A DG set pollution control RECD system can be an important retrofit solution for managing particulate emissions from eligible in-use diesel generator engines. For facility owners, however, selecting an RECD should not be treated as a simple equipment purchase. The generator's engine specifications, applicable regulatory requirements, product documentation, certification scope, installation conditions, and maintenance plan all need to be evaluated together.

The Central Pollution Control Board (CPCB) has established a system and procedure for compliance testing of Retrofit Emission Control Devices (RECDs) for in-use diesel-operated internal combustion engines used in generator-set applications up to 800 kW gross mechanical power. The procedure covers applicability, emission requirements, certification, testing equipment, and test procedures. Because environmental requirements can depend on the particular generator and regulatory situation, owners should verify the latest official requirements applicable to their installation rather than relying on generic statements about RECD compliance.

What Is a RECD?

RECD stands for Retrofit Emission Control Device.

It is designed to be installed on an existing diesel engine or generator-set exhaust system to help reduce particulate matter emissions. Unlike an emission-control system installed as part of a new engine's original design, an RECD is intended as a retrofit solution for an existing engine.

CPCB's published procedure establishes a technical framework for evaluating these devices. It specifically addresses RECDs for in-use diesel-operated internal combustion engines in genset applications up to 800 kW gross mechanical power.

The exact performance and applicability of an RECD depend on the certified product, engine application, operating conditions, and relevant technical requirements.

Why Are RECD Systems Important for DG Sets?

Diesel generators are widely used for standby and backup power in locations such as:

• Manufacturing facilities

• Hospitals

• Commercial buildings

• Data centres

• Hotels

• Educational institutions

• Construction projects

• Telecom facilities

• Industrial plants

• Residential and mixed-use developments

While a generator provides essential power reliability, its diesel engine produces exhaust emissions during operation.

An appropriately selected retrofit emission-control system can help address particulate-emission considerations associated with an existing generator.

However, installing an RECD should be part of a broader emission-management approach. Correct engine maintenance, appropriate fuel, proper operation, exhaust-system condition, and compliance with applicable requirements remain important.

Understanding the CPCB RECD Framework

CPCB's RECD procedure was developed in connection with the objective of reducing particulate matter through retrofit emission-control devices for eligible in-use diesel generator engines. The published document covers the certification system and testing procedure as well as technical requirements.

This is important for buyers because “RECD” is not simply a generic product category where every device can automatically be treated as equivalent.

A buyer should establish:

1. Which engine is being retrofitted?

2. What is its gross mechanical power?

3. Which RECD model is being proposed?

4. What is the documented application range?

5. What certification information supports the product?

6. What installation requirements apply?

These questions help separate a properly documented technical solution from a generic emission-control product.

Is Every DG Set Automatically Covered?

No universal conclusion should be made without checking the applicable requirements.

CPCB's RECD procedure identifies an applicability scope for in-use diesel-operated internal combustion engines up to 800 kW gross mechanical power for generator-set applications.

But the practical applicability of a particular RECD still depends on the engine and product.

For example, two generators with similar electrical ratings may have different engine models, power characteristics, or configurations. Their technical requirements may therefore differ.

Generator owners should verify their specific situation using current official requirements and appropriate technical documentation.

Start With the DG Set, Not the RECD

Before contacting a supplier, collect the generator's technical details.

Important information includes:

• Engine manufacturer

• Engine model

• Engine serial number

• Gross mechanical power

• Rated speed

• Generator rating

• Manufacturing details

• Existing exhaust arrangement

• Operating conditions

CPCB's technical documentation for genset engines itself identifies parameters such as engine model, rated speed, rated gross power, engine family, and other engine characteristics.

This information allows a supplier or technical team to determine whether a proposed RECD is appropriate for the application.

Why Gross Mechanical Power Matters

Generator owners often identify equipment by kVA.

However, the technical RECD framework uses gross mechanical power as an important parameter.

CPCB's published RECD procedure specifically covers eligible diesel genset engines up to 800 kW gross mechanical power.

Therefore, do not send only:

“I have a 500 kVA DG set.”

Instead, provide the engine model and documented gross mechanical power.

This produces a much stronger basis for technical evaluation.

Choosing a Suitable RECD

A suitable RECD should be selected based on documented application rather than marketing language.

Ask the supplier for:

• RECD manufacturer

• Product/model name

• Part number

• Applicable engine range

• Applicable power range

• Certification information

• Test documentation

• Installation requirements

• Maintenance requirements

CPCB publishes a list of manufacturers certified for RECDs applicable to diesel genset engines up to 800 kW. The published list dated May 9, 2025 shows that different manufacturers have different applicable engine-power ranges and may have certifications covering Phase I, Phase II, or both.

This demonstrates why selecting an RECD based only on the manufacturer's name is insufficient.

The exact application must be checked.

What Does Certification Mean for Buyers?

Certification documentation provides an important reference for evaluating whether a product has been assessed within the applicable technical framework.

But buyers should avoid interpreting certification as a universal approval for every engine.

Instead, compare the documentation with your DG set.

Check:

Manufacturer

Does the supplier match the documented manufacturer?

Model

Does the product model match the documentation?

Engine Range

Does the proposed application fall within the documented range?

Power Range

Does the DG engine's gross mechanical power fall within the applicable range?

Phase

Is the product applicable to the relevant engine phase/category?

CPCB's published manufacturer list provides these types of applicability distinctions.

Site Assessment Before Installation

An RECD is installed into an existing generator exhaust arrangement, so physical and engineering conditions should be evaluated before installation.

The site team should inspect:

• Existing exhaust pipe

• Pipe diameter

• Silencer arrangement

• Mounting space

• Exhaust routing

• Structural support

• Maintenance access

• Electrical requirements

• Controller location

• Sensor locations

The installation should be planned so that technicians can safely access the equipment for inspection and maintenance.

Exhaust Back Pressure Is an Important Consideration

Any modification to an exhaust system should be technically evaluated.

CPCB's RECD procedure includes exhaust back-pressure assessment as part of its testing framework.

Before installation, the technical team should consider:

• Existing exhaust back pressure

• Additional restriction from the retrofit system

• Engine manufacturer's applicable limits

• Exhaust pipe configuration

• Operating conditions

This is particularly important because an emission-control device should not be evaluated only by its physical dimensions.

Controllers and Monitoring Components

Depending on the RECD technology, the overall installation may include electronic controllers, sensors, monitoring features, alarms, or diagnostic functions.

Before purchasing, clarify:

• Controller model

• Sensor configuration

• Monitoring parameters

• Alarm functions

• Fault indications

• Maintenance alerts

• Data-recording capabilities, where applicable

The buyer should receive operating and maintenance information for the installed system.

Installation and Commissioning

A good RECD project should include more than simply mounting equipment onto the exhaust pipe.

The installation process may involve:

1. Site inspection

2. Technical assessment

3. Equipment positioning

4. Exhaust modifications

5. Mechanical installation

6. Sensor installation

7. Controller installation

8. Electrical connections

9. System checks

10. Commissioning

The final scope should be clearly defined in the supplier quotation.

Ask whether installation, commissioning, travel, exhaust modifications, electrical work, and operator training are included.

RECD Maintenance and Generator Maintenance

Installing an RECD does not eliminate the need for proper generator maintenance.

The engine should continue to receive appropriate servicing according to the manufacturer's requirements.

The RECD itself may also require periodic:

• Inspection

• Cleaning

• Sensor checks

• Component checks

• Functional verification

• Replacement of specified components

Ask the supplier for a written maintenance schedule before placing the order.

A system that is installed but poorly maintained may not provide the expected operational performance.

Documentation You Should Keep

For every DG set, maintain a dedicated technical file.

Generator Information

• Engine datasheet

• Engine model

• Serial number

• Gross mechanical power

• Generator details

RECD Information

• Product datasheet

• Model

• Part number

• Certification documents

• Test documentation

Installation Information

• Site survey

• Installation report

• Commissioning report

• Relevant photographs

Maintenance Information

• Service reports

• Inspection records

• Replacement records

• Fault history

Maintaining these documents makes future technical review much easier.

How to Evaluate a Supplier

Do not compare suppliers only by equipment price.

Evaluate:

Technical Capability

Can the supplier correctly identify the engine and recommend a suitable product?

Documentation

Can the supplier provide relevant certification and product information?

Installation

Does the supplier provide trained installation support?

Maintenance

Is a clear preventive-maintenance schedule available?

Service

Is technical assistance available after installation?

Spare Parts

Are important replacement components available?

A slightly higher initial price may be justified when it includes better technical support and a more complete installation scope.

What Is an RECD Device as per CPCB Norms?

When searching for an RECD device as per CPCB norms, buyers should focus on documented certification and applicability rather than relying on the phrase alone.

The important questions are:

• Is the manufacturer listed in relevant CPCB information?

• What exact product is certified?

• Which engine range does it cover?

• What power range applies?

• Which certification agency is identified?

• Does the proposed installation match the documented application?

CPCB's published manufacturer list identifies certification agencies such as ICAT and ARAI for listed products and provides their applicable engine-power ranges.

Therefore, a product should be verified against the actual DG-set engine rather than being accepted merely because its marketing material uses the phrase “CPCB approved.”

Common Mistakes to Avoid

Choosing by kVA Alone

Always obtain the engine's technical information.

Accepting Verbal Certification Claims

Request written supporting documentation.

Ignoring the Engine Model

A product's applicability can depend on the engine application.

Skipping a Site Survey

Existing exhaust conditions can affect installation.

Comparing Only Equipment Prices

Compare the complete supply and service scope.

Forgetting Maintenance

Plan ongoing inspection and service before installation.

Relying on Old Information

CPCB publishes and updates regulatory and technical information. Always check the latest available official material before making a compliance decision.

Frequently Asked Questions

What does RECD stand for?

RECD stands for Retrofit Emission Control Device.

What is the purpose of an RECD?

An RECD is a retrofit emission-control solution intended to reduce particulate emissions from eligible in-use diesel engines used in generator-set applications.

Does CPCB have an RECD certification framework?

Yes. CPCB has published a system and procedure covering applicability, certification, testing, and technical requirements for RECDs for eligible in-use diesel genset engines.

What DG engines are covered by the CPCB RECD procedure?

The published procedure covers in-use diesel-operated internal combustion engines for generator-set applications up to 800 kW gross mechanical power.

Does one RECD work for every DG set?

No. The appropriate product should be matched with the specific engine, power range, and documented application.

Does CPCB publish RECD manufacturer information?

Yes. CPCB publishes a manufacturer list showing applicable engine-power ranges and certification agencies.

Conclusion

A DG set pollution control RECD system should be selected through a combination of regulatory verification, engine identification, technical evaluation, product-document review, and professional installation planning. For generator owners, the most important lesson is simple: do not select an RECD only because a supplier describes it as “CPCB approved.” Verify the exact manufacturer, model, application range, certification information, and compatibility with the actual DG-set engine. A successful retrofit also depends on proper exhaust assessment, back-pressure considerations, installation quality, controller and sensor configuration where applicable, maintenance, and long-term service support.