Working principle of KMCH ultrasonic gas flowmeter

The working principle of KMCH ultrasonic gas flowmeter is based on the method of measuring the time difference between the propagation of ultrasonic pulses downstream and upstream of the gas.The measurement time difference proportional to the flow rate is converted into gas volume flow rate.

The KMCH ultrasonic gas flowmeter includes an electroacoustic transducer (PEA), a measuring part, and a signal processing device.

The measurement section can be composed of the KMCH ultrasonic gas flowmeter body or a section of the existing pipeline (cut in design).The signal processing device generates a transmitter for the KMCH ultrasonic gas flowmeter and produces a standard output signal to transmit gas flow rate and volume under operating conditions.

In the version with built-in calculator, the signal processing device also receives current signals from temperature and pressure sensors, calculates flow rate and calorific value under standard conditions, and records the readings in a log.

Depending on the version, the flow meter may include a flow preparation device:

• Straight line segment, including the location where temperature and pressure sensors are installed

• A flow regulator that eliminates the influence of local resistance

• Gas purification device - recommended for contaminated gases

• Silencer - It is recommended to use a flowmeter installed after a pressure regulator that operates under critical gas flow conditions.

The factory calibration and validation of flow meters can be carried out by incorporating all components included in the flow meter into the measurement pipeline (higher precision versions in special orders).

application area

A flow meter with a built-in flow computer, equipped with temperature and pressure sensors, can be used to measure volumetric flow under standard conditions.All components of the complex operate under full range operating conditions (-50..+50 ° C, IP67).

Advantages compared to other types of flow meters

Compared to turbine, differential, and mechanical flow meters:

• Wider dynamic range: from 1:100 to 1:400 (4% level)

• No flow obstruction: There is no possibility of pressure loss or damage to flow meter components;

• Lack of moving parts and the need for maintenance

• Bidirectional flow measurement;

Compared to Coriolis mass flow meters

• Measure under low pressure and flow rate;

• The ability to handle contaminated gases.

Measurement medium:Gases and gas mixtures

Positioning method on the pipeline:

• Pipeline type (DN50... DN300);

• Insertion type (DN100... DN1000).

• 
  

The maximum measurable gas flow rate of the pipeline KMCH ultrasonic gas flowmeter under working conditions:

Allow for 'overload' in terms of traffic within the range of Qmax to 1.1 * Qmax, while maintaining limitations on relative error.

Pipeline typeKMCH Ultrasonic Gas Flow MeterMinimum measurable gas flow rate under working conditions:

It must correspond to the table, depending on the accuracy level of the flowmeter and the design of the flow range.

Table - Minimum Flow Qmin, m3/h

Dynamic range:Standard (1:100) and extension (1:400).

Volume measurement error under operating conditions:

The relative error of measuring volumetric flow rate and gas volume under operating conditions, including the error (δ V,%) converted into pulse frequency or digital signal, is within the following limits (the values in parentheses are the values during simulation verification):

Within the flow range of 0.03 * Qmax ≤ | Q|≤ Qmax：

Within the flow range of 0.01 * Qmax ≤ | Q|≤ 0.03 * Qmax：

When the flow rate is below 0.01 * Qmax, the allowable error limit is reduced to a flow rate of 0.01 * Qmax:

Volume measurement error under standard conditions:

Self diagnosis and signal quality control

Recommended length of straight line segment:

• Front flow meter: 20 * DN (without flow shaper);

• Front flow meter: 10 * DN (with flow shaper);

• Rear flow meter: 5 * DN.

Solutions suitable for corrosive and droplet environments

Capacitive keyboard for explosion-proof area configuration.

Absolute pressure of the tested medium: 0.05 .. 16.0 MPa， The process connection complies with GOST, ANSI, DIN, etc. Minimum pressure loss

Built in calculator for measuring volumetric flow rate under standard conditions.

Measurement and indication of gas temperature and pressure, registration of indications, alarms, and settings

Measurement of forward and reverse flow rates

Temperature range:

• Measurement medium: -70 to+120 ° C;

• Environment: from -50 ° C to+50 ° C.

Explosion proof grade:1ExdIIC (T4-T6) X

Output signal:

• Frequency pulse;Discrete;4-20mA;

• RS-485 (Modbus RTU protocol).

Power Supply:20 . .. 140VDC / 80 ... 264 VAC；