Stulz BNB1000 User manual

ULTRASONIC/BNB
TECHNICAL MANUAL
Issue 10.94e
AIR CONDITIONING
We reserve the right to make technical changes

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List of contents
1. Application areas and method of operation ............................................................3
2. Technical data for the BNB model range.................................................................5
2.1 Humidifier section...........................................................................................6
2.2 Dimensional drawing ......................................................................................7
2.3 Description of unit...........................................................................................8
3. Capacity calculation for ultrasonic air humidifiers .................................................10
3.1 Questionnaire about ultrasonic humidifying systems....................................12
4. Switching operation and control............................................................................14
4.1 Design of two-point (ON-OFF) control..........................................................15
4.2 Design of proportional control ......................................................................21
4.3 Method of operation of proportional adapter ................................................27
4.4 Connecting pipes between the humidifiers
and the switching operation and control .......................................................29
4.5 Electrotechnical information on BNB............................................................31
5. Installation, commissioning and application limits.................................................33
5.1 Installation of BNB model range...................................................................34
5.2 Examples for the mounting of BNB humidifiers ............................................43
5.3 Commissioning of BNB humidifiers ..............................................................46
5.4 Precautionary measures during operation....................................................47
6. Accessories ..........................................................................................................48
6.1 Data sheet on safety transformers................................................................48
6.2 Information on conductivity measuring instrument .......................................49

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1. Application areas, method of operation
BNB Model range
Units of the ultrasonic BNB 1000 to BNB 8000 model range are available for direct room
humidifying. The key components of this unit consist of high-quality steel or high-quality
plastic. A fan is integrated into chassis which carries the mist generated in the water bath
out into the room. This unit is used, for example, for humidifying production rooms, EDP
rooms, warehouses, printing plants,museums, restoration workshops, theatres and many
other areas, in which optimum humidity is necessary for production, storage or to maintain
room air conditions.

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Method of operation
The STULZ ULTRASONIC model range of air humidifiers work in accordance with the
principle of ultrasonic atomization. A 48 V alternating voltage is rectified on a printed
circuit board and converted into a high frequency signal of 1.65 MHz. This signal is
transmitted to a transducer installed in a water bath which converts this signal into a high-
frequency mechanical vibration. The transducers installed are so-called thickness
transducers which change their thickness 1.65 million times per second corresponding to
the applied signal of 1.65 MHz.
The surface of the transducer vibrates at such a high
speed that the water can no longer keep up due to its
mass moment of inertia and a water column builds up
above the transducers immediately after the unit is
switched on. During the negative amplitude of the
transducer, the water cannot follow the rapid movement
andaninstantaneousvacuum is created. Bubblesoccur
due to cavitation which are “catapulted” to the edge of
the water column in the curve of positive amplitude and
collide with each other with a large force. During this
process the finest particles of water are atomized at the
edgeofthewatercolumn. Cardanwavesaregenerated
duetothefocusingofthesoundwaves right underneath
the water surface, in the center of which the smallest
water droplets detach and produce a mist which is
immediately picked up by the air flow.
After switching on transducer
Negative amplitude
Positive amplitude
vacuum
transducer
transducer
transducer

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2.Technical information on the BNB model range
The BNB ULTRASONIC humidifier works in accordance with the principle of ultrasonic
atomization. The mist, which is produced in a water tank with the aid of a transducer, is
blown into the room by a built-in fan. The humidifier consists of the atomization modules,
the supply module with a solenoid valve, via which the water supply runs, as well as float
switch and a housing in which a fan is accommodated. A switchgear cabinet must be
located externally which contains the control as well as the power supply of the unit.
Model BNB BNB BNB BNB BNB BNB
1000 2000 3000 4000 5000 8000
Output* l/h 1.0 2.0 3.0 4.0 5.0 8.0
2x2.5 2x4.0
Number of transducers 2 4 6 8 10 16
Transformer Primary: 110V/208V/230V/400V/460V ± 15V 50/60 Hz
Secondary: 12V/24V/36V/42V/48V/52V
Nominal output W 100 180 250 340 430 670
Transformer output VA 160 320 320 500 500 2x500
Weight kg 7.1 9.3 11.2 14.0 16.1 23.0
Dimensions A mm 254 364 474 584 694
1024
Dimensions P mm 220 330 440 550 660
990
We reserve the right to make technical changes/*output at: water height of 40 mm, air
temperature of 26°C, water temperature of 26°C, voltage 48 V.
Application condition: Temperature 5°C to 40°C, relative humidity below 90%.
Water supply: Only demineralized water < 20 µS/cm may be introduced into
the humidifier as supply water. The water pressure to the
humidifier should be between 0.5 bar and 6 bar, and the water
temperature between 5°C and 40°C.

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2.1 Humidifier section
The length of the humidifier section depends on various factors.
> even distribution of the mist in the air flow
> temperature of the air
> rel. humidity of the air
> air speed
The diagram below for determining the length humidifier section contains recommended
values depending on the most important parameters. The tolerance is ± 0.5 meters.
Humidifier section (m)
% rel. humidity upstream of the humidifier
Use of a proportional control is another alternative for reducing the humidifier section.
This reduces the output of the humidifiers as required for more than 90% of the operating
time and thus reduces the humidifier section, preserves the transducers and maintains
the even distribution of the mist even in part load operation.
- The measurement is made with the air flap control “max”. The humidifier section
reduces in the “min” position.
- Theremainderofthemiststream can be seenonablackbackground overthe specified
sections.

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2.2 Dimensional drawings
For dimensions A and P see Page 6 under “Dimensions”
Legend:
1 Humidifier unit 10 Safety overflow
2 Fan housing 11 Mist guide pipe
3 Mist guide cover 12 Ring and nut
4 Fan 13 Installation foot
5 Metal plug 14 Air filter
6 Cable 15 Water supply*
7 Metal plug 16 Shut-off valve*
8 Cable 17 Air flap controller
9 Water drain *
provided by customer

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2.3 Description of unit
Safety precautions
Automatic supply water monitoring by solenoid valve and float switch. Protective device
against running dry; if the water drops below a preset level, the float switch and relay are
automaticallyoperatedtoswitchoffthepowersupply. A thermostat switches off the current,
if the temperature in the air humidifier rises above a preset point.
Fuses and varistors are installed to protect the electronics.
Description of the main components
1. Humidifying unit
Ultrasonic atomization modules, the solenoid valve and the float switches are
accommodated in the high-quality steel housing.
2. ULTRASONIC atomization module
ThecompactULTRASONICatomizationmoduleisaccommodatedinthebaseofthewater
container. It contains the vibration generating circuit, an amplifier and a transducer. The
resultantultrasonicvibrationsaredirectedtowardsthe water surface. Thewaterisatomized
in this way.
3.Water supply solenoid valve and float switch
In order to achieve optimum atomization of the water. The water level in the container
must be kept as constant as possible.In order to meet this condition, a solenoid valve and
a float switch are used for automatic water supply control. With this equipment, if the water
level in the container falls below the normal level, the float switch switches to ON and the
solenoid valve opens, in order to release the water supply to the container. If the normal
water level is reached, the float switch switches to OFF and the solenoid valve is closed.

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4. Relay (external, in control box) and float switch (dry protection)
The transducer will be damaged if the humidifier is operated with a reduced water level. A
float switch and a relay (in the control station) are interposed to prevent such an operating
condition. If the water level falls below the safety level for any reason, the float switch
switches to OFF, operates the relay and thus switches off the electrical power supply to the
unit.
5. Fan
The mist generated in the water tank is carried into the room by the fan. A special design
makesitpossibletogenerateavariablesupportingairflowinorderto ensurerapiddispersal
of the aerosols.
Air outputs
Model BNB BNB BNB BNB BNB BNB
1000 2000 3000 4000 5000 8000
Output*
m3/min 1.2 1.8 2.4 3.6 4.2 6.6
* the values apply to a supply voltage of 48 V / 50 Hz

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3. Capacity calculation for ultrasonic air humidifiers
Example:
Humidification of a room with gap ventilation.
The following data is required to determine the humidifier output for rooms without a
ventilation system:
Example:
> Size of room (m)3500 m3
> Temperature, humidity in room 22°C /50% rel.
> Conditions of outside air (temp., humidity) 0°C /87% rel.
> Estimate of gap ventilation (windows, doors) 500 m3/h
The gap ventilation for a new building where the door is opened < twice per hour is < 1
times the room volume
Calculation of humidifier output
Determine the∆X from the room condition and the outside air condition in the h/x diagram
Determine the air quantity which is to be humidified
by 5 g/kg.
The example involves an air change/hour
Size of room 500 m3x 1 air change x 1.2 air density =
600 kg/hour
Humidifier output
Weight of air x ∆x = humidifier output required
600 kg/hour x 5 g/kg air = 3000 g/hour humidifier
output required