RECDs for Pharmaceutical Plants: Integrating Retrofit Work with Change Control

In most factories, fitting an emission control device to a diesel generator is an engineering job. A pharmaceutical plant is different. The same job has to pass through the quality system, because the generator feeds systems that protect product.

This guide treats the change control record as the backbone of the project. We walk through it stage by stage, from the first request to final closure, and show what a sensible entry looks like at each step when the change is an RECD for pharmaceutical plants. Your site’s own change control SOP always governs. What follows is a practical way to fill it in, not a replacement for it.

Why an Exhaust Retrofit Is a GMP Matter at All

A DG set does not touch the product. So why should QA care about a box on its exhaust pipe?

Because of what the generator keeps running when grid power fails. In a typical formulation or API plant, the standby supply may back up:

• HVAC for classified areas, including AHUs that hold pressure cascades between Grade C, Grade D and unclassified corridors
• Purified water and WFI loops, where circulation must not stop for long
• Stability chambers, which hold samples at defined temperature and humidity for months or years
• Cold rooms and refrigerators for temperature sensitive materials and finished goods
• BMS and EMS, the systems that record the environmental data you show auditors

Any work on the DG can interrupt that supply. Changeover between mains, DG and any temporary set is a moment of risk. A failed transfer can drop a cascade, warm a stability chamber or leave a gap in an EMS trend that later needs an explanation.

There is a second, less obvious link: where the exhaust goes. Many plants have fresh air intakes for AHUs on the roof or on an external wall. If a retrofit changes the stack height, direction or outlet location, exhaust could be drawn into an air handler serving a production area. That is a contamination question, and contamination questions belong to QA.

First Question: Is the DG a GMP or Non-GMP Utility?

Before you raise anything, check how your site has classified the generator. Most plants do this through a system impact assessment, usually part of their qualification approach.

• Direct or indirect impact system: the DG supports GMP critical utilities, and changes to it go through the quality change control procedure.
• No-impact system: the DG is treated as general plant infrastructure, and changes may go through an engineering change procedure with QA informed rather than approving.

In practice, many sites land in between. The DG itself is classified as no-impact, but the HVAC and water systems it feeds are direct impact. Some SOPs then require a quality change control for any modification that could affect power continuity to those systems. Others allow an engineering change with a mandatory QA review.

There is no single correct answer here. The site SOP decides, and if it is silent, ask QA in writing before work starts. A short email trail asking “which route applies?” is far easier to defend than a retrofit done under the wrong procedure.

The revised Schedule M, notified in December 2023, made change control and quality risk management explicit expectations for Indian manufacturers, as part of a pharmaceutical quality system. India Briefing’s summary of the revised Schedule M notes the compliance timelines: larger firms first, with an extended deadline for MSMEs that ran to 31 December 2025. If you are an MSME that has just moved onto the revised requirements, this may be one of the first utility changes you run under the new system.

Stage 1: The Change Request

The change request is where you describe what you want to do and why. Keep it factual and specific. Vague requests generate vague impact assessments.

Description of the change

A good description answers what, where and which equipment. For example (illustrative):

Installation of a CPCB type approved retrofit emission control device (DOC plus DPF) on DG Set 2, 750 kVA, located in the utility yard behind Block B. Work includes modification of the existing exhaust line between the turbo outlet flexible and the silencer, new supports, and installation of a local monitoring display with IoT connectivity.

Name the DG by its asset tag. Mention whether the existing exhaust pipe will be cut, rerouted or extended. If the stack outlet will move, say so here, because that drives the AHU intake question later.

Justification

For plants in Delhi NCR, the justification is usually regulatory. CAQM Direction No. 76 (29 September 2023) set out a path by capacity: sets of 19 to 125 kW to move to dual fuel, sets of 125 to 800 kW to adopt dual fuel or an RECD, and sets above 800 kW to fit an RECD. GRAP stages add further restrictions on DG use, with exceptions for emergency and essential services.

Write the justification so a reviewer outside engineering understands it. State the DG rating, which band it falls in, and the consequence of not acting: restricted operation during GRAP, risk of enforcement, and in reported cases, sealing of non-compliant DG sets. Add a line that the team has checked the current CAQM direction and SPCB requirements, since rules can be revised. Our overview of DG set emission regulations is a useful starting reference.

Attachments

Attach enough that reviewers do not have to chase information:

1. Vendor CPCB type approval certificate for the RECD model
2. General arrangement drawing showing the RECD, supports and exhaust route
3. DG nameplate photographs (engine and alternator)
4. Vendor site survey report, including backpressure calculation
5. Vendor quotation or scope of work

If nameplates are faded or documents are missing, fix that first. Our guide to DG nameplate photos for an RECD enquiry lists what to photograph.

Stage 2: The Impact Assessment

This is the heart of the record. Each affected function reviews the change and records whether it has an impact, and what action is needed. A table keeps it readable.

Area	Typical question	Likely outcome (illustrative)
HVAC and cleanroom pressure cascades	Will DG downtime or changeover interrupt AHUs serving classified areas?	Impact. Needs a power continuity plan and cascade monitoring during work.
Environmental monitoring	Could the work create dust, fumes or particles near production? Will EMS lose data?	Possible impact. Check EMS UPS backup and plan non-viable counts if work is near intakes.
Utilities (PW, WFI, compressed air, chilled water)	Will circulation stop during changeover?	Impact if supply is interrupted. Align with water system SOP on loop stoppage and restart.
Validation status	Does the change affect a qualified system or its qualified state?	Usually no requalification of HVAC or water. DG documentation may need an addendum.
Documents, SOPs, drawings	Which drawings and procedures describe the DG and its exhaust?	Impact. Update utility layout, SLD, PM schedule, DG operating SOP.
EHS and permits	Does the work need hot work permits? Does the consent to operate refer to stack details?	Impact. Hot work permit; check consent conditions with EHS.
Training	Do operators need to learn the RECD display, alarms and routine checks?	Impact. Training before handover.
Regulatory filings	Does the change need notifying to the licensing authority or in any marketing authorisation?	Usually none for a utility exhaust change. Regulatory affairs should confirm in writing.
Production and stores	Will batch manufacture or cold storage be affected?	Depends on scheduling. Align with campaign plan.

“No impact” is a valid answer, but each function should still sign against it. Regulatory filings rarely change for a utility modification like this, yet auditors look for evidence that someone asked.

Stage 3: The Risk Assessment

Revised Schedule M expects quality risk management to be applied to changes. Many sites follow the approach set out in ICH Q9: identify hazards, estimate their severity and likelihood, and decide controls proportionate to the risk. An FMEA style table is the most common format for engineering changes.

The scores below are illustrative only, on a 1 to 5 scale where higher is worse, and RPN = Severity x Occurrence x Detection. Your site will have its own scales and action thresholds.

Failure mode	Effect	S	O	D	RPN	Controls
Exhaust re-entrained into AHU fresh air intake	Odour, particulate or fumes in supply air to production	4	2	3	24	Check stack outlet position against intakes before approval; smoke test after install
Power interruption during changeover to temporary DG	Pressure cascade loss, stability chamber excursion	5	2	2	20	Planned window, tested transfer, trend monitoring, contingency SOP
Dust or debris from cutting and grinding	Contamination of adjacent areas or intakes	3	2	2	12	Screens, closed doors, cleaning after work, intake filters checked
Backpressure above OEM limit	Derating, overheating, inability to carry critical load	4	2	3	24	Vendor calculation pre-approval; measured backpressure at commissioning
Fire during hot work	Injury, asset damage, unplanned outage	5	1	2	10	Hot work permit, fire watch, extinguishers, area clearance
DPF soot loading from light-load running	Rising backpressure over time	3	3	2	18	IoT alarms, load testing routine, PM schedule

Two risks worth extra thought

Exhaust re-entrainment is the one most likely to be missed, because the person who designs the exhaust route rarely looks at the HVAC layout. Ask the vendor to mark AHU intake locations on the GA drawing. If the new outlet is closer, lower, or upwind under prevailing winds, raise it before approval, not after.

Backpressure matters because pharma DG sets are often sized close to their critical load. Any loss of usable output could leave HVAC or chillers short during an outage. A well designed RECD stays within the engine maker’s backpressure limit, but the record should show the calculation and later the measured figure. Our article on how exhaust backpressure affects a DG set explains the mechanics.

The last row deserves a note too. A DPF needs adequate exhaust temperature to burn off soot passively, which generally means meaningful load, often cited around 40 to 50% or higher depending on design. Many pharma standby sets run mostly on test runs at light load. If that describes your DG, plan periodic loaded runs, and read our guide on RECDs for DG sets that run only occasionally.

Classification and Approvals

Once the risk assessment is complete, the change is classified. Definitions vary by site, but a common pattern is:

• Minor: no impact on product quality, validated state or regulatory filings; limited documentation updates.
• Major: potential impact on GMP systems, requires risk controls, verification and QA approval of closure.

An RECD retrofit on a DG that backs up classified HVAC often ends up as major, mainly because of the power continuity and air intake risks, even though the device itself is simple. On a DG that serves only office blocks and the canteen, minor may be fair. Document the reasoning either way.

Typical approvers for a major utility change:

1. Engineering head: technical adequacy and implementation plan
2. QA head: GMP impact, risk assessment, classification
3. EHS head: hot work, fire safety, environmental consent conditions
4. Production head: schedule alignment and acceptance of downtime windows
5. Plant head or site head: final authorisation for major changes, where the SOP requires it

Get approvals before committing to site work. Fabrication drawings should match the approved version.

Stage 4: Implementation Plan and Pre-Requisites

Approval tells you the change is acceptable. The implementation plan tells everyone how it will happen without disturbing manufacture.

Align with batch campaigns

Look at the production plan for the next two to three months. Fitment often needs a day or two of DG downtime per set, though this varies with site conditions. Choose a window when:

• No sterile or critical batches are in progress in areas the DG backs up
• Stability chambers have spare capacity or a backup chamber is available
• The grid supply has been reliable in recent weeks

Many plants pair the work with a planned maintenance shutdown, when HVAC and water teams are already on standby.

Temporary power

If the DG cannot be spared even for a day, arrange a temporary rental DG with a tested changeover. Check whether a rental set itself is allowed to run under the current GRAP stage and CAQM rules, since restrictions apply to diesel sets generally. The temporary connection should be documented, tested before the permanent DG is isolated, and removed afterwards under the same change record.

Permits and site preparation

1. Hot work permit for any cutting or welding, with a named fire watch and extinguishers at the work point
2. Isolation and lockout of the DG, battery and fuel supply
3. Protection of adjacent areas: close or screen nearby doors and louvres, especially AHU intakes within the dust zone
4. Cleaning plan for the area after work, including checking pre-filters on nearby intakes
5. Line clearance, where your SOP requires it for work near production support areas

Material and vendor readiness

Confirm that supports, flanges, gaskets and insulation are on site before the shutdown starts. A missing flange is the most common reason a one day job turns into three. Our list of common RECD installation mistakes is worth sharing with the contractor before mobilisation.

Stage 5: Verification

Verification proves the change was done as approved and that the risks identified in Stage 3 are controlled. Write the acceptance criteria into the change record before work starts, so verification is a check against something agreed.

Commissioning and load test

• Visual inspection: supports, alignment, insulation, no exhaust leaks at joints
• No-load run, then stepped load test, ideally to the highest load the site can apply safely
• Exhaust temperatures at DOC inlet and DPF outlet recorded
• Smoke opacity check, as a quick visual and recorded comparison against pre-installation

Backpressure within OEM limit

Measure backpressure at rated or highest available load and compare it with the engine maker’s limit. Record the instrument used and its calibration status. This one number answers the derating question for QA, so it should be in the record, not only in the vendor’s report.

Changeover test

Simulate a mains failure and confirm the DG starts, takes load and transfers within the normal time. Watch the pressure cascade and stability chamber trends on the BMS during the test. If the cascade dips below limits for longer than your SOP allows, investigate before closing.

AHU intake smoke and odour check

With the DG on load, check at the nearest AHU fresh air intakes for smoke or diesel odour. A simple smoke pencil test near the stack outlet can show wind behaviour. Record observations under more than one wind direction if you can. An RECD with a DOC reduces odour compounds, as covered in our note on whether an RECD can reduce diesel exhaust odour, but stack position still matters.

Documentation updates

Close every document action listed in Stage 2:

• Utility layout drawing and P&ID or exhaust isometric
• Single line diagram, if any monitoring or control wiring was added
• DG preventive maintenance schedule, now including RECD checks
• DG operating SOP, including RECD alarm response
• Equipment master or asset register
• Spares list for the RECD

Training

Train DG operators and shift engineers on the RECD display, alarm meanings, and what to do if backpressure rises. Record attendance and a short assessment, per your training SOP.

Stage 6: Effectiveness Check and Closure

Many change control records allow closure once implementation is verified. For utility changes, a later effectiveness check is good practice, because some problems only show up with time.

For an RECD, a sensible plan is to review IoT trend data after about 30 days and again after about 90 days. Look at:

• Backpressure trend: stable, slowly rising, or rising fast?
• Exhaust temperature profile: is the DPF seeing enough heat to regenerate?
• Alarm history: any repeated alarms, and were they handled?
• Any EMS or BMS excursions during DG runs that coincide with the change

If backpressure is climbing steadily, revisit the loading routine before it becomes a problem during a real outage. Our RECD maintenance guide explains what normal and abnormal trends look like.

QA then signs closure.

Vendor Documents to Ask For

Your change record is only as good as the evidence behind it. Ask the RECD supplier for these before and after installation:

Document	When	Why it matters for change control
CPCB type approval certificate for the model	Before approval	Supports the regulatory justification
Test report or certificate	Before approval	Evidence of tested performance; see how to read an RECD test certificate
Site survey report	Before approval	Exhaust size, route, space, supports, nameplate data
Backpressure calculation	Before approval	Basis for the derating risk score
GA and fabrication drawings	Before approval	Attachment to the change request; input to drawing updates
Method statement and hot work plan	Before implementation	Feeds the EHS review and permit
Commissioning report with measured values	After installation	Primary verification evidence
O&M manual and spares list	After installation	Input to SOP and PM schedule updates
Training records	After installation	Closes the training action

At Aceget, we find pharma clients ask for this pack in a fixed order, so it helps to share the list on the first call. Our certifications page shows the type approval references for our models.

Common Audit Observations to Avoid

The examples below are illustrative, based on the kinds of gaps that typically appear when utility changes are reviewed. They are not quotes from any real inspection.

1. Work started before approval. The device was installed and the change control raised afterwards. Always approve first.
2. Impact assessment signed as “NA” without reasoning. Each “no impact” should carry a one-line reason.
3. No link between risk controls and verification. The risk table lists a smoke test at the intakes, but the verification section has no record of it.
4. Drawings not updated. The utility layout still shows the old exhaust route months after closure.
5. Temporary DG not covered. A rental set was used during the work but is not mentioned anywhere in the record.
6. Training records missing for shift staff. Day shift trained, night shift not.
7. Effectiveness check promised but never done. The record says “review after 90 days” and nothing follows.

Most of these are documentation failures, not engineering ones. A checklist stapled to the change record helps.

How This Fits With Other Compliance Work

The change control record sits next to, not instead of, your environmental compliance. Keep consent conditions and stack details current with EHS; our environmental compliance checklist for generator owners covers that side. For sets in the 125 to 800 kW band, a dual fuel kit adds a gas supply to the yard, so compare RECD vs dual fuel kit before raising the request.

Frequently Asked Questions

Does an RECD installation need a quality change control or an engineering change control?

It depends on your site SOP and how the DG has been classified in your system impact assessment. If the DG backs up HVAC for classified areas, purified water or stability chambers, many sites route it through quality change control. If unsure, ask QA in writing before starting.

Will we need to requalify our HVAC system after fitting an RECD?

Usually not, because the HVAC system itself is not modified. You do need evidence that power continuity was maintained during the work and that the exhaust does not affect AHU intakes. Your validation team should confirm this in the impact assessment.

Is a change in the DG exhaust reportable to the drug licensing authority?

For a utility exhaust modification, filings are rarely affected. Still, regulatory affairs should record the conclusion in the impact assessment. Check your licence conditions and any marketing authorisation commitments.

How long will the DG be out of service?

Fitment often takes a day or two per set, but survey, fabrication and planning happen before that. The RECD installation timeline guide gives a fuller picture. Plan the shutdown with production and utilities well in advance.

What if our DG mostly runs at light load during tests?

Light-load running can load the DPF with soot and cause wet stacking. Plan periodic loaded runs and watch the IoT backpressure trend during the effectiveness check period. Include this in the updated PM schedule.

Which vendor documents does QA usually need?

At minimum: type approval, test certificate, survey with backpressure calculation, drawings, method statement, commissioning report and O&M manual.

Plan the Retrofit Around Your Quality System

An RECD for a pharmaceutical plant is a modest piece of hardware with a large paper trail, and that is how it should be. If the change record is planned early, the retrofit becomes one more well managed utility change rather than an audit finding waiting to happen. Aceget supplies CPCB type approved retrofit emission control devices for DG sets from 25 kVA to 2500 kVA, with IoT monitoring that supports your effectiveness checks. To discuss a survey, the vendor document pack or a shutdown window that suits your batch plan, contact the Aceget team.