Kobold AFS-G1 User manual

Operating Instructions
for
Hygrostat
Model: AFS-G1

AFS-G1
page 2 AFS-G1 K04/1019
1. Contents
1.Contents ........................................................................................................ 2
2.Note .............................................................................................................. 3
3.Instrument Inspection .................................................................................... 3
4.Regulation Use ............................................................................................. 3
5.Operating Principle ........................................................................................ 4
6.Mechanical Connection ................................................................................. 5
7.Electrical Connection .................................................................................... 6
8.Operation ...................................................................................................... 7
8.1.Calibration ............................................................................................ 7
9.Maintenance ................................................................................................. 8
9.1.Cleaning Process ................................................................................. 8
10.Technical Information .................................................................................... 9
11.Dimensions [mm] ........................................................................................ 10
12.EU Declaration of Conformance ................................................................. 11
Manufactured and sold by:
Kobold Messring GmbH
Nordring 22-24
D-65719 Hofheim
Tel.: [phone]
Fax: [phone]
E-Mail: [email protected]
Internet: www.kobold.com

AFS-G1
AFS-G1 K04/1019 page 3
Note
Please read these operating instructions before unpacking and operating the unit,
and follow the instructions precisely as described herein.
The instruction manuals on our website www.kobold.com are always for currently
manufactured version of our products. Due to technical changes, the instruction
manuals available online may not always correspond to the product version you
have purchased. If you need an instruction manual that corresponds to the
purchased product version, you can request it from us free of charge by email
([email protected]) in PDF format, specifying the relevant invoice number and
serial number. If you wish, the operating instructions can also be sent to you by
post in paper form against an applicable postage fee.
The devices are only to be used, maintained and serviced by persons familiar
with these operating instructions and with any applicable regulations concerning
procedural safety and accident prevention.
When installed in machines, the measuring unit should be used only then when
the machines fulfil the EC-machine guide lines.
3. Instrument Inspection
Instruments are inspected before shipping and sent out in perfect condition. In
case of damage, please inform your parcel service/ forwarding agent
immediately, as they are responsible for damage during transit. Should damage
to a device be visible, we recommend a thorough inspection of the delivery
packing
Scope of delivery:
 Hygrostat model: AFS-G1
4. Regulation Use
Any use of the Hygrostat, model: AFS-G1, which exceeds the manufacturer’s
specification, may invalidate its warranty. Therefore, any resulting damage is not
the responsibility of the manufacturer. The user assumes all risk for such usage.

AFS-G1
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5. Operating Principle
The Hygrostat AFS-G1 serves as a two-position controller to regulate relative
humidity indoors or in air ducts.
The humidity sensing element in the sensor comprises several strips of plastic
fabric, each with 90 fibres of 3 µm diameter. These plastic fibres undergo a
special process to acquire hygroscopic properties, meaning that they will absorb
and release humidity. The molecular structure of the fibres changes when they
absorb water, giving rise to a measurable change in length. The length of the
plastic fibres is thus a measure of the relative humidity.
The swelling effect, acting primarily in longitudinal direction, is transferred over a
suitable lever system to a microswitch with an extremely small changeover
movement.
The measuring element reacts quickly and accurately to the change in air
humidity. The setpoint is set with the setpoint button so that the microswitch is
actuated by the lever system when the humidity setpoint is reached.
The special treatment of the measuring element ensures that its hygroscopic
properties remain stable, and that is sensitivity is maintained until destroyed by
external influence. Regeneration found in conventional instruments is not
required, but is also not damaging.
The harp-shaped measuring element is protected by a perforated probe tube and
is open to the housing. The Hygrostat is designed for use in unpressurised
systems.
The humidity measuring equipment is designed with a perforated sensor tube.
The humidity and temperature measuring elements are located in the interior of
the sensor tube. The humidity measuring element is arranged axially and the
temperature measuring element is seated sideways at the top or bottom between
the perforation holes.
The measurement accuracy depends on the degree of pollution of the element.
The humidity measuring element, in particular, loses its hygroscopic properties if
the surface is covered with grease, soot, smoke deposits, paint, resinous
substances, etc. By cleaning the elements, their function can be reproduced, but
only if no damage is caused by acids, alkaline solutions or other aggressive
substances (see Maintenance).

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AFS-G1 K04/1019 page 5
6. Mechanical Connection
 The Hygrostat must not come into direct contact with water (e.g. splashed
water when cleaning the climatic chamber etc.)
 The mounting location should be chosen so that a representative
measurement of the air humidity can be guaranteed, i.e. the humidity readings
at the mounting location should correspond to those in the room as much as
possible.
 The Hygrostat should be exposed to the flow of air.
 The installation position should be chosen to prevent condensed water from
entering the housing. The preferred installation position is "sensor vertically
pointing downwards" or "sensor horizontal". A blanking plate in the probe with
a 0,8 mm diameter hole prevents penetration of water in the installation
positions described above.
Installation position
7.

AFS-G1
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7. Electrical Connection
When installing, ensure that there is sufficient over-current protection (e. g. fuse)
for the device. In addition, a separation device (e. g. plug or switch) must be
installed.
Fx Relative humidity of the air (process value)
Fw Adjusted humidity at the set value generator (set value)
If the relative humidity Fx falls below the adjusted set value Fw,
then contact 1/2 opens and contact 1/4 closes.

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AFS-G1 K04/1019 page 7
8. Operation
Attention! With restrictions in the upper range of operation, the
possible tolerances (measurement accuracy, switching difference
and temperature coefficient) should be observed when adjusting the
switch point.
8.1. Calibration
The Hygrostats are factory set at a room temperature of 23 °C and 50% relative
humidity, relative to the average air pressure of 430m NN.
If however, subsequent adjustment should be necessary, the following procedure
should be observed:
 Ensure that the ambient humidity and the ambient temperature are constant.
 If possible, use a psychrometer for checking (do not use equipment with
capacitive sensors).
 Leave the equipment to be checked for at least 1 hour in a constant checking
climate.
 The adjuster screw is at the end of the sensor - fixed with screw securing
lacquer. After removing the lacquer, the adjuster screw can be moved. A right-
hand rotation means that the measured value goes down, and with a left-hand
rotation the measured value goes up. After calibration, the adjuster screw
should again be secured.
Attention! Moving the adjuster screw nullifies the guarantee.
Important: The water absorption capacity of the air is influenced, amongst other
things, by the temperature. This is a physical law (which can be seen from the hx
diagram of Mollier). The higher the air temperature, the greater the volume of
water vapour that can absorbed up to saturation point (100 % RH). If a Hygrostat
is calibrated at a fluctuating air temperature, there will be an irregular, non-
homogeneous measured medium, resulting in calibration errors. The table below
shows the influence of the air temperature on air humidity. If, for example,
calibration occurs at an air temperature of 20 °C and 50 % RH, and at a
temperature fluctuation of just ±1 °K, then there will be a humidity fluctuation in
the measured medium (air) of ±3.2 % RH.
10 °C 20 °C 30 °C 50 °C
10 % RH +/- 0,7 % RH +/- 0,6 % RH +/- 0,6 % RH +/- 0,5 % RH
50 % RH +/- 3,5 % RH +/- 3,2 % RH +/- 3,0 % RH +/- 2,6 % RH
90 % RH +/- 6,3 % RH +/- 5,7 % RH +/- 5,4 % RH +/- 4,6 % RH
9.

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9. Maintenance
The measuring element is normally maintenance-free in pure ambient air.
Aggressive media containing solvent can cause measuring errors and failure,
depending on the type and concentration. As with almost all humidity measuring
elements, deposits that eventually form a water-repellent film over the sensor are
harmful. Such substances are resin aerosols, lacquer aerosols, smoke deposits,
etc. The water-resistant property of the measuring elements allows cleaning to be
carried out in water. Solvents cannot be used for this purpose. A light-duty
detergent is recommended, but any residue should always be washed out
thoroughly. A special process ensures that sensors have good long-term stability.
Regeneration is not necessary, but is also not harmful.
9.1. Cleaning Process
1. Dip the sensor tube into a receptacle containing clean water (20 °C) and, with
a gentle rotating motion, disperse the dirt deposits. If the dirt contains grease
deposits, it is recommended that a mild detergent be added to the water.
Attention! Do not brush or treat with any other cleaning utensils.
Only the sensor tube should be immersed - not the housing.
The sensor tube is open to the housing interior (0.8 mm hole)
2. As mild detergents are known to contain chemical substances, rinse carefully
after cleaning. Cleaning residue will impair the measured result.
3. Air drying. Where a measuring element is moistened with water, the device
indicates 100 % relative humidity. If necessary, it is possible to carry out
sensitive recalibration at the adjusting spindle at the end of the sensor. This
should only be done where there are large deviations. Slight movement of the
adjusting spindle of a wet element will cause the measured value in the dry
area to be change greatly. Here, there is an intensifying effect of the
linearisation (factor 6). Indications of 98 – 100 % relative humidity at the wet
element are adequate. The accuracy in the dry area must be determined
under normal climatic conditions.
Attention! The measuring element must not be dried using warm or
hot air (hair dryer).
Cleaning should be carried out for no longer than 10 minutes.

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10. Technical Information
Physical details:
Measuring range
(scale range): 30...100 % RH
Measuring accuracy: >50 % RH: ±3.5 % RH
<50 % RH: ±4.0 % RH
Adjustment range
(range of operation): 35...100 % RH
measuring medium: air, non-pressurized, non-aggressive
Switch contact
Switching difference
(microswitch): approx. 3...6 % RH
Max. voltage: 250 VAC
(Caution! 250 V only on condition that there is
no build-up of condensate in the measuring
head – otherwise voltage arcing may result)
Switching capacity
of the changeover contact
Ohmic load (cos = 1): 15 A, 230 VAC
Inductive load (cos = 0,7): 2 A, 230 VAC
At low voltage: 100mA, 125 VAC
Contact material: silver
General
Allowable
ambient temperature: -30...+60 °C
Allowable
working temperature: 0...60 °C
Medium temp. Coefficient: -0,2% RH/K
(Relative to 20 °C and 50 % RH)
Allowable air speed: 8m/sec
with gauze protection (optional) 15 m/sec
Time constant
T63 at v=2 m/sec: 120 sec
Sensor length: 220 mm
Sensor material: high-grade steel
Mounting: Slots in the housing base for duct mounting
console for wall mounting (optional)
Mounting position: sensor vertically downwards or horizontally
Connecting terminals: for conductor cross sections 1.5 mm
Cable connection: via twist nipple M 20x1,5
Housing: ABS (Acrylnitril-Butadien-Styrol)
Type of protection: IP 54
Weight: approx. 0,7 kg

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11. Dimensions [mm]