how to measure

Kesalahan umum terbesar dalam pembelian Flow meter adalah kurangnya data dan spesifikasi dalam memilih jenis, type atau model flow meter. Minimnya pengetahun flow meter tentang jenis, model dan type flow meter mempunyai peranan penting dalam menentukan pemilihan flow meter. Biasanya Para Pembeli flow meter hanya didasrkan pada 2 kriteria saja, yaitu bisa membaca debit aliran ( bisa berfungsi) dan harga yang terjangkau. Sehingga saat beberapa lama flow meter digunakan yang terjadi adalah biaya maintenance yang tinggi dan tidak tercapainya tujuan dari pemasangan flow meter.

Untuk pengukuran Fluida yang sangat membutuhkan akurasi, dikarenakan proses maupun harga dari fluida yang mahal, biasanya di tuntut akurasi tinggi pada hasil pembacaan flow meter . Ada beberapa flowmeter dengan berbagi jenis dan kelebihan serta kekurangan. Namun Begitu ada suatu flow meter dengan kemampuan akurasi yang sangat prima, dimana akurasi bisa mencapai 0.1% bahkan lebih.

Akurasi flow meter biasanya dalam pengoprasian tergantung pada setabilitas temperature dan stabilitas pressure dari aliran fluida. Perubahan pressure bisa juga mempengaruhi akurasi flowmeter begitu juga perubahan temperature akan mempengaruhi hasil totalizer dari volume fluida yang di baca oleh flow meter. Akurasi ini sangat penting khususnya jika flow meter digunakan untuk mengukur cairan yang harganya tidak murah, yang mengakibatkan selisih pengukuran bisa berakibat pada kerugian akumulasi angka yang besar.

Dengan kondisi dan karakteristik suatu fluida baik cairan maupun gas seperti diatas sebaiknya menggunakan flowmeter jenis coriolis mass flow meter yang mampu menjangkau akurasi 0.1% atau dibawahnya. Beberapa keunnggulan dari coriolis flow meter ini adalah :

Akurasi bisa mencapai 0.1% atau lebih baik lagi
Repeatability : lebih baik dari 0.05%
Tahan terhadap korosi karena material sensornya stainless steel
Pperubahan temperature tidak mempunya pengaruh pada akurasi pembacaan
Aman jika Fluida mengandung partikel solid atau kotor karena tidak ada bagian parts sensor yang bergerak/berputar sehingga bisa dikatakan free maintenance.
Seting pembacaan dari mass bisa di setting ke volumetrik
Cocok untuk di operasikan pada filling dan custody

Jika karakteristik fluida yang sangat korosif serta mudah berubah bentuk karena perubahan temperature saat peroses dan cukup asam sebaiknya menggunkan flow meter jenis coriolis mass flow meter yang secara langsung menghitung mass dari cairan, sehingga perubahan volume karena perubahan temperature tidak merubah hasil dari pengukuran flow yang lewat flow meter.

Dikarenakan Coriolis flow meter menggunakan material stainless steel untuk type standart ini sudah bisa mewakili syarat industri pengolahan makanan yang menuntut kelas material food grade serta tahan terhadap korosi sehingga bisa juga dikatakan food grade flow meter

Sehubungan harga dari fluida yang sangat mahal maka Coriolis mass flow meter sangat cocok sekali guna mencegah dan mengurangi kerugian jumlah fluida dan turunanya, yang disebabkan oleh selisih perhitungan dan pengukuran sebab akurasi dari mass flow meter je nis coriolis ini mencapai akurasi tinggi yaitu 0.05% hingga 0.2 % tergantung spesifikasi yang di inginkan.

Karena Coriolis mass flow meter ini bisa di pesan dengan custem maka bisa digunakan untuk berbagai stadart dari stadart JIS, ANSI, DIN dan lainna begitu juga jenis material bisa juga digunakan untuk asam yang punya PH ekstrim, Temperature ekstrim dari -45 to +210°C. Dan juga bisa diaplikasikan pada pressure hingga 345 bars.

Berikut Karakteristik dan keunggulan Coriolis Flow Meter yang di produksi oleh Rheonik dari germany

APPLICATIONS

Suitable for virtually any mass flow application, such as: Batching, Dosing, General flow control, Injections, Filling
Loading of boats, vessels, rail tank wagons
High temperatures and other challenging applications
Highly viscous media (low pressure drop and excellent performance at low flow conditions)
Properly used for corrosive liquids and Low Flow
Properly used for beverages that require food grade instrument

FEATURES

The outstanding features include : Suitable for pressure up to 450 bar
Size : 1/4″ – 12 ” :
Measuring ranges : 0.002 kg/min to 25.000 kg/min ( depending on pipe size )
Accuracy : 0.1% and better
Repeatability : better than 0.05%
Optimised solutions for your batching operation
Extra compact design with minimal space requirement
EEx Approvals (i.e. ATEX, CSA, …)
Custody Transfer Approvals (i.e. PTB, NMI, …)
As heavy duty version available (increased wall thickness of measuring pipes for additional safety – 250 bar)

ADVANTAGES

No pressure effect – no deterioration of accuracy due to pressure changes by the patented Omega Shape
Medium flow rates in combination with high operating pressure
Patented torsion swinger design assures most stable and drift free measurement,
Increased signal to noise ratio by torsion swinger
Longest life time and increased safety (low stress in welds and increased wall thickness against abrasion)
No moving parts, practically no maintenance
Removable connection block

Specification :

Typical measuring ranges : 0.002 kg/min to 25.000 kg/min
Flow Accuracy : 0.1% and better
Repeatability : better ± 0.05% of rate
Density : better than ± 0.001 g/cc
Temperature : -200 to +350°C
Pressure range : Measuring Loops max. 93 bar – max CL 600 / PN 40
Material of Wetted Parts :

1.4571 / SS 316Ti (standard),
1.4539 / SS 904L on request,
Hastelloy C22 on request
Tantalum and Other material on request

Housing :

Stainless Steel: 1.4301 / SS 304 ( standart) and others on request
Protection class: IP 65 (Nema 4X) and higher on request

Electrical connection

Junction box / aluminium coated (standard) IP 65 (Nema 4X) (Junction box in SS optional)
Cable entry M25 x 1.5 (M20 x 1.5, ½” and ¾” NPT optional)
Max cable length between RHM and RHE :

100 m (330 ft)
200 m (660 ft) only with factory approval

Approvals

ATEX (CESI 02 ATEX 053 X) : Ex II 1 G, EEx ia IIC T6-T1

CSA (220705) Class I, Div 1 and 2, Groups A, B, C and D;Type 3

Custody Transfer Approvals (PTB 1.32-97027224 and NMI TC 3382)
PED according to directive 97/23/EC available

3A Sanitary Approvals

Transmitter and Display mounting : wall mounting, Pannel Mounting, Rack Mounting
Outputs :

2 analog outputs,
1 frequency/pulse output
3 digital outputs (Lt, +/-, error…)

Inputs : 2 inputs (hold, reset, zero)
Power supply :

230 VAC +/- 10% or
115 VAC +/- 10% or
24 VDC
Cable entries: 4 x M25 x 1.5 – others optional

Interface :

RS 422/485/232 – optional
HART – optional

Power consumption : < 15 W

The last ten years ultrasonic flow meter is very popular not only in the laboratory but also in many industries such as industrial water treatment, industrial waste water treatment, food and beverage industry and chemical industry. Due to popular demand, Ultrasonic flow meter effective enough because the price is not too expensive and inexpensive installation costs and maintenance costs can be said to be free maintenance

Another advantage is the use of ultrasonic flow meter accuracy is adequate and flexible. With ultrasonic flow meters, the user can choose from a variety of electronic packages, and also use the device in areas requiring explosion-proof devices. value-added benefits this provides a striking contrast to the turbine or variable-area flow meters, which is less accurate, offers the ability to output less invasive to the process media.
As any engineer knows, ultrasonic flow meters measure the velocity of a liquid through a pipe by using ultrasonic transducers. The results are variable depending on the temperature, density or viscosity of the liquid. Some meters are also able to measure the liquid level and this, with the pipe size, enables the correct calculation of the flow rate and total discharge involved.

The most significant advantage of ultrasonic flow meter is an ultrasonic flowmeter ability to measure flow without disrupting the flow of both liquid and gas. Noninvasive Measurements were taken from two or more transducers attached to the exterior of the pipe. Shift the frequency of the ultrasonic signal sent through a liquid or gas is measured, then the signal is sent through a cable to the electronics housed in the flow computer.

Other advantages of using ultrasonic flow meters include :

Improved accuracy
No pressure drop
High turn-down ratio
No moving parts
Minimum maintenance
Long-term cost savings

Choosing the type and model of Ultrasonic Flow meter

To determine what type and model of ultrasonic flow meter that best matches our desires and effective for a particular application is to consider where and how the flow meter will be used. There are three types of ultrasonic flow meter the most preferred and and find that the Hand Held ultrasonic Flow Meter, portable Ultrasonic flow meter and Open Channel Flow Meter.

These are non-intrusive, clamp-on devices used to measure flow in pipes ranging from 10 mm to 10,000 mm in diameter with incredibly high accuracy. In fact, independently certified meters have achieved accuracy better than 1% of the actual flow. This is a robust range of flow meters suited to a wide variety of water quality, with pipe sizes ranging from 15mm to 500mm in diameter and pulse emitters being able to be fitted to the flow meters if necessary.

Hand Held Ultrasonic Flow Meters

Handheld flow meters are most commonly used to measure slurries and dirty fluids in the chemical industry, food processing and water treatment plants where basic flow measurement is occasionally required. Facility engineers working in office buildings or small-scale process plants frequently need to monitor HVAC-R systems. Typically, these engineers will use a handheld unit to accomplish this task.

Ultrasonic sensor over a Parshall Flume at a WWTP headworks

Open Channel Ultrasonic Flow Meter

Ultrasonic flow meters measure the level in a channel by transmitting a pulse of sound from the face of the sensor to the surface of the flow stream and measuring the time for the echo to return. The transit time corresponds to the distance between the face of the sensor and the surface of the water. When the meter is initially set up, a pre-determined distance (or level in some meters) is set. This distance is either the zero level (no flow present) or a specific level in the flume or weir. With this initial calibration it is only a matter of simple arithmetic to determine the liquid level. This level is then applied to either pre-programmed discharge equations or strapping tables to output a flow rate

Because the sensor is not in contact with the water, ultrasonic sensors have no scheduled maintenance. Ultrasonic sensors are not affected by chemicals, grease, suspended solids, or silt in the flow stream.