CMA Dishmachines FLOWRATE SENSOR 0387I User Manual

FLOW RATE SENSOR 0387I

0 .. 4 M/S

User’s Guide

CENTRE FOR MICROCOMPUTER APPLICATIONS

http://www.cma-science.nl

Figure 1. The Flow rate sensor 0387i

2

Description

The Flow rate sensor 0387i measures the velocity of flowing water. It can be used to
study the discharge, flow patterns, and sediment transport of flowing water.
The Flow rate sensor is equipped with impeller rod with 5-meter cable. To assemble
the sensor, simply unfold the four sections of the impeller rod and slide them
together. Connect the rods to one another with a small push.
The sensor is delivered with three riser rods (short, medium, and long). The total
length of the impeller rod, including all 3 risers, is 1.5 m.
When the Flow rate sensor is placed in a
stream, water flows against the blades of the
impeller, causing it to turn. The faster the
water flows, the faster the impeller turns. A
bar magnet rotating with the impeller triggers a
reed switch with each half rotation. The switch
sends a pulse to the signal conditioning box,
where the pulses are converted into a voltage
signal that is proportional to flow rate.

The Flow rate sensor is equipped with a BT­plug and can be connected to the following
CMA interfaces: €Lab, CoachLab II/II+ and
ULAB. Furthermore the sensor can be used
with Texas Instruments CBL™, CBL2™ and
Vernier LabPro.

Sensor specifications

The Flow rate sensor has a memory chip (EEPROM) with information about the
sensor. Through a simple protocol (I2C) the sensor transfers its data: name, quantity,
unit and calibration to the interface1.

Storage and Maintenance of the Flow rate sensor

When you have finished using the Flow rate sensor, simply rinse it with clean water
and dry it using a paper towel or cloth. The probe can then be folded up and stored.
To prolong the life of your Flow rate sensor, we recommend that the moving parts of
the impeller rod be lubricated, after every few field uses.
When using the impeller rod, avoid hitting the impeller blade on rocks and other
hard surfaces. If the impeller blade is bent, it will decrease the accuracy of the
sensor.

1

This is valid for the following interfaces: CMA €Lab, BT inputs of CoachLab II/II+ and ULAB,

TI CBL™and CBL2™, and Vernier LabPro.

Figure 2.
Left: the sensor impeller
Right: the sensor bar magnet with reed
switch.

3

Examples of experiments

The Flow rate sensor can be used in the following experiments:

• Calculating Discharge

Stream flow or discharge is the volume of water that moves through a specific
point in a stream during a given period of time. To determine discharge, a
cross-sectional area of the stream or river is measured. Then, the velocity of the
stream is measured using a Flow rate sensor. The discharge can then be
calculated by multiplying the cross-sectional area by the flow velocity.

• Determining sediment transport rate for a stream or other body of water

The amount of sediment and maximum particle size that can be transported by
moving water is related to the flow velocity. Therefore, flow velocity data
obtained using the Flow rate sensor can be used to determine what size particles
will stay in motion at a particular flow velocity. For a given flow velocity there is
a range of behavioral possibilities for sediment particles lying on the bed, or
entrained within the flow, of a stream. For example, at a measured flow velocity
of 1 m/s, silt and sand (though not compacted clay) will be eroded from the
stream bed and transported downstream. At the same velocity, all sediment
particles between 10 mm and 100 mm that were already in motion will continue
in motion. Particles greater than 100 mm will be deposited. Thus, a Flow rate
sensor can be a valuable observational tool when used in sediment transportation
studies.

• Measuring and comparing flow rate at various locations in a stream

Using the Flow rate sensor, it is
possible to map flow characteristics
of a stream by taking measurements
at different spots and depths. To
understand the flow characteristics
within streams of moving water, it is
helpful to construct Stream Lines
and Vector Lines.
The first illustration shows how
Stream Lines depict possible paths
of a single fluid particle.
Vector Lines represent both the flow
rate and direction. The longer and
broader the line, the greater the flow
velocity. Vector Lines convey useful
information about the stream flow
characteristics.