micronAir MICROMISER 12 Service manual

MICROMISER 12 & 16
ATOMISERS
FOR USE ON UAVs
Operator's Handbook
and
Parts Catalogue
Micron Sprayers Limited
Bromyard Industrial Estate
Bromyard
Herefordshire HR7 4HS
United Kingdom
Telephone: [phone]
Fax: [phone]
E-mail: [email protected]
Web site: www.micron.co.uk
Iss 1W
04/2021

TABLE OF CONTENTS
1. INTRODUCTION...........................................................................................1
2. SPECIFICATION...........................................................................................2
3. INSTALLATION.............................................................................................4
3.1. Atomiser........................................................................................4
3.2. Liquid Feed ...................................................................................4
3.3. Motor Venting................................................................................6
3.4. Electrical Connections...................................................................7
3.4.1. Power Supply........................................................................7
3.4.2. Atomiser Speed Control (Micromiser 12 Only)......................9
3.4.3. Atomiser Speed Output.......................................................10
3.4.4 Interface with Flight Control System....................................11
4. OPERATION ...............................................................................................12
5. HEALTH & SAFETY....................................................................................12
6. CALIBRATION ............................................................................................13
6.1. Flow Rate....................................................................................13
6.2. Spray Droplet Size ......................................................................14
7. MAINTENANCE ..........................................................................................15
7.1. Fault Finding ...............................................................................17
8. PARTS LISTS .............................................................................................19
8.1. Micromiser Atomiser ...................................................................19
8.2. Cable Assembly ..........................................................................19
9. CONVERSION FACTORS ..........................................................................20
APPENDIX I – Interface with Flight Control System....................................21

MICRONAIR MICROMISER 12 & 16 ATOMISERS FOR USE ON UAVs
1. INTRODUCTION
Micronair Micromiser atomisers can be installed on Unmanned Aerial Vehicles
(UAVs) to spray a wide range of liquids in droplets of precisely controlled size.
Applications include spraying of agricultural crops, migrant pests (locusts etc) and
mosquito control using adulticides or liquid larvicides.
Micromiser atomisers are intended for Ultra Low Volume (ULV) and Low Volume
(LV) applications.
Spray droplets are produced by a rotating toothed disc. Droplet size is determined
by the rotational speed of the disc, which is driven by a 24 V DC brushless motor for
maximum reliability.
Unlike hydraulic spray nozzles, the atomiser does not require a high liquid pressure
to operate and there are no small internal orifices to block. This allows the atomiser
to handle viscous materials and liquids with a high solids content.
Each atomiser can operate at flow rates of up to 300 ml/min, with the minimum flow
rate determined only by the liquid delivery system used.
The brushless motor has integrated drive electronics and requires only a 24 V DC
supply to operate. A pulse output is provided for the measurement of disc speed or
for monitoring of atomiser performance.
The atomiser is available in two versions:
Micromiser 12 with rotational speed variable over the range of 1,500 – 12,000 RPM
to produce spray droplets of 60 – 300 µm VMD. This atomiser should be used for
application on crops and ground targets. The atomiser motor incorporates closed-
loop speed control to ensure constant rotational speed regardless of liquid flow rate.
The rotational speed is set by means of an external potentiometer or voltage input.
This allows the spray droplet size to be pre-set or varied by a customer provided
control system.
Micromiser 16 with a fixed rotational speed of 15,000 – 16,000 RPM to produce
small spray droplets of 45 – 60 µm VMD. This atomiser should be used for space
spraying application of insecticides to control flying insects such as mosquitoes

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MICRONAIR MICROMISER 12 & 16 ATOMISERS FOR USE ON UAVs
2. SPECIFICATION
Dimensions: Length 105 mm (including atomiser disc but excluding
connector), diameter 58 mm (max), 32 mm (motor
housing)
Weight: 240 g
Mounting: By two M4 tapped holes
Liquid feed connection: Push-in fitting for 6 mm O/D rigid plastic tube
Vent connection: Push-in fitting for 3 mm O/D rigid plastic tube
Electrical connection: 4 pin M12 sealed connector (A-coding)
Environmental protection: IP65 (with motor vent tube connected)
Ambient temperature: -10 – +40 ºC nominal (minimum temperature must not
be below freezing point of liquid being sprayed)
Input voltage: 24 V DC
Power consumption: 1.5 – 10 W (dependant upon disc speed and liquid flow
rate)
Motor rating: Continuous
Disc speed: Micromiser 12: adjustable 1,500 – 12,000 RPM
Micromiser 16: fixed 15,000 – 16,000 RPM
Speed output: 5 V pulse output (one pulse/disc revolution)
Spray droplet size: Micromiser 12: 60 – 300 µm VMD
Micromiser 16: 45 – 60 μm VMD
(dependant upon disc speed & liquid properties)
Liquid flow rate: 0 – 300 ml/minute

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MICRONAIR MICROMISER 12 & 16 ATOMISERS FOR USE ON UAVs
Fig 1. – Micromiser Atomiser
Fig 2. – Micromiser Atomisers on Multi-rotor UAV

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MICRONAIR MICROMISER 12 & 16 ATOMISERS FOR USE ON UAVs
3. INSTALLATION
3.1. Atomiser
Many different configurations of UAV (multi-rotor, fixed-wing etc) can be used for
aerial spraying. The following points provide general guidance on the installation of
Micromiser atomisers but are not intended to make specific recommendations. It is
the responsibility of the installer to establish the optimum placement of atomisers
and to carry out trials to assess the spray distribution on the target.
Atomisers are normally mounted on booms extending laterally from the structure
of a multi-rotor UAV or below and slightly behind the trailing edge of a fixed-wing
UAV.
Each atomiser should be attached to a mounting bracket on the boom with two
M4 screws in the tapped holes in the side of the atomiser housing (25 mm
between hole centres) as shown in Fig. 3. M4 x 12 mm stainless steel cap head
screws are supplied with the atomiser and these are suitable for a bracket with a
thickness of 2 – 6 mm. If alternative screws are used these should also be
stainless steel.
The boom structure and bracket must be sufficiently rigid to avoid excessive
vibration in flight.
The booms must be positioned to provide adequate clearance under the
atomisers whilst the UAV is resting on the ground or manoeuvring during take-off
or landing. If necessary, the booms should have sufficient dihedral angle to
maintain ground clearance.
The orientation of the atomisers depends upon the direction and speed of flight of
the UAV. In the case of a fixed-wing UAV or a multi-rotor UAV that flies in only
one direction and sprays at a relatively high airspeed (>10 km/hr) the atomisers
should be mounted with the axis of the motor horizontal with the disc at the rear.
This is similar to the installation of rotary atomisers on conventional agricultural
aircraft and helicopters. In the case of a UAV that reverses its direction of flight
(relative to the airframe) at the end of each spray run or a UAV that will spray at
low airspeeds the atomisers should be mounted with the axis of the motor vertical
with the disc downwards.
3.2. Liquid Feed
The liquid feed to the atomiser is by a tube connected to the inlet fitting on the face
of the housing as shown in Fig. 3. The standard fitting supplied with the atomiser is
a push-fit type that accepts a 6 mm outside diameter flexible tube. If required, this
fitting can be replaced with an alternative type with a M5 male thread to screw into
the atomiser housing.
Spray liquid is fed to the atomiser by means of a pump provided by the installer.
This can either be a positive displacement type (eg a gear pump) with a speed
controller to adjust the output to provide the required total flow rate or a centrifugal or
diaphragm type with a flow control valve. It is recommended that the flow control
valve should be fitted in a by-pass line to return excess flow from the pump to the
tank.

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MICRONAIR MICROMISER 12 & 16 ATOMISERS FOR USE ON UAVs
Fig. 3 – Mounting of Atomiser and Connections
0 100 200 300
FLOW (ml/MIN)
0
50
100
150
200
250
300
350
INLET PRESSURE (mm HEAD OF WATER)
PRESSURE MEASURED
AT INLET WITH WATER
Graph 1 – Inlet Pressure vs Flow Rate

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MICRONAIR MICROMISER 12 & 16 ATOMISERS FOR USE ON UAVs
As there are no small orifices in the atomiser, the liquid pressure required at the
atomiser inlet is very low – see Graph 1. If multiple atomisers are installed It is
recommended that a restrictor orifice should be fitted in the feed line to each to
create some back-pressure and to balance the flow between atomisers.
The system should incorporate a filter before the inlet to the pump to reduce the risk
of blockages, particularly if restrictor orifices are installed.
3.3. Motor Venting
In order to avoid condensation inside the motor, the atomiser is fitted with a vent port
that must be connected to a tube that can supply air from an area away from spray
droplets – see Fig. 3. The standard vent fitting supplied with the atomiser is a push-
fit type that accepts a 3 mm outside diameter flexible tube. If required, this fitting can
be replaced with an alternative type with a M5 male thread to screw into the atomiser
housing.
The rotation of the atomiser disc creates a small negative pressure inside the motor
housing and this is sufficient to draw air into the vent port. The tube must run
upwards throughout its length so as to avoid any loops that could trap moisture – see
Fig. 4. On a multi-rotor UAV the vent tubes should be run to a point towards the top
of the airframe. On a fixed-wing UAV the tubes should run forwards to a point clear
of the spray boom. If necessary, the open ends of the tubes should be under a
cover to prevent ingress of water from rain or washing.
Fig. 4 – Orientation of Atomiser Vent Tube

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MICRONAIR MICROMISER 12 & 16 ATOMISERS FOR USE ON UAVs
3.4. Electrical Connections
The atomiser is fitted with a sealed 4 pin male M12 connector (A-coding). Pin
numbers are as shown in Fig. 3 and pin assignments are as follows:
Pin Number Wire Colour* Function
1 Brown +24 V DC supply
2 White Tacho (RPM) pulse output
3 Blue Ground
4 Black Speed control input (Micromiser 12 only)
*When using standard moulded cable
It is recommended that the cable with moulded connector supplied with the atomiser
should be used to prevent moisture ingress. If an alternative re-wireable connector
is used it must be filled with non-corrosive silicone rubber compound.
The cable used to connect the atomiser to the power supply or controller should
have a minimum conductor size of 0.33 mm2(22 AWG).
3.4.1. Power Supply
Both the Micromiser 12 and Micromiser 16 atomisers require a 24 V DC power
supply. This will normally be provided by the main battery of an electrically powered
UAV. If the available supply is greater than 24 V it will be necessary to install a step-
down (buck) voltage converter. If the available supply is less than 24 V it will be
necessary to install a step-up (boost) voltage converter. One converter can be used
to supply several atomisers connected in parallel provided that its output current
rating is at least 0.5 A per atomiser. Small buck and boost converter modules are
readily available from electronic equipment suppliers and internet sellers.
IMPORTANT: Micromiser atomisers must be operated with a smooth DC power
supply. Under no circumstances should a pulsed (PWM) power supply or voltage
converter (eg a PWM motor speed controller) be used. A pulsed power supply will
damage the internal motor controller and its use will void all warranties.
The supply to the voltage converter (if fitted) or atomisers must be protected by a
fuse or circuit breaker. The recommended rating is 1 A per atomiser. Each atomiser
motor incorporates a controller with a slow-start ramp, so there is no significant
current surge when the motor starts.
Graph 2 shows the relationship between current consumption, atomiser rotational
speed and liquid flow rate for the Micromiser 12. Graph 3 shows the relationship
between current consumption and liquid flow rate for the Micromiser 16 when
operated from a 24 V supply.

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MICRONAIR MICROMISER 12 & 16 ATOMISERS FOR USE ON UAVs
1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000
ATOMISER RPM
0
50
100
150
200
250
300
350
400
450
500
MOTOR CURRENT (mA)
200 ml/min
300 ml/min
100 ml/min
Dry
Graph 2 – Current Consumption of Micromiser 12 vs Atomiser RPM and Flow Rate
0 100 200 300
FLOW (ml/MIN)
0
100
200
300
400
500
MOTOR CURRENT (mA)
Graph 3 – Current Consumption of Micromiser 16 vs Flow Rate at 24 V Input