What Should You Ask During an RECD Factory Visit?

Most RECD brochures look alike. The certificates carry similar logos, the product photos are clean, and every supplier promises reliable particulate capture. An RECD factory visit is where those claims meet reality. Three hours on the shop floor will tell you more about a supplier than three weeks of email, because you can see how parts are stored, how welds are checked, how filter elements are canned and how test records are kept. You can also judge something paper never shows: whether the people answering your questions actually do the work.

This guide is organised as a walking route through a typical RECD plant. At each stop you will find a bank of questions, a description of what a good answer sounds like, and the red flags that should make you pause. Use it alongside our wider guide on how to choose between CPCB-approved RECD vendors, which covers the desk-based checks you should finish before you book a trip.

Who should go? Send at least two people. An engineer who understands the DG sets on site should look at fabrication, testing and fitment. Someone from procurement should focus on documents, capacity, commercial terms and the supplier’s organisation. If you have a DG service partner who will live with the equipment after installation, invite them too.

When in the buying cycle? The best moment is after you have a shortlist of two or three suppliers and before you place a purchase order.

What mindset? Observe more than you talk. Ask open questions (“How do you handle a weld that fails inspection?”) rather than leading ones (“You do inspect welds, right?”). Above all, ask to see records. A confident answer is good. A confident answer followed by the logbook, the report or the calibration certificate is much better.

Before You Travel: Send an Agenda and a Document Request

A visit without an agenda tends to become a long presentation followed by a quick walk past the cleanest machine in the building. Send a short written agenda a week in advance listing the areas you want to see and the time you want to spend at each. Ask the supplier to keep the following records ready so you can look at originals, not just slides:

• Type approval or emission compliance test certificates for each RECD model, with the engine power ranges each certificate covers.
• Recent Conformity of Production (CoP) test records and the schedule for the next CoP check.
• ISO certificates (for example a quality management certificate) with scope and expiry date.
• A sample Factory Acceptance Test (FAT) report from a past order, with customer details masked if needed.
• Calibration certificates for test instruments such as pressure gauges, manometers, flow meters and controller test equipment.
• A list of installation references by DG rating and sector, with contact names you are allowed to call.
• An organisation chart showing design, production, quality and service responsibilities.
• The service network list, showing which cities have engineers and which are covered by travel.

Before you travel, read up on how to read an RECD test certificate so you know which fields to check on the day. It also helps to refresh the basics of what an RECD is and how it works if anyone in your team is new to the subject. A supplier who resists the document request, or replies that “everything will be explained on the day”, has already given you useful information.

Stop 1: Reception and Meeting Room

The first hour usually happens around a table. Keep the company presentation short and steer the discussion towards design ownership and certification. The regulatory background matters here. Under the CPCB circular dated 01.02.2022 on the system and procedure for emission compliance testing of RECDs for DG engines up to 800 kW gross, certified models are subject to periodic Conformity of Production checks. Testing is carried out by recognised agencies such as ARAI in Pune and ICAT in Manesar. You can read the source documents on the Central Pollution Control Board website.

1. Who owns the design of your RECD models, and where is the design team based?
2. Which models are certified, and for which engine power ranges does each certificate apply?
3. How do you track certificate validity, and when was your last Conformity of Production check?
4. What happens to a model if a CoP sample does not meet requirements?
5. Who signs your internal test reports, and who signs off a unit for despatch?
6. How do you match a model to a specific DG set when two engines share a kVA rating?

What a good answer sounds like

The supplier names the models, opens the certificates in front of you and points to the power range on each one. They know the date of the last CoP check without hunting for it, and they can show the register or tracker they use to follow validity. They are clear about what they make and what they buy, and they explain how they select a model from engine data rather than kVA alone. That approach lines up with the checks described in our guide to verifying that an RECD is CPCB-tested for your DG set.

Red flags

• Certificates shown only as photos on a phone, or only as low-resolution copies.
• Vague answers about who holds the design, or reluctance to say which components are bought in.
• No one can say when the next CoP check is due.
• Model selection described purely by kVA, with no mention of exhaust flow or engine data.

Stop 2: Raw Material Stores

Stores are often skipped because they look dull. Do not skip them. RECD bodies are usually fabricated from stainless steel, and the filter core depends on a ceramic or metallic substrate and, in many designs, a catalytic coating. If the raw material is wrong, no amount of good welding later will fix it. This matters even more for sites near the sea, as our article on choosing an RECD for coastal, salt-laden environments explains.

1. Which stainless steel grades do you use for the body, flanges and internals?
2. Can you show me the mill test certificate for the sheet on this rack, and how it links to the heat number on the material?
3. Where do you source substrates and catalyst-coated elements, and how do you inspect them on arrival?
4. How are ceramic parts stored to prevent chipping, moisture pick-up and stacking damage?
5. Do you follow first-in, first-out, and how is it enforced?

What a good answer sounds like

A storekeeper or quality inspector picks a sheet at random, reads the heat number and pulls the matching mill certificate from a file within a couple of minutes. Incoming inspection has a written plan, and you can see a goods-received register with inspection status marked. Ceramic parts sit in their original packaging on racks, not on the floor, and there is a separate, labelled area for rejected or quarantined material.

Red flags

• Mixed grades of sheet stored together without identification.
• No quarantine area, or rejected parts sitting next to accepted stock.
• Substrates stacked loose or exposed to damp.
• “We trust our supplier” offered as the incoming inspection method.

Stop 3: Fabrication and Welding Shop

The fabrication shop decides whether the unit will fit your exhaust line first time and whether it will stay leak-free after years of heat cycling. Look at real work in progress, not just a finished display piece.

1. How are your welders qualified, and can I see the qualification records for the people working today?
2. Which welding process do you use for stainless, and how do you control heat input and discolouration?
3. How are welds inspected, and at which stages?
4. Do you use jigs or fixtures to keep inlet and outlet alignment consistent between units?
5. How are flanges machined, and how do you check bolt circle, face flatness and orientation against the drawing?
6. How do you handle a customer-specific flange or inlet orientation?

What a good answer sounds like

Welders have identification on their records and the shop can show which welder worked on which unit. Visual weld inspection is routine, and there is a defined method for anything beyond that, such as dye penetrant checks on critical joints. Jigs are visible and labelled by model. Flanges are machined to a drawing, and a dimensional check sheet travels with each body through the shop.

Red flags

• Every unit made “by eye” with no fixtures for repeat models.
• Heavy weld discolouration, spatter or grinding marks hiding uneven beads.
• No drawing at the workstation.
• Flange details “adjusted at site” as a standard practice.

Stop 4: Filter Element Canning and Assembly

This is the heart of the product. A diesel particulate filter only works if exhaust gas actually passes through the filter element rather than around it. If you need a refresher on why, read what a diesel particulate filter is and how it helps. Spend proper time here and ask to watch at least one element being mounted.

1. How is the substrate mounted and canned in its shell?
2. How is the support mat handled, cut and stored, and how do you check mounting pressure or gap?
3. What design features stop gas from bypassing the element?
4. How do you check for bypass before the unit leaves the assembly area?
5. How is each element serial-numbered, and how is that number linked to the finished RECD?
6. If an element is replaced in the field, how is the new serial number recorded against the unit?

What a good answer sounds like

The assembly team follows a written work instruction kept at the station. Mat material is stored in a clean, dry place and cut to a template. Each element carries a permanent serial number, and the build record links that number to the RECD serial, the shell, the controller and the date of assembly. The supplier explains which items are consumables or wear parts, which ties into the questions in our guide on what to request in an RECD spare parts list. They are also realistic about upkeep and do not over-promise, a topic covered in what a “maintenance-free” RECD claim actually means.

Red flags

• Elements without permanent serial numbers, or numbers written in marker pen.
• No way to trace which element went into which RECD.
• Mat material lying open on a dusty bench.
• Assembly area closed to visitors “for confidentiality” with no alternative offered, such as a recorded demonstration.

Stop 5: Testing and Quality Control

Testing is where RECD manufacturing quality becomes measurable. In-house tests do not replace certification by a recognised agency, but they show whether each unit leaving the plant behaves like the certified model. Pressure drop deserves special attention, since excessive restriction affects engine performance. Our article on how exhaust backpressure affects a DG set explains why.

1. Do you run a flow bench or pressure drop test on every unit, or on samples? What are the acceptance limits?
2. How do you leak test the body and joints?
3. How is the controller or monitoring panel bench-tested before despatch?
4. When were your test instruments last calibrated, and by whom? Is the calibration lab accredited?
5. Can I see your non-conformance register for the last few months?
6. What does your FAT procedure cover, and can customers witness it?

What a good answer sounds like

Test instruments carry calibration labels with due dates, and the matching certificates are on file, ideally from an NABL-accredited laboratory. The FAT procedure is a written document with defined checks and acceptance values, and customers are welcome to witness it. A non-conformance register exists and contains real entries. A register with no entries at all is less reassuring than one showing problems found and closed. If you plan to witness testing, read our comparison of factory acceptance and site acceptance tests for RECD projects so you know which checks belong at the factory and which belong on site.

Red flags

• Gauges with expired or missing calibration labels.
• A flow bench that is clearly unused, or no pressure drop testing at all.
• FAT described as “a visual check before packing”.
• An empty non-conformance register, or none at all.
• Customers not permitted to witness tests on their own order.

Stop 6: Packing and Despatch

A well-built RECD can still arrive cracked. The despatch bay tells you how much the supplier cares about what happens after the truck leaves.

1. What crate or skid design do you use for each size of unit?
2. How are the ceramic elements protected against shock and vibration in transit?
3. Do you fit tilt or shock indicators on crates?
4. Are open flanges and electrical connections capped and sealed?
5. What documents travel with the unit: packing list, test report, manual, serial number record?
6. How are accessories such as gaskets, fasteners, sensors and cables packed and identified?

What a good answer sounds like

Crates are built to suit each model, with lifting points and centre of gravity marked. Flanges are blanked, and loose accessories travel in labelled boxes that match the packing list line by line. A documentation pouch is fixed to the crate. The supplier is happy to share their packing checklist, which makes it easier to apply our RECD delivery inspection checklist when the consignment reaches your site.

Red flags

• Units wrapped in plastic film and strapped to an open pallet.
• Accessories thrown loose into the crate.
• Test reports “sent later by email” as standard practice.

Stop 7: Engineering, Installation and After-Sales

Your last stop should be the engineering and service team. Many RECD problems on site trace back not to the product but to poor selection or rushed fitment. The service team also decides how your experience will feel in year three, long after the sales visit is forgotten. That is the theme of our article on why after-sales service matters more than price.

1. How do you carry out a site survey, and what does the survey report include?
2. How do you calculate backpressure for a given exhaust layout, and which engine data do you need from us?
3. Are your installation teams in-house or subcontracted? Who supervises subcontractors?
4. What is your typical service response time in our city, and how is it measured?
5. Which spares do you stock, and where?
6. What training do you provide to our operators and maintenance staff?
7. Can you give us three references with similar DG sets that we can call ourselves?

What a good answer sounds like

The engineering team asks for engine make, model, rating and exhaust flow data before quoting, as described in our guide to using OEM exhaust flow data when specifying an RECD. They show a sample survey report with photographs, measurements and a layout sketch. They are open about whether installers are employees or partners, and they explain who holds responsibility for workmanship. Photos of completed work, like those in our installation gallery, are useful, but a phone call with a real customer is worth more.

Red flags

• Quotes issued on kVA alone with no request for engine or exhaust data.
• No written backpressure assessment.
• References offered only as logos, with no contacts.
• Service response promised in hours, with no named engineer anywhere near your region.

Many of these questions overlap with the ones you would ask any equipment dealer. Our list of questions to ask before choosing a generator dealer is a useful companion for this part of the visit.

Questions About Capacity and Delivery

A good factory with no spare capacity can still let you down. Demand for RECDs in the National Capital Region rises ahead of winter, when restrictions under the Graded Response Action Plan come into force. CAQM directions for the NCR refer to RECDs with at least 70% PM capture for in-use DG sets up to 800 kW. If you have several sets to retrofit, timing matters. Our explainer on GRAP rules for DG sets in Delhi NCR sets out the background.

• What is your realistic monthly output, by size range?
• What is your current order book, and what lead time would apply to an order placed this week?
• Which components have the longest procurement lead time, and do you hold buffer stock?
• Can you split a multi-set order into phased deliveries so priority sites are done before the GRAP season?
• What happens to our slot if our site is not ready on the agreed date?

Compare their answers with the stages described in what to expect from an RECD installation timeline. If the supplier quotes a lead time that seems far shorter than everyone else, ask what makes it possible. Sometimes the answer is ready stock. Sometimes it is optimism.

A Factory Visit Scorecard

Impressions fade quickly, and the last factory you saw always seems the best. A simple scorecard turns your notes into something you can compare. Score each area from 1 to 5 on the day, while the evidence is fresh, and multiply by the weight. The weights below are a starting point. Adjust them to suit your priorities.

Area	Weight	1 (weak) evidence	5 (strong) evidence
Certification and CoP control	20%	Copies only, no CoP dates known	Originals shown, power ranges clear, CoP tracker maintained
Material traceability	10%	No mill certificates, mixed stock	Heat numbers traced to certificates on request
Fabrication and welding	10%	No jigs, no drawings at stations	Qualified welders, fixtures, dimensional check sheets
Element canning and traceability	15%	No serial link between element and unit	Work instructions, permanent serials, full build record
Testing and QC	15%	Visual checks only, expired calibration	Pressure drop and leak tests, calibrated instruments, witnessed FAT
Packing and despatch	5%	Open pallets, loose accessories	Model-specific crates, indicators, complete document packet
Engineering and installation	10%	kVA-only selection, no survey format	Data-led selection, backpressure calculation, supervised teams
After-sales and references	10%	No contacts, unclear spares	Named engineers, local spares, callable references
Capacity and delivery	5%	Lead time vague or unrealistic	Clear output figures, phased delivery plan offered

To compare two or three vendors, fill in one sheet per supplier during the visit, with each team member scoring independently. Afterwards, compare scores and talk through any area where your scores differ by two points or more. Treat any area scored 1 as a potential deal-breaker regardless of the total. A supplier who scores well overall but cannot trace elements to units, for example, may still be the wrong choice for a regulated application.

Can’t Travel? Running a Virtual Factory Visit

Sometimes a physical trip is not practical, especially for multi-city organisations or urgent orders. A live video walk-through can cover much of the same ground if you plan it properly. Follow the same route and the same question banks, and ask the supplier to use a phone or tablet on a stable connection rather than a fixed meeting-room camera.

Request these specific shots:

• A close-up of a heat number on a stainless sheet, followed by the matching mill certificate.
• A weld on a unit in progress, filmed slowly from end to end.
• The serial number on a filter element and the build record that references it.
• Calibration labels on test gauges, held steady so the due date is readable.
• A pressure drop or leak test being carried out, with the reading shown on screen.
• A packed crate opened to show internal supports and accessory boxes.

Ask permission to record the session and share the recording with colleagues who could not join.

After the Visit: Follow-Up in Writing

The visit is only useful if what you learned ends up in your decision. Within two working days, send the supplier short minutes listing what you saw, the answers they gave and any commitments they made. Ask them to confirm or correct the minutes in writing.

List any outstanding documents with a deadline: the certificate copy they could not find, the calibration certificate for the flow bench, the reference contacts. Then feed the findings into your technical evaluation. If the supplier’s offer differs from what you saw at the factory, raise it formally using the approach in our guide on reviewing deviations in an RECD technical offer.

Finally, carry the important points into the purchase order. Name the FAT procedure you saw and your right to witness it. Reference the packing standard and document packet. Align the warranty with what was discussed, using our explainer on RECD warranty terms, parts, labour and exclusions. If you plan to start with a single unit before rolling out across sites, agree measurable criteria up front, as set out in how to agree acceptance criteria for an RECD trial installation.

Frequently Asked Questions

How long should an RECD factory visit take?

Allow around three hours for a single plant: roughly one hour in the meeting room and two hours on the shop floor. Add time if you plan to witness a FAT or call references from the supplier’s office.

Is a factory visit necessary if the supplier already holds CPCB certification?

Certification confirms that a model met the test requirements, and Conformity of Production checks confirm that production stays in line. A visit adds a view of the things that affect your particular order: traceability, packing, engineering support and service. For large orders, it is a sensible part of RECD vendor due diligence.

Should we tell the supplier our questions in advance?

Share the agenda and the document request, but not every question. You want records prepared so time is not wasted, while still leaving room to see how the team responds to questions they did not expect.

Can we inspect units built for our own order?

Yes, and you should ask for it. Many buyers combine a second visit with a witnessed FAT on their own units before despatch. Agree the date, the checks and the acceptance values in writing beforehand.

What if two suppliers score almost the same?

Look first at the areas you weighted most heavily, then at the reference calls. Practical feedback from customers running similar DG sets is often the best tie-breaker. Understanding how exhaust after-treatment systems work will also help you judge which supplier’s design explanation made more sense.

Conclusion: Make Your RECD Factory Visit Count

An RECD factory visit is not a courtesy call. It is a structured check that tests whether a supplier’s processes match its paperwork. Walk the route from reception to despatch, ask open questions at every stop, and insist on seeing records. Score what you see, follow up in writing and carry the findings into your purchase order. Done this way, the visit becomes one of the most useful steps in your supplier factory audit checklist, and it protects you from surprises after installation.

Aceget welcomes customers who want to see how our RECDs are designed, built and tested. You can review our certifications, learn more about our company and team, and contact us to arrange a factory visit or a live virtual walk-through at a time that suits your team.