1. Introduction to Filtration and Strainers

Before discussing polypropylene strainers individually, let’s help you understand how filtration systems work and how strainers are part of these systems.

What Are Strainers?

Strainers are mechanical devices that are fitted to pipelines for the removal of solid particles, debris, and contaminants from fluid streams. Strainers serve as a protective device (guardians) for pumps, valves, heat exchangers, etc., by preventing the cost associated with wear, clogging (inoperable) pumps, valves, heat exchangers, and other sensitive equipment.

Strainers can be in the form of either basket, Y-type, duplex, T-type, etc., as well as made from a variety of materials (metal, plastics, composites), depending on the…

How Material Affects Performance

The construction type/material will have a direct effect on the chemical compatibility, the temperature range, the mechanical strength, and the lifespan performance of the strainer systems. In certain industrial processes where highly corrosive fluids or aggressive chemicals are being used, they will make conventional metal strainers unsuitable or have a short lifespan. The use of PP strainers has advantages in this environment.

2.What Is a PP Strainer?

Polypropylene Strainers are designed and built using primarily polypropylene, a type of thermoplastic polymer that is resistant to chemicals. 

PP Strainers can come in various shapes and styles (e.g., perforated, basket strainers, or mesh-lined strainers) and can be used for filtering water; chemical processing applications, pipes in industry; and at wastewater facilities.  This is due to the chemical-resistant properties of polypropylene; the strainers can withstand the effects of corrosion and abrasion, as well as function correctly in many types of aggressive fluids (i.e., with aggressive liquids).

3. Key Advantages of PP Strainers

3.1 Excellent Chemical Resistance

Polypropylene strainers have a distinct benefit in that they are resistant to many different types of chemicals.

Metal materials such as carbon steel or stainless steel can corrode when exposed to acids, bases, chlorides, and oxidizers; however, polypropylene can remain unchanged in environments where chemical degradation can occur.

Prolonged exposure to polypropylene will not cause degradation with the following types of chemicals:

• Acetic acid
• Sulfuric acid (dilute)
• Caustics
• Chlorinated water
• Salt

Thus, polypropylene strainers are best suited for applications where the filtrate could contain chemicals that could corrode the strainer and damage the filtering system.

3.2 Lightweight, Easy to Install

Polypropylene strainers are significantly lighter than metal strainers, which results in numerous advantages for both practical applications as well as cost savings for the user:

• Easier to handle during both the installation and maintenance processes
• Requires less structural support
• Faster installation within field solutions
• Labor savings

For very large filtration systems, particularly those that are mounted at altitude or in restricted spaces, the lightweight nature of polypropylene strainers facilitates maintenance and provides a safer environment for servicing.

3.3 No Corrosion

Polypropylene is a thermoplastic polymer that will not corrode, unlike metals; therefore, polypropylene will provide long-term reliability in areas where wet conditions exist, such as:

• Water treatment plants
• Sea water filtration systems
• Industrial wastewater treatment system
• Chemical processing

All metal strainers will eventually develop rust or pitting due to corrosion.

3.4 Cost-Effectiveness of Polypropylene Strainers

Using polypropylene (PP) strainers in many industrial applications provides a cost advantage for the following reasons:

• Lower raw material and manufacturing costs
• Reduced maintenance costs
• Longer service life in corrosive environments
• Fewer replacements than metal strainers

Because of these factors, companies that utilize PP strainers can expect to obtain an excellent return on their investment while optimizing their operational budget.

3.5 Enhanced Customization of Design Options

Polypropylene strainers can be manufactured in a variety of sizes and configurations to best suit specific filtration needs. The following options are available:

• Custom mesh or perforation sizes
• Types of construction, such as threaded, basket style, and Y shape
• Connection methods such as flange, thread, and welds
• Heavy-duty vs. normal-duty construction

The material itself is highly versatile and can be molded and also manufactured into many different styles and designs, which can meet many different process applications.

3.6 Non-Conductive and Safe for Use with Delicate Fluids

Unlike metal strainers, non-conductive polypropylene strainers can provide a safe and effective solution for applications where electrical conductivity should be avoided, such as:

• Electroplating facilities
• Fluid electronics
• Critical chemical formulation.

Using non-conductive materials also helps to reduce the possibility of short circuits in applications where electrical grounding or static electricity might create issues.

3.7 Resistant to Scale and/or Foul fouling Issues

The accumulation of mineral deposits (scaling) is one of the biggest problems facing water systems today. Scale accumulations can occur in systems with hard water (which is usually the case) and systems that are flooded with highly mineralized water.

When compared to metal strainers, polypropylene strainers are far less likely to allow for the accumulation of scale; this results in:

• The performance of the strainer has improved over long periods
• Less frequency of needing to clean the strainer
• Consistency of filtration is improved.

Applications such as cooling tower systems, irrigation systems, or industrial water loops would all benefit significantly from using polypropylene strainers.

3.8 Poorly Conductive Heat

PP has a much lower thermal conductivity than metals and can assist in the prevention of:

• Loss of heat due to contact with products that are sensitive to temperature
• Thermal shock events
• Lost heat from the filtration system

Although PP is not recommended for use at extremely high temperatures, it is able to maintain the temperature in the operating range.

3.9 Recyclable and Environmentally Friendly

As a plastic, Polypropylene is one of the most widely recycled globally. At the end of its service life, PP strainers can either be recycled or reused, helping organisations meet their sustainability goals.

This gives industries looking for more sustainable industrial practices another reason to choose PP.

3.10 Reduced Maintenance Downtime

PP strainers are much less likely to corrode or become fouled compared to their metal counterparts, so PP strainers require less frequent maintenance and will not need to be replaced or inspected as often.

This results in:

• Less time spent on maintenance
• More time for systems to be operational
• Faster operational cycle
• More productive work

For companies that cannot afford to lose a lot of time because of extended downtimes, manufacturing and nuclear power plants, for example, this is a major benefit from an operational perspective.