2. KeyĀ Issues
Nozzles are mechanical devices that are used to control the 3) Exposure to high temperature : Melting or
fluid flow characteristics when they enter or leave an softening of nozzle material establishes maximum
enclosed pipe or chamber, through an orifice. The various temperature limits. However, these limits must be
fluid flow characteristics that need to be controlled are mass reduced when corrosion, erosion, oxidation or
and rate of fluid flow, direction, shape, pressure and the chemical attack are also present in the given
speed of the fluid. Nozzle are also used for dispensing application
various media such as powder, steam, abrasives, adhesive, 4) Caking/ bearding : buildāup of material on the
water chemical, coolants, coating, ink, lubricants. inside, on the outer edges or near the orifice is
They may look simple enough, but spray nozzles are highly caused by liquid evaporation. A layer of dried
engineered precision components that can wear over time or solids remains and obstructs the orifice or internal
suffer damage during normal operations or even cleaning. flow passages.
There are several factors to influence or shorten the nozzle 5) Clogging : unwanted solid particles can block the
operating life, sometimes more than one at the same time : inside of the orifice. Flow is restricted and spray
1) Erosion/ Wear : Nozzle wear is indicated by an increase in pattern uniformity disturbed.
nozzle capacity and by a change in the spray pattern, in which 6) Accidental damage : damage to a nozzle orifice
the distribution (uniformity of spray pattern) deteriorates and can occur if a spray nozzle is dropped or scratched
increases drop size. Choice of a wear resistant material of during installation, operation or cleaning
construction increases nozzle life. Because many single fluid 7) Improper reāassembly : some spray nozzles
nozzles are used to meter flows, worn nozzles result in require careful reāassembly after cleaning to
excessive liquid usage. ensure that internal components, such as gasket,
2) Corrosion : spray nozzle material can break down due to oārings and valves, are properly aligned. Improper
the chemical properties of the sprayed material or the reāassembly causes leaking and inefficient spray
environtment. The effect is similar to that caused by erosion performance.
and wear, with possible additional damage to the outside
surfaces of the spray nozzle. Corrosion is material related and
caused by chemical attack. There is a very wide range of
materials from which nozzle can be made and the proper
selection of the nozzle material will minimise problems.
3. SelectingĀ Material
Improved reliability, proper performance and maximum wear life of a spray nozzle often begin with the
correct material selection. Corrosion and erosion caused by abrasive wear are the most common factors that
could lead to degradation of a nozzleās performance. It is important to select the right nozzle material
depending on the environmental conditions of the given process. Spray nozzles are generally made of such
materials as bronze, stainless steel, or plastic.
Brass (Bronze) is the easiest material for nozzle manufacturers to work with and is a common material, but
bronze nozzles have insufficient resistance to abrasion at middle/high pressure, and limited resistance to
corrosion by corrosive chemicals.
Due to its relatively high abrasion and corrosion resistance, stainless steel is widely employed in nozzle
manufacture. When the liquid to be sprayed or the surrounding atmosphere is corrosive however, spray
nozzles made of SUS316 or SUS31L stainless steel, both of which have more resistance to corrosion, are more
suitable.
Relatively few types of spray nozzles are manufactured from plastic. Plastic nozzles are useful for spraying
chemicals that corrode metal nozzles too quickly. Unlike metal, plastic materials do not display corrosion
rates. That is the corrosion of plastic materials is dependent totally on the materialās chemical resistance
rather than an oxide layer, so the material is either completely resistant to a chemical or it deteriorates.
Thermoplastics deteriorates is indicated by material softening, discoloration, charring, embrittlement, stress
cracking, swelling, dissolving and other effects.
LEFT: Stainless steel full cone nozzle. RIGHT: same
stainlessĀ steelĀ andĀ bronzeĀ nozzle PVDFĀ plasticĀ nozzle after spraying with limestone slurry. The
nozzle erosion and corrosion occurred in less than 2
weeks, demonstrating the need for choosing the
correct nozzle material to suit the conditions.
4. WearĀ Test COMPARATIVEĀ WEARĀ TESTĀ
TestĀ MediumĀ :Ā 2.5Ā %Ā kaolinĀ inĀ water
Ceramic : Highly resistant to abrasive and provides superior wear resistance in abrasive applications and high
pressure. Ceramics have excellent corrosion resistance except in very high pH environments.
Polyacetal POM (Polyoxymethylen) : Provide good resistance to alkalis, susceptible to high concentrated acids.
Can be used in temperature +90 Ā°C exhibits a high thermal stability and high resistance to hydrolysis. POM shows
good sliding properties and high resistance to wear and tear because of the strength and smooth surface. There
is a very low risk of stress cracks.
Polyvinyldene fluoride (PVDF) : Excellent resistance to strong acid and alkalis, good resistance to wear, resist
many reagents and high temperatures (up to 130Ā°C), susceptible to high temperature above water boiling in
combination with concentrated sulphuric and nitric acids. Preferred in industrial spraying applications.
Stainless steel : Good resistance to chemicals and provide average wear resistance
BrassĀ Ā (bronze)Ā Ā :Ā Ā Ā AverageĀ Ā resistanceĀ Ā toĀ Ā mostĀ Ā chemistryĀ Ā andĀ Ā poorĀ Ā wearĀ Ā resistance,Ā Ā susceptibleĀ Ā toĀ Ā corrosionĀ
especiallyĀ withĀ fertilisers
PEEKĀ :Ā isĀ usedĀ toĀ replaceĀ metalsĀ inĀ harshĀ environments.Ā ThisĀ highestĀ performanceĀ engineeredĀ thermoplasticĀ
offersĀ excellentĀ resistanceĀ toĀ wear,Ā chemicals,Ā fatigueĀ andĀ highĀ temperaturesĀ upĀ toĀ 320Ā°FĀ (160Ā°C).
5. Application
Most nozzle are constructed of stainless steel, but PVDFĀ NozzleĀ forĀ EtchingĀ andĀ ElectronicĀ Industry
some are made of plastic material such as POM, PVDF nozzles are especially suited to the spraying of
PVDF, PEEK. acids during etching operations. And their high thermal
PVDF Nozzles PVDF (polyvinyldene fluoride), the stability makes them ideal for high temperature
durable yet economical fluoroplastic that stands up stripping operations. For spraying corrosive fluids or for
to wear, heat, and corrosion. operation in corrosive environtments. PCB (printed
PVDF Nozzle for Food Industry circuoit board) manufacturers are looking for nozzles to
In general, foods are not corrosive, but consumable increase product yield. Nozzle made from PVDF material
foods like sauces and fruits can have pH ranges offer consistent spray patterns along with superior
between 2.0 and 3.5, this can be very aggressive chemical resistance, capable of effectively spraying a
environment over time. PVDF plastics components variety of chloride, acid, basses, oxidizing agent and
are often machined and used in the processing of ammonia base etchants, these chemical resistance
cranberry, hot sauces, alcoholic beverages, lime nozzles can withstand temperatures up to 300 Ā°F at 100
juices and a few other relatively common foods. The psi (149 Ā°C at 7 bar).
abrasion resistance of PVDF and its ability to be
sterilized with various chemicals and steam also
adds to the attractiveness of this material for food,
dairy and beverage applications.
PVDF is an extremely pure polymer, physiologically
non toxic, and meets the european directive
90/128/EEC relating plastic material to contact with
foodstuffs. It is particular suitable for high purity
applications handling hot and cold water in the
semiconductor, and pharmaceuticals industries.
6. Conclusion
PVDFĀ isĀ anĀ outstandingĀ choiceĀ asĀ aĀ nozzleĀ PVDFĀ PROPERTIESĀ DATAĀ SHEET
materialĀ forĀ manyĀ reasons: Structure :Ā Crystalline
ChemicalĀ resistance SpecificĀ densityĀ :Ā 1.77
PVDF is typically resistant to: most acids salts and WaterĀ absorptionĀ rate (%):Ā 0.03
weak bases, halogens and halogenated solvents,
alcohols, oxidants, Deāionized water, UV and nuclear
ElongationĀ Ā atĀ breakĀ (%):Ā 50
radiation. TensileĀ strength (psi):Ā 5.800
Temperature range CompressionĀ strengthĀ (psi):Ā 10.000
PVDF can be used at temperatures as high as 285Ā° F FlexuralĀ strengthĀ (psi):Ā 7.800
(140Ā°C) depending on the chemical environment FlexuralĀ modulusĀ (psi):Ā 260.000
and operating pressures of the system. Like most Impact (Izod ft.Ā lbs/in):Ā 6.6
fluoropolymers PVDF is inherently flame retardant. Hardness:Ā R95
Abrasion resistance
PVDF is one of the most abrasion resistant
DeflectionĀ temperatureĀ (deg.Ā F)
fluoropolymers. In abrasion tests PVDF ranks with ā @Ā 66Ā psi:Ā 300Ā (150Ā deg.C)
the best plastics and in most nozzle applications it ā @Ā 264Ā psi:Ā 190Ā (90Ā deg.Ā C)
will outlast many metals, PVC and PTFE. UtilizationĀ temperatureĀ (deg.Ā F)
Mechanical strength ā min:Ā ā40Ā (ā30Ā deg.C)
PVDF is one of the most rigid fluoropolymers. ā max: 310Ā (150Ā deg.Ā C)
PVDF's exceptional tensile strength allows nozzle MeltingĀ pointĀ (deg.Ā F):Ā 340Ā Ā (170Ā deg.Ā C)
construction without the thick sections normally
associated with plastics, while allowing operating
CoefficientĀ ofĀ expansion:Ā 0.000022
pressures normally available only with metallic ArcĀ resistanceĀ :Ā 60
materials. Dielectrical strengthĀ (kV/mm):Ā 22
FDA acceptance UVĀ resistanceĀ :Ā Good
PVDF is accepted by the FDA for use in a broad ChemicalĀ resistanceĀ :Ā Excellent
range of food and pharmaceutical applications
where stainless steel was once the only choice.
7. THANKĀ YOU
www.sugison.com
nozzleĀ forĀ candyĀ fillerĀ Ā PTĀ YUPIĀ INDONESIA
materialĀ fromĀ pvdf (polyvinyldenfluoride)
www.grahamika.indonetwork.co.id
machiningĀ byĀ PT.Ā MaximaĀ Sukses