ISTEC Corporation, your Flow Measurement and Control Specialist
 

ISTEC CORPORATION
Flow Measurement & Control
5 Park Lake Road, Unit 6
Sparta, NJ 07871 USA
Tel 973-383-9888
Fax 973-383-9088
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Aquametro Contoil Meter Data

FUNCTION

Contoil flow meters work on the volumetric principle of rotary piston meters (positive displacement meters). The main features of this measuring principle are large measuring ranges, high accuracy, suitability for high viscosities and independence from power supply; flow disturbances do not influence proper operation.

Rotary Piston Meters

CONSTRUCTION

Rotary piston, guide roller and drive are the only moving parts in contact with the liquid. Their movement is transmitted by a magnetic coupling through a sealing plate. The hydraulic part is completely separated from the totalizing module.

VZF/VZFA 15 - 50

Connections are made radially with two cable entries underneath the display unit which can be mounted and rotated through 90° steps.

VZO/VZOA 15 - 50

With the exception of the counter with the RV Reed Pulser, the roller counter can be rotated through 360° for optimum readability.

VZO/VZOA 4 and 8

The connections for the inlet and outlet are situated vertically from below in the base plate. With the OEM meter version the connections are situated on the side.

Aquametro Contoil Model VZF/VZFA 15 ... 50 Aquametro Contoil Model VZO/VZOA 15 … 50 Aquametro Contoil Model VZO/VZOA 4 and 8

MEASURING ERROR LIMITS: Reference Conditions

Measuring error limits according to technical data of meter in% of actual value for the whole measuring range.

REFERENCE CONDITIONS

Liquid:
  Calibration oil similar to extra light heating oil, density at 20°C = 814kg/m3
Viscosity = 5.0mm2/s according to DIN 51757 / ISO 3104 (corresponds to 4.1 mPa.s)
Temperature:
  18...25°C

Horizontal mounting, readings from counter.
Contoil® Oil meters are never to be tested with water, otherwise they will get damaged.

Referenced Conditions

Aquametro Contoil Meter Materials

DIMENSIONS in mm
VZO/VZOA 4 and 8

Aquametro Meter VZO/VZOA 4 and 8 Dimensions


DIMENSIONS in mm
FLOW SENSORS (all types)

Aquametro Contoil Meter Flow Sensor Dimensions


Nominal Size
L
B
a
0F
b
h1
p
r
DN 15
165
105
260
95
45
65
G 3/4"
G 1/2"
DN 20
165
105
260
105
54
74
G 1"
G 3/4"
DN 25
190
130
305
115
77
101
G 1-1/4"
G 1"
DN 40
300
210
440
150
116
153
G 2"
G 1-1/2"
DN 50
350
280
165
166
209

DIMENSIONS of TRANSDUCER GROUPS / MEASUREMENT TRANSDUCER

Oil Flow Meter
VZF / VZFA
VZO 15 - 25
VZO 40 - 50 / VZOA 15 - 50
Max. Temperature
130/180°C
130°C
180°C
130°C
180°C
Pulsers
all
RV
IN
RV
IN
RV
IN
RV
IN
Dimensional Drawing
1
2
3
6
5
4
7
5
4
6
5
4
7

VZF(A), VZO(A) DIMENSIONAL DRAWINGS (1 - 7 from table above)

Aquametro Contoil Dimensions of Transducer Groups


DISPLAY / ROLLER COUNTER

Display / Roller Counter

Auqametro Contoil Optimal Meter Selection

Aquametro Contoil Fuels and Suitable meter Sizes

CHARACTERISTICS of DIFFERENT FUELS


Fuel     Extra Light Light Medium Heavy Bunker C

Density at 15°C min.
max.
kg/dm3
kg/dm3
0.82
0.86
0.82
0.95
0.82
0.96
0.82
0.99
0.90
1.01

Specific Volume at Average Density   l/kg 1.19 1.12 1.12 1.11 1.08

Viscosity at 20°C
Viscosity at 40°C
Viscosity at 100°C
  mPa.s
mPa.s
mPa.s
8
3
14
5
50
16
3
420
60
10
4200
380
35

Energy Value   kWh/kg 11.8 10.6 11.4 11.2 11.0

 

INDICATIVE VALUES on POWER for BURNERS and ENGINES


Burner
Power
up to kW
Flow Rate Heating Fuel EL
kg/j
l/h
Fuel Oil Meter
Flow Rate
Qmin...Qcont l/h
Size
DN

500
1 300
4 000
10 000
20 000
60 000
200 000

42
113
336
840
1 680
5 040
16 800

50
135
400
1 000
2 000
6 000
20 000

1...50
4...135
10...400
30...1 000
75... 2 000
225...6 000
750...20 000
4
8
15
20
25
40
50

 

Formula for Consumption in liters/hour:
Example:
 
Burner Power in kW
600 kW = 62 l/h
 


= 62 l/h
Energy value of fuel in kWh/kg x density in kg/dm3
11.8 kWh/kg x 0.82 kg/dm3
 

 

ENGINES

Engine
Power up to
approx. PS
ca.kW
Diesel Fuel Consumption
l/h
Fuel Oil Meter 1)
Flow Rate
Qmin...Qcont l/h
Size
DN

250
680
2 000
5 000
10 000
30 000
100 000

184
500
1 470
3 680
7 360
22 000
73 600
50
135
400
1 000
2 000
6 000
20 000
1...50
4...135
10...400
30...1 000
75...2 000
225...6 000
750... 20 000
4
8
15
20
25
40
50

1) For differential measurement the flow meter has to be selected according to the pump flow rate and the flow in the return pipe.

Formula:
1 HP = 0.736 kW
1 kW = 1.36 HP
1 kg Diesel at 0.84 kg/dm3 = 1.19 l
Rule of thumb:
approx. 190 g/kWh correspond to 0.226 l/kWh
approx. 140 g/HP correspond to 0.167 l/HP/h

PLANNING

Flow meters are precision measuring instruments. They achieve optimal results if

  • a few important rules are observed during plant design,
  • mounting and commissioning are carried out with care, the meters are used for their defined purpose only.

LAYOUT of PIPEWORK

  • The quantities consumed by all consumers must be registered by the meter.
  • Rotary piston meters do not require flow conditioners or inlet runs (after bends, T-pieces or fittings). They may be mounted in horizontal, vertical or inclined position, except with the head pointing downwards.
  • The layout of piping must ensure that the meter is at all times filled with liquid and that no inclusions of air or gas may occur. Do not install the instrument at the highest point of the installation.
  • Meter and accessory equipment must be easily accessible.

Pipework Layout

SELECTION of the METER and ANCILLARIES

To be considered when selecting the meter:

  • Operating temperature
  • Viscosity of the medium
  • Operating pressure
  • Flow rate
  • Resistance of the material against fuel to be metered and working conditions

The technical data are valid for the following reference conditions: EL heating fuel / diesel at 20°C. For higher viscosities or if the meter is mounted on the suction side of a pump, it is necessary to determine the pressure drop and the flow rate that can still be attained by using the pressure loss curves (page 25ff). If the pressure drop is more than 1 bar, it is advised to use the next larger meter size. Maximum permissible pressure drop = 3 bar.

MOUNTING on PRESSURE SIDE OF PUMP (burners)

Mounting on Pressure Side of Pump

MOUNTING on SUCTION SIDE OF PUMP (burners)

Mounting on Suction Side of Pump

IMPURITIES in PLANT or FUEL

Should impurities occur in the plant or in the fuel, a dirt filter has to be installed before the meter. The filter mounted in the meter inlet is only a safety filter and is too small to act as a dirt filter.


Maximum Mesh Size of Dirt Filter
Meter
VZF
VZO
VZFA/VZOA

Maximum Mesh Size of Dirt Filter
DN 4
DN 8
DN 15
DN 20
DN 25
DN 40
DN50


0.250mm
0.400mm
0.400mm
0.600mm
0.600mm

0.080mm
0.100mm
0.250mm
0.400mm
0.400mm
0.600mm
0.600mm

0.80mm
0.100mm
0.100mm
0.100mm
0.250mm
0.250mm
0.250mm

STOP VALVES or COCKS

In order to avoid backflow and draining, stop valves have to be mounted after the meter. Backflow and draining cause measuring errors and can damage the meter.

Stop Valves or Cocks

FILLING/DOSING

For filling and dosing the valve has to be mounted between meter and outlet. The shorter the pipe section between meter and outlet, the higher the accuracy. Fast opening and shutting of the valve should be avoided (pressure hammer!).

Filling/Dosing

REMOTE PROCESSING/ANCILLARIES

Any backflow must be avoided on meters equipped with pulsers for remote processing. If this cannot be achieved by appropriate plant design, a non-return valve should be fitted.

ELECTRICAL WIRING and INSTALLATIONS

Electrical wiring and installations are subject to statutory regulations which must be taken into account when planning the system. For installations in zones subject to explosion hazards, consult an appropriate expert.

The following factors should be taken into account during plant design:

  • Ancillaries Connected to the Meter
  • Environmental Interference
  • Maximum Permissible Cable Lengths (with or without amplifier)
  • Junction Boxes, Cable Guides

CABLE LENGTH on the VZF METER OUTPUTS

A cable with wire diameter of 0.5mm is generally suitable up to 25 m and such of 0.8mm will go up to 100m. In all other cases the limiting factors should be considered.

ANALOG CURRENT OUTPUT: (4 - 20mA)

Limiting factors are supply voltage (U) and resistance of the load (RL). To ensure the maximum current signal of 21.5 mA with sufficient operating voltage for the meter the following formula is used to calculate the maximum permissible resistance (RL) which consists of the resistance of the cable plus the resistance of other components within the circuit. Knowing the resistance of the other components, the maximum permissible length for the cable can then be calculated.

 
(U – 5) V
  Example:  
(24 – 5) V
 
19 V
 
RL=
[Ω] Supply Voltage
RL =

=

= 883 Ω
 
0.0215 A
  U = 24V  
0.0215 A
 
0.0215 A
 

SEMICONDUCTOR RELAY OUTPUT: (Volume Pulses, Frequency Signal, Limit Switch)

Limiting factors depend on the input specification of the higher system or the totalizer. The ability of the input to detect the actual state of the switch is specified by the system manufacturer.

For the relay switch a maximum of 100 Ω at ON-state has to be considered together with the cable's resistance. A minimum of 10M Ω at OFF-state has to be considered together with the cable's capacity. The maximum permissible length of the cable depends on the individual properties for resistance and capacity.

PULSERS IN and RV

POWER SUPPLY

Our range of products includes passive pulsers for the remote processing of flow data. The pulser generates one pulse per unit of volume and is to be supplied with power from the pulse processing device.

Pulsers IN
Pulsers RV
Power supply 5...48V AC/DC
Power supply 5...15V DC

SELECTION of the APPROPRIATE PULSER

The selection of the most appropriate pulser and pulse value depends on the application. As a rule, remote totalization demands rather large pulse values, whereas analogue signals, dosing control or indication of actual flow rate tend to need small values. Battery supplied devices can only be used together with Reed pulsers.

SELECTION of the PROCESSING DEVICE

The pulse length depends on the flow rate. Continuous contact may occur at zero flow. The device connected must therefore be able to accept continuous load; otherwise, protective measures have to be taken. For remote totalization, it is recommended to use an electronic pulse counter with a low power consumption and bounce filter.

CORRECT PULSE PROCESSING

Interrupted flow may cause hydraulic oscillation of the liquid in certain plants (hydraulic vibration with minimal backward/forward flow). The pulses which can occur in such cases may be interpreted as forward flow by the connected device. Such faulty pulses do not affect the indication of the actual value since they can only occur at almost zero flow. However, if the pulser controls a counting device, hydraulic vibration must be avoided by an appropriate modification or layout of the plant.

PULSE VALUES

Pulse values depend on type and nominal size of the meter. They are listed in the technical information of the meter concerned.

PULSE PERIOD

Pulse Period

Pulse Period as well as On- and Off-times can be Calculated with the following Formula:
 
Pulse Period (in s) =
pulse value in liters 3600

flow Q in l/h
 
On-time =
pulse period in s x on-time in% of pulse period

100
 
Off-time
=
pulse period in s minus on-time
 
We recommend that this calculation be carried out for the highest and lowest expected flow rates.

DIESEL ENGINE

DIRECT CONSUMPTION MEASUREMENT

Instead of returning the fuel back into the main tank, an intermediate tank equipped with a heat exchanger should be installed on the supply side of the system. The flow measurement is taken in the supply pipe to the intermediate tank. The load on the meter and the measuring result correspond precisely to the consumption.

Direct Consumption Measurement

DIFFERENTIAL MEASUREMENTS

For differential measurements, the piping remains unchanged, with circulation back into the tank. A flow meter is installed in both supply and return pipes. The consumption is determined as the difference between the amount in the supply section and the amount in the return section. The meter loads therefore correspond to the supply and return flow rates.

Based on the interface variable set, local measurements at the terminal of generator (such as the reactive and active power, terminal current and voltage) can be chosen to describe the relationship between the generator set and the AC grid. Furthermore, based on the interface equations, the relation between the terminal measurements and the immeasurable variables in the differential equations of generator (such as the d and q-axis stator circuit currents, the transient EMF in the q-axis) can be established. Thus, it is easy to transform the immeasurable variables into local measurements, and then the nonlinear controller using only local measurements can be designed easily.

 

Differential Measurements

REASONS FOR USING SPECIAL METERS for DIFFERENTIAL MEASUREMENTS

Standard meters feature a large measuring range and a max. permissible error of ±1%. This makes them unsuitable for differential measurements, as the following example shows:

Full load Supply
Return
400 l/h
150 l/h
Error ±1%
Error ±1%
= nominal ±4.0 l
= nominal ±1.5 l
 
  Consumed 250 l/h
Maximum divergence
  Divergence nominal ±5.5 l
  Consumed = 5.5100 : 250 = ±2.2%      

 

Min. load Supply
Return
400 l/h
360 l/h
Error ±1%
Error ±1%
= nominal ±4.0 l
= nominal ±3.6 l
 
  Consumed 40 l/h Divergence nominal ±7.6 l
  Maximum divergence      
  Consumed = 7.6100 : 40 = ±19%      

For an optimal result, special meters are therefore used for differential measurements. These are precisely matched to the operating conditions and are calibrated in pairs. This means that the measurement error can be significantly reduced (for example: ±0.1% at constant flow rates on the supply side and ±0.3% with slightly variable flow rates on the return side).

LOAD ON METERS

Example: Engine power 500hp vehicle with electric pump

Vehicle with Electric Pump

Effective loads on meters Supply
Return
constant 180 l/h
100...174 l/h

Example: Engine power 500hp, vehicle with revolution speed dependent pump 1:4

Vehicle with Revolution Speed Dependent Pump

Effective loads on meters Supply
Return
45...180 l/h
39...100 l/h

CONSUMPTION MEASUREMENT on SHIPS

On ships, care is usually taken to ensure that the engine can still be operated at full power even if the filter is heavily contaminated or if the meter is damaged. When switching over to the bypass, attention may be drawn to the necessary maintenance via an alarm output, and the engine can be temporarily operated without measuring the consumption.

Temporarily Operated without Measuring the Consumption.

The magnetic valve opens as soon as the pressure drops below a defined level.

Opens as soon as the Pressure Drops Below a Defined Level

Float or valve control in the intermediate tank is required. Formation of gas is to be avoided. The magnetic valve opens as soon as the pressure drops below a defined level. For measuring the consumption of more than one engine, each will require a separate installation similar to the one above.

INSTALLATION of METER on SUCTION SIDE of PUMP

Installation of Meter on Suction Side of Pump

See PRESSURE DROP CURVES

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