang cukup besar (~ 0-10 Bar), dan manometer tabung U memiliki skala terkecil pengukuran sebesar 1000 . 9,81 . 0.001 = 9.81 Pa = 0.0981 mbar

Soal perhitungan.

Pada percobaan pengukuran tekanan menggunakan manometer analog, didapatkan nilai tekanan sebesar 3 mbar.

Jika percobaan dilakukan pada manometer tabung U dengan percepatan gravitasi dimisalkan 10m/s^2, hitunglah perbedaan ketinggian yang dihasilkan

(a). Jika fluida yang digunakan adalah minyak dan raksa.

(b). Menggunakan fluida yang disebutkan pada poin (a), tetapi dengan tekanan 30 mbar (sesuai perhitungan maksimum perbedaan tekanan menggunakan penggaris/apabila fluidanya naik 30 cm).

Jawab

(a). Jika fluida nya adalah minyak

3mbar = 800 kg/m^3 . 10 m/s^2 . Δh

300 Pascal = 800 kg/m^3 . 10 m/s^2 . Δh

Δh = 0.0375 m

Jika fluida nya adalah raksa

3mbar = 13600 kg/m^3 . 10 m/s^2 . Δh

300 Pascal = 13600 kg/m^3 . 10 m/s^2 . Δh

Δh = 0.0022 m

(b). Jika fluida nya adalah minyak

30mbar = 800 kg/m^3 . 10 m/s^2 . Δh

3000 Pascal = 800 kg/m^3 . 10 m/s^2 . Δh

Δh = 0.375 m

Jika fluida nya adalah raksa

30mbar = 13600 kg/m^3 . 10 m/s^2 . Δh

3000 Pascal = 13600 kg/m^3 . 10 m/s^2 . Δh

Δh = 0.022 m

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Darell:

What tools can be used to measure pressure?

AI:

There are several types of tools that can be used to measure pressure. Some of the most common tools include:

Pressure gauges: These devices use a Bourdon tube or diaphragm to measure the pressure of a fluid or gas. They are available in analog or digital versions, with a variety of pressure ranges and connection options.

Pressure transducers: These devices convert pressure into an electrical signal, which can be displayed on a digital readout or transmitted to a data acquisition system. They are often used in industrial and laboratory applications.

Manometers: These devices use a liquid column to measure pressure, and are often used in low-pressure applications such as vacuum systems or air flow measurement.

Barometers: These devices measure atmospheric pressure, and are commonly used in weather forecasting and aviation.

Vacuum gauges: These devices are designed to measure the pressure in a vacuum system, and are available in a range of types including thermal conductivity gauges, ionization gauges, and Pirani gauges.

Differential pressure gauges: These devices measure the difference in pressure between two points in a system, and are often used in HVAC and filtration applications.

The selection of the appropriate tool will depend on the specific application and the range of pressures being measured. It's important to choose a tool that is accurate and reliable, and to ensure that it is calibrated and verified on a regular basis.

Darell:

Why are there so many tools just for measuring pressure?

AI:

There are many tools available for measuring pressure because pressure is an important physical quantity that is used in a wide range of applications across many different industries. Pressure is defined as the force per unit area, and is typically measured in units of pounds per square inch (psi), Pascal (Pa), or bar.

Different tools are designed to measure pressure in different ranges, from low-pressure applications such as vacuum systems or air flow measurement, to high-pressure applications such as hydraulic systems or oil and gas pipelines. Additionally, different tools may be designed to measure different types of pressure, such as differential pressure or absolute pressure.

The accuracy and reliability of pressure measurements is critical in many applications, such as in the aerospace, automotive, and oil and gas industries. Inaccurate measurements can lead to equipment failure, safety issues, and even environmental damage.

Because of the importance of pressure measurement in so many different applications, there are a wide range of tools available to meet the needs of different industries and applications. The selection of the appropriate tool depends on factors such as the range of pressures being measured, the accuracy required, and the specific application.

Darell:

How can we calibrate and verify the measurement of a pressure gauge?

AI:

Calibrating and verifying the measurement of a pressure gauge involves several steps to ensure the accuracy of the readings. Here are the general steps:

Determine the range of pressure that the gauge is designed to measure. This information should be available in the manufacturer's documentation or on the gauge itself.

Choose a suitable reference standard that can measure the same pressure range as the gauge.

Connect the reference standard to the pressure gauge using a suitable adapter or connector.

Apply a known pressure to the reference standard and record the reading on both the reference standard and the pressure gauge.

Repeat step 4 at various pressures throughout the gauge's range.

Compare the readings from the reference standard and the pressure gauge. If there is a significant difference between the two, adjust the gauge as necessary to bring it into calibration.

Verify the accuracy of the gauge by performing a series of checks at regular intervals. This may involve recalibration or adjustments if the gauge falls out of calibration.

It's important to note that the calibration and verification process may vary depending on the type of pressure gauge being used and the specific application. Additionally, calibration and verification should be performed by qualified personnel with the appropriate equipment and training.