| Q |
What is a vortex flowmeter? |
| A |
Yokogawa developed the first vortex flowmeter in 1968, and in 1979 completed development of its next-generation YEWFLO vortex flowmeter. Vortex flowmeters detect and convert into electrical signals pressure changes that are caused when a shedder bar creates Karman vortices. |
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| Q |
What is the measurement principle of an vortex flowmeter? |
| A |
When a shedder bar is placed in a fluid, Karman vortices are generated on the downstream side. The vortex frequency is proportional to the flow velocity, and corresponds to a specific range of Reynolds numbers.The vortex frequency (f) is calculated by the formula; f=St*v/d
v: flow velocity, d: width of shedder bar, St: Strouhal number |
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| Q |
What are the advantages of a vortex flowmeter? |
| A |
| The features of vortex flowmeters are described in JIS Z 8766 (2002) Vortex flowmeters -- Methods of flow measurement. These are as follows: |
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| a) |
Frequency output is proportional to flowrate. |
| b) |
No moving parts are required because of vibration created by Karman vortices. |
| c) |
Wide measurement range |
| d) |
Can measure gas, steam and liquid |
| e) |
Outputs volumetric flowrate without influence of density, temperature, or pressure |
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| Q |
What types of vortex flowmeters are available? |
| A |
Use the digitalYEWFLO sizing program to select the right size. Please contact our sales department for further information. The digitalYEWFLO can measure gas, steam, and liquid, but please avoid using it with multiphase flow, adhesive fluids, or corrosive fluids. |
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| Q |
Are there any reference materials for the digitalYEWFLO (DY) series vortex flowmeters? |
| A |
Catalogs, general specifications, and drawings can be downloaded from our website.
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| Q&A for the product |
| Q |
Is it necessary to adjust the zero point regularly? |
| A |
No. A vortex flowmeter normally does not have a zero point because it calculates the flow rate based on vortex frequency. |
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| Q |
Is initial adjustment necessary with the digitalYEWFLO? |
| A |
No. After power on, the digitalYEWFLO is adjusted automatically by means of the SSP function; however, it can be adjusted manually to compensate for excessive piping vibration. |
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| Q |
Can an arrester be attached to the digitalYEWFLO? |
| A |
Yes. It can be attached to the power supply cable. As an option, the arrester can be attached to the base board. The arrester limits the power supply voltage to 30 V DC. |
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| Q |
Can the digitalYEWFLO measure reverse flow? |
| A |
No, the digitalYEWFLO cannot measure reverse flow because of its measurement principle. |
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| Q |
Can the digitalYEWFLO converter be rotated in the field? |
| A |
Yes. The digitalYEWFLO converter can be rotated 90 degrees in any direction. With the explosion proof type, please move it to a non-hazardous location before performing this procedure. Please follow the procedures set out in the instruction manual. A digitalYEWFLO flowmeter with the converter oriented in the opposite direction (rotated 180 degrees) can also be ordered. |
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| Q |
Can the digitalYEWFLO be installed upside-down? |
| A |
The device can operate in this position; however, water leaking into the converter can cause it to malfunction. If there is any chance that the converter will be exposed to water, we do not recommend installation in this position. |
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| Q |
Can a digitalYEWFLO be installed on a vertical pipe with a downward flow direction? |
| A |
This is not recommended. The digitalYEWFLO should be installed on a pipe that is fully filled with liquid; therefore, the flow direction should be upward. |
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| Q |
Can the digital YEWFLO converter be installed with the electrical connection port facing upward? |
| A |
No. The electrical connection port direction must face downward to prevent water from getting into the converter. |
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| Q |
Will the installation of a valve or change of the valve type have any impact on the required 20D straight pipe length? |
| A |
Regardless of valve type, it is best to install a valve on the downstream side of the digitalYEWFLO; however, if installation on the upstream side is required, maintain a straight pipe length of at least 20D on the upstream side and 5D on the downstream side. |
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| Q |
What is the required straight pipe length? |
| A |
A swirling flow or uneven flow velocity distribution affects the output of vortex flowmeters. These conditions can be caused by upstream piping; the installation of valves and pumps; joints and welding burrs; and so on. Therefore, maintaining the minimum recommended straight pipe length is the most important consideration in piping design, ensuring a straight flow.The straight pipe length depends on the piping design. Please install the vortex flowmeter as specified in the instruction manual.
The installation of a straightening vane (available on a special order basis) on the upstream side of the vortex flowmeter can also be an effective means for maintaining a straight flow. Please contact a sales representative. |
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| Q |
Does the installation of anything on the upstream side affect the straight pipe length? |
| A |
For anything installed on the upstream side, please add the appropriate straight pipe length. |
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| Q |
What happens if the straight pipe is not long enough? |
| A |
It is difficult to quantify the impact this will have on accuracy because it depends on the measurement conditions. Please maintain the required straight pipe length to ensure accurate measurement. |
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| Q |
Why is it necessary to provide the saturated vapor pressure value to perform the liquid calculation with the digitalYEWFLO sizing program? |
| A |
The saturated vapor pressure is the pressure under which steam or gas and liquid are in equilibrium at a given temperature. Liquid evaporates at certain temperature and pressure levels, which causes cavitation. As vortex flowmeters rely on the generation of Karman vortices, they cannot accurately measure flow in the presence of vapor bubbles.
The digitalYEWFLO sizing program can check for cavitation; when its calculations show that cavitation is occurring, an error message is displayed. Depending on which liquid has been selected for the program, there is a preset saturated vapor pressure value. For mixed fluids, please provide your own saturated vapor pressure value. Please contact a sales representative for more information. |
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| Q |
Can the digitalYEWFLO be used in processes that are ANSI Class 900 or above? |
| A |
Yes. We have models that are rated up to ANSI Class 2500. Please contact a sales representative. |
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| Q |
Can the digitalYEWFLO multi-variable type measure variable pressure superheated steam? |
| A |
The digitalYEWFLO can only measure superheated steam when there is a constant pressure. If this needs to be measured under variable pressure, a pressure meter may be needed to perform compensation. |
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| Q |
Can the MASS YEWFLO be replaced with the digitalYEWFLO multi-variable type? Are there any precautions? |
| A |
The MASS YEWFLO directly outputs the mass flow rate, whereas the digitalYEWFLO outputs the mass flow rate by temperature correction. There are no major differences in the saturated steam measurement, but in the case of superheated steam, the digitalYEWFLO requires a constant pressure value.
Also, the MASS YEWFLO's signal cable (YF011) cannot be used by the digitalYEWFLO. Please use the digitalYEWFLO's dedicated DYC signal cable. |
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| Q |
Do you have any 250 mm or 300 mm digitalYEWFLO multi-variable type models? |
| A |
Yes, these can be supplied by special order. |
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| Q |
Is a shorter straight pipe used with the digitalYEWFLO reduced bore type? |
| A |
The straight pipe length for the digitalYEWFLO reduced bore type is the same as with the digitalYEWFLO standard type. |
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| Q |
Is the pressure loss value for the digitalYEWFLO reduced bore type larger than that of the standard type? |
| A |
The pressure loss for the R1 type (one size down) is about 15 percent higher; for the R2 type (two sizes down), it is about 28 percent higher. |
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| Q |
What is the rangeability of the digitalYEWFLO? |
| A |
It is about 40:1 at maximum, depending on the fluid. |
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| Q |
Are consumable parts still available for the YEWFLO series? |
| A |
The maintenance period of the previous YEWFLO Series; YEWFLO Style E, MASS YEWFLO and YFCT Flow Computing Totalizer; has already expired. Including calibration, maintenance and parts supply is not possible. |
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| Q |
What are the properties of the duplex stainless steel used in the shedder bar? |
| A |
It is equivalent to JIS SUS329J1, ASTM A890Gr CD4MCuN/EN (DIN) 1.4517. The austenitic-ferritic stainless steel (duplex) has high mechanical strength and high corrosion resistance. |
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| Q |
Can you still make the digitalYEWFLO out of Hastelloy-C? |
| A |
Yes, as a special order. Please contact a sales representative. |
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| Q |
Can you provide an instruction manual for models in the YEWFLO series? |
| A |
Yes, print only (no electronic files). Please contact a sales representative. |
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| Q |
Is it possible to do the sizing calculation for models in the YEWFLO series? |
| A |
Yes, but only for the YEWFLO Style E; however, the previous sizing data cannot be used in the digitalYEWFLO sizing program because the program configuration is quite different. Please contact a sales representative. |
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| Q&A for the application |
| Q |
Are there any reference materials of applications for the digitalYEWFLO? |
| A |
We offer the application leaflets as follows
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The following are answers to frequently asked general questions about Vortex flowmeters.
