Flow Totalizer Check Procedure | Working principle | Formula

This article is about Flow Totalizer Check Procedure, Working principle of totalizer, formula used for calculating flow in totalizer and what is difference between totalizer and flow meter.

This Guideline provides a method to check that the stream flow computer totalizers are functioning correctly by injecting simulated flow signals at the back of the panel and comparing the actual totalizer increments against the expected increments.

What is Flow Totalizer?

A flow totalizer is a device or instrument used to measure and display the total volume or mass of fluid that has passed through a pipeline or system. It is commonly used in industries such as oil and gas, water treatment, and manufacturing, where accurate measurement of fluid flow is crucial for process control and billing purposes.

The flow totalizer typically takes inputs from flow meters or sensors installed in the pipeline and calculates the cumulative flow by integrating the flow rate over time. It provides real-time data on the total amount of fluid that has passed through the system, allowing for accurate monitoring, analysis, and management of fluid flow.

flow totalizer working principle

The working principle of a flow totalizer involves measuring the flow rate of a fluid and integrating it over time to calculate the total volume or mass of fluid that has passed through a pipeline or system. Here are the basic steps involved:

1. Flow Measurement: The totalizer receives inputs from flow meters or sensors installed in the pipeline. These devices measure the flow rate of the fluid, typically in terms of volume per unit time (e.g., liters per minute) or mass per unit time (e.g., kilograms per hour).
2. Data Acquisition: The flow totalizer continuously collects the flow rate data from the flow meters or sensors. It records the flow rate at regular intervals, typically in short time increments (e.g., seconds or minutes), to capture accurate and precise measurements.
3. Integration: The totalizer integrates the flow rate data over time using mathematical calculations. It sums up the flow rates measured at each interval to calculate the total volume or mass of fluid that has passed through the system since the totalizer was initiated or reset.
4. Display and Output: The calculated total volume or mass is displayed on the flow totalizer’s output screen or indicator. It provides real-time information on the cumulative flow and may also include additional data such as flow rate, time, and any other relevant parameters.
5. Reset and Accumulation: The totalizer can be reset to zero to start measuring a new batch or period. Alternatively, some totalizers have the capability to accumulate multiple measurements, allowing for continuous tracking of total flow over extended periods.

By following these steps, a flow totalizer accurately tracks and displays the total volume or mass of fluid flowing through a system, enabling precise measurement, monitoring, and control of fluid flow processes.

Read Also: Turbine Flowmeter Design Requirement in Process Industry

Flow totalizer Formula

The formula for calculating the total flow using a flow totalizer depends on the specific application and the units of measurement used. Generally, the formula can be expressed as:

When using a flow meter’s built-in totalizer pulse, it is important to consider potential issues such as the loss of pulses due to PLC malfunctions or interruptions. If the pulses are lost, it can result in inaccurate total flow calculations. To mitigate this risk, it is recommended to implement robust error detection and handling mechanisms in the PLC programming. This can involve monitoring the pulse count and implementing fail-safe measures to handle pulse loss situations, such as triggering alarms or logging the event for troubleshooting.

The Flow totalizer formula Total = Total + (Flow / TimeConversion) * TaskPeriod is commonly used for flow totalization. However, there is a risk associated with adding small numbers in real format, which can lead to rounding errors and loss of precision over time. To address this, it is advisable to use appropriate data types and precision in the programming language or software platform being used.

Using higher precision data types, such as double or decimal, can help minimize rounding errors. Additionally, it is good practice to periodically validate the accuracy of the totalization results by comparing them with known reference values or conducting calibration checks to ensure the formula is providing accurate and reliable results.

Flow Totalizer Check Procedure

Preparations:

• Ensure that the meter stream is off-line and out of service.
• Give a brief description of the test in the Metering Log Book.
• Record the results of this test on the Flow Totalization Test Sheet (TS004).
• Verify that the certificates for the test equipment are valid. Check that the test equipment serial numbers and certification dates are accurately recorded on the test sheet and correspond with the test equipment used. Ensure the flow computer tag and serial numbers are recorded on the test sheet.

Calibration Equipments:

A) Frequency Generator
B) Frequency Counter / Timer

PROCEDURE:

The stream totalizer shall be checked using the following procedure:

a) Liaise with Operations department to zero the stream flow computer or record the stream totals, as appropriate.

b) Disconnect the turbine meter field input. Connect the turbine meter simulator to the turbine meter input.

c) Connect the timer/counter across the output of the pulse generator. The timer counter should be set up to count the number of pulses injected.

d) Fix the line density, reference density, temperature and pressure at the flow computer to known values.

e) Adjust the frequency at which the batch of pulses is fed into the flow computer in order to not exceed the pre-set high or low alarms for flow rate.

f) Use the simulator to inject a suitable number of pulses.

g) Note the initial and final values of the gross volume, net volume and mass totals.

h) Complete the flow tantalization test sheet. If the calculated and actual totals are within tolerance the test is complete. The flow computer should be returned to the ‘As Found’ state with the fixed line density, reference density, temperature and pressure values removed from use.

i) If the calculated and actual totals are out of tolerance investigate the reason and attempt corrective action. If a significant error is still observed, change the flow computer.

i) Once the calculated and actual totals are within tolerance complete the test sheet and ensure it is marked with appropriate comments. The test is complete; return the flow computer to the ‘As Found’ condition with the fixed line density, reference density, temperature and pressure values removed from use.

j) Enter details of all tests in the Metering Log Book. Record if the flow computer has been replaced and the serial number of the replacement flow computer.

Flow Totalization Test Sheet

When Frequently Instrument should be calibrated?

Frequency As needed.

totalizer vs flow meter

A totalizer and a flow meter are two different components used in measuring fluid flow, but they serve distinct purposes:

Flow Meter: A flow meter is a device used to measure the rate of fluid flow, typically expressed in units such as liters per minute or cubic meters per hour. It provides real-time information about the instantaneous flow rate of the fluid passing through it. Flow meters can use various principles, such as differential pressure, ultrasonic, magnetic, or turbine, to determine the flow rate accurately.

Totalizer: A totalizer, on the other hand, is a feature or device integrated with a flow meter that accumulates and displays the total volume or mass of fluid that has passed through the flow meter over a specific period of time. It provides cumulative information about the total flow quantity, allowing users to monitor the overall consumption or production of the fluid.

In essence, a flow meter provides continuous real-time flow rate measurements, while a totalizer focuses on accumulating and displaying the cumulative total flow quantity. The totalizer relies on the measurements obtained from the flow meter to calculate and update the total flow.

Read Also: ANALOG TO DIGITAL CONVERSION CHANNELS | FLOW COMPUTER

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