If you operate a diesel generator for backup or standby power, understanding RECD compliance for diesel generators can help you make better decisions about emission-control equipment, documentation, installation and maintenance. RECD requirements should not be approached as a simple equipment purchase because the suitability of a retrofit device depends on the specific engine, power range, applicable phase and supporting technical documentation.

The Central Pollution Control Board (CPCB) has published a system and procedure for emission-compliance testing of Retrofit Emission Control Devices for diesel power-generating-set engines up to 800 kW gross mechanical power. The procedure was revised on July 24, 2023. For a DG-set owner, the practical question is not merely “Do I need an RECD?” It is also: Which device is applicable to my generator, what documentation should I verify, and how should I maintain the system after installation?

Start With Your Generator, Not the RECD

One of the most common procurement mistakes is searching for an RECD before collecting the DG-set's technical information.

Begin with the generator.

Record:

• DG-set manufacturer

• Engine manufacturer

• Engine model

• Engine serial number

• Generator capacity in kVA

• Gross mechanical engine power in kW

• Manufacturing details

• Existing exhaust arrangement

• Applicable phase, where relevant

CPCB's published RECD information is organized around in-use diesel genset engine power ranges, rather than simply the generator's advertised kVA rating. The published manufacturer information also distinguishes Phase I and Phase II applicability.

That is why the engine's actual technical details matter when selecting an RECD.

Why kVA Alone Is Not Enough

Generator owners often identify their equipment by kVA:

• 125 kVA

• 250 kVA

• 500 kVA

• 750 kVA

• 1000 kVA

However, RECD evaluation documents can identify the underlying engine by parameters such as rated power, engine model and other technical characteristics. CPCB's RECD test-report format specifically records the base engine, engine model, rated power and RECD model/type.

Therefore, don't send a supplier only the statement:

“We have a 500 kVA DG set.”

Provide the engine model and relevant power information as well.

Understand What an RECD Actually Is

RECD stands for Retrofit Emission Control Device.

It is a retrofit emission-control technology intended for applicable existing diesel power-generating-set engines.

The CPCB procedure establishes a framework for emission-compliance testing of these devices. It also includes performance considerations involving emissions, smoke, specific fuel consumption, regeneration characteristics, compatibility and exhaust back pressure.

This is important because an RECD should not be evaluated solely on the basis of its physical appearance or a general claim that it “reduces pollution.”

The technical documentation matters.

Does Every DG Set Use the Same RECD?

No assumption should be made that one RECD model is automatically suitable for every diesel generator.

CPCB's published RECD information identifies applicability according to engine-power ranges and phases. Its test-report format also includes the engine types for which the REC device is qualified as an application range.

Before purchasing, confirm:

Engine model → Engine power → Applicable range → RECD model → Supporting documentation

This verification can prevent an unsuitable product from being selected.

Check the Applicable Phase

Phase is another important consideration.

CPCB's published RECD manufacturer information identifies products according to Phase I and Phase II applicability.

As a generator owner, ask the supplier to clearly state which phase the proposed RECD covers.

Do not assume that a product documented for one phase automatically applies to another.

The supplier should be able to provide the relevant product and certification information for the proposed installation.

Review the Exact RECD Model

A quotation that says only:

“CPCB-approved RECD system”

does not provide enough information for a technical comparison.

Ask for the exact:

• Manufacturer

• RECD family

• RECD type/model

• Part number

• Applicable engine range

• Certification/test information

• Phase applicability

CPCB's published RECD test-report format includes fields for the manufacturer, RECD family, type/model and identifying part numbers.

This makes model-level identification particularly useful during procurement.

Ask for Supporting Documentation

Before placing an order, request documentation relevant to the actual product being offered.

A basic documentation package should include:

Product Information

• Technical datasheet

• Exact model

• Product specifications

• Applicable engine range

Certification Information

• Relevant certificate/test report

• Certification agency

• Applicable application range

• Phase information

Installation Information

• Installation instructions

• Exhaust requirements

• Mounting requirements

• Electrical requirements

Maintenance Information

• Maintenance manual

• Inspection instructions

• Service requirements

• Replacement components

CPCB's published test-report format itself contains detailed information concerning the base engine, RECD model, testing procedure and performance results.

Check the Certification Agency

When reviewing an RECD proposal, look beyond the phrase “certified.”

CPCB's published RECD manufacturer information and test documentation identify certification/test agencies associated with the evaluation process. The test-report format also records the relevant testing procedure and performance results.

As a buyer, ask:

• Which agency performed the applicable testing?

• What exact product was tested?

• Which engine was used?

• What application range was established?

• Does the proposed product correspond to the documented model?

The goal is to establish a clear link between the tested product and the product being supplied.

Don't Ignore the Base Engine

An RECD does not exist independently of the engine.

CPCB's RECD test-report format contains a detailed section for the base engine, including manufacturer, model, engine serial number, rated power, rated speed and other technical characteristics.

This demonstrates why engine information is important during product evaluation.

If a supplier asks for your engine model and technical specifications, that is not unnecessary paperwork. It is part of establishing whether the proposed retrofit is technically appropriate.

Examine the Exhaust System Before Installation

Before installing an RECD, inspect the existing exhaust system.

Check:

• Exhaust-pipe diameter

• Flanges

• Silencer

• Pipe length

• Bends

• Mounting points

• Available space

• Exhaust outlet

• Maintenance access

Take photographs and measurements before finalizing the installation plan.

A product that appears suitable in a catalogue may require modifications once the actual DG-set exhaust arrangement is examined.

Pay Attention to Exhaust Back Pressure

Exhaust back pressure deserves specific attention.

CPCB's RECD procedure includes exhaust back pressure among the technical requirements considered during RECD evaluation.

Therefore, the installation team should assess the complete exhaust arrangement rather than simply connecting the device to the existing pipe.

This becomes particularly important when the exhaust system already contains several bends, long pipe runs or restrictive components.

Understand What the RECD Does Not Automatically Prove

Installing an RECD should not automatically be interpreted as proof that every environmental requirement applicable to a facility has been fulfilled.

There may be separate requirements concerning:

• Generator emissions

• Noise

• Stack/exhaust arrangements

• Consent conditions

• State-level requirements

• Site-specific directions

• Monitoring and record keeping

CPCB separately maintains information concerning generator-set emission compliance and type approval/Conformity of Production procedures for applicable engines.

Therefore, keep RECD documentation separate from other DG-set compliance documents.

Maintenance Is Part of Responsible Ownership

An RECD should not be treated as a device that requires attention only once.

Follow the manufacturer's maintenance instructions and keep service records.

Depending on the specific system, maintenance may involve checking:

• Sensors

• Controllers

• Exhaust components

• Mounting arrangements

• Relevant emission-control components

• Regeneration-related functions

• Other manufacturer-specified parts

Do not create a generic maintenance interval without referring to the selected product's documentation.

Watch for Performance Changes

Generator operators should report unusual conditions such as:

• Unexpected alarms

• Changes in exhaust behaviour

• Unusual smoke

• Abnormal engine performance

• Sensor warnings

• Controller faults

• Physical damage

• Unusual exhaust-system noise

The operator should not attempt unauthorized modifications to the RECD.

Technical faults should be investigated by appropriately qualified personnel or the equipment supplier.

What Should You Ask an RECD Supplier?

Before purchasing, ask these practical questions:

Product

1. What is the exact RECD model?

2. What engine-power range does it cover?

3. What phase does it apply to?

4. What certification/test documentation is available?

Installation

1. What exhaust dimensions are required?

2. What modifications are necessary?

3. Is installation included in the quotation?

4. Is commissioning included?

Operation

1. What maintenance is required?

2. What components need periodic replacement?

Support

1. What warranty is provided?

2. Are spare parts available?

3. What after-sales support is available?

4. Who will handle technical service?

A supplier that can answer these questions clearly makes the purchasing process easier to evaluate.

How to Evaluate an RECD Manufacturer in India

If you are searching for an RECD manufacturer in India, do not compare companies only on price.

Consider:

• Product-specific documentation

• Applicable engine-power range

• Phase applicability

• Certification/test information

• Engineering support

• Installation capability

• Commissioning

• Maintenance assistance

• Spare-parts availability

• Warranty

• After-sales service

CPCB's published information can be used as an important verification reference, but the exact product and application should still be checked before purchase.

Be Careful With “CPCB Approved” Claims

One of the most important lessons for generator owners is to ask what a compliance statement actually means.

If a supplier says:

“Our RECD is CPCB approved.”

ask for:

• Exact model

• Supporting document

• Application range

• Engine-power range

• Phase

• Certification agency

• Test information

This is especially important because CPCB's technical documentation evaluates specific RECD applications and identifies the engine types/application range for which a device is qualified.

Don't Purchase Based Only on a Deadline

Another common mistake is buying an RECD immediately because someone says:

“The deadline is approaching.”

Before making a compliance-sensitive purchase, verify the actual regulatory source.

Check:

1. The official CPCB information

2. The applicable notification or direction

3. The equipment category

4. The engine power

5. The applicable phase

6. Any relevant SPCB/PCC requirement

7. Any site-specific condition

CPCB's official website maintains dedicated information for generator sets and related environmental requirements.

Regulatory information can change, so an old article or supplier message should not be treated as the final authority.

A Simple Owner's Decision Process

Use this sequence when evaluating your DG set:

1. Identify

Know your engine model and power.

2. Verify

Check current applicable CPCB and local requirements.

3. Match

Select an RECD with documented applicability to your equipment.

4. Inspect

Evaluate the exhaust system and installation location.

5. Document

Keep product, certification and installation records.

6. Maintain

Follow the manufacturer's maintenance instructions.

7. Review

Periodically confirm that your documentation and equipment remain appropriate.

This approach is more reliable than treating RECD installation as a single procurement activity.

Final Takeaway

For a generator owner, RECD compliance is best understood as a combination of technical suitability, product verification, correct installation, documentation and ongoing maintenance. CPCB's published RECD procedure applies to diesel power-generating-set engines up to 800 kW gross mechanical power and establishes a framework for emission-compliance testing. Its documentation addresses factors including emissions, smoke, specific fuel consumption, regeneration characteristics, compatibility and exhaust back pressure. That means choosing an RECD should involve more than comparing prices. The owner should confirm the engine model, gross mechanical power, applicable phase and exact RECD model before proceeding. For businesses evaluating an RECD manufacturer in India, supporting documentation, application range, installation capability and after-sales service should all be considered alongside the product's commercial price.