When To Choose a Plastic Solenoid Valve

Figure 1: 2-way plastic solenoid valve

Plastic solenoid valves offer significant advantages such as excellent chemical compatibility, cost-effectiveness, and lightweight design. Understanding their features, limitations and ideal applications is crucial for an informed decision while selecting a solenoid valve. While metal solenoid valves, such as those made from brass or stainless steel, are commonly used for their durability and high-pressure capabilities, plastic variants provide unique benefits in specific applications. This article discusses the critical factors to consider when choosing a plastic solenoid valve over its metal counterparts, ensuring optimal performance and longevity in the system.

When to choose a plastic solenoid valve
Advantages of plastic solenoid valves
Applications for plastic solenoid valves
Material properties of plastic solenoid valves
Limitations and considerations
When to choose metal valves
FAQs

When to choose a plastic solenoid valve

Use a plastic solenoid valve if:

The valve must be corrosion-resistant to aggressive chemicals, acids, or saline solutions
Budget constraints require a more economical solution
The valve must be lightweight
Minimal magnetic interference is necessary as plastic valves are non-magnetic, preventing unwanted interactions with sensitive equipment. Some metals might have slight magnetic properties when exposed to strong magnetic fields.
The system operates under low to medium pressure, e.g., 10-20 bar (150-300 psi)
Operating temperatures are within 60-80 𐩑C (140-176 𐩑F). This is a typical range and special plastic materials can handle higher temperatures as discussed later.
Electrical conductivity must be avoided, as plastic valves are non-conductive, preventing electrical hazards and interference

Advantages of plastic solenoid valves

Resistance to corrosion: Plastic valves are inert to a wide range of corrosive substances, like acids, bases, and organic solvents; this makes them ideal for chemically aggressive environments. Some advanced plastics, like PVDF, can resist biofouling, making them suitable for applications in marine environments and biotechnology.
Material properties: The diverse range of plastics ensures compatibility with many chemicals and fluids. Plastics like PTFE have non-stick properties, preventing residue buildup, making them ideal for food and beverage applications. It's essential to consult with a valve manufacturer or refer to a chemical compatibility chart to ensure the chosen plastic is compatible with the specific chemicals in the application.
Lightweight: Plastic valves are significantly lighter than their metal counterparts, which simplifies installation and reduces shipping costs. The reduced weight also minimizes the stress on piping systems, potentially extending the lifespan of the entire system. This is particularly advantageous for portable equipment and applications with space constraints.
Cost-effective: Generally, plastic solenoid valves are more affordable than metal valves, both in terms of initial cost and long-term maintenance. The lower cost of plastic valves can be particularly beneficial in large-scale applications, such as agricultural irrigation systems, where hundreds or thousands of valves may be required.
Insulation properties: Plastic materials naturally provide electrical insulation, making plastic solenoid valves suitable for applications where minimizing electrical interference is crucial. Additionally, their insulating properties can be beneficial in preventing heat transfer through the valve, which is important in automotive and medical applications.

Applications for plastic solenoid valves

This section details the specific uses of plastic solenoid valves in various industries. It highlights their roles in water treatment, chemical processing, aquariums, food and beverage production, and agricultural irrigation, emphasizing their corrosion resistance, reliability, and compliance with industry standards.

Water treatment and management: Plastic body solenoid valves are suitable for chlorinated water and chemicals. They comply with EPA standards, making them perfect for swimming pools and drinking water systems. They are also used in residential and commercial water systems for irrigation and water softening.
Chemical processing: Plastic solenoid valves can withstand exposure to potent chemicals, harsh acids, and bases, ensuring reliable performance in critical chemical processes where the margin for error is minimal.
Aquariums and aquaculture: Plastic solenoid valves are essential in aquariums and aquaculture for managing water flow, oxygenation, treatment, and filtration. Their resistance to saltwater and biological materials helps maintain optimal conditions for marine life.
Food and beverage industry: The food and beverage industry requires sanitary and sterile environments to ensure product safety. Plastic solenoid valves are non-toxic and easy to clean, making them suitable for applications such as precise dispensing of flavors and additives, as well as advanced brewing technologies. However, it is important to ensure that the specific type of plastic used in the solenoid valve is food-grade and certified for use in such applications. Compliance with standards such as the U.S. Food and Drug Administration (FDA) regulations, NSF International standards, and European Union (EU) food safety standards is essential.
Agriculture and irrigation: Plastic solenoid valves are extensively used in agricultural irrigation systems due to their lightweight and corrosion-resistant properties. They are ideal for controlling the flow of water and fertilizers in drip and sprinkler irrigation systems. Their cost-effectiveness and ease of maintenance make them a popular choice in large-scale agricultural operations.

Material properties of plastic solenoid valves

Table 1: Material properties of plastic solenoid valves

Material	Chemical resistance	Temperature tolerance	Mechanical strength	Applications
Polyvinyl chloride (PVC)	Excellent resistance to acids, alkalis, and salts. Limited resistance to solvents and aromatic hydrocarbons	Typically up to 60 𐩑C (140𐩑 F)	Good tensile strength and rigidity	Water treatment, irrigation systems, and general-purpose fluid control
Polypropylene (PP)	Superior resistance to a wide range of chemicals, including acids, alkalis, and organic solvents	Can withstand temperatures up to 90 𐩑C (194 𐩑F)	High impact resistance and flexibility	Chemical processing, food and beverage industry, and pharmaceutical applications
Polyvinylidene fluoride (PVDF)	Exceptional resistance to chlorine, bromine, and other halogens, as well as strong acids and bases	Can operate at temperatures up to 150 𐩑C (302 𐩑F)	High tensile strength and abrasion resistance	High-purity applications, semiconductor manufacturing, and aggressive chemical environments
Polytetrafluoroethylene (PTFE)/Teflon	Unmatched resistance to almost all chemicals, including strong acids, bases, and solvents	Can handle temperatures up to 260𐩑 C (500 𐩑F)	Low friction coefficient and excellent non-stick properties, but relatively low mechanical strength	Extreme chemical environments, high-temperature applications, and non-stick requirements
Polyamide (Nylon)	Good resistance to oils, greases, and hydrocarbons. Limited resistance to acids and alkalis	Typically up to 150𐩑 C (302 𐩑F)	High mechanical strength and excellent wear resistance	Automotive parts, industrial components, and consumer goods
Polyphenylene sulfide (PPS)	Excellent resistance to chemicals, including acids, alkalis, and organic solvents	Can withstand temperatures up to 200 𐩑C (392 𐩑F)	High mechanical strength and dimensional stability	Electrical components, automotive parts, and chemical processing equipment
Polyether ether ketone (PEEK)	Outstanding resistance to a wide range of chemicals, including acids, bases, and organic solvents	Can operate at temperatures up to 143 𐩑C (289 𐩑F)	Exceptional mechanical strength and high-temperature stability	Aerospace, medical devices, and high-performance industrial applications

Note: The operational temperature of a valve depends on factors such as design, materials, thermal expansion, and the temperature tolerance of electrical components. Always check the specific valve specifications provided by the manufacturer to ensure it meets your application requirements.

Limitations and considerations

While plastic solenoid valves offer numerous advantages, there are certain limitations and considerations to keep in mind when selecting them for specific applications:

Temperature and pressure limitations: Plastic solenoid valves generally have lower temperature and pressure tolerances compared to metal valves. For instance, PVC solenoid valves typically operate up to 60 𐩑C (140 𐩑F), while PTFE can handle up to 260 𐩑C (500𐩑 F). Similarly, their pressure ratings are often lower, which limits their use in high-pressure applications. These limitations can be mitigated with the use of composite materials and plastic-metal hybrids.
Potential for UV degradation: Some plastics, such as PVC, can degrade when exposed to ultraviolet (UV) light over extended periods. This can lead to brittleness and reduced mechanical strength. For outdoor applications, it is important to select UV-stabilized plastics or provide protective coatings to mitigate this issue. It is recommended to check the manufacturers' specifications on UV resistance to ensure the chosen material will perform reliably under UV exposure.
Mechanical wear and tear: While plastics offer good chemical resistance, they may not be as durable as metals in terms of mechanical wear and tear. Abrasive fluids or high-velocity flows can cause erosion and wear on plastic components, potentially leading to leaks or failures over time.
Material compatibility: While plastic valves generally offer broader chemical compatibility than metal valves, they are not immune to degradation from certain chemicals. Exposure to incompatible substances can lead to leaks or valve failure. It is crucial to double-check the specific plastic material and internal components to ensure they are suitable for the intended media.

FAQs

What are plastic solenoid valves used for?

Plastic solenoid valves are used in applications requiring chemical resistance, cost-efficiency, and lightweight design, such as water treatment, irrigation, and food and beverage industries.