vortex flow meters FAQs

basic specifications

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

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

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.
Darhor DH900 Vortex flowmeter can measure gas, steam, and liquid, but please avoid using it with multiphase flow, adhesive fluids, or corrosive fluids.

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.

Q    Is initial adjustment necessary with the Darhor DH800?
A    No. After power on, the Darhor DH800 is adjusted automatically by means of the SSP function; however, it can be adjusted manually to compensate for excessive piping vibration.

Q    Can an arrester be attached to the Darhor DH800?
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.

Q    Can the Darhor DH800 measure reverse flow?
A    No, the Darhor DH800 cannot measure reverse flow because of its measurement principle.

Q    Can the Darhor DH800 converter be rotated in the field?
A    Yes. The Darhor DH800 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 Darhor DH800 flowmeter with the converter oriented in the opposite direction (rotated 180 degrees) can also be ordered.

Q    Can the Darhor DH800 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.

Q    Can a Darhor DH800 be installed on a vertical pipe with a downward flow direction?
A    This is not recommended. The Darhor DH800 should be installed on a pipe that is fully filled with liquid; therefore, the flow direction should be upward.