The NEWLAND ATOMISER : TECHNICAL DATA

INTRODUCTION

1.1 General:- Introduced in 1996, The Newland Atomiser is based on technology originally developed at Cranfield University, nr.Bedford, UK in 1990-92 for airborne spraying of insecticide.

Spinning discs have often been used for atomisation, but a porous cylinder provides better dispersion of liquid over the rotating surface, and, together with a brushless dc motor giving reliability at high speed, produces effective atomisation from a more compact device.

1.2 The Feed Tube:- The Feed Tube is unseen but is a vital part of the Atomiser. It is a stationary tube which screws into the top of the Atomiser and conducts the input liquid down the inside of the shaft. The Spray Tip (if fitted) at the lower end of the Feed Tube disperses the liquid out over the axial length of the Spray Head.

MOUNTING & HANDLING

2.1. Mounting:- The Atomiser is normally operated in the vertical position with the rotating Spray Head at the bottom, and the liquid input to the Feed Tube at the top - as shown in the diagram, but the unit can be used at an angle too, provided the Spray Head is always lower than the liquid input. Operation upside-down however, ie. with the Spray Head at the top and the liquid input beneath, is not possible - this way the shaft can fill up, leading to flooding of the Atomiser's bearings.

There are six vent holes in the underside of the Electronics Housing - they allow any liquid overflow inside the unit to escape and must not be sealed, nor should any mounting block them.

A special Mounting Kit, including a padded bracket suitable for holding the Atomiser is available from Newland Design. It fits around the Motor Housing, and leaves the vent holes clear.

Suspending the Atomiser is acceptable provided the weight is taken by the Power Lead, and not the Feed Tube (but check the cable gland is tight). Do not suspend the unit by the Feed Tube.

The high rotational speed of the Atomiser can give rise to noise and vibration if it is not carefully mounted. Ensure that mountings are firm, with no loose screws &c..

The Atomiser warms up during running, reaching 40 - 50° C in normal ambient temperatures, after about 15 minutes.

2.2. Weight:- The standard Atomiser in stainless steel weighs 750 g; about 1 kg with packaging.

2.3. Operating & Storage Temperatures:-

1.  May be extended to 85 ° C for short periods.
2.  If not set by the freezing point of the liquid

2.4. Wetted Parts:- In the standard unit, these are made from the following materials: stainless steel alloys 304, 316 (AISI), 1802(Sandvik); porous and non-porous polypropylene.

In addition at the top of the Shaft, inside the Electronics Housing (at "X" in the diagram 1.3.) there is a Nitrile seal seated on a sleeve of PTFE with 25%-Graphite fill: the seal can be omitted from assembly on special request to the factory at time of ordering.

2.5. Handling Precautions:- The Atomiser incorporates precision bearings and high-quality machining and should be protected from severe shock and mishandling.

The Spray Head should be protected from contamination by dirt or grease. The Spray Head should be inspected regularly, and replaced if distorted, cracked, or very dirty. Spare Spray Heads are available from Newland Design; for replacement procedure, see 6.3..

Nothing should be attached to the Spray Head; the rotating parts of the Atomiser are dynamically balanced to give smooth running, and any additional mass can cause vibration of the Feed Tube, or undue wear on the bearings.

ELECTRICAL SUPPLY

3.1.Input Voltage:- The Atomiser needs a supply of 10 - 25 VoltsDC, Absolute Maximum 30 VDC.

The speed of the Spray Head is proportional to the voltage applied; maximum speed is at 25 V. There is a speed limiter incorporated in the electronics of the Atomiser, set at 32,500 rpm.

Input voltages higher than 30 VDC will destroy the electronics.

3.2. Input Current:- Current consumption is proportional to speed, and the liquid flow rate through the unit. There is a current limiter incorporated in the electronics of the Atomiser, set at 2 Amps.

A special Power Supply for the Atomiser, allowing operation from the 230/115 VAC mains supply, is available from Newland Design (see p.8) - this unit also has a speed control. A 24 V battery supply is also suitable.

The Atomiser's body is electrically isolated but can be connected to earth if required.

3.3. Connector:- The Power Lead to the Atomiser is normally fitted with a ¼" jack plug connector, which fits in the socket on the Newland Design Power Supply unit. At option 4 mm plugs, or any other connector specified by the customer at time of ordering can be fitted.

The motor in the Atomiser is a BRUSHLESS DC motor which will NOT operate on a reversed-polarity supply. Be sure to connect correctly! (Brown or Red = +ve, Blue or Black = 0V). Prolonged connection to reverse polarity will destroy the electronics in the Atomiser, and may damage the supply.

LIQUID SUPPLY

4.1. Input Pressure:- The Atomiser should be supplied with liquid without significant pressure head. A reservoir just above the Atomiser is often suitable, simply allowing gravity to input the liquid.

Although the Atomiser is not damaged by high pressure itself, it can be damaged by excessive flow. As the Atomiser does not regulate its own flow rate, and as maximum flow may be obtained (with water) from a head of only about ½metre (0.05 barg), close flow control will usually be necessary to restrict flow rate where the input is at significant pressure (eg. the mains water supply).

Do not connect the Atomiser directly to the mains water supply without close flow control, or a pressure reducing valve. The Metering Valve and Dosing Valve available from Newland Design, give close flow control and accept input pressures up to 100 psi (6 barg).

With liquids more viscous than water, some moderate input pressure may be required, to achieve flow rates above say, 5 litres/hour. In this case, a peristaltic or metering pump is usually satisfactory. Also, with more viscous liquids it is usually advisable to remove the Spray Tip (if fitted) from the end of the Feed Tube (remember - it is a left-hand thread - clockwise to remove).

4.2. Input Flow Rate:- The Atomiser is designed for flow rates up to about 20 litres/hour. The Atomiser will not fail above this figure, but the power of the motor becomes inadequate to handle higher flow rates. Then liquid may flood back up the shaft, and out of the vent holes.

Liquid flow through the Atomiser should never exceed 25 litres/hour or damage to the Atomiser's seals or bearings could occur through flooding.

Note, flow rate increases slightly with the speed of the Atomiser, due to suction generated by the unit.

4.3. Connection:- Liquid enters the Atomiser through the ¼" O/D stainless-steel hose-tail connector at the top of the Feed Tube. Flexible tubing (5 mm bore) should be used to connect the liquid; it is not recommended to connect metal or other rigid tubing directly to the unit as this would conduct the vibration of the Atomiser. Also, the liquid supply should be easy to disconnect, to allow removal of the Feed Tube for inspection. Suitable tubing is available from Newland Design.

4.4. Particulates:- The Atomiser is not especially sensitive to particulates in its input. The unit handles normal tap water (including hard water) without needing special treatment. Only if there are significant amounts of undissolved solids in the liquid is there a need for filtration. If blockage does occur, both Feed Tube and Spray Head are easily replaceable - see 6.2. & 6.3. Spares are available from Newland Design.

4.5. Viscosity:- The inside diameter of the Feed Tube (~3 mm) effectively sets the maximum viscosity of the input liquid to the Atomiser - if the liquid runs down the Feed Tube in a reasonable time, then the Atomiser can probably handle it. Some viscous liquids (including most oils) can be handled very effectively by the Atomiser.

4.6. General:- If liquid is input to the Atomiser while it is switched off, then the liquid will slowly drip out. Solenoid Valves are available from Newland Design for connection into the liquid input line, to switch on and off the liquid automatically, simultaneously with the Atomiser.

When liquid enters the Atomiser it slows down slightly and the noise level changes, as the motor feels the extra load. The Atomiser's speed is not regulated, so it is normal for changes in input flow rate to cause changes in speed.

ATOMISATION PERFORMANCE

5.1. Size of Droplets:- The size of the droplets produced by the Atomiser depends mainly on: rotation speed, flow rate, liquid surface tension. When supplied with pure water at minimal input pressure, an Atomiser with standard Feed Tube has a flow rate of about 5 litres/hour, and on 24 VDC runs at about 30,000 rpm, giving an average droplet diameter of 40 m m.

The higher the speed, the smaller the droplet size. The maximum speed is obtained with 25 volts input; above this speed droplet size would not reduce much anyway. If the dc voltage to the Atomiser is reduced, the speed is reduced and larger droplets are obtained. The lowest speed is obtained with 10 volts input, where the relatively large, but consistently sized droplets are useful in some coating applications. Note that the Atomiser's speed is affected slightly by the flow rate - the higher the flow rate, the lower the speed.

The lower the flow rate, the smaller the droplet size. Flow rate can be reduced and hence droplet size reduced by restricting the input flow. A Flow Controller is available from Newland Design, which incorporates a needle valve, as well as a indication of flow rate (with aqueous liquids only). Flow rate can be increased by increasing the pressure on the input, but flow rate must never exceed 25 litres/hour. Note, that flow rate also increases slightly with the speed of the Atomiser, due to suction generated by the unit.

The lower the surface tension, the smaller the droplet size. Surface tension has a large effect on atomisation, because it represents the energy needed to break the liquid up into droplets. Note that surface tension is not the same as viscosity, and some viscous liquids (including most oils) have much lower surface tensions than water and can be handled very effectively by the unit. Pure water has a high surface tension, and a tiny amount of surfactant (eg. detergent) dissolved in it will reduce it significantly, so improving atomisation.

5.2. Size of Spray Cloud:- The size of the spray cloud produced by the Atomiser depends mainly on: liquid flow rate, rotation speed, liquid surface tension, and air conditions, such as air velocity and humidity &c.. When supplied with water at about 5 litres/hour, an Atomiser running at full speed produces in still air, an average spray cloud diameter of about 1 metre.

The higher the flow rate, the larger the spray cloud. The higher the rotation speed, the larger the spray cloud. At low flow rates and high speeds, the droplet size is too small and the spray too diffuse for a spray cloud to be defined. At high flow rates and low speeds the spray cloud takes a parabolic shape, with the droplets falling like drizzle, useful in some coating applications.

The low-momentum spray produced by the Atomiser and the small droplet size, mean that in some applications, forced air movement helps to improve spray dispersion or evaporation.

In humidification applications an air velocity of at least 1 metre/second is preferable, and at flow rates of up to about 10 litres/hour, an evaporation time of at least one second should be allowed for.

 5.3. Alternative Spray Heads:- The standard Spray Head is of porous polypropylene. For certain applications Spray Heads of other materials may be fitted - porous polyethylene, porous PVDF, and porous stainless steel are available.

5.4. Running in:- The Atomiser has a running-in period from new, of about 100 hours - during which power consumption reduces, speed increases, and atomisation performance improves. Also, if a unit is left unused for some time, grease in the bearings will settle, giving rise to another brief running-in period when it is started again.

CLEANING & MAINTENANCE

6.1. General:- The Atomiser is not especially sensitive to particulates in its input. The unit handles normal tap water (including hard water) without needing special treatment. Only if there are significant amounts of undissolved solids in the liquid is there a need for filtration.

If a sudden blockage or loss of flow does occur, then the Feed Tube should be removed from the Atomiser and inspected first, as this is the part through which the liquid flows first.

The condition of the Spray Head can be judged from appearance. Over a period of time very small particles accumulate inside, impairing its performance, so replacing this part becomes advisable. If the Spray Head is distorted, cracked, or very dirty it should be replaced.

When used with average-quality tap water at about 5 litres/hour, the Spray Head should be replaced about every 2,000 hours' running. Higher flows and liquids with more particulates may mean a shorter interval. Liquids with few particulates may mean an indefinite lifetime for the Spray Head.

You can probably remove both Feed Tube and Spray Head, without dismounting the Atomiser from its normal running position. First, disconnect the liquid input to the unit, and run it for 10 seconds to expel all liquid from inside. Then switch off the power supply.

6.2. To Replace the Feed Tube:- Using a spanner (½" or 13mm A/F), unscrew the Feed Tube from the top-plate of the Atomiser and carefully withdraw the Feed Tube from the shaft.

Don't bend the Feed Tube! If the Feed Tube is bent it might rub against the inside of the Atomiser shaft causing noise and vibration, and perhaps damage to the Feed Tube as well.

If there is a plastic Spray Tip fitted to the lower end of the Feed Tube, check that the holes in it are clear - use a pin to clear them if necessary. The Spray Tip is screwed into the end of the Feed Tube and can be removed and replaced if necessary (Note! it has a left-hand thread - closkwise to remove, anti-clockwise to replace).

Insert Feed Tube back into the Atomiser carefully, and tighten up well, using the spanner.

6.3. To Replace the Spray Head:- Hold the Spray Head firmly by the (black) non-porous discs at each end which retain the porous material, and unscrew (by hand) the End Nut.

Hold the body of the Atomiser in one hand, and with the other, pull the Spray Head off the Shaft, slowly but firmly - it is a close fit.

If you have removed both the Feed Tube and Spray Head, then you can clean the inside of the Shaft, with a long cotton-bud. Use a pin to clear any blocked holes in the Shaft.

Now push a new Spray Head on, as far as it will go (up to the seal).

Replace the End Nut, making it finger-tight. Threadlocking adhesive must not be applied!

WARRANTY, &C.

7.1. Lifetime:- The high rotation speed of the Newland Atomiser does not imply a very limited lifetime (some jet engines and gas turbines actually rotate a good deal faster). The Atomiser employs precision high-speed bearings which are rated for long-term continuous operation. Furthermore the Atomiser's design has reduced the rotating mass to the minimum (less than 50 grams!), the shaft is dynamically balanced, and the motor is brushless.

Since the product's introduction in 1996 no unit in service has suffered bearing failure, but if any rough running does become apparent, a bearing refit can be completed in 48 hrs at Newland Design.

7.2. Warranty:- Each Atomiser is guaranteed for one year from the date of despatch against all defects of workmanship, provided the unit is used in accordance with the instructions and not connected to unsuitable electricity supply or liquid supply, and provided the unit is not opened.

This warranty does not apply to the porous parts, which are replaceable, disposable and inexpensive.

 7.3. General:- Demonstrations of the Atomiser system are offered to OEMs within the UK and other potential quantity purchasers. Please note, that units are available for hire from Newland Design.

For unit pricing, hire charges, terms and availability, please see Price List.

Droplet sizing data, obtained from independent laser diffraction tests, is available on request.

The Atomiser has been independently tested for EMC, to BS EN 50081-1 and is CE-marked.

The Newland Electric Atomiser is designed and manufactured by Newland Design Ltd in the UK.

All information herein is believed to be accurate and reliable, but Newland Design Ltd does not accept responsibility for damage or loss which might arise from its use.

Newland Design offers application advice, recommendations on accessories, and how to interface the Atomiser with customer's systems.

POWER SUPPLY

 8.1. General:- The NT2 Power Supply from Newland Design provides the 10 - 25 VDC, 2 Amps maximum required by the Atomiser. The power supply includes an isolating transformer and is a linear type, not switched-mode and provides a voltage (and hence speed) control on the front panel.

The standard power output connector is a ¼" jack socket, but other connectors can be fitted at customer option.

The unit is in a robust anodized aluminium enclosure and is sealed to IP65 (excluding connector).

The Power Supply unit has thermal overload shutdown; there is no fuse inside the Power Supply unit itself, but a 3A fuse is fitted in the UK-style and other mains plugs if appropriate.

The power rating of the Power supply is 60 W, slightly more than the Atomiser's requirement, so allowing powering of eg. a DC solenoid valve at the same time as the Atomiser.

8.2. Alteration of Input Voltage:- The Power Supply unit will accept 230 VAC 50 Hz or 115 VAC 60 Hz input. The voltage is factory set for the destination country, but can be altered by the customer by internal modification (requiring use of one crosstip and one blade screwdriver).

Remove the back panel of the power supply using a crosstip screwdriver (you may need to prise it off to break the sealant), and pull out the small terminal block just inside the unit.

Using a small blade screwdriver, exchange the thin output wires from the transformer to the terminal block (ie. not the mains wires carrying the power input to the Power Supply) as follows:

230 VAC operation: Orange+Violet connected together and not connected to any input; Brown & Black connected to the Brown & Blue mains inputs to the terminal block.

115 VAC operation: Brown+Orange connected together and connected to Brown on the input side of the terminal block; Violet+Black connected together and connected to the Blue on the input.

Before replacing the panel, remember to re-apply the sealant (if protection against moisture is required), and re-label the panel with the correct input voltage.

ACCESSORIES

9.1. Mounting Kit:-> This includes a padded Bracket which holds the Atomiser around the Motor Housing, leaving the Atomiser's vent holes clear. There is also a mounting hole for a Solenoid Valve. The additional mounting Plate provides mounting points for the Solenoid Valve, Metering Valve and Dosing Valve

9.2. Solenoid Valve:- This is manufactured for Newland Design by KIP Inc. of Connecticut, USA, and is a stainless steel normally-closed 12 Volts DC valve with a low-power coil (only 2.5 Watts).

The Valve's coil has spade terminals to which may be connected flying leads from the Atomiser carrying the regulated 12 VDC supply output by the Newland Design Power Supply.

The Solenoid Valve may be mounted close to the Atomiser using the Mounting Kit. If mounted this way, there is only a small volume (~5 ml) of liquid between the output of the Valve, and the end of the Feed Tube in the Atomiser, which is generally expelled by the deceleration of the Atomiser on switch-off, so ensuring virtually no liquid left stagnant within the Atomiser.

The same Valve is available with other coil voltages - eg. 24 VDC, 230 VAC, 115 VAC, if required.

9.3. Metering Valve:- This is manufactured for Newland Design by Key Industries Inc. of USA and includes a Needle Valve to control the flow rate through the Atomiser, and a flow indicator working by ball float within a tapered tube. The material is polycarbonate. The principle of operation limits the accuracy of flow measurement to use with aqueous liquids. The standard maximum flow is 18 litres/hour, but other scales are available. Maximum input pressure: 6 barg.

The Metering Valve requires to be mounted vertically, with the input at the bottom; the Mounting Kit provides for this.

9.4. Hose Restrictor:- This is a hose clamp operated by a thumbscrew. It fits around the Flexible Tubing (O/D 8mm) available from Newland Design, to give control of flow rate. This method of flow control is not as precise as the Metering Valve, but it makes no contact with the input liquid, and is suitable for non-aqueous liquids.

9.5. Dosing Valve:- This is manufactured for Newland Design by Conoflow Ltd. of Dorset, UK. and is essentially a very precise needle valve, allowing close control over very low flows. As little as one droplet per 10 seconds may be reliably dispensed by this valve. This Valve is manufactured from stainless steel with a PTFE bush. Maximum input pressure: 6 barg.

9.6. Flexible Tubing:- This is Food/Medical grade PVC tubing (8 mm O/D, 4.8 mm bore) which fits the ¼" hose tail inputs to the Atomiser, Solenoid Valve, Metering Valve and Dosing Valve. It also fits through the Hose Restrictor.

9.7. Spare Spray Heads & Feed Tubes:- The porous Spray Heads used in the Atomiser are disposable (see section 6, "Cleaning & Maintenance"). Spare Spray Heads and spare Feed Tubes are available from Newland Design. The standard material for the Spray Head is polypropylene, but some other plastics, and porous stainless steel are available to special order.