Tecfluid COVOL User Manual
Oscillating
piston flowmeter
series COVOL
Instructions manual
R-MI-COVOL Rev.: 4 English version
PREFACE
Thank you for choosing the oscillating piston flowmeter series
COVOL from Tecfluid S.A.
This instruction manual allows the installation and operation of the
oscillating piston flowmeter series COVOL. It is recommended to
read it before using the equipment.
WARNINGS
This document shall not be copied or disclosed in whole or in
any part by any means, without the written permission of
Tecfluid S.A.
Tecfluid S.A. reserves the right to make changes as deemed
necessary at any time and without notice, in order to improve
the quality and safety, with no obligation to update this manual.
Make sure this manual goes to the end user.
Keep this manual in a place where you can find it when you
need it.
In case of loss, ask for a new manual or download it directly
from our website www.tecfluid.com Downloads section.
Any deviation from the procedures described in this instruction
manual, may cause user safety risks, damage of the unit or
cause errors in the equipment performance.
Do not modify the equipment without permission. Tecfluid S.A.
is not responsible for any problems caused by a change not
allowed. If you need to modify the equipment for any reason,
please contact us in advance.
2
TABLE OF CONTENTS
1 WORKING PRINCIPLE ......................................................................... 4
2 RECEPTION ........................................................................................... 5
3 INSTALLATION .................................................................................... 5
3.1 Filter .......................................................................................... 5
3.2 Open discharge ........................................................................ 6
3.3 Position ..................................................................................... 6
3.4 Straight pipe sections .............................................................. 6
3.5 Valves ....................................................................................... 6
3.6 Pumps ........................................................................................ 6
3.7 Electrical connection ............................................................... 7
4 MAINTENANCE .................................................................................... 8
4.1 Disassembly ............................................................................. 9
4.2 Mounting ................................................................................... 9
4.3 Replacing the reed switch group ............................................ 10
5 PART LIST ............................................................................................ 11
6 TECHNICAL DATA ................................................................................ 12
7 DIMENSIONS ......................................................................................... 13
8 K FACTOR (PULSES / LITRE) .............................................................. 16
9 ADDITIONAL INSTRUCTIONS FOR THE ATEX VERSION ................. 16
9.1 Intrinsic safety .......................................................................... 16
9.2 Flameproof enclosure .............................................................. 16
9.2.1 Earth connection ........................................................................ 17
9.2.2 Maintenance ............................................................................. 17
9.2.3 Technical data for the ATEX version ...................................... 17
9.2.4 Marking ..................................................................................... 18
9.2.5 Dimensions ............................................................................... 19
10 TROUBLESHOOTING ........................................................................... 23
3
1 WORKING PRINCIPLE
By means of oscillating piston and an annular measuring
chamber.
1– The first figure shows the COVOL flowmeter at the beginning
of a cycle, when the measuring chamber (in blue) is
completely full.
2– The flow of the liquid through the flowmeter makes a force on
the oscillating piston, so that it starts turning. From this moment
the measuring chamber is divided in two parts: inlet (in red) and
outlet (in blue).
3– The liquid fills progressively the inlet measuring chamber (in
red), as it is getting emptied on the outlet (in blue). In the middle
of the cycle (see figure) the two chambers are the same size.
4– At this stage the outlet measuring chamber has already
emptied almost all the liquid corresponding to a cycle, while on
the inlet it is almost filled with the liquid corresponding to the next
cycle.
5- At the end of the cycle, the inlet measuring chamber takes all
the space. From this moment it can be considered that this is
already the outlet chamber, so we are again at the beginning of
the cycle.
As one can see, a constant volume of liquid is moved in each
cycle.
The piston includes a magnet inside that activates a reed switch
each complete turn. The output signal can be treated by means of
an electronic converter.
4
2 RECEPTION
COVOL oscillating piston flowmeters are supplied individually packaged for protection during
transport and storage, including their corresponding instructions manual, for their installation
and use.
All the flowmeters have been verified in our flow rigs, obtaining the K factor for each
device.
3 INSTALLATION
The installation must be made in a point that ensures that the pipe is completely full of
liquid.
Highest points in the installation as well as downwards pipes must be avoided, since air
pockets or vacuums might occur.
In installations where air can be present, a degasser must be installed before the
flowmeter.
Partially full pipe can involve important measurement errors.
3.1 Filter
The installation of a filter before the COVOL oscillating piston is mandatory. This way a
correct performance is guaranteed and severe damage is avoided.
The mesh size must be between 0.1 and 0.2 mm², in order to avoid that bigger particles
can block or get embedded in the oscillating piston, stopping or slowing it and providing
false readings.
5
3.2 Open discharge
When the flow measurement is to be made before an open discharge, it is necessary to
install the flowmeter in a section of pipe with a trap which avoids the presence of air inside
the meter.
3.3 Position
The installation and position of the flowmeter can be either vertical, horizontal or inclined.
The flow direction does not affect the flowmeter accuracy.
3.4 Straight pipe sections
Straight pipe run is not required, the flowmeter can be installed just before or after
disturbing elements.
3.5 Valves
Regulating or shut-off valves must always be installed after the flowmeter, in order to
assure that pipe is full of liquid.
3.6 Pumps
Pumps must always be installed before the flowmeter in order to avoid cavitations.
6
This way the presence of air pockets in the flowmeter is avoided, which could cause false
readings. In particular, the associated electronics would show a volume higher than real.
Note: In order to avoid cavitations, the API Std 2534 standard must be taken into
account. This standard states that on the outlet of the flowmeter the pressure must be at
least twice the pressure drop of the flowmeter (in case of COVOL, this pressure drop is
3 mH2O or 0.3 bar, for fluids with viscosity 1 mPa·s at maximum flow rate), plus 1.25
times the vapour pressure of the liquid or its most volatile components.
3.7 Electrical connection
It is important to keep the connecting cable between the flowmeter and the associated
electronics away from mains or power supply cables, in order to avoid interferences. In
any case, those should be separated at least 5 cm.
The COVOL oscillating piston flowmeter has a connector fastened to the counter by
means of 4 screws. The connector consists of 3 parts joined by threaded nuts. (See
figure).
Loosening the larger nut in the middle of the connector allows us to withdraw the half
where the cable will be later soldered.
The other half of the connector is fixed to the counter and should not be removed, except
when servicing the detector (See point 4.3 of the MAINTENANCE section).
The removable part of the connector consists of the cable gland at the top and the
electrical connection protector housing.
7
Before starting the installation, check that the cable gland is the right size for the cable to
be used. This will guarantee the instrument will stay watertight. The cable gland used is
for cables with outside diameters between 6 mm and 10 mm.
The electrical connection protector housing is dismounted by loosening the second nut.
When this is removed, the three connector terminals are visible.
The terminals are numbered 1 to 3 and the connection is as follows:
N. 1 & 2: Electrical switch connection.
N. 3: This terminal has a shortcircuit with terminal N.1. Don’t connect
Before soldering the connections, unscrew the cable gland and feed it, together with the
electrical connection protector housing, over the cable.
The joint between the cable and the connector should always be soldered, and should be
tidy and without short circuits between terminals.
Peel the outside insulation to free the inner cables. It is recommended to tin the ends of
the wires to avoid loose ends.
Once the connections have been made, the housing should be mounted screwing it on
and then the cable gland should be tightened to avoid entry of any liquid or humidity.
Once assembled the half of the connector, the mounting in the base has only one position
defined by the keyway between the two parts.
Check that the rubber seal is in its position inside the connector base. If this is the case,
introduce the connector half in the base, positioning by the keyway, and screw on the nut
until the end of the thread is reached.
anything to this terminal.
4 MAINTENANCE
In normal working conditions the COVOL flowmeter has a long life. Normally it will not be
necessary to change any parts.
The life of the parts depends mainly on the abrasive characteristics of the product to be
measured and the flow rate.
The combination of these two factors, together with the construction material of the
flowmeter, makes it difficult to estimate the life of the device in good working conditions
If the maximum flow rate for each DN shown in the chart below is exceeded the life of the
pieces can be considerably reduced.
Flow ranges
DN
10 / ¼" (H) 25-250 500 100
10 40-350 800 100
15 150-1500 2700 20
25 500-4500 9000 10
40 800-8500 15500 4
50 1500-16000 28000 2
80 3000-28000 50000 1
100 5000-60000 104000 0.2
Flow scales
l/h water
Max. intermittent
l/h water
8
pulses / litre
approx.
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