Cleaning the level sensor
Cleaning the air pressure sensor (-AA versions)
Calibration 20
Setting the zero point
Testing by the manufacturer
Level measurement with pressure sensors 20
Overview of DCX 22
Accessories 26
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Product overview
The data loggers in Series DCX are autonomous, battery-powered data collectors
which can measure the water level (water column, i.e. pressure) and temperature over
lengthy periods.
Series DCX is designed for level measurements and is generally used for long-term
data acquisition in applications with brackish water, salt water or fresh water.
Series DCX is also available with a connecting thread for process applications.
Various versions are available in Series DCX. The standard material is stainless steel,
316L (DIN 1.4435). For added resistance to media, the logger can be manufactured to
order from Hastelloy or titanium as options. The key distinguishing features of products in
Series DCX are their measuring methods and the diameter of the probe.
DCX-22 AA
Probe diameter
16 = Ø 16 mm
18 = Ø 18 mm
22 = Ø 22 mm
25 = Ø 25 mm
38 = Ø 38 mm
Version
.... Absolute pressure measurement / without cable
VG Relative pressure measurement / with cable
SG Absolute pressure measurement / with cable
AA Absolute pressure measurement with 2 sensors / with cable
PVDF For use in aggressive media.
Special housing made of polyvinylidene uoride (PVDF) with high
resistance to chemicals / Available for probe diameter of 25 mm,
without cable only
Maximum pressure ranges and cable lengths
Designation
DCX-16absolute0,8…11 bar abs.
DCX-16 VGrelative0…10 bar rel.
DCX-16 SGabsolute0,8…11 bar abs.
DCX-18absolute0,8…11 bar abs.
DCX-18 VGrelative0…10 bar rel.
DCX-18 SGabsolute0,8…11 bar abs.
DCX-22absolute0,8…11 bar abs.
DCX-22 Baroabsolute0,8…1.3 bar abs.
DCX-22 VGrelative0…10 bar rel.
DCX-22 SGabsolute0,8…11 bar abs.
DCX-22 AA
DCX-25 PVDFabsolute0,8…11 bar abs.
DCX-38 VGrelative0…
Measuring
principle
absolute/absolute
Max.
pressure range
0,8…11 bar abs.
300 mbar rel. 0…3 mH2O
Max. mH2O
0…100 mH2O
0…100 mH2O
0…100 mH2O
0…100 mH2O
0…100 mH2O
0…100 mH2O
0…100 mH2O
0…100 mH2O
0…100 mH2O
0…100 mH2O
0…100 mH2O
0…100 mH2O
** For other system lengths, please contact our sales staff
3
Max. cable length**
–
500 meters
500 meters
–
500 meters
500 meters
–
–
500 meters
500 meters
80 meters
–
500 meters
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Overview of structural designs, Series DCX
Different versions of the autonomous data loggers in Series DCX are available from
KELLER in order to meet the requirements for the measuring point, the on-site environ-
mental conditions and the uid to be measured:
Series DCX-16
- probe diameter 16 mm
-VG-SG
Series DCX-18
- probe diameter 18 mm
- powered by rechargeable battery
- completely welded in
- screw-on cable
-VG-SG
Series DCX-22
- probe diameter 22 mm
- AA version
- high-accuracy version
- customized versions
-VG-SG-AA
on request
Series DCX-25 PVDF
- probe diameter 25 mm
- for use in aggressive media
Special housing made of polyvinylidene uoride (PVDF)
with high resistance to chemicals. Pressure sensor in
Hastelloy or titanium, according to choice
Series DCX-38 VG
- probe diameter 38 mm
- to measure low pressures or
levels (measuring ranges: 0,5 / 1 / 3 mWS)
- capacitive measuring cell with gold-plated
ceramic diaphragm
- Moisture absorber cartridge included in scope of delivery
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Measuring principle for Series DCX
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Surface of
water
DCX-
-AA version-VG version-SG version
③
optional
②
Cable
capillary tube
Cable with integrated
①Level sensor
P1 = medium pressure [bar]
TOB1 = medium temperature [°C]
①
①①①
②Air pressure sensor
P2 = air pressure [bar]
TOB2 = air temperature [°C]
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③Reference aperture
For physical compensation of the ambient pressure (air pressure)
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Ambient pressure (Air pressure)
General information
Fluctuations in the groundwater level (or the levels of other uids) can be determined
and located precisely by measuring the prevailing (hydrostatic) pressure at a dened
depth below the surface of the water. To convert the pressure [bar] into the water
column level [mWS], it is only necessary to know the density of the uid.
Example pure water (H2O): 100 mbar ≈ 1,02 mWS
p = N/m2 =
h =
ρ
*
g kg/m3 *
m/s
mWS
2
p = hydrostatic pressure (0,1 bar = 10,000 N/m2)
ρ = density (kg/m3)
g = gravitational acceleration (m/s2)
h = height of water column (m)
Level measurement
In open systems, i.e. with the classical method of measuring
the lling level, the difference between the pressure acting
on the level sensor (total pressure) and the ambient pressure
acting on the water (air/atmospheric pressure in most cases) is
always measured. The pressure difference determined in this
Hydrostatic pressure
of the water
Total pressure
way corresponds to the hydrostatic water pressure.
As a result of this measurement method, the level measurement becomes independent
of weather-induced uctuations in air pressure that act on the surface of the uid. The
following methods of compensating for air pressure are available:
Relative measurement method (VG)
In the relative measurement method, the sensor cable has an integrated capillary tube
which provides the reference to the ambient air pressure directly on the level sensor.
The sensor pressure measured in this way is therefore physically compensated for air
pressure.
Advantage: high accuracy and resolution
Disadvantage: high ambient humidity at the measuring point may disrupt or interrupt
compensation for air pressure and, in extreme cases, may even damage
the level sensor (→ use moisture absorber cartridges)
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Air pressure
Absolute measurement method (SG)
With the absolute measurement method, the prevailing total pressure on the level sen-
sor is determined (= air pressure + hydrostatic water pressure). To compensate for
the inuence of uctuations in air pressure, a second data logger is positioned on the
surface as a barometer.
Advantage: very robust, impervious to ambient humidity
Disadvantage: no integrated air pressure compensation
Absolute/absolute measurement method (A/A)
Total pressure and air pressure are each determined by means of a pressure sensor
(A/A technology) and are calculated mathematically in the device by subtracting the two
measured values. A sensor cable without a capillary tube is used for this measurement
method, and this is why AA systems are highly resistant to the ambient humidity prevailing at the measuring point.
Advantage: very robust, impervious to humidity or ooding
Disadvantage: slight reduction in measurement accuracy because of measurements
by two sensors
Level measurements in closed receptacles
For level measurement in closed receptacles/vessels,
the internal pressure in the vessel is measured instead of
the air pressure. The A/A measurement method is usually
selected on account of the humidity prevailing inside the
vessel.
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Internal
pressure
Water
pressure
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Functionality of Series DCX
Autonomous data loggers in Series DCX record the values measured for pressure and
temperature together with the time of each measurement.
The following types of recording and initial conditions are supported:
Recording intervalConstant
storage interval
Event-controlled
recording
Initial conditionsDirectly after programming is completed
Specied, user-dened time
Recording starts when a value has been undercut
Recording starts when a value has been exceeded
→ Constant storage interval and event-controlled recording can be used simultaneously
Interval ≥ 1 second
If value is exceeded
If value is undercut
If value changes
Data memory
The following table gives an overview of recording periods for various constant
measurement intervals. (Data memory size: 2 Mbit)
TypeInterval Number of
channels
DCX-221 sec1Total pressure > 15 h 54 min
DCX-221 min1Total pressure > 21 h 7 h
DCX-221 h1Total pressure > 3 y 6 m
DCX-221 sec2
DCX-221 min2
DCX-221 h2
DCX-221 d2
DCX-22AA1 sec5Air pressure and air temperature,
DCX-22AA1 min5Air pressure and air temperature,
DCX-22AA1 h5Air pressure and air temperature,
DCX-22AA1 d5Air pressure and air temperature,
Measurement channelRecording period
Total pressure and medium temperature
Total pressure and medium temperature
Total pressure and medium temperature
Total pressure and medium temperature
total pressure and medium tempera-
ture, calculated water column level
total pressure and medium tempera-
ture, calculated water column level
total pressure and medium tempera-
ture, calculated water column level
total pressure and medium tempera-
ture, calculated water column level
> 7 h 57 min
> 14 d 4 h
> 2 y 4 m
> 56 y 9 m
> 3 h 10 min
> 7 d 2 h
> 1 y 2 m
> 28 y 4 m
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Installation instructions
Important information
KELLER website
At www.keller-druck.com, you will nd a software section where you can download
all KELLER’s software programs free of charge. The site contains the latest software
versions together with datasheets and operating instructions for the corresponding
products.
Service and Support
For service and support, please contact your local dealer or contact us at www.kellerdruck.com
Guidelines on safe and efcient use
• Treat the product with care and keep it in a clean place that is free of dust.
• This product must only be used within the specied temperature range
(→Product datasheet)
• Do not drop or throw the device
• Do not attempt to modify the device
• The sensor pressure diaphragm is sensitive to contact. Do not press the diaphragm in
by hand or damage it with sharp objects. Do not direct water jets at the diaphragm.
• Only use this device for non-ammable uids with no explosion hazard. KELLER
offers a series of measurement equipment products suitable for use in areas with
explosion hazards (ATEX zones). For more information, please contact our sales
staff.
•
Aggressive media may damage the product. Make sure that the materials in the product
are not attacked by the medium to be measured.
• With relative versions (VG), the end of the cable must be located in a dry environment
in order to prevent condensation forming. If the cable ends in a humid environment, it
is highly advisable to use moisture absorber cartridges.
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• The level measurement sensor must not freeze up in the medium
• Do not glue, block or contaminate any ventilation components as this will substantially
impair measurement accuracy.
• Fasten/secure the product so that the logger cannot fall into the measuring point in
case of a handling error.
Warranty conditions
The warranty does not apply to faults on the device caused by normal wear, incorrect
use or misuse, or failure to comply with KELLER’s instructions.
Data security
KELLER assumes no responsibility for data loss of any nature, and shall not pay com-
pensatory damages in case of data loss. Data stored in the product may be lost if the
product is repaired or replaced. You should always create a backup of all data stored in
the product before releasing it for repair or replacement.
Disposal of old electrical equipment and batteries / rechargeable batteries
To prevent possible damage to the environment or to health due to uncontrolled waste
disposal, this product must be separated from other waste and recycled correctly in
order to ensure sustainable use of the raw materials. Remove rechargeable
batteries that have been installed permanently. Permanently installed rechargeable batteries must be removed only by a waste processing facility or a trained service technician.
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