Understanding the Venturi Effect in Chemical Injectors: How Switching Between High and Low-Pressure Lances Controls Chemical Flow

Chemical injectors are essential tools for professional high-pressure cleaning, allowing you to seamlessly apply cleaning chemicals during your wash. There are several types of chemical injectors, each functioning differently depending on the system. For example, premium Ehrle models, like the Ehrle HD and Ehrle KD series, incorporate dosing and injection systems to mix chemicals with water for maximum cleaning efficiency.

In contrast, injectors such as the ST160 that we frequently fit to Nailsea engine-driven pressure washers (such as the Honda Driven or WF Range) don’t use active dosing or injection. Instead, they rely on a fascinating principle of fluid dynamics known as the Venturi effect. If you’re unfamiliar with the Venturi effect, the inner workings of these injectors might seem like a bit of a mystery. And indeed, there is an element of intrigue since you don’t physically adjust a dial or flip a switch to control the chemical flow.

So how does this work? The key lies in simply changing your lance setting. When you switch from a high-pressure to a low-pressure setting, the pressure washer “knows” it’s time to start or stop applying the chemical. But what’s happening behind the scenes? How does this simple, manual adjustment signal the change?

In this article, we’ll dive into the mechanics of the Venturi effect and how it powers these chemical injectors, demystifying the process for both professional cleaners and those curious about how their equipment operates.

What is the Venturi Effect?

The Venturi effect describes how the speed and pressure of a fluid change as it flows through a narrow section of a pipe. When water flows through a constriction, the fluid must speed up, and as it does, the pressure in the narrow section drops. This drop in pressure creates a vacuum effect, which can be harnessed to draw chemicals into the water flow without the need for an additional pump.

In a chemical injector, this principle is used to pull cleaning chemicals into the water stream, allowing them to mix before being sprayed out through the lance.

How Chemical Injectors Work with the Venturi Effect

A chemical injector is installed along the flow of water between the pump and the lance. Inside the injector, the water passes through a Venturi tube. This tube has a narrow section that speeds up the water flow and creates a pressure drop. This low-pressure zone then draws chemicals into the water flow from an attached chemical supply.

However, the injector’s ability to draw chemicals depends on the pressure of the water. This is where high-pressure and low-pressure lances or adjustable/vario lances come into play.

Switching Between High-Pressure and Low-Pressure Lances

Many high-pressure cleaning systems come with two types of lances:

• High-pressure lance: Used for intense cleaning with water alone.
• Low-pressure lance: Used to mix and spray chemicals when needed.

High-Pressure Lance: No Chemical Injection

When using a high-pressure lance, the water is forced through the system at maximum speed and pressure. While this is excellent for cleaning tough dirt and grime, it does not allow the chemical injector to work. Here’s why:

• The high-pressure water maintains relatively equal pressure throughout the system. This consistent pressure is later used, in a similar way to the Venturi effect, to convert pressure into velocity for effective cleaning. However, without a significant pressure difference, the Venturi effect cannot occur sufficiently enough in the injector, meaning no vacuum is created to draw chemicals into the water.
• In high-pressure mode, the injector effectively turns off, and only water is sprayed.

Low-Pressure Lance: Chemical Injection Activated

When you switch to a low-pressure lance, the flow of water is effectively increased through the system reducing in a lower pressure. As a result:

• The pressure difference inside the narrowing tube of the chemical injector becomes low enough to trigger the Venturi effect, creating a vacuum that pulls the chemical into the water stream.
• In this mode, the chemicals mix with the water and are sprayed at a lower pressure, perfect for applying detergents or cleaning solutions.

Using Adjustable/Vario Lances for Chemical Injection Control

Many high-pressure cleaning systems feature adjustable or vario lances, allowing you to change pressure settings without the need to swap lances. These lances offer the convenience of both high and low pressure in one tool by simply twisting or adjusting the nozzle. This adjustable mechanism works similarly to switching between separate high- and low-pressure lances but requires only a quick adjustment at the nozzle. Typically, this involves twisting or pulling the nozzle protector to widen or narrow the nozzle’s orifice, thereby changing the pressure.

How Adjustable Lances Work

• High-pressure setting: When set to high pressure, the nozzle creates a strong, concentrated stream of water. This does not allow for chemical injection because the Venturi effect is not strong enough to pull the chemicals into the water.
• Low-pressure setting: When adjusted to low pressure, the nozzle allows water to flow more slowly, reducing the pressure. This reduction activates the Venturi effect, and the chemical injector begins to draw the cleaning solution into the water stream.

Why The Venturi Effect Matters for Your Cleaning System

Understanding the role of the Venturi effect and how switching between high-pressure and low-pressure settings activates or deactivates the chemical injector allows for:

• Greater Control: You can control when and how much cleaning solution is mixed with water by adjusting the lance or switching between high- and low-pressure modes.
• Efficiency: The ability to use chemicals only when necessary and switch back to high-pressure water alone means that less cleaning solution is wasted, reducing both cost and environmental impact.
• Versatility: With adjustable lances or a dual-lance system, operators can switch quickly between applying chemicals for deep cleaning and using high-pressure water for rinsing, without needing to stop and manually add detergents.

Conclusion

The Venturi effect is a simple yet powerful principle that enables chemical injectors to function in high-pressure cleaning systems. By understanding how this effect works and how to switch between high-pressure and low-pressure lances or use adjustable/vario lances, you can maximise the efficiency and effectiveness of your cleaning equipment. Whether you’re using it for commercial cleaning, agricultural applications, or industrial settings, mastering this technique ensures optimal results every time.

Structofoam is a specially formulated plastic material known for its durability, strength, and lightweight properties. It is commonly used in industrial and commercial products, including vacuum cleaners, due to its exceptional performance characteristics. Here’s why Structofoam is so beneficial:

Key Features of Structofoam:

• Durability: Structofoam is highly resistant to impacts and harsh conditions. It doesn’t crack, dent, or corrode easily, making it perfect for tough industrial environments.
• Lightweight: Despite its strength, Structofoam is relatively lightweight. This makes products made from it easier to handle and transport without compromising on durability.
• Chemical Resistance: It can withstand exposure to various chemicals and substances commonly found in industrial settings, ensuring a longer lifespan for the products.
• Thermal Stability: Structofoam maintains its integrity under a wide range of temperatures, making it suitable for different working conditions.

Application in NES570, NED570, NES900, and NED900 Vacuums:

In the NES570, NED570, NES900, and NED900 industrial vacuum cleaners, Structofoam is used for the main body construction. Here’s why it’s advantageous:

• Robust Construction: These vacuum cleaners can endure the wear and tear of daily use in demanding environments like construction sites and factories.
• Ease of Use: The lightweight nature of Structofoam ensures that the vacuums are easy to maneuver, even with their large capacity and powerful motors.
• Long-Lasting: The chemical and thermal stability of Structofoam means that the vacuum cleaners will remain reliable over many years of use, even in tough conditions.

Structofoam contributes significantly to the overall reliability and efficiency of the NES570, NED570, NES900, and NED900 vacuums, making them an excellent choice for heavy-duty industrial cleaning tasks.

Explore Our Structofoam Vacuum Cleaners:

• NES570: Single motor vacuum cleaner designed for industrial use.
• NED570: Dual motor version for extra power and efficiency.
• NES900: Larger capacity single motor vacuum for heavy-duty cleaning.
• NED900: Dual motor variant with enhanced suction and durability for the toughest jobs.

Discover the power and durability of Structofoam in our range of industrial vacuums. Whether you need a robust solution for a construction site or a reliable cleaner for a factory floor, our NES570, NED570, NES900, and NED900 models have you covered.

What is Maximum Inlet Temperature in Pressure Washers (and why does it matter?)

The “Maximum Inlet Temperature” specification on a pressure washer chart denotes the highest temperature of the water that can be safely fed into the pressure washer system. The “Maximum Inlet Temperature” figure holds critical importance as exceeding this threshold can lead to detrimental consequences, particularly concerning the internal components of the pressure washer, notably the pump. For instance, most cold water pressure washers are engineered to accommodate a maximum water inlet temperature of 40°C (104ºF). Therefore, the water supplied to most cold water pressure washers should not surpass 40ºC to ensure optimal operation and longevity of the equipment.

Reasons for Specifying Maximum Inlet Temperature:

1. (Primary Reason) Preventing Damage to Internal Seals and Components: 

The pump, valves, and various internal components of a pressure washer contain seals and gaskets made of rubber or plastic. Exposure to excessively high water temperatures can cause these seals to expand, deform, or deteriorate, leading to leaks and diminished performance.

2. Maintaining Proper Cooling of the Pump: 

Water flowing through the pressure washer pump serves, in part, the function of cooling it during operation. Elevated inlet water temperatures increase pump temperatures, potentially resulting in overheating and premature failure of seals or other vital components.

3. Avoiding Boiling Water Inside the System: 

Standard residential pressure washers are not designed to handle boiling water or steam. Introducing water above the maximum inlet temperature threshold could induce boiling or steam formation inside the pump, compromising performance, and posing safety hazards.

4. Material Limitations: 

The metals, plastics, and rubber utilised in typical pressure washer construction have temperature limitations beyond which they may degrade, warp, or fail prematurely when subjected to excessive heat from the inlet water.

Incorporating the Ehrle KS Series Exception:

It’s noteworthy to mention exceptions to the typical maximum inlet temperature specification of 40°C, such as the Ehrle KS series (KS 823 and KS 1140), which boast a higher water inlet temperature of 80°C. These models are specifically engineered to accommodate hotter inlet water temperatures, thereby expanding their range of applications without compromising performance or risking damage to internal components.

Summary

The maximum inlet temperature rating serves as a safeguard for internal seals, facilitates proper pump cooling, prevents boiling within the system, and ensures the materials can withstand the heat from the water supply. Exceeding this temperature threshold can result in severe damage to pressure washers not explicitly designed for hot water operation.

By adhering to the specified maximum inlet temperature, users can optimise the performance and durability of their pressure washer equipment while mitigating the risk of costly repairs or replacements.

Ensuring Electrical Safety: Understanding Electrical Protection in Pressure Washers

Electrical protection is a critical aspect of pressure washer design, aimed at safeguarding both the equipment and users from potential hazards associated with electrical overloads and short circuits. Specifications such as fuse ratings and types, indicated by designations like 13A (slow-blowing) and 3 x 16 A (slow-blowing), play a pivotal role in ensuring safe operation and durability. In this guide, we’ll delve into the significance of electrical protection in pressure washers, the implications of fuse ratings and types, and the importance of adhering to proper electrical standards.

Understanding Fuse Ratings and Types

1. Ampere Rating: The ampere rating specifies the maximum current that a fuse or circuit breaker can handle before it trips or blows. For instance, a 13A fuse can allow up to 13 amperes of current to pass through before interrupting the circuit.
2. Slow-Blowing Fuses: Also known as time-delay fuses, these are designed to tolerate temporary surges in electrical current, which are common during motor startups. Slow-blowing fuses provide protection against overcurrent conditions while accommodating the initial high current draw of electric motors.

Application in Pressure Washers:

• Single vs. Multiple Fuses: Specifications like 3 x 16 A (slow-blowing) indicate that the pressure washer employs a three-phase electrical connection, with each phase protected by a separate 16A slow-blowing fuse. This setup is typical in industrial-grade machines requiring balanced power distribution across three phases.

Importance of Correct Electrical Protection:

1. Preventing Electrical Hazards: Proper electrical protection safeguards against electric shocks, fires, and other hazards associated with overcurrent conditions or short circuits.
2. Ensuring Equipment Durability: By preventing damage to electrical components, appropriate protection measures contribute to the longevity and performance of the pressure washer.
3. Compliance and Safety Standards: Adhering to recommended fuse ratings and types ensures compliance with safety standards and electrical codes, enhancing overall safety for users and operators.

Electrical protection is a fundamental aspect of pressure washer design, aimed at ensuring safe operation and equipment durability. Understanding fuse ratings and types, such as 13A (slow-blowing) and 3 x 16 A (slow-blowing), is crucial for selecting and maintaining pressure washers in accordance with proper electrical standards. By prioritising electrical safety measures, users can mitigate risks and prolong the lifespan of their pressure washing equipment, ensuring safe and effective operation in various applications.

Pump Speed and RPM in Pressure Washers: A Comprehensive Overview

In the realm of pressure washers, understanding pump speed and RPM (revolutions per minute) is essential for assessing machine performance and longevity. The RPM of a pressure washer’s pump directly impacts crucial factors such as flow rate (LPM – litres per minute) and pressure output (BAR). In this guide, we’ll explore the significance of pump speed and RPM, their effects on pressure washer operation, and best practices for optimising performance.

The Role of RPM in Pressure Washer Performance

RPM, or revolutions per minute, measures the speed at which the pump in a pressure washer operates. RPM, as a metric, is pivotal as it dictates how rapidly the pump rotates around its axis within a minute, directly influencing the pressure washer’s functionality.

Factors Influencing Pump RPM

1. Design Variations: The RPM of a pressure washer pump can vary depending on the machine’s design and intended application. Industrial petrol pressure washers, for instance, often utilise a reduction gearbox to lower engine speed to a suitable RPM for the pump, typically around 1450 RPM. This reduction in speed minimises wear and tear on pump components, thus extending the pressure washer’s lifespan.

2. Drive System Adjustments: Pump RPM can also be adjusted via different drive systems. Belt drive pressure washers, for example, employ pulleys to regulate RPM from the engine to the pump. This mechanism allows the engine to operate at its most efficient RPM while adjusting the pump speed as needed for optimal performance and durability.

3. Operational Considerations: Operating a pressure washer pump within its recommended RPM range is crucial for maintaining efficiency and longevity. Attempting to significantly increase pump RPM beyond design specifications can lead to potential damage to both the pump and the engine.

Optimising Pressure Washer Performance:

1. Balanced RPM: Striking a balance between pump RPM and engine speed is essential for maximising pressure washer efficiency. Higher RPM doesn’t necessarily equate to better performance; it’s about operating within the optimal range for the specific machine and application.

2. Maintenance Practices: Regular maintenance, including lubrication and inspection of pump components, is key to preserving pump health and prolonging its operational lifespan. Following manufacturer recommendations for maintenance schedules is advisable.

3. Performance Monitoring: Monitoring pressure washer performance, including pump RPM, flow rate, and pressure output, helps identify any deviations from expected levels. Prompt troubleshooting and corrective action can prevent potential issues from escalating.

Pump speed and RPM play a pivotal role in determining the performance and longevity of pressure washers. Understanding the significance of RPM, along with its impact on flow rate and pressure output, empowers users to make informed decisions regarding machine selection, operation, and maintenance. By adhering to recommended RPM ranges and adopting best practices for optimisation, users can ensure efficient and reliable performance from their pressure washers over the long term.