- Principle of Silicone Tubing
- Types of Silicone Tubing
- Applications and Benefits of Silicone Tubing
- Cleaning, Sterilization, and Methods of Joining Silicone Tubing
- And much more…
Chapter 1: Principle of Silicone Tubing
This chapter will discuss what silicone tubing is, including its manufacturing process.
What is Silicone Tubing?
Silicone tubing is a very tough elastomer that exhibits high strength, flexibility, and resistance. Silicone tubing can be stretched without tearing and is highly versatile. It cannot be weakened with repeated bending and twisting due to its significant flexibility. Because silicone tubing is very hygienic and non-toxic, it can be produced as a medical-grade material, making it a popular choice for healthcare and medical applications.
Silicone has properties that allow it to work well over a broad range of temperatures and adapt easily to sudden changes in temperature. Silicone tubes are also weather resistant. Silicone tubing has a major role in a variety of industries and applications involving the transfer of liquids and gasses. Silicone tubing has a fantastic range of properties that make it the preferred material for tubing in many situations.
Silicone exhibits excellent properties, including UV and heat resistance, making silicone tubes ideal for the electrical and aerospace industries. It is easy to clean and sterilize the material, making it ideal in environments that prioritize hygiene, such as medical and pharmaceutical industries and food production. Silicone tubing is available in different sizes and colors. It is also available in different grades, like high-temperature silicone tubing.
High-temperature silicone tubing can resist extreme variations in temperature, unlike plastic or rubber tubing. There is also food-grade silicone tubing, a very reliable and FDA-compliant material that exhibits stability, temperature resistance, and non-stick properties. This, in turn, makes it ideal for the production of food and beverages. Medical grade silicone tubing is another type that meets several requirements for cleanliness and non-toxicity that are necessary for the medical industry.
Manufacture of Silicone Tubing
Silicone tubing is manufactured through a widely used method called the rubber extrusion process.
The extrusion process is preferred because it is cost-effective and can produce large batches of products in a very short lead time. This part-forming process is generally performed by rubber fabricators. The process is initiated when a heated and cured silicone formulated compound is preformed into a slab or strip.
The next step is to feed the formed silicone into a screw extruder. The screw extruder forces the compound through the hardened steel die. The extruder head holds the die in place, and the die shapes the silicone tubing once the silicone has been forced through. The silicone profile then exits the die and is cured by being continuously pulled through a heated and cured oven.
Several ovens are used to circulate hot air vertically and horizontally: salt bath cure, steam vulcanization, and infrared cure. Some fabricators prefer to perform the vulcanization of the silicone after it has been extruded into a long trough filled with salt water. However, this technique has the main challenge of choosing the right raw materials that are capable of performing best in their specific temperature and mechanical controlled processes and will enable the meeting of specifications by the final products.
Difference Between the Extrusion and Injection Processes of Silicone Tubing
The difference between these two processes starts from the shape of the product, application field, and production direction. A length of silicone tubing between 50 and 130 feet (15 and 40 meters) of the extruded body requires curing from high temperature and sulfurized from the input of the extrusion to the opening of the mold.
After passing over a length greater than 50 feet, the vulcanization of the tunnel used for drying must be re-sulfurized. Theoretically, silicone tubing of the extrusion process is infinitely long without having a stop at the inlet. The other process used is the solid-liquid injection process which utilizes liquid glue production. The method of production is a bit similar to plastic injection. This method is initiated by injecting the liquid glue into the mold after high-temperature sulfurization.
The liquid glue is then de-molded. This solid-liquid injection process exhibits a rich product structure. Since the products are produced by liquid glue, their hardness is much lower than that of the products formed by the silicone tubing extrusion. Solid-liquid injection silicone tubing is very soft and comfortable compared to extruded silicone tubing. The solid and liquid injection silicone tubing is mostly used in the power industry.
Silicone has good properties of resistance and insulation, which is why it is preferred in the power industry. The solid-liquid injection is based on fixed and irregular shapes, and the extrusion process in the power field is based on round tubes, but both methods are capable of withstanding ultra-high voltage characteristics. They are mostly utilized in power transmission lines as well as terminals. The extrusion process in the power communication field is round silicone tubes, while the injection is irregular.
The silicone tubing extrusion process is mostly utilized in the medical field for cooperation with the solid-liquid injection process. The extrusion process is mostly responsible for producing drainage pipes. The liquid-injection process functions to mainly produce irregular pipes. The extrusion process produces regular pipes, but the raw materials of the liquid process and the cost of all aspects of the equipment will be more than the cost of the extrusion process. Therefore when producing regular pipelines, the lower-cost extrusion process can be utilized.
Silicone Tubing Sizes
The size of the silicone tubes determines the use of silicone tubing.
The most common use for small silicone tubing is electrical sleeving. This is so because of its thin walls and flexibility. For the carrying of liquids and powders, medium-sized silicone tubing is utilized. Large silicone tubing is mostly utilized in applications involving air ducts and dielectrics.
Medium silicone tubing is often employed in the pharmaceutical and food industries. It is mainly used in applications where hygiene is critical. Platinum silicone tubing is a common all-rounder tubing free of ketones and peroxide. This makes it ideal for the medical, food, dairy, and vending industries. This type of silicone tubing makes sure of the preservation of the taste. It does not also taint the produce that it carries. Cured silicone tubing is also utilized as a general purpose form of tubing that is very good and can be used with food.
Chapter 2: Types of Silicone Tubing
The different types of silicone tubing include:
Silicone Peroxide Cured Tubing
Silicone peroxide tubing is available in a translucent format in different diameters. This type of silicone tubing mostly suits applications that do not require high purity, repeated sterilization, and critical dosing. Silicone peroxide tubing is most commonly used for different pump and transfer applications.
These applications include automotive and industrial applications. This product is can withstand temperatures as high as 392 °F (200 °C). In addition, peroxide-cured silicone tubing is more cost-effective than many other compounds. This makes it most suitable for general tubing applications.
Platinum Cured Silicone Tubing
Platinum cure silicone tubing has many advantages over peroxide cure silicone tubing. These advantages make it very popular in the food and beverage industries. This type of silicone tubing exhibits a high tear strength. It has a broad range of temperatures ranging from -40 °F (-40 °C) to 392 °F (200 °C). This enables the use of this product in many different applications and environments without deterioration.
Platinum cured silicone tubing contains no peroxide by-products, is non-yellowing, and features a high gloss finish. This type of silicone tubing is most suitable for use in peristaltic pumps. It also has a long life expectancy, which makes it suitable for this application compared to other products. Platinum cured silicone tubing can be used in hot or cold water applications. It is predominant in the non-invasive medical and pharmaceutical industries.
Silicone Dairy Tubing
As suggested by the name, this type of silicone tubing is specifically designed and manufactured for use in the dairy industry. This is because of the product’s high mechanical wear and tear strength properties. Most silicone dairy tubes are platinum cured, bringing many benefits to this tubing over other tubing products. For example, silicone dairy tubing is non-yellowing and does not contain any peroxide by-products.
This tubing does not harden or corrode after long periods of use. It also features an extra-smooth inner bore for improving the rate of flow and hygiene levels.
Silicone Fuel Tubing
Silicone fuel tubing is most commonly utilized in the radio-controlled model car industry. This type of silicone tubing exhibits high resistance to methanol and nitro fuels, keeping the fuel cleaner and reducing the tubing’s deterioration. This tubing is found in many different aesthetically pleasing colors to match any car color. It must be noted that silicone fuel tubing is designed to be used with radio-controlled model cars and is not ideal for use with petrol.
High-Temperature Silicone Tubing
High-temperature silicone tubing is resistant to extreme temperature variations. The name of a silicone hose is typically followed by a number, like 550. This number indicates the hose's absolute maximum point of heat tolerance. Choosing the appropriate high-temperature silicone hose will be simple if you know the temperatures you anticipate.
High-temperature ducting products do require one point of distinction, though. A hose may be able to withstand very high temperatures, but this does not mean it won’t burn or catch fire. The difference between a product's thermal resistance and burn point is that the term "burn point" describes a substance's capacity to ignite when in contact with fire. It should be verified that the hose was manufactured following the requirements for flame retardant materials if you need a high-temperature duct that can withstand coming into contact with flames.
A high-temperature silicone hose may need to be flexible depending on the requirements of the application. A high-temperature duct that can bend and flex in confined spaces is extremely useful. A silicone high-temperature hose is flexible, but it may eventually experience flex fatigue if continually bent. If the material is flexed in numerous ways, it may eventually rip. A high-temperature silicone hose will often maintain its straight shape unless manually bent.
A high-temperature silicone hose can resist chemicals as well as temperatures. The silicone compound has the capacity to withstand chemical exposure. A silicone high-temperature hose can often withstand coming into contact with specific oils, solvents, and gasses. The best course of action is to confirm that a silicone hose is compatible with the chemicals used in the application.
Food-Grade Silicone Tubing
For usage in food and beverage applications, food-grade silicone is a strong, long-lasting substance that offers a healthier, more inert substitute for plastics. The absence of plasticizers in silicone makes it much less likely for BPA and other dangerous chemicals to leak into food and beverages. It also stops flavors and aromas from transferring to the food or beverage it contacts. Silicone is a great material for food storage and transportation to combat single-use plastics since it is strong, non-porous, and temperature-tolerant.
This type of silicone tubing is reliable. Its advantages include stability, temperature resistance, and non-stick properties. This makes it most suitable for use in the food and beverage industries. Food-grade silicone tubing does not react with food ingredients and fluids and can be sterilized in standard autoclaves. It features surface qualities that resist the buildup of transported material on the inside.
Using food-grade silicone, building robust and long-lasting food-grade components is simple. Specific advantages of selecting food-grade silicone over other plastics include the following:
- Damage prevention: Extreme temperatures can be withstood by food-grade silicone without harm or deterioration.
- Durability: Food-grade silicone won't dry out, crumble, rot, peel, harden, crack, or become brittle over time.
- High and low temperature resistance: Silicone made for food may tolerate temperatures as low as -103 °F (-75 °C) and as high as 450 °F (232 °C).
- Certification NSF-51: The NSF-51 certification assures that plastic items are safe for use with food and defines the standards for independent testing.
- Neither poisonous nor odorous: The substance has no smell and doesn't include any phthalates, lead, latex, or BPA.
- Environmentally responsible: Silicone used for food is regarded as non-hazardous waste.
Medical Grade Silicone Tubing
This type of silicone tubing meets many requirements for cleanliness and non-toxicity necessary for use in the medical field. It is sterile and non-reactive. Medical-grade silicone tubing also features compound compositions that make it completely non-toxic, odorless, and tasteless. It does not have any tendency to support the growth of bacteria. To make this type of silicone tubing pure, it is enhanced by processes like platinum curing before manufacture. Medical-grade silicone tubing does not react with sensitive drugs and body tissues.
Colored Silicone Tubing
This assortment of colored tubing has a thick wall and is made of general-purpose silicone rubber, making it appropriate for usage at high vacuum levels. Although sold by the meter, coils of 30 meters are kept in stock. Colored silicone tubing is available in a wide variety of colors. Among other applications, it is mostly utilized in the electrical industry for sleeving electrical cables.
General Purpose Silicone Tubing
This type of silicone tubing is suitable for use in applications that do not require high-pressure hoses as well as compound purity of a high level. Because of its excellent thermal and flexibility properties, it can be utilized on most domestic appliances as well as hobby or workshop applications.
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Chapter 3: Applications and Benefits of Silicone Tubing
This chapter will discuss the applications and benefits of silicone tubing.
Applications of Silicone Tubing
The applications of silicone tubing include:
Silicone Tubing in the Medical Field
Silicone tubing exhibits properties that make it useful in the medical field. It has already been seen that silicone tubing is very tough, easy to clean, and easy to sterilize. Because of these properties, it is valued by medical practitioners. However, one of the most important properties that silicone tubing exhibits from a medical standpoint is its biocompatibility. This means that it is neither harmful nor toxic to living tissues and is unlikely to yield an allergic response. This makes it a popular material for medical implants, drains, catheters, feeding tubes, and other medical products that have biocompatibility as a key requirement.
Silicone tubing is vital for these devices. It provides important sealing, gasketing, and safe fluid transfer properties that are not possible when most other materials are used. The medical sector utilizes silicone tubing that is usually of a higher grade. Its manufacture is performed using the continuous extrusion and vulcanization process. It is possible to produce very fine tubes often used for capillaries. Wider tubes that can be used to transport crucial fluids can also be produced.
Silicone tubing is highly regarded for use in analytical instrumentation because of the need for flexible and sterile equipment.
Electronic Equipment and Automotive
Silicone tubing is excellent for electrical insulation, making it suitable for use in electronics across several industries. It is mostly used for insulating electrical components in automotive enclosures.
Water Filtration and Purification
Since silicone tubing is non-toxic and has a smooth inner and outer surface, it is utilized mostly in water filtration and purification systems.
Food and Dairy Processing
Food-grade silicone tubing is optimal for dairy processing equipment, beverage dispensing, and other food industry applications requiring sterile and flexible materials with high chemical and heat tolerance.
In the aerospace industry, silicone tubing is extensively utilized in equipment like climate control and conveyance systems. Because silicone tubing has high tensile strength, flexibility, and temperature resistance, silicone tubing is also used for vacuum seals on vehicles and aircraft.
Other uses of silicone tubing are listed below:
- Coolant systems in automobiles
- Custom color tubing
- Aquarium air devices
- General purpose industrial applications
- Siphon hoses for microbreweries and home brewers
Benefits of Silicone Tubing
The benefits of silicone tubing include:
Silicone tubing is highly flexible over a range of temperatures. Compared to some high-temperature rubber tubing, silicone tubing does not become soft when exposed to high temperatures or harden at low temperatures. This makes it ideal for use in extreme environments.
Silicone tubing has a broad temperature range, allowing it to withstand temperatures from -130 °F to 600 °F (-90 to 315.5 °C). Silicone tubing is also resistant to UV radiation and ozone; therefore, it is less likely to degrade from exposure. This property makes silicone tubing ideal for outdoor use or aerospace applications.
Silicone tubing exhibits high tensile strength. Because of this quality, its wear, tear, and breakage are reduced. This makes it most suitable for high-traffic industries like plumbing and food service. Silicone tubing has a long life expectancy because of its flexibility and toughness. It does not easily crack or break because it has good elongation at break and tensile strength. This allows it to withstand the daily stressors of a brewery, dairy farm, water treatment plant, milking parlor, or aquarium.
Silicone tubing has many color options available and can also be color matched.
Smoother Surface Finish
Food and medical grade silicone tubing have a smooth inner and outer surface finish, making them suitable for applications where a smooth, sterile surface is required. This surface helps to prevent contamination like that found in food service, medical, and analytical instrumentation industries.
Silicone tubing exhibits excellent properties, including extreme durability, resilience, and resistance against repeated compression cycles.
Range in Hardness
Silicone tubing has resistance to surface penetration, or hardness ranging from 20 Shore A – 90 Shore A.
Silicone tubing is pliable, allowing it to be utilized in confined or high-pressure applications where a more rigid rubber material would break or tear. In addition, silicone tubing allows easier monitoring and controlling of fluid flow.
Resistance to Autoclaving, UV, and Fungus
Silicone tubing can withstand ultraviolet radiation (UV) and impede pathogen growth. This, in turn, makes it ideal for use in food processing areas, pharmaceutical, and medical industries. Additionally, silicone tubing is hygienic and sterile. It does not bolster the growth of bacteria or any solid buildup. Silicone tubing also offers good resistance to ozone and weather. Finally, it offers protection against salt water, cleanser, synthetic concoctions, and different chemicals.
Ease of Manufacturing
Silicone tubing can be manufactured in a wide variety of sizes and lengths.
Easy to Clean
Silicone tubing is easy to clean with little effort. It does not become fragile, brittle, or stiffened even after repeated use of chemicals.
Tasteless, Odorless and Inert
Silicone tubing does not interact with what it carries. This makes it appropriate for food, water, air, and beverage applications because it does not tarnish the nature and quality of the products being handled.
Despite all of these advantages, It is not recommended to use silicone tubing for transporting concentrated fuels or oils since these materials are capable of breaking down the structure of the tubing.
Chapter 4: Cleaning, Sterilization, and Methods of Joining Silicone Tubing
This chapter will discuss how to clean, sterilize, and join silicone tubing.
Cleaning Silicone Tubing
If silicone tubing is used in a food production area like a homebrew setup or a soft drink dispensing machine, regular line cleaning is crucial. Silicone tubing is easy to clean; it is ideal for home brewing setups since it can be boiled to clean off all the gunk inside the hoses. This cleaning method must be performed regularly to prevent buildup, blockages, or unsavory smells.
When silicone tubing is used in other applications like the automotive industry, cleaning the interior of the pipe may not be regularly required or necessary at all. One of the easiest ways to clean silicone tubing is to use hot soapy water to wipe down or push through the tubes.
Since silicone is highly resistant to heat, it does not matter how hot the water is. However, if certain cleaning products are used on silicone tubing, they will react negatively, causing damage and discoloration. When cleaning silicone tubing, avoid using WD40 or cleaning products that are petroleum-based.
Sterilizing Silicone Tubing
Silicone tubing is utilized in a variety of medical instruments and equipment because it is easy to sterilize. Several sterilization methods that can be normally carried out in a medical laboratory are available. The first and most widely used method of silicone tubing sterilization is called gamma irradiation. However, this technique may change the properties of the silicone and result in a higher propensity for the silicone material to kink. Another alternative to gamma irradiation is called electron beam irradiation, which has similar physical effects.
The third method of silicone tubing sterilization is called ethylene oxide. It is an effective method of sterilization because the silicone tubing absorbs the ethylene oxide, but the ethylene must be removed before the machine’s use.
Methods of Joining Silicone Tubing
The methods of joining silicone tubing include:
(IPA) Isopropyl Alcohol
IPA is used for the lubrication of the silicone so that it will slide over a barbed fitting. IPA absorbs water and therefore is inherently hygroscopic. IPA is used in its pure form when used with silicone tubing. It is easy to obtain and is relatively cost-effective.
IPA is also effective in that it evaporates without leaving a residue on medical devices. Its main disadvantage is that it takes longer to dry. This can make the process time-consuming, thus slowing down the production rate and costing the manufacturer more time and money. Other techniques, like applying low temperature to the silicone tubing, assist in speeding up the drying process.
Another method of joining silicone tubing is to use silicone oil-based lubricants. This method is most commonly used by engineers; it is intuitive since using silicone fluid to join silicone ensures the materials’ compatibility. However, silicone oil has some major disadvantages.
The first disadvantage is that its application can be very messy due to the nature of the oil, which never evaporates and is engineered to stay on a surface indefinitely. Silicone tends to easily migrate to other surfaces; therefore, if a manufacturer only needs to coat a specific part of a device, it is hard to contain the fluid during coating.
This, in turn, will make the coating and joining process time-consuming since more cleanup is required once the part is joined. The risk of contamination is also increased during the coating process since the oil can attract and capture dust and dirt in the surrounding environment. Even
if a clean room is used, there is a heightened chance of contamination. Furthermore, medical-grade silicone costs more than other lower grades used in other industries.
The process of silicone swelling can be likened to when a sponge absorbs water. The silicone tubing swells in size like a sponge when it starts absorbing the solvent, then shrinks. After shrinking, it will recover its original dimensions once the solvent has evaporated. This results in a tight-seal attachment to the metal part or barbed fitting. Silicone swelling makes attaching silicone tubes or parts with barbed fittings quick and simple.
Since the silicone only needs an increase in size by 1 to 2% in many cases, the complete swelling process can occur in less than a minute. First, the silicone end to be connected to the barbed fitting is dipped into a vessel of the swelling agent. The swelling of the submerged tube or part starts almost immediately. The time the tubing remains in the solution determines how much it will swell. This can be accurately timed in high-volume operations to ensure maximum efficiency.
The swelling solvent immediately starts to evaporate once the part has been removed from the fluid. As the swelling solvent evaporates, the part recovers its original state. Compared with other methods, the whole silicone swelling process – both the swelling of the silicone and the recovering of the silicone back to its original size – can be very quick.
As mentioned above, silicone tubing is a tough elastomer that exhibits many good properties, including high resistance to temperature ranges, high flexibility, good wear and tear resistance, and resistance to UV and ozone. These benefits make silicone tubing a popular choice in a variety of applications, such as in the medical and food industries. Its high flexibility and strength make it a better choice over other rubber materials that can be used in its place. One of the other benefits that make silicone tubing a popular choice in the medical field is that it is easy to clean. This can be easily done by boiling it to remove the dirt that builds up in the material. The flexibility and high tensile strength of silicone tubing make it suitable for various applications in the medical, automobile, dairy, food, beverage, and pharmaceutical industries. Because of the different grades in which silicone tubing is available, careful considerations must be made when opting for silicone tubing for a specific type of application.