Choosing the right DG set pollution control RECD system is becoming an important consideration for industries, hospitals, commercial buildings, institutions, data centres, and other facilities that operate diesel generator sets. Yet RECD compliance should not be approached as a simple “buy and install” exercise. The generator's engine specifications, the applicable CPCB framework, certification status, installation conditions, and current requirements of the relevant pollution-control authority all need to be considered together.
The Central Pollution Control Board (CPCB) has published a specific procedure for Retrofitted Emission Control Devices (RECDs) intended for in-use diesel-operated internal combustion engines used in generator-set applications up to 800 kW gross mechanical power. The procedure focuses on particulate matter reduction and establishes requirements relating to applicability, testing, certification, installation, monitoring, and maintenance.
Why DG Set Emission Control Needs a Practical Approach
Diesel generator sets continue to play an important role wherever reliable backup electricity is required. However, combustion in a diesel engine generates particulate matter and other exhaust pollutants. For existing generator sets, retrofitting an appropriate emission-control device can be a practical way of addressing particulate emissions without replacing the complete generating equipment.
The important point is that RECD should be treated as an engineered retrofit rather than an ordinary exhaust accessory. CPCB's procedure contains requirements concerning the design, durability, installation, monitoring, and operational integrity of an approved RECD. It also requires the manufacturer, importer, or retrofitter to provide installation documentation covering the hardware, software, communication provisions, and technical requirements needed for correct installation on the DG set. For an owner, that means the quality of the retrofit matters just as much as the name of the device.
What Exactly Is an RECD System?
A Retrofitted Emission Control Device is a system designed to be installed on an in-use diesel engine to help control exhaust emissions, particularly particulate matter within the applicable CPCB framework.
Depending on the technology, the complete system may involve an emission-control unit together with monitoring hardware, sensors, controller functions, warning systems, and installation components. CPCB's procedure specifically refers to on-board diagnostics and operator-warning functionality for approved RECDs. It also provides for monitoring arrangements capable of detecting incorrect operation or removal of the RECD and generating an audible or visual warning.
This is why buyers should evaluate the complete system rather than comparing only the size or appearance of the exhaust-mounted equipment.
Understanding the CPCB Scope in 2026
CPCB's published RECD procedure covers in-use diesel-operated internal combustion engines for generator-set applications up to 800 kW gross mechanical power. This technical limit is one of the first things a generator owner should check before starting the selection process. The reference to gross mechanical power is particularly important because DG sets are commonly marketed using kVA ratings. A generator described commercially as a 250 kVA, 500 kVA, or 625 kVA machine should still be evaluated using the engine's documented technical specifications.
Owners should therefore identify the engine manufacturer, exact engine model, gross mechanical power, rated speed, and other relevant information from the engine nameplate or manufacturer documents. Approximate conversion between kVA and kW should not replace documented engine data when evaluating RECD suitability.
Certification Is the Foundation of a Reliable RECD Purchase
One of the biggest risks in the market is treating the words “CPCB approved” as sufficient proof of compliance. CPCB maintains a published list of manufacturers certified for RECDs applicable to diesel genset engines up to 800 kW for specified capacity ranges. The official list dated 9 May 2025 identifies manufacturers, applicable ranges of in-use engine power, whether the certification relates to Phase I, Phase II, or both, and the certification agency associated with the listed approvals.
This is an important distinction for buyers. Certification information should be connected to the actual product and its application, not merely to a company name. A supplier should be able to identify the RECD family or model, relevant product details, intended application, and supporting certification or test documentation. That documentation should then be compared with the generator installed at the facility.
Why Engine Compatibility Cannot Be Ignored
Imagine a manufacturing facility with three DG sets. All three may appear similar because their generator ratings are close, but they could use different engine manufacturers, engine families, rated speeds, or mechanical-power characteristics. Installing the same RECD on all three simply because their kVA ratings look similar would be an unreliable approach.
A proper selection considers the actual engine application. This is consistent with the technical structure of CPCB's RECD framework, where testing and certification are tied to the device and its intended application range. For this reason, the purchase process should begin with engine identification, not with a generic search for the cheapest RECD.
Installation Requirements Are Part of the System
A technically suitable RECD can still create problems if the installation is poorly planned. CPCB's procedure requires approved RECDs to be designed and constructed so they can be correctly mounted and continue to meet the applicable requirements during normal use. It also requires manufacturers, importers, or retrofitters to provide detailed installation documentation.
From a site perspective, this means the existing exhaust arrangement needs to be studied before installation. Space availability, exhaust-pipe dimensions, mounting supports, sensor positions, controller location, access for maintenance, and exhaust back-pressure are all relevant engineering considerations. An experienced installation team can identify these issues before work begins, reducing the possibility of repeated exhaust modifications or commissioning delays.
Monitoring and Warning Functions Matter
An RECD is expected to remain effective during operation, which is why monitoring is an important element of the CPCB procedure. The procedure calls for approved RECDs to have an on-board diagnostics and operator-warning system capable of indicating failures that affect RECD efficiency. It also specifies monitoring for particulate-reduction devices to detect incorrect operation or removal of the system and trigger an appropriate warning to the operator.
This has a direct operational benefit. Facility personnel should not have to discover an emission-control problem only when the generator is being serviced or inspected. The system should provide an appropriate warning mechanism according to its design.
Maintenance Protects Long-Term Performance
Installing an RECD does not remove the need for maintenance. In fact, CPCB's procedure explicitly requires the RECD manufacturer to provide written instructions describing correct operation and maintenance and to explain how proper maintenance supports the intended emissions performance.
The facility should therefore understand what routine inspections are expected, how warnings are handled, which components require servicing, and whether any consumables or reagents apply to the particular technology. A maintenance programme should also cover documentation. Service reports, installation records, commissioning details, technical certificates, and component-replacement records can become valuable evidence when the equipment is reviewed later.
Choosing an RECD Supplier for DG Sets
When selecting an RECD supplier for DG sets, facility managers should look beyond the initial quotation. A capable supplier should be able to discuss the proposed model, engine application, certification documents, site requirements, installation methodology, commissioning process, warranty, maintenance arrangements, and availability of technical support.
The quotation should also make clear what is actually included. One supplier may quote only the core RECD, while another may include the controller, sensors, exhaust modification, installation, commissioning, and operator training. A slightly higher initial price may therefore represent better overall value when the complete project scope is included.
For critical facilities, service capability is particularly important. An emission-control system that cannot be supported with spare parts or technical assistance can become a long-term operational concern.
What Generator Owners Should Check Before Purchase
Before ordering, the owner should establish the exact DG-set and engine details and then compare the proposed RECD documentation against those specifications. The current CPCB framework should be reviewed alongside any requirements applicable to the specific location. CPCB maintains generator-set notifications and guideline resources on its official website, while its broader site publishes regulatory updates and communications.
This is particularly important because regulatory requirements and implementation directions can change. A compliance statement published in an old brochure or article should not automatically be treated as current. The relevant State Pollution Control Board, Pollution Control Committee, environmental consent conditions, and local directions may also need to be checked before the project is finalized.
Why “CPCB Compliant” Should Be Verified Carefully
Marketing language can make RECD selection confusing. Terms such as “CPCB approved,” “CPCB certified,” and “CPCB compliant” may appear interchangeable in commercial material, but the buyer should ask for documentary evidence supporting the specific product being offered.
The official CPCB vendor information itself is structured around manufacturers, applicable engine-power ranges, phases, and certification agencies. Therefore, the strongest purchasing decision is one where the product identity, certification evidence, application range, installation documents, and maintenance provisions are all clearly documented.
A Better Way to Think About RECD Compliance
For generator owners in 2026, RECD compliance should be viewed as a complete lifecycle activity. It begins by identifying the engine and confirming the applicable regulatory requirement. It continues with selecting an appropriately documented device, engineering the installation, commissioning the system, monitoring its operation, and maintaining the equipment correctly.
The CPCB procedure's emphasis on installation documentation, monitoring, warning systems, durability, and maintenance demonstrates that emission control is not intended to end once the device has been physically attached to the exhaust. For companies managing multiple DG sets, this lifecycle approach can also make future maintenance and compliance reviews much more organized.
Conclusion
A reliable DG set pollution-control strategy requires more than purchasing an exhaust-mounted device. CPCB has established a defined technical and certification framework for RECDs used with applicable in-use diesel genset engines up to 800 kW gross mechanical power, with particular attention to particulate reduction, testing, installation, monitoring, and maintenance. For DG owners, the most important lesson is to verify the complete chain: the actual engine, the applicable requirement, the exact RECD model, the certification documentation, the installation conditions, and the long-term maintenance arrangement.
A professional supplier should support that process with product-specific documentation and technical assistance instead of relying on a generic “CPCB approved” claim. Finally, regulatory compliance should always be checked against current official information. CPCB maintains dedicated generator-set resources, and requirements may also arise from State or local pollution-control authorities and site-specific environmental conditions.
Frequently Asked Questions
What is a DG set pollution control RECD system?
It is a retrofit emission-control system intended for applicable in-use diesel generator engines, particularly for controlling particulate emissions within the relevant CPCB framework.
What is the CPCB power range for the RECD procedure?
The published procedure covers in-use diesel-operated internal combustion engines used for generator-set applications up to 800 kW gross mechanical power.
Can an RECD be selected only by DG-set kVA?
No. The engine's documented gross mechanical power, model, application, and relevant certification range should also be considered.
What documents should I ask an RECD supplier for?
Request the exact product/model details, applicable certification or test documentation, application information, installation instructions, warranty terms, maintenance instructions, and commissioning records.
Does installing an RECD automatically guarantee regulatory compliance?
No. Correct product selection and installation are important, but the facility must also meet the current requirements applicable to its generator, location, consent conditions, and other directions from competent authorities.