Trace Humidity Monitoring up to -90 °C
td
testo 6781
Committing to the future
New, condensation-proof sensor with sol-gel technology
Highest compressed air quality requirements
2
Monitor trace humidity, avoid damage
Air, compressed air and gases are used in all
areas of industry. Humidity is normally
undesirable because it can cause damage or
impair the quality of the end product, as the
adjacent graphic shows.
Optimizing the regulation of adsorption
dryers
The regeneration cycle can be reduced by
controlling the parameter trace humidity
(°C
td
). That saves energy costs!
Gas engineering: humidity
causes damage and reduces
the value of the gas in the
system
Granulate drying: dry air is a
requirement for product quality
Medical compressed air:
minimum humidity as a hygiene
requirement
Compressed air systems: dryer
monitoring to avoid damage
caused by humidity
Trace humidity monitoring with testo 6781 avoids follow-on
damage caused by humidity
>>
Manufacture Distribution Consumer
Corrosion in pipes
and components
Pneumatic drives:
– Interrupted lubrication
– Mechanical damage
Formation of ice in
outside and low-
Compressor
Dryer
e.g. medical
compressed
air
Damp powder
sticks together
Bacterial growth
(European drug
legislation)
e.g. transport air for
pharma. powder
ISO 8573
Action Compressed air drying
testo 6781
Monitoring/controlling
Class
1
2
3
4
5
6
7
-70
-40
-20
3
7
10
–
-94
-40
-4
37
44
50
–
0,003
0,12
0,88
5,51
7,28
8,93
–
0,37
18
147
1083
1432
1756
–
Semi-conductor prod.
Granule dryer
Transport air
Working/energy air
Blow air
°C
td
°F
td
g/m
3
ppm
v
(at 7 bar)
Trace humidity Typical application
Applications in the monitoring of compressed air quality
What is compressed air quality?
The international standard ISO 8573 defines
seven classes of compressed air quality and
defines the humidity, the oil content, the
particle content etc. which the compressed
air is allowed to have. Class 1 represents the
highest requirements. Class 2, for example, is
fulfilled when the pressure dewpoint does not
exceed -40 °C
td
or -40 °Ftd, or an absolute
humidity of 0.12 g of water vapour per m
3
or
18 ppm
V
(parts per million by volume) (see
table on right).
The main way of ensuring compliance with a
quality class involves installing a suitable dryer
e. adsorption dryer). Its monitoring and,
where appropriate, its control, is handled by
the testo 6781.
Pressure dewpoint transmitter testo 6781 up to -90 °C
td
3
Configuration options for the testo 6781
This results in a typical ordering code:
0555 6781 AXX BXX CXX FXX KXX MXX
B02
B03
B04
B05
B06
C00
C02
C03
C04
C05
C06
C07
C08
K01
K02
K03
K04
K05
K06
K07
K08
F01
F02
F03
F04
F05
F06
F07
F08
F09
F10
F11
0 to 1 V (4-wire, 24 VAC/DC)
0 to 5 V (4-wire, 24 VAC/DC)
0 to 10 V (4-wire, 24 VAC/DC)
0 to 20 mA (4-wire, 24 VAC/DC)
4 to 20 mA (4-wire, 24 VAC/DC)
without display
with display/English
with display/German
with display/French
with display/Spanish
with display/Italian
with display/Japanese
with display / Swedish
°C
td
/ min / max
°F
td
/ min / max
% RH/Min/Max
%RH / min / max
°C
tdA
/ min / max
°F
tdA
/ min / max
ppmV / min / max
g/m³ / min / max
g/ft³ / min / max
g/kg / min / max
g/lb / min / max
German/English instruction manual
French/English instruction manual
Spanish/English instruction manual
Italian/English instruction manual
Dutch/English instruction manual
Japanese/English instruction manual
Chinese/English instruction manual
Swedish/English instruction manual
Order no. 0555 6781
A01 Bxx Cxx Fxx Kxx
Axx Process connection
Bxx Analog display/supply
Cxx Display
Fxx Humidity parameter / min limit value / max-limit value / hysteresis (pre-set)
Kxx IM languages (for bilingual printed IMs)
Mxx Protective filter
A01
A02
Process connection G1/2
Process connection NPT 1/2’’
Mxx
M01
M03
Sintered stainless steel cap
Sintered PTFE filter
· Measurement of dewpoints in the
measuring range -90 to +30 °C
td
· New, very condensation-proof sensor with
sol-gel technology guarantees highest
process security and fast response
· Display with multi-language user menu.
· Atomatic self-adjustment ensures high
accuracy and long reliability
· Self-monitoring guarantees high systam
availability
· The P2A software for parameterization,
adjustment and analysis saves time and
costs in commissioning and maintenance
Areas of application:
· Pressure dewpoint measurement in the
ISO Classes 1 (<-70 °C
td
) and 2 (<-40 °Ctd)
· Monitoring of adsorbtion dryers, granulate
dryers and medical compressed air
· Quality assurance for noble gas
preparation
4
Pressure dewpoint transmitter testo 6781 up to -90 °C
td
Supply
Analog outputs
Other outputs
Resolution 12 bit
Load max. 500 Ω
Meas. cycle 1/sec
Inputs/outputs
Current/accuracy 0 to 20 mA ±0.03 mA (4-wire)
4 to 20 mA ± 0.03 mA (4-wire)
Output type 0 to 1 V ±1.5 mV (4-wire)
0 to 5 V ± 7.5 mV (4-wire)
0 to 10 V ±15 mV (4-wire)
Digital Mini-DIN for P2A software
Voltage supply 20 to 30 VAC/DC, 300 mA current
consumption, galvanically separate
signal and supply line
- Hysteresis
- Linearity
- Reproducibility
* Determination measurement inaccuracy according to GUM
GUM (GGuide to the Expression of UUncertainty in MMeasurement): ISO guideline for the
determination of measurement inaccuracy, in order to make measurements
comparable worldwide. The following inaccuracies are used for the determination:
This total view results in an additional dewpoint-dependent and process-dependent
inaccuracy contribution of ±0.03 K x measurement value (in °Ctd) + 0.2 K x (25 °C process temperature in °C).
Outside the stated measuring range, a measurement inaccuracy of ±5 K applies
(typically).
Display
Model
Miscellaneous
Display optional: 2-line LCD with multi-language
operating menu
General technical data
Material Metal housing
Dimensions 208 x 60 x 35 mm
Weight 0.5 kg
Resolution
Protection class IP 65
EMC EU guideline 2004/108/EC
- Adjustment site/factory
calibration
- Test site
Measuring range Resolution
0 to +100 %RH 0,001
0,001 to 28 g/kg 0,001
0,01 to 194 g/lb 0,01
0 to 31 g/m3 0,001
0,001 to 14 g/ft3 0,001
1 to 42500 ppm(V) 1
-90 to +30 °Ctd 0,1
-130 to +86 °Ftd 0,1
-110 to +30 °CtdA 0,1
-165 to +86 °FtdA 0,1
-40 to +70 °C 0,01
-40 to +158 °F 0,01
Technical data
Operation temperatureWithout
display
With display
-40 to +70 °C / -40 to +158 °F
Storage temperature -40 to +80 °C / -40 to +176 °F
Operation temperature -20 to +80 °C / -4 to +176 °F
Storage temperature 0 to +50 °C / +32 to +122 °F
Process temperature -40 to +70 °C / -40 to +158 °F
Process pressure max. 50 bar
Operating conditionsOperating conditions
Humidity/trace humidity
Parameters
Measuring range -90 to 30 °Ctd / -130 to 86 °Ftd
Measurement uncertainty* -20 °C
td
to -40 °Ctd: ±1,5K
-40 °C
td
to -60 °Ctd: ±2K
-60 °Ctdto -75 °Ctd: ±2,5K
Response time t63 ≤ 3s for switch
from -75 °C
td
to -30 °C
td
t90 ≤ 9s for switch
from -75 °C
td
to -30 °C
td
t63 ≤ 300s for switch
from -30 °C
td
to -75 °C
td
t90 ≤ 1080s for switch
from -30 °C
td
to -75 °C
td
Autom. self-adjustment Cycle adjustable:
1 h / 6 h / 12 h / 24 h
Units °Ctd, °Ftd, %rF, %RH
Calculated variables °C
tdA
, °F
tdA
(normed atmosph.
dewpoint), ppmV, g/m³, g/ft³, g/kg, g/lb
5
Accessories – tailored to every application
Precision measurement chamber up to 35 bar (ideal for lowest humidity) for optimum flow impact onto sensor
with freely adjustable flow valve Pre-setting of valve: 1 l/min at 7 bar 0554 3312
Flow-through gauge for precision measurement chamber for adjusting specific flow impact onto sensor when process pressure
deviates from pre-setting of flow valve 0554 3313
2 m PTFE hose with compressed air connections up to +140 °C / +284 °F (max. 9 bar / 130psi),
only with measurement chamber (only up to -60 °Ctd) 0699 2824/4
Preliminary filter to protect measurement chamber and sensors against contamination 0554 3311
Cooling coil for process temperatures higher than 50 °C (up to 200 °C), only with measurement chamber 0554 3304
Mains unit (desktop instrument) 110 to 240 VAC/24 VDC (350 mA) 0554 1748
Mains unit (top-hat rail mounting) 90 to 264 VAC/24 VDC (2.5 A) 0554 1749
Process display testo 54-2 AC, two relay outputs (to 250 VAC / 300 VDC, 3A), mains supply 90 to 230 VAC 5400 7553
Process display testo 54-7 AC, two relay outputs (to 250 VAC / 300 VDC, 3 A), mains supply 90 to 260 VAC,
with RS485 output for online monitoring and with totalizer display 54007555
Certificates
ISO calibration certificate, two adjustment points -10/-40 °C
tpd
at 6 bar 0520 0136
Humidity ISO calibration certificate, pressure dewpoint measuring instruments, freely selectable calibration points 0520 0116
from -40 to 0 °C
tpd
at 6 bar (-40 to 32 °F
tpd
) at 87 psi
Accessories for testo 6781 Order no.
햳
햶
햴
햲
Selection assistance for applications
Pre-filter is additionally used for
contaminated air and when process
pressure corresponds to pre-setting of
precision measurement chamber
For dry air (e.g. granulate dryers, max.
140 °C), a PTFE tube is additionally used
and the valve of the measuring chamber
is opened fully
(suitable up to -60 °C
td
).
Use of precision measurement chamber
for clean air and when process pressure
corresponds to pre-setting
A
B
C
D
E
NPT ½”-thread
G ½-
thread
testo 6781
testo 6781
햲
햲
햲
햵
햵
햳
Flow-through gauge is additionally used
when air is clean and process pressure
deviates from pre-setting of precision
measurement chamber (1 to 35 bar)
The cooling coil is additionally used for
process temperatures >50°C (to 200°C)
and process pressure corresponding to
the pre-setting
햴
햲
햲
햶
0981 6284/msp/R/Q/02.2010 Subject to change without notice.
Optimizing processes and saving time in commissioning and maintenance
On-site adjustment
The Testo transmitters are delivered ready to use. For
professional application, the following functions are available
via the easy-to-use software
– Parameterization of unit and scale
– Sensor adjustment (1-point) and adjustment of the analog
outputs
– Parameterization and adjustment history of all activities of
the P2A software are registered in the PC
P2A software
A selected working point can be easily adjusted by manually
entering a reference value.
Just a few operatring steps are sufficient in the P2A
software to carry out the adjustment.
Conclusion: Saved time and lower operating costs!
P2A software = P aramerization
A djustment
A nalysis
find out more at: www.testo.com/saveris
– Integration of transmitters for all
measurement parameters with
standardized current and voltage
interfaces,
e. g. 4 to 20 mA, 0 to 10 V
– testo Saveris analog coupler available as
a wireless or Ethernet version
Now new:
Integrate the testo 6781 into
testo Saveris
TM
using the testo
Saveris analog coupler
Using the P2A software, unit and scale can be easily parameterized, for example.
The measurement data monitoring system measures temperature and
humidity values in the environment and in processes.
Integrate the testo 6781 into testo Saveris
TM
In industrial processes, exact temperatures,
humidity values and pressure relationships
play a crucial role.
In a multitude of applications, testo Saveris
helps to collect, safely store and present
these data wirelessly or via Ethernet. A
selection of alarms that can be used flexibly
supports the responsible parties to keep
the values in the required range.
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