What Is a Chemical Injection Pump and How Does It Work?

A chemical injection pump is a metering pump that delivers a controlled amount of chemical into a process at a specified flow rate and pressure. It works by drawing chemical from a supply source and forcing a measured volume into a pipeline, vessel, or process stream. Chemical injection pumps are commonly used for corrosion control, scale prevention, hydrate inhibition, water treatment, and other applications requiring accurate chemical dosing.

At MJ Systems, chemical injection is a core specialty. The company provides chemical injection pumps, metering equipment, flow measurement, instrumentation, pulsation control, and packaged systems for demanding industrial applications. Serving upstream, midstream, downstream, petrochemical, water treatment, and other industries, MJ Systems focuses on matching equipment to each application’s actual operating conditions. Its portfolio includes technologies from manufacturers such as CheckPoint Pumps & Systems and Hydra-Cell, along with Rheonik Coriolis flow meters, AW-Lake flow meters, and other supporting equipment. This application-focused approach helps customers create chemical injection systems designed for accurate dosing, reliable operation, and long-term performance.

How Chemical Injection Pump Systems Deliver Accurate Dosing

A chemical injection pump creates controlled flow so a specific amount of treatment chemical enters a process. Depending on the pump design, a piston, plunger, or diaphragm creates the pumping action needed to move the chemical from its supply source into a higher-pressure process.

A typical chemical injection system includes more than the pump itself. Depending on the application, it may incorporate:

• A chemical storage tank or supply
• Chemical injection pump
• Suction and discharge piping
• Valves
• Flow meters
• Pressure instrumentation
• Level instruments
• Pulsation dampeners
• Controls
• An injection point

Together, these components allow operators to store, deliver, measure, and control chemicals at the required rate.

How Does a Chemical Injection Pump Work Step by Step?

A chemical injection pump typically operates through a repeating suction and discharge cycle that moves a controlled volume of chemical into the process.

The basic process can be summarized in four steps:

1. Chemical enters the pump. During the suction portion of the cycle, the pumping mechanism creates the conditions needed to draw chemical from the supply tank into the pump head.
2. A measured volume is captured. The pump’s displacement determines how much chemical is moved during each cycle.
3. The chemical is pressurized. The pump creates enough discharge pressure to overcome the pressure at the injection point.
4. Chemical enters the process. The measured chemical is discharged into the pipeline, vessel, well, or other process equipment.

This cycle repeats continuously or according to the system’s control strategy.

Because many chemical injection applications involve high process pressures and relatively low flow rates, the pump needs to deliver chemical accurately while overcoming downstream pressure. This combination makes positive displacement and metering pumps common choices for chemical injection.

What Are Chemical Injection Pumps Used For?

Chemical injection pumps are used whenever a process requires controlled delivery of a treatment chemical.

In oil and gas operations, common applications include:

• Corrosion inhibitor injection
• Scale inhibitor injection
• Hydrate inhibitor injection
• Paraffin and wax control
• H2S scavenger injection
• Biocide injection
• Foamer and defoamer injection

Chemical injection is also used in water treatment, petrochemical processing, power generation, food processing, and other industrial applications.

The purpose varies, but the principle remains the same: deliver the appropriate chemical at the correct rate and pressure.

For oil and gas operators, this can be particularly important for flow assurance and asset protection. Proper chemical treatment can help manage corrosion, deposits, hydrates, and other conditions that may affect equipment or interfere with production.

What Types of Chemical Injection Pumps Are Available?

The appropriate chemical injection pump depends on pressure, flow, fluid properties, accuracy requirements, available power, and the operating environment.

Plunger pumps use a reciprocating plunger to move chemical through the pump. These pumps can be well suited to applications requiring accurate injection at high pressures.

MJ Systems supplies CheckPoint chemical injection pumps for demanding oil and gas applications. Depending on the specific model, these pumps are available in pneumatic, electric, and solar configurations, providing options for different operating environments.

Diaphragm pumps use a diaphragm to displace the process fluid. MJ Systems also supplies Hydra-Cell positive displacement pumps, which use a hydraulically balanced diaphragm design. Because the pumping chamber does not rely on dynamic seals, packing, or cups, this technology can be useful when leakage, maintenance, abrasive fluids, or difficult chemicals are important considerations.

For applications requiring controlled-volume metering, project specifications may also call for API 675 pump performance. API 675 addresses reciprocating controlled-volume pumps used in petroleum, chemical, and gas industry services.

The best technology is not necessarily the pump with the highest pressure or flow capability. It is the pump that matches the complete operating requirements of the application.

Why Is Accurate Metering Important in Chemical Injection?

Accurate metering helps ensure that enough chemical is delivered to achieve the intended treatment without unnecessary over-injection.

Underdosing may reduce treatment effectiveness. For example, insufficient corrosion inhibitor or scale inhibitor could leave equipment inadequately protected. Overdosing, on the other hand, can waste chemicals and increase operating expenses.

Chemical injection systems may therefore use flow measurement to verify actual delivery.

MJ Systems supplies several types of flow meters that can support demanding chemical injection applications, including:

• Rheonik Coriolis flow meters
• AW-Lake flow meters
• Litre Meter positive displacement flow meters

Coriolis meters can be particularly useful when accurate mass flow measurement is required. Other meter technologies may be appropriate depending on flow rate, pressure, viscosity, chemical properties, and measurement objectives.

Flow measurement provides operators with greater visibility into what the system is actually delivering instead of relying solely on calculated pump output.

What Should You Consider When Choosing a Chemical Injection Pump?

Choosing a chemical injection pump starts with understanding the actual process conditions.

Important selection factors include:

1. Flow rate: Determine minimum, normal, and maximum chemical injection requirements.
2. Discharge pressure: The pump must overcome pressure at the injection point while delivering the required flow.
3. Chemical properties: Consider viscosity, concentration, solids, temperature, and other fluid characteristics.
4. Material compatibility: Wetted pump components must be compatible with the chemical being handled.
5. Metering accuracy: Determine the level of accuracy and repeatability the application requires.
6. Available power: Evaluate electric, pneumatic, hydraulic, solar, or other available power sources.
7. Pulsation: Determine whether pulsation dampeners are needed to improve system stability.
8. Controls and measurement: Consider how injection rates will be adjusted, monitored, and verified.
9. Maintenance: Evaluate service requirements and accessibility in the operating environment.

Looking at these factors together is more effective than choosing a chemical injection pump based solely on maximum pressure or capacity.

In more complex applications, working with an experienced chemical injection pump supplier can also help ensure the pump, flow meter, valves, controls, and supporting equipment function together as a complete system.

Frequently Asked Questions About Chemical Injection Pumps

Is a chemical injection pump the same as a metering pump?

A chemical injection pump is often a type of metering pump because its purpose is to deliver a controlled amount of chemical into a process. However, the exact pump design and performance requirements depend on the application.

Can chemical injection pumps operate at high pressure?

Yes. High pressure chemical pumps are available for demanding applications such as oil and gas production. The required pressure rating should be determined by the actual discharge pressure, required flow rate, chemical properties, and operating conditions.

What is API 675 for chemical injection pumps?

API 675 is an American Petroleum Institute standard covering reciprocating controlled-volume pumps and pump units used in petroleum, chemical, and gas industry services. Whether API 675 is required depends on the application’s project specifications.

How do you know if a chemical injection pump is working correctly?

Operators can evaluate pump operation through factors such as chemical consumption, discharge pressure, calibration, and measured flow. Adding an appropriate flow meter can provide direct verification of the chemical injection rate.

Find the Right Chemical Injection Solution With MJ Systems

A chemical injection pump works by delivering a controlled volume of chemical into a process at the flow rate and pressure required for effective treatment. While the principle is straightforward, reliable chemical injection depends on correctly matching the pump, materials, measurement equipment, controls, and supporting components to the application.

MJ Systems provides chemical injection pumps, metering equipment, flow meters, pulsation dampeners, valves, level instruments, and packaged systems for demanding industrial applications. With technologies from leading manufacturers and application-focused engineering support, MJ Systems can help customers evaluate individual components or develop a more complete chemical injection solution.

Need help selecting a chemical injection pump for your application? Contact MJ Systems to discuss your operating requirements.