Yokogawa digitalYEWFLO (DY) - Manual (Page 5)

INTRODUCTION
IM 1F2B4-01-YIA
Page 1
I. INTRODUCTION
1.1 G
ENERAL
O
VERVIEW
This manual provides installation, parameter setting, calibration, maintenance and troubleshooting
instructions for the YEWFLO Vortex flowmeter. Also included are standard specifications, model code
definitions, dimensional drawings and a parts lists.
All YEWFLO’s are shipped pre-configured for your application. Therefore, if you included correct
process conditions with your order, no electronic setup or parameter setting is required. For piping
and wiring connections, refer to the Installation section.
If your process conditions have changed since your order was placed, please refer to the ‘QUICK
START’ section which is designed to simplify configuration of the YEWFLO software parameters.
Please refer to the index for immediate access to a specific procedure or the glossary located at the end
of this manual for further information on a specific term.
If you have any questions concerning the YEWFLO you received, please contact your local Yokogawa
Industrial Automation Representative or our headquarters office in Newnan, GA at 770-254-0400.
If you have technical questions regarding the installation, operation, setup or application of a
YEWFLO, please contact our Technical Assistance Center (TAC) at 800-524-SERV.
Yokogawa has manufactured this instrument according to rigorous ISO 9000 quality standards. To
ensure quality performance we recommend referencing our YEWFLO sizing program to determine the
level at which your application should be run as well as a straight meter run of 20 diameters upstream
and 5 diameters downstream. In addition to these suggestions, please follow the instructions in this
manual carefully.
We are not responsible for any instrument’s performance, if that instrument has not been properly
applied or installed in accordance with this manual, nor can we be responsible for the performance of
any instrument which has been modified or repaired by an unauthorized service center.
Note: Existing YEWFLO Style C vortex flowmeters may be upgraded to provide the features and benefits
of the New microprocessor-based Style "E" YEWFLO.
1.2 P
RINCIPLE OF
O
PERATION
1.2.1 Vortex shedding
How many of you have seen a flag flapping in the breeze on a windy day? Everybody has. How many
of you have noticed that the flag flaps faster as the wind blows faster? Few haven’t. When you see a
flag flapping in the breeze, you are witnessing the same phenomenon that makes a vortex flowmeter
work. The flapping frequency is proportional to the velocity of the wind, and it’s linear! The flapping
is caused by a vortex alternately being created on either side of the flag, and moving downstream with
the wind. The vortex is a swirl of low pressure, like a tornado, that pulls the flag in the direction of the
vortex. The passing of alternating vortices down the length of the flag causes it to flap. The faster the
wind blows, the faster these vortices are created, and the faster the flag flaps. Frequency is
proportional to velocity .