RECD Spare Parts Lists: What Should Buyers Request Before Ordering?

It is the second week of December in Gurugram. GRAP restrictions are in force, the grid is unsteady, and the backpressure sensor on your RECD has stopped reporting. The controller shows a fault, the facility team cannot confirm the device is working, and the supplier says a replacement sensor will take three weeks. Nobody asked for an RECD spare parts list when the order was placed, so nobody knows the part number, the price or whether a second unit is sitting anywhere in the country. This article explains what a good RECD spare parts list should contain, why you should ask for it before you sign the purchase order, and how to use it to compare offers on real lifecycle cost rather than the headline price.

RECDs are simple in principle, but each carries parts that wear or fail without warning. When those parts are unavailable, the generator runs without working after-treatment or not at all. In an NCR winter, when the GRAP rules for DG sets in Delhi NCR tighten what can operate, neither option is comfortable.

Why the Spares Conversation Belongs Before the Purchase Order

Most buyers leave spares until after installation. That habit costs money and time. Three reasons to settle it at the enquiry stage:

1. Leverage. Before the order, the vendor is competing for your business and will usually agree to fix spare prices, hold stock or offer a commissioning kit. After the order, you are a captive customer for parts that only that vendor supplies.
2. Price lock and lead time. A list with prices, validity periods and lead times turns vague promises into commitments you can enforce. Without it, the price of a filter element in year three is whatever the vendor says it is.
3. Fair comparison. Two devices with similar purchase prices can have very different running costs. A spares list is the only reliable way to see that difference before you commit.

If you are preparing a formal enquiry, build the spares request into the document from day one. Our guide on how to write a technical RFQ for an RECD project shows where it fits alongside performance, scope and testing clauses.

Anatomy of an RECD: Where Spares Come From

To judge a spares list, you need a rough picture of what is inside the device. Designs differ between manufacturers and between ratings, which is one reason two DG sets of the same kVA can need different RECDs. Still, most units share the same broad subsystems. For each, here is what wears, how failure shows up, and whether you should hold a spare.

Filter element, substrate and catalyst

This is usually the most expensive replaceable item. Wear drivers include ash build-up from lubricating oil, thermal shock, cracking from repeated cold starts and contamination from fuel or oil problems. A generator that burns oil will shorten element life considerably, which is why engine oil consumption affects RECD suitability so directly. Warning signs are backpressure that cleaning cannot bring down, downstream smoke, or a sudden pressure drop suggesting a crack. Critical sites should at least confirm vendor-held stock in writing. Above all, any replacement element must be the same certified model and specification as the original, so that the test certificate and compliance documents remain valid.

Housing, flanges, gaskets and fasteners

A well-specified housing rarely fails; the joints do. Gaskets compress and harden with heat cycling, and every time the element is removed for cleaning, the gaskets at that joint should ideally be replaced. Fasteners can seize, stretch or lose their thread, especially in humid or coastal air. Signs of trouble include soot streaks around flanges, a ticking sound under load and exhaust smell inside the DG room. Hold a set of gaskets and fasteners per service interval as a minimum.

Sensors and pressure lines

Most RECDs monitor exhaust backpressure, and many also measure temperature upstream or downstream of the filter. The sensing lines run close to hot pipework, so tubes can crack, fittings can loosen and condensate can block the line. Sensors themselves age with heat and vibration. Because backpressure is the main indicator of filter health, and because exhaust backpressure directly affects the DG set, a failed sensor leaves you blind to a problem that can harm the engine. One spare backpressure sensor and a short length of sensing tube with fittings is a modest outlay that removes a lot of risk. RECD gasket and sensor spares are the two categories most buyers forget, and the two that most often cause avoidable downtime.

Controller, alarm panel, display and power supply

The control unit logs readings, raises alarms and, in some designs, manages regeneration. Electronics fail through voltage spikes, heat in poorly ventilated DG rooms, moisture and dust. A dead display can look like a device failure even when the filter is fine. Ask whether the power supply module, display and fuses are separately replaceable, and what the lead time is for a complete controller.

Regeneration hardware, where fitted

Passive designs rely on exhaust heat alone. Active designs add hardware to raise temperature and burn off trapped soot: electric heaters, small burners or fuel dosing systems with pumps, injectors and valves. Heater elements can open-circuit, injectors can clog, and dosing pumps can lose prime. If your device has active regeneration, these parts belong high on the spares list, because a failed regeneration system leads quickly to a loaded filter. For passive devices, check the list is not padded with parts that do not apply.

Supports, bellows, clamps and insulation jackets

Bellows absorb vibration and thermal movement between the engine and the RECD. They fatigue over time, and a split bellows leaks hot exhaust into the room. Our article on flexible bellows in an RECD exhaust system covers how they fail and how to inspect them. Clamps loosen and insulation jackets degrade where disturbed during maintenance. A spare bellows of the correct size is worth considering for sets that run long hours. Clamps and jacket fasteners are cheap enough to hold as a matter of routine.

Cleaning accessories and tools

Some designs need special removal tools, lifting lugs or alignment pins, which are easy to lose. Ask for a list of any non-standard tools and make sure at least one set stays on site, labelled and stored with the spares.

The Three Tiers of RECD Spares

A useful way to organise recommended spare parts for an RECD is to split them into three tiers, according to when they are needed and how bad it is to be without them.

Tier 1: Commissioning spares

Commissioning spares are the parts supplied with the unit for use during installation and site acceptance testing. Gaskets get damaged when flanges are aligned. A fastener drops into a cable trench. A sensing line is cut too short. Having these items on hand means the installation team does not stop work to wait for a courier. They should arrive in the same consignment as the device and be listed on the packing list, so you can check them on arrival using an RECD delivery inspection checklist.

Tier 2: Operational spares for the first two years

Operational spares cover routine wear across roughly the first two years of use. Two years spans a full summer and winter and gives enough history to adjust quantities. Typical items are gaskets for each scheduled cleaning, fasteners, clamps, sensing tubes, fuses and consumables for any regeneration system. The vendor should base quantities on your expected running hours and the cleaning interval in the RECD maintenance guide for that model. Be wary of any list that recommends no operational spares at all; it often goes with a “maintenance-free” claim that deserves a closer look.

Tier 3: Critical or insurance spares

Critical insurance spares are parts you hope never to use, but whose absence would stop the generator or leave it non-compliant for weeks. They tend to have long lead times, sometimes because they are imported, and high consequences. The filter element, a complete controller, the backpressure sensor and regeneration heaters or dosing units fall into this group. Many buyers ask the vendor to hold them, with a written dispatch commitment.

Part	Tier	Typical failure or wear driver	Stock on site?	Lead time question to ask
Flange gaskets (all joints)	1 and 2	Heat cycling, removal for cleaning	Yes	Are gaskets standard sizes or made to your drawing?
Fasteners, nuts and washers	1 and 2	Seizing, corrosion, loss during work	Yes	What grade and coating, and can we buy locally?
Backpressure sensor	2 and 3	Heat, vibration, ageing	Yes	Is it stocked in India or imported per order?
Temperature sensor	2 and 3	Heat, cable damage	Consider	Does replacement need recalibration on site?
Sensing tubes and fittings	1 and 2	Cracking, condensate blockage	Yes	Standard fitting sizes or proprietary?
Filter element / substrate	3	Ash loading, thermal cracking, oil contamination	Consider or vendor-held	How many weeks from order to dispatch, and is it the same certified model?
Controller / display	3	Voltage spikes, heat, moisture	Vendor-held	Can settings and logs transfer to a new unit?
Power supply module and fuses	2	Supply disturbances	Yes	Is the module separately replaceable?
Regeneration heater or burner parts	2 and 3	Element burnout, fouling	Consider	Which parts are bought out, and from where?
Dosing pump, injector, valves	2 and 3	Clogging, loss of prime, seal wear	Consider	Service kit available, or full assembly only?
Flexible bellows	3	Fatigue from vibration and movement	Consider	Exact length and flange rating on record?
Clamps and support hardware	2	Loosening, corrosion	Yes	Standard items or custom fabricated?
Insulation jacket	2	Damage during maintenance	Consider	Made to order, and how long to fabricate?
Special tools and lifting accessories	1	Loss, misplacement	Yes	Is a replacement set available separately?

What a Proper RECD Spare Parts List Must Contain

A list that simply says “gasket set, 1 no.” is not much use. A proper RECD spare parts list is a data document. Each line should let someone reorder the right part years later without phoning the salesperson. Insist on these fields.

Field	Why it matters
Part number	The only unambiguous way to order. Descriptions vary; part numbers should not.
Description	Lets maintenance staff identify the part without a drawing.
Drawing reference	Links the part to its position in the general arrangement, so you know where it fits.
Material and specification	Gasket material, fastener grade and sensor range decide whether a local substitute is acceptable or not.
Quantity per unit	How many are fitted to one device, which tells you how many a full change needs.
Recommended stock quantity	The vendor’s advice for your hours and site, which you can then challenge or accept.
Unit price	Needed for budgeting and for comparing offers.
Price validity	A price with no validity date is a price that can change tomorrow.
Lead time	Tells you which parts must be stocked and which can be ordered when needed.
Shelf life and storage conditions	Rubber and electronics age on the shelf. You need to know when to rotate stock.
Interchangeability across models	On multi-set sites, shared parts reduce the total stock you must carry.
OEM or bought-out	Bought-out items can sometimes be sourced locally; OEM items usually cannot.
Source country	Imported parts carry customs, exchange rate and shipping risks that affect lead time.

Watch interchangeability and the OEM or bought-out flag closely. Different elements for sets of similar size multiply the stock you need, and a bought-out part relabelled with the vendor’s own number may be available far more cheaply elsewhere.

For larger projects, the spares list should sit alongside the main bill of quantities for an RECD retrofit, with commissioning spares inside the supply price and operational spares as a separate optional item.

Matching Spares to Your Site

The right holding depends on usage, distance from the vendor and the cost of the set being unavailable.

Standby sets in residential and office buildings

Housing societies and office buildings usually run their sets for limited hours. Commissioning spares, a modest set of gaskets and fasteners, and one backpressure sensor are often enough. The element can generally be vendor-held, provided the dispatch commitment is in writing. RWAs planning their first purchase may find our RECD purchase planning guide for housing societies useful for budgeting this alongside the device itself.

Critical facilities: hospitals and data centres

Where the generator protects life-safety or business-critical loads, downtime is not an option. These sites should hold most Tier 3 items on site or have a contracted vendor-held reserve with a short dispatch time. Hospitals need spares that let a team restore the system quickly without disturbing backup power, as explained in our article on RECDs for hospitals and critical backup loads. Data centres often run regular load tests, which add hours and cycles; the guidance on RECDs for data centres and redundancy testing explains how that changes wear patterns.

Remote and telecom sites

For unattended sites, the cost of a part is small next to the cost of a second trip. Spares should be packed as site kits, so a technician carries everything needed for a full gasket change, sensor replacement and clamp check in one visit. Our article on RECDs for remote, unattended telecom sites discusses how alarm reporting and spares planning work together.

Multi-set campuses

Campuses, industrial parks and malls with several sets gain a lot from standardisation. If the same element, sensor and gasket set fit most of the fleet, a common spares pool can serve every set at a fraction of the cost of individual holdings. Shopping malls face an extra twist, because sets may belong to different tenants; see coordinating DG retrofits across tenants for how to agree a shared approach.

Harsh environments: coastal and dusty locations

Salt-laden air attacks fasteners, clamps and electrical connections. Coastal sites should hold more fasteners and clamps than inland ones, and ask about stainless or coated alternatives, as covered in choosing an RECD for coastal environments. Dusty industrial locations put more strain on controller enclosures, cable glands and sensing lines; the article on RECD selection for dusty industrial locations explains which components suffer most.

Pricing, Validity and Lead Times

Spare parts price validity is where buyers gain most at the enquiry stage. Get these terms in the purchase order, not an email.

• Price lock. Fixed prices for listed spares for a defined period, commonly two or three years from commissioning. Longer is better if the vendor will agree.
• Escalation formula. After the lock ends, prices should rise by an agreed method, such as a published index or a fixed annual percentage cap, rather than at the vendor’s discretion.
• Committed lead times. A maximum dispatch time for each tier, with Tier 3 items given the shortest commitment you can negotiate.
• Buyback or return of unused spares. If you replace the generator or the device becomes redundant, can unopened spares be returned for credit?
• Consignment stock. For larger sites or fleets, the vendor keeps spares at your premises but you pay only when you use them.
• Availability period. A written commitment that spares will be available for a stated number of years after supply.

These terms interact with warranty and service contracts. Parts replaced under warranty should not be charged, so check how the spares list lines up with RECD warranty terms on parts, labour and exclusions. If you plan to include the RECD in an annual maintenance contract, the principles in how to negotiate an AMC contract for your generator apply here too: be clear about which spares the AMC covers and which are billed separately.

Red Flags in a Vendor’s Spares Offer

None of these is automatically disqualifying, but each needs an explanation.

• The vendor declines to give a spares list until after the order is placed.
• Prices are shown as “on request” or “as applicable at the time”.
• No part numbers, only generic descriptions.
• The filter element is listed without confirming it is the same certified model as the unit tested for compliance.
• Lead time for the element is “subject to availability” with no upper limit.
• Every part is labelled OEM-only, including standard fasteners and clamps.
• The list recommends no operational spares because the device is described as maintenance-free.
• Active regeneration parts are missing from the list for a device that clearly has them.
• Nobody can say where the spares are physically stocked.

A visit to the manufacturing unit is often the quickest way to test these answers. Our list of questions to ask during an RECD factory visit includes checks on spares stores and part traceability. The spares offer previews later support, which is why after-sales service matters more than price.

How Spares Affect Total Cost of Ownership

The purchase price is the number everyone sees. RECD lifecycle cost is the number that actually leaves your budget. The example below is entirely hypothetical. The figures are invented round numbers in “cost units” to show the method, not real prices for any product. For actual price ranges and what drives them, see our article on RECD cost in India.

Assume two offers for the same generator, running enough hours that the element needs replacing once in five years, with routine gasket and sensor spares every year.

Item (hypothetical cost units)	Offer A	Offer B
Device purchase price	100	115
Annual gaskets, fasteners and sensing parts (x5 years)	4 x 5 = 20	2 x 5 = 10
Backpressure sensor replacement (once)	8	4
Filter element replacement (once, year 4)	60, no price lock	35, price locked
Downtime cost from long lead time (estimated)	10	0
Five-year total	198	164

On paper, Offer A is 15 units cheaper. Over five years it costs 34 units more, mainly because of the element price and the lack of a lock. For a hospital or data centre, the downtime line alone can outweigh everything else. Run the calculation with your own hours, the vendor’s quoted prices and a realistic view of what an outage costs you.

Who does the work matters too; our comparison of in-house maintenance versus AMC for generators helps you decide whether spares sit on your shelf or in the vendor’s van.

Sample Request Text You Can Paste into an RFQ

Adapt this wording for the technical or commercial section of your enquiry.

The bidder shall submit, with the offer, a complete spare parts list for the proposed RECD, divided into (a) commissioning spares included in the supply, (b) recommended operational spares for two years of operation at the running hours stated in this enquiry, and (c) recommended critical spares. For each item the bidder shall state the part number, description, drawing reference, material or specification, quantity fitted per unit, recommended stock quantity, unit price, price validity period, maximum lead time from order to dispatch, shelf life and storage requirements, interchangeability with other models offered, whether the item is manufactured by the bidder or bought out, and country of origin. The bidder shall confirm that replacement filter elements will be of the same model and specification as the unit covered by the submitted emission compliance test certificate. Prices for listed spares shall remain fixed for a period of not less than [__] years from the date of commissioning, after which any increase shall follow the escalation method stated in the offer. The bidder shall state the period for which spares availability is guaranteed and any terms for return of unused spares.

Storage and Record Keeping for Spares

Lost, damaged or expired spares are not spares.

• Respect shelf life. Rubber and fibre-based gaskets can harden or lose resilience over time, especially in heat. Ask the vendor for a shelf life for each sealing item and rotate stock so the oldest is used first.
• Keep electronics dry. Sensors, fuses and power supply modules should stay in their original packaging, in a dry, ventilated store away from the DG room’s heat and diesel fumes.
• Protect the element. A spare filter element should be stored flat or as the vendor advises, in its crate, protected from knocks and moisture.
• Maintain a spares register. Record each item, part number, quantity, date received, location, date used and the set it went into.
• Link the register to compliance records. When an element or sensor is replaced, file the part number and date with the device’s compliance documents, so inspectors can see that like-for-like certified parts were used.
• Label the shelf. On multi-set sites, mark which sets each part fits.

Good records also help when the regulatory position is checked. The Central Pollution Control Board circular dated 01.02.2022 sets out the System and Procedure for emission compliance testing of RECDs for DG engines up to 800 kW gross, with testing carried out by agencies such as ARAI and ICAT. In the NCR, directions from the Commission for Air Quality Management refer to RECDs with at least 70% PM capture efficiency for in-use DG sets up to 800 kW. Traceable records show that only certified like-for-like parts were fitted.

Frequently Asked Questions

Can I use a locally made filter element to save money?

It is not advisable. The emission compliance test applies to a specific device and element specification. A different element, even if it fits physically, may not perform the same way and may leave your compliance documents unsupported. RECD filter element replacement should always use the same certified model and specification.

How many gasket sets should I keep on site?

Enough for every planned element removal over the period you are covering, plus one set for unplanned work. If your cleaning interval means two removals a year, a two-year operational holding would be four sets plus a spare. Adjust for your actual running hours.

Are commissioning spares normally included in the RECD price?

Often they are, but not always. Ask the vendor to list commissioning spares separately and confirm in writing that they are part of the supply. If they are not included, price them before the order so they do not appear later as an extra.

Should a housing society hold a spare filter element?

Usually not, because standby sets in residential buildings run limited hours. A written commitment from the vendor to dispatch an element within an agreed time is normally a better use of funds. Hold gaskets, fasteners and a backpressure sensor instead.

What if the vendor stops supplying spares for my model?

This is why an availability commitment belongs in the purchase order. Ask the vendor to guarantee spares for a stated number of years and to give advance notice of any discontinuation, with a final buy opportunity.

Conclusion: Make the RECD Spare Parts List Part of the Decision

An RECD spare parts list is not paperwork to collect after installation. It is one of the clearest tools you have for comparing offers, locking prices, planning stock and protecting your generator from long, avoidable outages. Ask for it at the enquiry stage, insist on part numbers, prices, validity and lead times, split it into commissioning, operational and critical tiers, and size your holding to the way your site actually runs.

Aceget supplies CPCB-certified RECDs with a documented spares list, part numbers and clear lead times for each model. You can browse our retrofit emission control device range by DG set rating, or contact our team to request a spares schedule along with your quotation.