Can an RECD Be Transferred to Another Diesel Generator?

A retrofit emission control device (RECD) is a substantial piece of equipment. It is fabricated from steel, loaded with catalyst and filter elements, tested against a standard and, in many cases, paid for with a five or six figure invoice. So when a generator is sold, replaced or moved, it is natural to ask whether the RECD can simply follow the owner to the next machine. Unbolt here, rebolt there, job done.

The honest answer is that it can sometimes be done, but it is rarely as simple as that picture suggests, and in several common situations it is not worth attempting. An RECD is not a universal accessory like a battery. It is closer to a key cut for one lock: it works because several dimensions match one engine, and moving it means checking whether the next lock has the same cuts.

This guide breaks the question into four common moves and five “cuts” that decide whether an RECD can travel. By the end, you will know which move you are making, what has to match, what paperwork needs attention, and when it is smarter to leave the device where it is.

The short answer

An RECD can sometimes be reused on another diesel generator, but only when the receiving engine falls within the same type approval band, has compatible exhaust characteristics and back pressure limits, matches the physical mounting, and the device is in good condition and properly documented for the new installation. Because no public guidance we reviewed sets out a formal transfer procedure, treat every relocation as a fresh engineering and compliance exercise, involve the original supplier, and confirm the position with your State Pollution Control Board before you start.

Four moves that make people ask

The question does not arise in the abstract. It comes up in four practical situations, and the right answer differs for each.

Move 1: You are selling the generator, and the RECD is fitted to it. Should the RECD stay with the set, or does the seller keep it?

Move 2: You are replacing the generator with a newer one. The old set is leaving, and the RECD is fairly recent. Can it go onto another older set in your fleet, or be sold?

Move 3: You are relocating a set between your own sites. The generator and RECD move together, but the installation environment changes.

Move 4: The engine in the same set is being replaced or overhauled. The generator stays, but its engine changes. Does the RECD stay valid?

Keep your own move in mind as you read. We return to each one after we look at what makes an RECD specific to an engine.

Five cuts of the key

Imagine an RECD as a key with five cuts. All five must line up with the lock, which is the engine and its exhaust, for the key to work properly.

Cut 1: The type approval band

RECDs are type approved by testing at CPCB-recognised laboratories, and the approval covers a defined range of engine capacities, not every engine ever made. The Maharashtra Pollution Control Board circular on RECDs, summarised by TeamLease RegTech, notes that devices must be certified by one of four CPCB-approved testing agencies and must achieve at least 70 percent reduction in particulate matter. In practice, each supplier’s approval specifies capacity bands. For instance, one manufacturer’s certificate set might list bands such as 15 to 119 kW, 110 to 250 kW and 330 to 797 kW, while another manufacturer’s bands can be different.

What must match: the receiving engine’s rated power has to fall inside the band on the device’s certificate. A device approved for a 110 to 250 kW band cannot lawfully be presented as compliant on a much larger engine. The reverse is also a problem in a different way, because a device sized for a large engine can be poorly matched to a small one.

How to check: read the certificate, and compare it with the new engine’s plate. Our guide on how to read an RECD test certificate explains where the band appears.

Cut 2: Exhaust characteristics and back pressure

Engines of the same power can differ in exhaust flow, temperature and permissible restriction. An RECD adds resistance to the exhaust path, and the total must stay within the limit the engine maker allows. As we explain in our article on exhaust back pressure in DG sets, the value that counts is the one for the particular engine and RECD combination. A device that runs comfortably on one engine may be marginal on another.

What must match: the engine’s maximum allowable exhaust restriction, the flow it produces at rated load, and the resulting back pressure once the RECD and the existing silencer and pipework are all in place.

How to check: ask the vendor for the declared back pressure for the new engine model and measure it at commissioning.

Cut 3: The physical fit

An RECD has an inlet and outlet of a given diameter, a defined length, a mounting arrangement and a weight. The generator you are moving it to may have a different exhaust pipe size, a different silencer position, different canopy dimensions or a stack that exits in another direction.

What must match: flange sizes and orientation, available length and clearance, support points that can carry the weight, and access for cleaning and servicing.

How to check: a site survey, with photographs of the receiving exhaust route. Our guide on DG nameplate photos for RECD enquiries lists the shots that make a remote review possible.

Cut 4: The documentation identity

An RECD arrives with paperwork: the type approval, the test report, an installation record and a commissioning sheet. Those documents say which device model was tested and for what capacity. As we note in our guide to verifying a CPCB-tested RECD, a certificate for one model should not automatically be treated as proof for a different model, and identification plates on the device should be consistent with the certificate.

What must match: the device on the new set must be the same model shown on the certificate, the plates must be intact, and the installation record has to describe the new installation, not the old one.

How to check: compare the device plate with the certificate, and ask your vendor to issue a fresh installation and commissioning record for the new set.

Cut 5: Condition and remaining life

A used RECD has been through thousands of hours of hot exhaust. The catalyst may have lost activity, the filter may hold ash that cleaning cannot remove, and the housing may have cracks, corrosion or damaged welds. Kirloskar’s RECD product page quotes an operational life of about 10 to 12 years or 40,000 hours and maintenance about every six months or 500 hours, which gives a useful idea of how much life a well-kept device can have. But it also shows why a device with unknown history is a gamble.

What must match: the device must still be able to deliver its declared emission reduction and stay within its back pressure limit.

How to check: an inspection and, ideally, refurbishment and a post-installation performance check. Our RECD maintenance guide covers cleaning and regeneration that give a clue to condition.

The compatibility gate

Put the five cuts together and you have a simple gate. If any row fails, the transfer either needs modification or should not go ahead.

Cut	Pass condition	Who confirms
1. Approval band	New engine’s rated power sits inside the certificate band	Vendor, using the certificate
2. Back pressure	Total restriction on the new engine stays within its maximum	Vendor, then measured on site
3. Physical fit	Flanges, length, supports and access all work without unsafe improvisation	Site survey
4. Paperwork	Device model, plates and certificate agree, and a new installation record is issued	Vendor and you
5. Condition	Device inspected, cleaned or refurbished, and performing as declared	Vendor’s technician

Move by move: what to expect

Move 1: Selling the generator with an RECD fitted

In most cases the RECD stays with the generator. The buyer needs a compliant, complete set, and a set without its RECD may not be usable in an area where retrofit is mandated. It is also easier for the device to stay in place than for a technician to remove it and fit blanking arrangements.

If you are the seller, the RECD adds value only if it is documented. Hand over copies of the type approval certificate, the installation and commissioning report, the back pressure readings, the maintenance log and any warranty paperwork. Our guides on what determines a diesel generator’s resale value and checking a used generator’s engine hours explain how these records influence price.

If you are the buyer, verify the RECD as if you were buying it new: match the plate to the certificate, ask for the maintenance history and check that the set’s engine is the one the device was sized for. Our second-hand diesel generator buying guide has a wider checklist. Also remember that compliance follows the operating location. Regional rules differ, and the set’s registration or consent for one premises does not automatically carry to another, so confirm the position for the new site with the relevant pollution control authority.

Verdict: transfer to the buyer as part of the set is normal. Separating the RECD from the set is rarely useful.

Move 2: Replacing the generator with a newer one

This is where people most want to reuse the RECD. A newer set built to current emission norms may not need a retrofit at all, so the old device seems to be surplus. Before you plan a reuse, check whether the new set really is exempt in your state and whether the choice you made is the right one. Our article on RECD versus buying a new CPCB IV+ genset shows the cost logic behind that decision.

If you also own another older set that falls within the same approval band, reuse becomes conceivable. The financial case depends on a simple calculation:

Saving = price of a new device avoided, minus the cost of removal, inspection, refurbishment, any new mounting or piping, re-testing, downtime and the risk premium of a device with a history.

For small and medium capacities, where a new device costs relatively little, the saving often disappears once labour and re-fabrication are counted. For larger capacities, the sums are bigger and the case can be stronger, but so are the fabrication and commissioning costs. For typical price ranges, see our overview of RECD cost in India.

If reuse is not practical, ask the original supplier whether they will buy the device back, or offer it to another user in the same band through them so that the paperwork trail stays clean. If the RECD has to be scrapped along with the set, see our guides on generator scrap disposal rules in India and on how to safely dispose of an old diesel generator. Catalyst elements can hold recoverable material, so ask the vendor how they handle end of life before you sell parts to a scrap dealer.

Verdict: possible in a narrow set of cases, usually not the cheapest path once everything is counted.

Move 3: Relocating a set between your own sites

When the generator and its RECD move together, the engine and device pair stay matched. The risks are physical and administrative. The new site may have a different exhaust route, different ambient temperature or altitude, or a different stack height. The device also spends time being dismantled, transported and reinstalled, which is a chance for damage or lost plates.

Plan the move as a mini project. Record back pressure and smoke before dismantling. Photograph every flange and support. Tag the RECD and keep its plate visible. After reinstallation, measure again and record the results. If regional rules require notification or a fresh consent for the new premises, sort that out before the set runs. Our guides on what happens during a pollution control board inspection and how often to renew a DG set pollution certificate describe the paperwork inspectors typically look for.

Verdict: the most workable move, as long as the pair stays together and the reinstallation is documented.

Move 4: Replacing or rebuilding the engine in the same set

If the engine is overhauled and its rating remains unchanged, the RECD stays matched, though a health check is sensible because a major overhaul may change oil consumption and exhaust behaviour. If the engine is replaced by another model, the exhaust flow, back pressure limit and even the approval band may change. In that case the RECD needs to be re-verified as if it were being installed on a new set, and a new set of documents should be created.

Verdict: a like-for-like rebuild is usually fine with a fresh performance check. A different engine model means going through all five cuts again.

Four ways a transfer can go wrong

• Wrong band. The device is used on an engine outside its type approval range. This risks a compliance failure even though the device looks the part.
• Choked engine. The new engine cannot tolerate the total exhaust restriction, and power drops or temperatures climb.
• Paper mismatch. The certificate describes a device that is on another set. When an inspector reads it against what is fitted, it does not add up.
• Lost warranty and support. The device’s original warranty and service arrangements are usually tied to the original supply and installation. Once the device moves, both need to be confirmed again, and the engine maker’s warranty position for the new installation should also be checked. Our article on whether an RECD affects your generator’s OEM warranty explains how to keep that clean.

A step by step plan if you decide to move an RECD

1. Write down your move. Which of the four moves is it?
2. Collect the paperwork. Certificate, test report, installation record, maintenance log, warranty documents.
3. Collect the receiving engine’s details. Make, model, rated power, serial number, back pressure limit, exhaust dimensions and photographs.
4. Ask the original supplier for a feasibility opinion. Include the five cuts in your request.
5. Check the regulatory position. Confirm with your State Pollution Control Board or consultant how a relocated or reinstalled device should be documented. For the broader NCR rules on emission controls and DG sets, the PIB release on regulated operations of DG sets sets out the capacity-based framework.
6. Inspect the device. Look for cracks, corrosion, damaged insulation, blocked elements and missing plates.
7. Refurbish if needed. Clean, repair or replace elements as advised.
8. Adapt the mounting. Fabricate new flanges or supports if the fit is different.
9. Install, commission and measure. Record back pressure, temperature and visible smoke at agreed loads.
10. Issue new documents. Obtain a fresh installation and commissioning record for the new set, and store it with the old certificate.
11. Restart the maintenance clock. Log the reinstallation date and follow the maintenance schedule.

Red flags when someone offers a “used RECD”

Because a market for used devices exists, buyers should be careful.

• No certificate or plate. A device that cannot be identified cannot be verified.
• “It fits any generator.” An RECD is matched to an engine and band. A blanket claim is a warning sign.
• No maintenance history. You are buying an unknown amount of remaining life.
• No offer of a fresh installation record. A responsible seller expects the paperwork to be redone.
• A price close to a new device. After refurbishment and re-fitting, the saving needs to be real to justify the risk.

When leaving the RECD where it is makes sense

Reuse feels thrifty, but the best answer is often to leave the device where it is. If the RECD is on a set that is being sold, let it go with that set and claim the value in the price. If a set is being scrapped, ask the vendor about buy-back or end of life handling. If you need an RECD for another set, a properly sized new device with its own certificate and warranty is usually simpler than adapting a used one, and our article on whether retrofitting an old DG set is worth it can help you judge the bigger decision.

Frequently asked questions

Can I move my RECD to another generator of the same kVA?

Sometimes, but the same kVA is not enough. The engine make, model, rated power band, exhaust flow and back pressure limit also need to line up, and the physical connections must fit. Ask your vendor to review the specific engine before you assume compatibility.

Does the RECD certificate stay valid if the device moves?

The certificate describes a device model and the capacity range it was tested for. It supports compliance on a new engine only if that engine falls inside the approved range and the device is the same model shown on the certificate. A fresh installation record for the new set is also advisable. Confirm the local acceptance requirements with your pollution control authority.

Is it legal to sell an RECD separately from the generator?

We have not found a public rule that forbids it, but there is also no standard process that makes it simple. A separated device without a certificate, installation record or maintenance history is hard for a buyer to verify, so most buyers will hesitate. It is generally better to sell the device through or with the involvement of the original supplier.

Who pays for removing and reinstalling an RECD?

The owner, unless the supply contract says otherwise. Budget for removal, inspection, any refurbishment, new mounting arrangements, commissioning and downtime.

Will the RECD warranty follow the device?

Do not assume so. Warranties are usually linked to the original supply and installation. Ask your supplier in writing whether coverage continues after relocation, and under what conditions.

What if my new generator already meets current emission norms?

Then you may not need an RECD on it, depending on the manufacturing date and your state’s rules. In that case the old RECD can either stay with the old set when it is sold or be offered back to the supplier. Confirm the rule for your location before you decide.

Can one RECD serve two generators after I move it?

No practical arrangement is recommended. Sharing a device between two sets brings its own back pressure and operational problems, which we explain in our guide on whether two diesel generators can share one RECD.

Planning a move or a sale?

If you have a set with an RECD and a move, sale or replacement on the horizon, send us the certificate details and photographs of the device and the receiving exhaust, and we will help you judge whether reuse makes sense or whether a fresh device is the cleaner route. You can review capacity specific options on our retrofit emission control device page, see our certifications, or reach the team on the contact page.