Metal Tube Float Flow Meter Flange Thread Multiple Connection Methods Gas And Liquid Measurement 4-20 M A

Gas Rotor Flowmeter

Gas rotameter is a common instrument used to measure the instantaneous flow rate of fluid (liquid, gas). It is suitable for measuring the flow rate of transparent fluids, suitable for measuring medium with low pressure and low temperature. It is widely used in chemical, food, environmental protection, metallurgy, machinery, pharmaceutical and other industries as well as scientific research departments to measure single-phase non-pulsating fluids (liquid or gas). ) flow.

The pulsation of the gas rotameter flow itself, if there is a reciprocating pump or regulating valve upstream of the planned instrument location, or there is a large load change downstream, etc., the measurement location should be changed or the pipeline system should be remedied and improved, such as adding a buffer tank; if The oscillation of the instrument itself, such as the gas pressure is too low during measurement, the valve upstream of the instrument is not fully open, the regulating valve is not installed downstream of the instrument, etc., should be improved and overcome, or an instrument with a damping device should be selected.
The series of gas metal tube rotor flow meters have a variety of measurement forms for users to choose from based on different user needs and occasions. According to the output form, they are divided into local indication type, remote transmission type, and control alarm type. According to the output type, The forms include local indication type, remote transmission type, and control alarm type; according to the explosion-proof requirements, it can be divided into three types: ordinary type, intrinsic type, and isolation explosion-proof type.

Features
Better-Smart instrument direct supplier
Suitable for / Transparent glass tube Suitable for small diameter and low flow rate
one
Performance / Range ratio Reliable operation, low maintenance, long life
two
Flow range / Small pressure loss has a wide flow range of 10:1
three
Convenient / Simple structure Local pointer indication is close to linear
Four
Intelligent / Measuring range The intelligent indicator has an LCD display that can display instantaneous and cumulative flow, and can also output high surge and alarm outputs.
five
Rich variety / Corrosion resistance includes local type, remote transmission type, jacket type, explosion-proof, corrosion resistance, etc.

working principle
Explanation of the working principle of gas rotor flowmeter
During the measurement process of the gas rotor flowmeter, the number of rotations of the rotor has a certain proportional relationship with the cumulative flow rate of the fluid. The flow rate of the fluid can be calculated based on the number of rotations of the rotor. The linear shape set on the rotor surface of the gas rotor flowmeter is an involute linear shape. During the use of the meshing teeth, the contact between the tooth surfaces of the two rotors is large. During the rotation, Relative sliding and relative rolling occur between the two rotors, resulting in wear and meshing between the rotors. The wear of the rotor of the gas rotameter will reduce the degree of meshing between the rotors, thereby reducing the flow measurement accuracy.

Conversion formula
Scale and conversion of gas rotameter
JJG257-1994 "Rotameter Calibration Regulations" uses a bell-type or soap film-type gas flow standard device to calibrate the flowmeter, and the standard flow rate under the standard scale state.

It is a correction from the flow meter's previous state to the scale state during the test. At this time, the scale state is equal to the standard state, and the test gas and the calibration gas are the same. If this is not the case, it is necessary to distinguish between the scale state and the standard state, add some parameters, and redefine the symbols as shown in Table 1.

3. Scale qN and qCN

3.1 Standard status scale

Scale and conversion of gas rotameter

When measuring the actual flow rate in front of the flowmeter using a gas flow standard device such as a bell jar or soap film, it can be obtained by the following formula:

When using a standard rotameter to measure the actual flow rate in front of the flowmeter, it is obtained by the following formula:

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When measuring the actual flow rate in front of the flowmeter using a gas flow standard device such as a bell jar or soap film, it can be obtained by the following formula:

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When using a standard rotameter to measure the actual flow rate in front of the flowmeter, it is obtained by the following formula:

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After passing the non-standard status scale, since the usage status is consistent with the scale status, the scale flow display value read directly is the flow value required by the user, without any conversion, which improves measurement efficiency.

4. Convert from qN to qmN and qm0

The actual use status of some flow meters with standard calibration is different from the scale status, and conversion is required when using it. When actually using it, measure the pressure and temperature in front of the flow meter. The actual flow rate in front of the flow meter is expressed in qm. The formula is as follows:

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5. Estimation of the current state of the flow meter

The correct installation of the flow meter in the system is to install a fully open stop valve upstream and a flow regulating valve downstream. When in use, the upstream stop valve should be slowly opened, and then the downstream flow regulating valve should be used to adjust the flow. When the flow meter stops When measuring, the stop valve should be closed slowly, and then the flow regulating valve should be closed.

However, many manufacturers of flowmeters now install needle-type flow regulating valves on the upstream base for pressure reduction and flow restriction to ensure that there are no throttling parts downstream of the rotameter. At this time, the measured upstream of the flowmeter inlet is 5 times the nominal diameter. The pressure within the range is actually the pressure in front of the valve. To ensure accurate pressure measurement, disassemble the base and directly connect the air source to the glass cone tube for calibration. Restoration after calibration often cannot guarantee the sealing quality and often damages the glass cone tube. .

Because there are no throttling parts downstream of the flow meter, it is more convenient to measure the back pressure of the flow meter in this case. The back pressure of the flow meter plus an estimated pressure difference can approximately obtain the front pressure of the flow meter. The pressure difference between the upstream and downstream of the float is equal to gravity minus the sum of dynamic pressure and buoyancy. The formula is as follows:

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This pressure difference is very small relative to gravity (estimated to be about 10%), so the formula is simplified to:

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The estimated pressure difference of the φ3mm spherical steel float is about 15Pa.

At this time, the back pressure of the flow meter is closer to the front pressure of the flow meter than the front pressure of the valve. Using this method to estimate the working state pressure does not require disassembly of the base, and the calibration process is simpler.

Gas rotameter installation steps
1. Clean the welding slag and debris in the pipeline before installing the flow meter;
2. The installation inclination of the upright part of the calibration flowmeter perpendicular to the ground shall not exceed 5°. Otherwise, the measurement accuracy will be affected.
3. Position In order to ensure the measurement accuracy of the flow meter, a straight pipe section of no less than 10xDN should be added to the inlet end of the flow meter, and a straight pipe section of no less than 5xDN should be added to the outlet end. The regulating control valve should be installed at the flow meter during measurement. downstream.
4. Model If the measured medium is a large pulsating flow or two-phase flow, a buffer should be installed upstream of the flow meter to reduce or weaken the pulsation to ensure that the flow of the medium is single-phase stable. At the same time, it is recommended to use a damping type flow meter. .
5. Measuring medium When the measuring medium is dirty or contains magnetically conductive particles, it is recommended to install a filter or magnetic filter upstream of the flow meter.
6. The installation of the support flow meter should be able to properly support the vibration of the pipeline or reduce the axial load of the flow meter. Otherwise, the support of the fixed flow meter should be added.
7. Maintenance In order to facilitate the maintenance and repair of the flow meter, the cleaning of the magnetic filter and the regular maintenance of the user's pipelines, it is recommended to use the bypass pipeline as shown in the figure.
8. Stability When the flow meter is used for gas measurement, it should be ensured that the working pressure in the pipeline is not less than 5 times the pressure loss of the flow meter, so that the flow meter can operate stably and normally.
9. Before using the electric remote transmission and the flow meter with alarm limit switch, open the instrument cover and connect the wires correctly according to the wiring diagram.
10. According to the warning plate on the indicator of the meter, take out the damping piece that prevents the float from vibrating during transportation, and then use the meter after restoring it.
11. If the flow meter is turned on, because there is no pressure in the pipeline or the system has not reached the normal working pressure of the instrument, slowly open the control valve until the system is normal before the instrument can be used. Otherwise, it is easy to cause the pointer to jump or the float to suddenly move. A rose damaged by impact.
12. User use: When the user uses it, if the density of the measured fluid is different from that of water, or the parameters and working status of the measured gas are different from the manufacturer's regulations, the flow meter indication reading should be converted. The conversion method is shown in the appendix.
Manufacturer strength
Smart instrument direct supply manufacturer
The company has complete production and processing equipment. The electronics workshop has a modern SMT assembly line and a complete electronic design and development laboratory. The machinery workshop has multiple precision CNC lathes, ordinary lathes, processing, fully automatic circumferential seam welding machines, drilling machines and other equipment. The calibration workshop has two liquid calibration test lines and a small and medium flow gas calibration test line to ensure that each product is tested according to actual conditions. Calibration and verification to ensure product quality.
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FAQ
1. Q: What information need to be provided to choose the suitable model?
A: Application field, Nominal pressure ,Medium & medium temperture , Power supply , Output,
Flow range, Accuracy, Connection and other parameters.
2. Q: Are you a trade company or a manufacturer?
A: We are an ISO approved manufacturer specialized in level and flow measuring instruments.
OEM & ODM service are available. Welcome to visit us in China.
3. Q: What is your MOQ?
A: To start our cooperation, sample order is acceptable.
4. Q: What is your delivery date for the Intelligent Mini Micro Turbine Fuel Oil Diesel Flow Meter?
A: The delivery date is about 3-15 working days after receipt of payment.
5. Q: What is your payment terms?
A: We support T/T, PayPal ,Western Union.
For mass production order, it is 30% deposit in advance and 70% balance before shipment.
6. Q: Do you have a warranty for the Flow Meter?
A: Yes, we have the warranty of 12 months.