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P118i Ultrasonic Flowmeter and Analyzer
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7. Product Overview
7.1 Introduction
The Model P118i Ultrasonic Flowmeter is a state-of-the-art universal transit-time flowmeter designed using ARM
technology and low-voltage broadband pulse transmission. While principally designed for clean liquid
applications, the instrument is tolerant of liquids with the small amounts of air bubbles or suspended solids found
in most industrial environments.
7.2 Features of Flowmeter
With distinctive features such as high precision, high reliability, high capability and low cost, the flowmeter
features other advantages:
1. With ARM COMA chip, low power consumption, high reliability, anti-jamming and outstanding benefits.
2. Clear, user-friendly Menu selections make flowmeter simple and convenient to use. U.S., British and Metric
measurement units are available. Meanwhile, almost all-universal measurement units worldwide may be
selected to meet customer
’
s requirements.
3. With the SD Card, 512 files can be stored; the time interval can be within 1 second.
4. Parallel operation of positive, negative and net flow totalizer with scale factor and 7 digit display.
The flow meter ensures the higher resolution and wider measuring range by the 0.04nS high resolution, high
linearity and high stability time measuring circuit and 32 bits digits processing program.
7.3 Theory of Operation
This Ultrasonic Flowmeter and Analyzer adopts the time-difference measurement principle. The ultrasonic waves
emitted by the sensor in a fluid, the flowing in the propagation direction of acoustic wave propagation velocity
downstream increases, decreases the upstream direction, have different propagation distance in the same
transmission time, measure the flow rate according to the difference of the transmission time and the fluid flow
velocity.
When the ultrasonic signal is transmitted through the flowing liquid, there will be a difference between the
upstream and downstream transit time ( travel time or time of flight ), which is proportional to flow velocity,
according to the formula below.
down up
T T
T MD
V
•
∆
× =
θ
2 sin
Remarks:
V Medium Velocity
M Ultrasonic frequency of reflection
D Pipe Diameter
θ
The angle between the ultrasonic signal and the flow
T
up
Transit time in the forward direction
T
down
Transit time in the reverse direction
Δ
T=T
up
–
T
down
Downstream Transducer
Upstream Transducer
Flow
D
T
down
T
up