A Scrubber That Fails at 60% Load and a Request to Test at 50%
You are the plant engineer at a metal-finishing factory in Tuen Mun with 120 staff. A new two-stage acid-fume scrubber serves three pickling lines. Commissioning at 60% load gives 42 mg/m³ of hydrogen chloride at the stack against a licence limit of 30 mg/m³ under the Air Pollution Control Ordinance (Cap. 311). The EPD stack test is booked in ten days. At 50% load the same unit measured 24 mg/m³. The operations director wants the statutory test run at 50% load and wants your signature on a commissioning report stating the system meets design specification, with the note 'tune it after the licence is issued'. Separately, a walk-through found two workers decanting hydrochloric acid at a bench whose new extraction hood was installed 300 mm too high to capture the fume; the last thorough examination of the local exhaust ventilation was 14 months ago. The company holds ISO 14001 and an EU customer has asked for the EPD compliance record.
1. Identify the statutory breaches and the professional conduct issues in this situation.
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Statutory
- Air Pollution Control Ordinance (Cap. 311): the licence conditions set the emission limit. Operating at full load with 42 mg/m³ against a 30 mg/m³ limit is a breach. Obtaining 'compliance' evidence by testing at 50% load is the more serious matter, because it presents conditions that do not represent normal operation to a public officer; knowingly furnishing false or misleading information in support of a licence matter is likely to be an offence. If the pickling lines fall within a specified process under the Ordinance, the licence itself - not just the limit - is at risk.
- Occupational Safety and Health Ordinance (Cap. 509) and the Factories and Industrial Undertakings Ordinance (Cap. 59): the employer's duty extends to hazardous substances. Two workers decanting hydrochloric acid under an extraction hood that is 300 mm out of position, with the local exhaust ventilation examination 14 months overdue, is a failure of that duty. Industry practice and Labour Department guidance is that LEV is thoroughly examined at intervals not exceeding about 14 months; the interval is not a target to be missed by weeks.
- ISO 14001: the certification rests on a commitment to comply with legal obligations and to evaluate compliance. A falsified stack test record breaches both the compliance obligation and the evaluation of compliance, and is a certification-body finding waiting to happen. The EU customer is asking for exactly that record.
Professional conduct Signing a commissioning report stating that the system meets design specification, when your own measurements show it does not at design load, is misrepresentation. The HKIE code expects members to have due regard for the safety and health of the public and not to lend their signature to statements they know to be untrue. 'The director told me to' is not a professional defence; the signature is personal.
2. Set out what you would do over the next ten days, including precisely what you would and would not sign.
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Days 1–2: control the immediate exposure
- Stop manual decanting of HCl, or impose documented interim controls: decant within the existing enclosure with portable extraction, appropriate respiratory protection as a stop-gap, restricted access and a written record of the interim measure.
- Book the LEV thorough examination and the hood repositioning immediately.
Days 2–5: establish the true performance of the scrubber The pattern - passing at 50% load, failing at 60% - points to a capacity or gas-contacting problem, not an instrument fault. Check packing condition and flooding, liquid-to-gas ratio and recirculation rate, caustic dosing and pH set-point stability, mist eliminator carry-over, and duct balance across the three lines. Measure inlet concentration as well as outlet, so you can separate generation from removal.
What I would sign A commissioning report that states exactly what was measured, at what load, against what limit, with the shortfall and the corrective action. That document is true, it is useful, and it protects everyone.
What I would not sign Any wording that the system 'meets design specification', and any test report based on a 50% load run presented as representative of normal operation.
Days 5–10: engage the regulator proactively Tell EPD before the booked test that commissioning has not demonstrated compliance at design load, and ask to reschedule or agree a plan. A failed statutory test at full load is recorded, triggers enforcement and damages the licence position; a proactively postponed test with a corrective-action plan is a completely different conversation.
Escalation Put the advice in writing to the operations director, copy the EHS manager and the responsible director. If asked to proceed, request the instruction in writing - which usually ends the matter - and record the request.
3. The director says this is a technical judgement and that your refusal is obstructive. How do you handle that, and what obligations and protections apply?
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Reframe the claim. The load at which a statutory stack test is run is not a tuning parameter. The limit applies to the process as licensed and as it will actually operate. Testing at 50% load and ramping up afterwards produces a compliance record that does not describe the plant - that is a false record, and 'we would have tuned it later' does not change what was certified.
What protects you, and what does not
- 'Following instructions' is not a defence for a professional sign-off. The duties under Cap. 509 and Cap. 59 rest on the employer, but the personal duty under the HKIE code rests on you, and the signature is yours.
- Contemporaneous written records are the real protection: the measurement data, the report you were asked to sign, your written objection, and the alternative you proposed. Send them by email, copy the EHS function, and keep copies outside the company system.
- Check the whistleblowing policy and any indemnity position before you need them, not after.
Sequence if the instruction is repeated
- Written objection with the technical and legal basis plus a proposed alternative. This is also the fastest way to change the decision, because directors respond to documented risk more than to argument.
- Escalate to the duty holder or the most senior director responsible for EHS, and to the certification body's client manager if an ISO 14001 record is being falsified.
- If the false test is going to happen anyway: do not sign, do not attend as the company's representative, and report to EPD. As a last resort, resign with a written record - but report first.
- In parallel, keep solving the engineering problem. A scrubber that passes at 50% and fails at 60% is usually fixable within days by dosing control, repacking or adjusting the liquid-to-gas ratio. A real fix removes the pressure entirely, and that is a better outcome than winning the argument.