Injectors

Chemical injectors for professional foam and detergent application

Chemical injectors are used to introduce detergent or foam chemical into the water stream of professional cleaning systems. They are widely used with pressure washers, foam systems, industrial cleaning installations, agricultural cleaning equipment and other applications where controlled chemical application is required.

A correctly selected injector allows the cleaning chemical to be drawn from a separate container and mixed with the water stream without requiring a separate high-pressure chemical pump.

For professional systems, however, selecting an injector only according to its maximum pressure is not sufficient. Water flow, working pressure, injector nozzle size and the equipment installed downstream of the injector all influence its operation.

How does a chemical injector work?

Most professional pressure washer chemical injectors use the Venturi principle. Water passes through a restricted injector nozzle, increasing its velocity and creating a pressure difference that draws chemical through the suction connection.

The chemical is then mixed with the water stream and transported towards the gun, lance or foam-producing device.

The ability of the injector to draw chemical therefore depends on the complete hydraulic system rather than on the injector alone.

Important factors affecting injector performance

• water flow rate in litres per minute,
• working pressure,
• injector nozzle diameter,
• pressure loss downstream of the injector,
• foam lance or application nozzle,
• hose diameter and length,
• chemical viscosity,
• chemical suction hose length,
• dosing insert or metering valve setting.

R+M Suttner chemical and foam injectors

The injector range available from UMYTEC is primarily based on professional R+M Suttner systems. Different injector series are designed for different chemical configurations and foam-generation methods.

R+M Suttner ST-160 – single chemical injector

The ST-160 is a compact solution for introducing one chemical into the water stream. It is suitable where a straightforward single-chemical dosing system is required.

UMYTEC offers ST-160 versions with either interchangeable dosing inserts or an ST-161 metering valve.

The correct injector nozzle must be selected according to the operating conditions of the pressure washer and the downstream application equipment.

R+M Suttner ST-164 – double chemical injector

The ST-164 is designed for applications requiring two separate chemicals. Two suction connections allow the operator or system to select between connected cleaning products.

This can be useful where different detergents, foam products or cleaning stages are required from one installation.

UMYTEC offers ST-164 versions with:

• interchangeable dosing inserts,
• ST-161 adjustable dosing valves,
• versions without compressed air,
• versions with a compressed-air module.

R+M Suttner ST-167 – injector without compressed air

The ST-167 is a stainless-steel bypass injector designed for chemical application without an integrated compressed-air supply.

Its bypass design allows the injector to remain installed in the water line. Depending on the operating position, water can pass through the bypass section for washing or rinsing, or through the injection section when chemical suction is required.

This configuration is particularly useful in professional installations where the same line is used for both chemical application and rinsing.

R+M Suttner ST-168 – injector with compressed air

The ST-168 combines chemical injection with an additional compressed-air connection.

The air required for foam production is introduced at the injector, allowing the system to generate dense foam when combined with the appropriate downstream gun, hose and foam lance.

Because the air is introduced at the injector, the downstream foam lance must be selected specifically for this system configuration.

How to choose the correct chemical injector

Correct injector selection starts with the hydraulic parameters of the system. The most important values are water flow and working pressure.

1. Determine the water flow

Identify the actual operating flow of the pressure washer or pump in litres per minute. Injector nozzle sizing is closely related to the amount of water passing through the system.

2. Determine the working pressure

Use the normal operating pressure rather than only the maximum rated pressure of the pump or pressure washer.

A machine rated to a high maximum pressure may operate at a significantly lower pressure in the actual foam application.

3. Select the correct injector nozzle

The injector contains its own calibrated nozzle orifice. Different injector nozzle sizes are intended for different water-flow and pressure combinations.

An injector nozzle that is too restrictive can create excessive back pressure or cause the pressure washer to enter bypass. A nozzle that is too large may result in insufficient pressure difference for effective chemical suction.

4. Decide how many chemicals are required

For one chemical, ST-160, ST-167 or ST-168 configurations may be appropriate depending on the system.

If the installation needs to switch between two separate chemicals, the ST-164 double injector is specifically designed for this purpose.

5. Decide whether compressed air is available

Compressed air can substantially influence foam production.

If the system is designed to introduce compressed air at the injector, select a compatible version such as the ST-168 or an ST-164 configuration equipped with an air module.

For systems without compressed air, choose the corresponding non-air injector and compatible foam lance.

6. Check downstream components

The injector cannot be selected independently of the rest of the system. Check the:

• spray gun,
• foam lance,
• application nozzle,
• hose diameter,
• hose length,
• connections and threads.

Interchangeable dosing inserts vs. ST-161 dosing valves

R+M Suttner injectors are available with different methods for controlling the amount of chemical being drawn into the water stream.

Interchangeable dosing inserts

Interchangeable inserts use calibrated openings to determine chemical suction. They provide a simple and repeatable way of setting chemical concentration.

This solution is suitable where the required dosing level remains relatively constant.

ST-161 adjustable dosing valve

The ST-161 metering valve allows chemical suction to be adjusted without changing a dosing insert.

This is particularly useful when:

• different detergent concentrations are required,
• chemical properties vary,
• the operator needs easier adjustment,
• the system is commissioned or fine-tuned on site.

Typical applications for professional chemical injectors

Professional pressure washing

Chemical injectors allow detergent to be introduced into a professional pressure-washing system without pumping concentrated chemical directly through the high-pressure pump.

The injector, gun, lance and application nozzle must be designed as one complete hydraulic system.

Self-service and professional car wash systems

Injectors can be used for detergent and foam application in professional vehicle-washing installations where controlled chemical suction and reliable operation are required.

Selection should account for the water flow of each washing bay, required chemical concentration and the foam equipment installed downstream.

Food-industry and hygiene cleaning

Professional foam cleaning is frequently used on equipment, walls and floors because foam increases the contact time of the cleaning chemical on vertical and irregular surfaces.

Injector material compatibility with the cleaning chemical is particularly important in these applications.

Agriculture

Foam and chemical systems are also used for cleaning agricultural machinery, animal housing and other demanding installations where large surfaces require controlled detergent application followed by rinsing.

Fixed industrial cleaning installations

Bypass injectors can be integrated into fixed cleaning lines where operators alternate between chemical application and water rinsing without repeatedly removing the injector from the installation.

Compatibility with foam lances, guns and hoses

A professional foam system consists of more than the chemical injector itself. Injector performance is influenced by the complete downstream assembly.

Depending on the injector configuration, related components may include:

• professional spray guns and lances,
• foam lances,
• pressure and foam hoses,
• nozzles,
• chemical suction hoses,
• non-return valves,
• compressed-air supply components,
• fittings and adapters.

For compressed-air foam systems, the gun, hose and lance should provide sufficient internal flow area and must match the method by which air is introduced into the system.

Maintenance and troubleshooting

Chemical injectors have relatively few moving components, but their performance can deteriorate because of chemical deposits, blocked suction components or wear.

Typical symptoms of an injector problem

• injector no longer draws chemical,
• chemical concentration becomes inconsistent,
• foam becomes noticeably thinner,
• pressure drops unexpectedly,
• pressure washer repeatedly enters bypass,
• chemical continues to flow when it should stop.

Components to inspect

• injector nozzle,
• dosing insert,
• ST-161 metering valve,
• chemical suction hose,
• chemical filter,
• non-return valve,
• O-rings and seals,
• downstream foam nozzle or lance.

Deposits from concentrated chemicals can restrict small passages over time. Flush the system according to the requirements of the chemical and equipment manufacturer and avoid allowing incompatible chemicals to remain inside the injector for prolonged periods.

If an existing injector needs replacement, use the complete model designation and injector nozzle size rather than selecting a replacement only by physical appearance.

Frequently asked questions about chemical and foam injectors