Choosing the correct ejector valve airflow is critical when designing a high-speed color sorting machine.

A valve rated at 100 LPM may be suitable for one sorting application, while a 400 LPM valve may be required for another. The difference is not simply about choosing a "stronger" valve. It depends on the material being sorted, particle weight, required ejection force, operating pressure, response time, nozzle design, and compressed-air system.

For example, in different color sorting applications, around 100 LPM can be suitable for bottle flake sorting, while around 400 LPM may be required for mineral or ore sorting.

This article explains why these airflow requirements can be so different and how color sorter OEMs can select the right ejector valve. 

Also welcome to contact us for your specific color sorter project.

Quick Answer: 100 LPM or 400 LPM?

The simplest way to understand the difference is:

• Around 100 LPM: suitable for some lightweight materials such as bottle flakes, where controlled and precise air ejection is required.

• Around 400 LPM: suitable for applications such as mineral or ore sorting, where heavier particles may require significantly stronger airflow.

• Neither airflow is universally better. The correct specification depends on the material and the actual pneumatic requirements of the sorting machine.

• Response time is also critical. A high-flow valve with slow response may not perform as well as a lower-flow valve with fast and precise switching.

For high-speed color sorting, engineers should evaluate airflow, response time and ejection force together.

What Does LPM Mean on a Color Sorter Ejector Valve?

LPM means liters per minute and is used to describe the airflow capacity of a pneumatic valve.

Before comparing airflow specifications, it is useful to understand how an ejector valve works inside a color sorting machine. See our guide to how a color sorter valve works to learn how the detection, control and pneumatic ejection process are connected.

For example:

100 LPM

means the valve has an airflow capacity of approximately 100 liters per minute under specified test conditions.

400 LPM

means the valve can provide approximately four times the nominal airflow capacity of a 100 LPM valve, assuming the specifications are measured under comparable conditions.

However, LPM should never be considered as an isolated specification.

Actual pneumatic performance can also be affected by:

• Working pressure

• Valve orifice

• Port size

• Tubing diameter

• Tubing length

• Nozzle design

• Pressure drop

• Pulse duration

• Switching frequency

• Air supply capacity

Therefore, two valves with the same nominal LPM rating may not provide exactly the same performance in a real color sorting machine.

Why Does Bottle Flake Sorting Need Around 100 LPM?

Bottle flakes are lightweight plastic materials produced from waste bottles after processes such as crushing, washing and flaking.

Compared with minerals or ore, bottle flakes generally require less force to change their trajectory.

In a bottle flake color sorting machine, the ejector valve needs to generate a short and accurately timed air pulse to separate the target material.

A lower airflow configuration, such as around 100 LPM, can therefore be appropriate for certain bottle flake sorting applications.

The main objective is not to generate the maximum possible airflow.

Instead, the valve should provide:

• Sufficient ejection force

• Fast response

• Precise air pulses

• Stable high-frequency operation

• Controlled compressed-air consumption

If airflow is unnecessarily high, the machine may consume more compressed air than necessary and could potentially disturb nearby particles.

For lightweight plastic flakes, controlled airflow and precise timing can be more important than maximum airflow.

Why Can Mineral or Ore Sorting Require Around 400 LPM?

Minerals and ore can have substantially higher density and weight than plastic flakes.

The ejector valve therefore needs to produce enough pneumatic force to change the trajectory of the rejected particle.

For these applications, a higher-flow valve such as around 400 LPM may be required.

Higher airflow can provide greater instantaneous air capacity for the ejection process.

This can be important when:

• The material is heavy

• Particle size is larger

• A stronger trajectory change is required

• The ejection distance is relatively large

• The sorting machine operates at high speed

However, choosing a 400 LPM valve does not automatically guarantee better sorting.

The complete pneumatic circuit must still provide adequate pressure and flow.

100 LPM vs 400 LPM Ejector Valve

For OEMs looking for high-speed ejector valves for color sorting applications, Pneutech offers the PHF Series high-frequency ejector valves, with different flow configurations for different sorting requirements.

The following comparison provides a practical starting point for color sorter OEMs.

These are application examples, not fixed industry standards.

The actual airflow requirement should always be confirmed through the machine's pneumatic design and sorting tests.

Is 400 LPM Better Than 100 LPM?

No.

A higher LPM rating simply means the valve has a greater airflow capacity.

It does not mean that the valve will automatically provide better sorting performance.

Consider two hypothetical valves:

Valve A

• Airflow: 100 LPM

• Response time: <1 ms

• Short and precise air pulse

• Used for bottle flake sorting

Valve B

• Airflow: 400 LPM

• Response time: <1 ms

• Higher air capacity

• Used for mineral sorting

Both valves can be excellent choices for their intended applications.

The correct question is not:

Which valve has the highest LPM?

Instead, ask:

How much airflow is required to reliably eject the rejected material while maintaining accurate separation?

Airflow and Response Time Must Be Evaluated Together

For high-speed color sorting machines, the valve must combine sufficient airflow with fast and repeatable switching. Our high-frequency ejector valve series for color sorting is designed for applications where response time and high-frequency operation are critical.

For high-speed color sorting machines, response time can be just as important as airflow.

A typical sorting process looks like this:

Camera detects the particle

↓

Control system identifies the particle

↓

Electrical signal is sent to the ejector valve

↓

Valve opens

↓

Compressed air is released

↓

Particle trajectory changes

The entire process happens within a very short period.

If the valve responds too slowly, the air pulse may arrive too late.

Even if the valve has a very high airflow rating, the machine may still experience inaccurate ejection.

This is why some color sorter OEMs specify requirements such as:

Response time: <1 ms

For high-speed sorting applications, engineers should therefore evaluate:

• Opening response time

• Closing response time

• Switching frequency

• Pulse duration

• Airflow

• Pressure stability

rather than focusing only on LPM.

How Material Characteristics Affect Ejector Valve Selection

The required airflow is closely related to the physical characteristics of the material.

1. Material Weight

A heavier particle generally requires more pneumatic force to change its trajectory.

This is one reason why mineral sorting may require substantially higher airflow than bottle flake sorting.

Different materials require different ejection forces. Rice, plastic flakes, minerals and other materials can have very different particle sizes, densities and weights. For a broader comparison of valve requirements across different materials, see our sorter valve selection guide for rice, plastic and mineral sorting.

2. Particle Size

Larger particles may require more air force depending on their mass and aerodynamic characteristics.

Particle size should therefore be evaluated together with material density.

3. Material Shape

Bottle flakes, plastic pieces, grain and minerals have very different shapes.

Flat plastic flakes, for example, can behave differently in an air stream compared with dense mineral particles.

4. Material Velocity

The faster the material is moving, the more precise the timing of the air pulse becomes.

A high-speed machine therefore requires both:

Fast valve response + accurately controlled airflow.

5. Ejection Distance

The distance between the nozzle and the material also affects the required pneumatic performance.

A longer distance can require careful optimization of:

• Valve airflow

• Nozzle size

• Tubing

• Pressure

• Pulse duration

Don't Ignore the Nozzle

The ejector valve is only one part of the pneumatic system.

The complete system can be simplified as:

Air Supply → FRL → Ejector Valve → Tubing → Nozzle → Material

The nozzle determines how the compressed air is delivered to the material.

A high-flow 400 LPM valve does not necessarily produce the desired ejection result if the downstream nozzle or tubing restricts the airflow.

Similarly, using a small nozzle with an oversized valve may not provide the expected improvement.

For this reason, color sorter OEMs should evaluate the complete pneumatic circuit rather than selecting the valve independently.

How Tubing Length Can Affect High-Speed Ejection

Tubing between the valve and nozzle contains a volume of compressed air.

The longer the tubing, the more pneumatic volume the system may need to pressurize or discharge.

For high-speed sorting applications, excessive tubing length can therefore affect the effective response of the system.

When designing a color sorter, engineers should consider:

• Valve location

• Tubing length

• Tubing inner diameter

• Number of valves

• Nozzle configuration

• Operating pressure

A compact pneumatic layout can help reduce unnecessary flow restrictions and pneumatic delay.

How to Select the Right Airflow for Bottle Flake Sorting

For bottle flake sorting, start by evaluating:

Material

• PET bottle flakes

• Plastic flakes

• Flake size

• Flake weight

• Moisture and cleanliness

Pneumatic requirements

• Required airflow

• Working pressure

• Nozzle size

• Tubing size

• Ejection distance

Valve requirements

• Response time

• Switching frequency

• Voltage

• Mounting configuration

• Number of channels

If testing indicates that approximately 100 LPM provides sufficient ejection force, a 100 LPM-class configuration can help avoid unnecessary compressed-air consumption.

The final specification should always be verified through actual sorting performance.

How to Select the Right Airflow for Mineral Sorting

Mineral and ore sorting requires a different approach.

Start by evaluating:

• Material density

• Particle size

• Particle weight

• Conveyor or chute speed

• Ejection distance

• Required trajectory change

• Working pressure

• Required airflow

For heavier materials, a higher-flow configuration such as around 400 LPM may be appropriate.

The objective is to generate enough air force to reliably remove rejected material from the product stream.

However, the compressed-air system must also be sized accordingly.

What Happens If the Ejector Valve Has Too Little Airflow?

If airflow is insufficient, several problems can occur:

Incomplete ejection

The rejected particle may not move far enough away from the product stream.

Reduced sorting accuracy

Some defective material may remain in the accepted product.

Higher reject loss

The machine may need to use longer pulses or compensate with other parameters.

Unstable performance

The result may change as pressure or material conditions fluctuate.

For heavy mineral sorting, insufficient airflow can be particularly problematic.

What Happens If the Ejector Valve Has Too Much Airflow?

More airflow is not always beneficial.

Excessive airflow can result in:

• Higher compressed-air consumption

• Greater compressor demand

• Higher operating cost

• Disturbance of nearby particles

• Unwanted movement of accepted material

• More difficult pneumatic control

The goal is therefore to find the minimum effective airflow that reliably performs the required separation.

This is especially important for machines with hundreds or thousands of ejector channels.

How Many Ejector Valves Does a Color Sorter Need?

The number of ejector valves depends on the machine architecture.

Factors can include:

• Chute width

• Number of sorting channels

• Number of nozzles

• Material throughput

• Particle size

• Sorting accuracy requirements

• Machine configuration

A high-channel-count machine may require many valves operating independently at high frequency.

In such systems, total compressed-air consumption becomes an important engineering consideration.

For example, using a 400 LPM valve configuration across a large number of channels can create significantly greater potential air demand than using a 100 LPM configuration.

Therefore, airflow should be evaluated at both the individual valve level and system level.

A Practical Selection Guide for Color Sorter OEMs

Before selecting an ejector valve, prepare the following information for your pneumatic valve supplier.

Material information

• What material are you sorting?

• Bottle flakes?

• Plastic?

• Rice?

• Seeds?

• Minerals?

• Ore?

• Coffee beans?

Particle information

• Particle size

• Particle weight

• Material density

• Material shape

Pneumatic information

• Required airflow

• Working pressure

• Maximum pressure

• Nozzle size

• Tubing diameter

• Tubing length

Dynamic information

• Required response time

• Switching frequency

• Pulse duration

• Continuous operating conditions

Mechanical information

• Valve dimensions

• Mounting method

• Port configuration

• Manifold arrangement

• Number of channels

Electrical information

• Voltage

• Power

• Connector

• Driver board

• Control signal

Providing this information allows the supplier to recommend a valve based on the actual application rather than simply offering the highest-flow model.

100 LPM vs 400 LPM: Example Applications

The following examples illustrate why different sorting applications may require different valve configurations.

Again, these airflow values should be considered application examples rather than universal specifications.

Why Real Testing Is Still Necessary

Pneumatic calculations provide a starting point, but color sorting performance ultimately needs to be validated under real operating conditions.

The same ejector valve may perform differently depending on:

• Air pressure

• Particle characteristics

• Nozzle design

• Valve position

• Tubing

• Machine speed

• Ambient conditions

• Required ejection distance

A proper validation process should test:

1. Ejection accuracy

2. Response time

3. Air consumption

4. Sorting purity

5. Reject rate

6. Continuous operating stability

This is particularly important when developing a new color sorter or replacing an existing valve.

Why High-Speed Ejector Valve Response Time Matters

Airflow determines how much air the valve can deliver.

Response time determines when that air becomes available.

For high-speed color sorting, both are essential.

A suitable ejector valve should provide:

Sufficient airflow

Fast response

Stable high-frequency operation

Reliable service life

The best valve is therefore not necessarily the valve with the largest airflow rating.

It is the valve that matches the machine's complete pneumatic and sorting requirements.

Pneutech High-Speed Ejector Valves for Color Sorting Applications

Pneutech supplies pneumatic ejector valve solutions for color sorting applications where airflow, response time and high-frequency operation are critical.

Different sorting materials may require different valve configurations.

For example:

• Bottle flake sorting: approximately 100 LPM may be suitable for certain machine configurations.

• Mineral and ore sorting: approximately 400 LPM may be required for applications involving heavier particles.

• High-speed sorting: fast response time is critical regardless of airflow.

• OEM projects: valve configuration can be evaluated according to the machine's airflow, pressure, mounting and control requirements.

For OEMs developing or upgrading color sorting machines, we recommend providing the application details before selecting the valve.

If you are looking for a color sorter ejector valve for bottle flake, mineral, ore or other sorting applications, see our PHF Series high-frequency ejector valves or contact us with your required airflow, response time and working pressure.

FAQ

Is 100 LPM enough for bottle flake sorting?

It can be suitable for certain bottle flake sorting applications, particularly when the material is relatively lightweight and the pneumatic system is designed for controlled ejection. The actual requirement should be confirmed through testing.

Why does mineral sorting need more airflow?

Mineral and ore particles can be significantly heavier than bottle flakes. A stronger air pulse may therefore be required to change their trajectory and achieve reliable rejection.

Is 400 LPM too much for plastic sorting?

It depends on the material and machine design. If a plastic sorting application can achieve reliable ejection with approximately 100 LPM, using a 400 LPM valve may create unnecessary compressed-air demand.

Is response time more important than airflow?

Neither specification should be considered alone. Airflow determines the available pneumatic capacity, while response time determines how quickly the air pulse can be delivered. High-speed color sorting requires both.

Can I replace a 100 LPM valve with a 400 LPM valve?

Not necessarily. Before replacement, check the valve dimensions, port size, pressure, airflow, response time, driver compatibility, nozzle and compressed-air capacity. A higher-flow valve may require changes to the pneumatic system.

What information should I provide when asking for a color sorter ejector valve?

Provide the material being sorted, required airflow, working pressure, response time, voltage, number of channels, mounting dimensions, tubing/nozzle information and control requirements.

Conclusion

100 LPM and 400 LPM ejector valves are not simply two different performance levels of the same application. They can serve very different sorting requirements.

For lightweight materials such as bottle flakes, an ejector valve around 100 LPM may provide sufficient airflow while maintaining precise ejection and controlled air consumption.

For heavier materials such as minerals and ore, an ejector valve around 400 LPM may be more appropriate when stronger air ejection is required.

The key is to select the valve according to the actual application:

Material → Particle characteristics → Ejection force → Airflow → Response time → Pneumatic system

If you are developing a color sorting machine and need help selecting an ejector valve, send us your material, required LPM, working pressure, response time, voltage and valve configuration. We can evaluate a suitable pneumatic solution for your application.