Onsite Calibration of Optical Particle Counters

Ground zero — why this procedure exists at all

This procedure did not begin with a marketing brief. It began with a damaged instrument.

A customer of ours sent a $60,000 optical particle counter to a service facility in the United States for calibration. It returned damaged beyond repair. The asset was lost — not because of a calibration error, not because of a technical fault, but because of the freight and handling chain it was forced into to access an accredited calibration that did not exist locally.

The customer didn’t ask us to absorb the loss. They asked us to fix the underlying problem. They asked us to invest in every alternative we could engineer that would eliminate the same risk for the next time, and the time after that. They were specific: develop an accredited onsite calibration procedure, in conjunction with a leading particle counter manufacturer, so the asset never has to leave the facility.

We didn’t push back. We pushed forward. Years of investment, a partnership with the OEM, a measurement uncertainty programme built from first principles, and a NATA assessment process later, the procedure exists, it is accredited, and it is on our scope.

This is a technical note about that procedure — what it covers, what it doesn’t, what has been engineered out of it, who performs it, when it happens, and why none of it is mandatory.

What is actually accredited

Envirocal holds ISO/IEC 17025 (2017) accreditation through NATA — Accreditation No. 20872, Site No. 25061, accredited 27 September 2021. Two scope items matter for this discussion. The wording below is taken from our published Scope of Accreditation.

Particle counters — Air

Determinants: Flow rate; Particle count; Particle size
Technique: Comparison with a reference meter; Comparison with a reference standard
Procedure: ISO 21501-4
Capability: Including on-site calibrations. Flowrate: 3.5% of reading at flow rates from 1 L/min to 100 L/min. Polystyrene latex (PSL) spheres particle size: 12.8% for particles from 0.1 µm to 10 µm diameter.

The single most important phrase in either entry is “Including on-site calibrations.” That is not marketing language. It is the published outcome of a NATA technical assessment of our onsite methodology against ISO 21501-4. It means our onsite procedure has been examined on the bench and in the field, by independent technical assessors who hold the same expertise as the metrologist who developed it. It is not a laboratory procedure performed in the field. It is a separately assessed onsite methodology with its own measurement uncertainty budget and its own evidence base.

If a calibration is performed onsite by a provider whose accreditation does not contain that wording, it is not an accredited onsite calibration regardless of what the certificate paperwork looks like. Read the scope, not the cover page.

The customer holds the choice — not us

The procedure is not mandatory. Our laboratory calibration option remains fully available, accredited to the same standards, performed in the same way, with the same traceability. Onsite calibration is a customer-preferred option, offered to customers who specifically request it because it solves a problem they have identified in their own operation.

Before any onsite visit is scheduled, the customer is supplied with the full set of pre-arrival documentation. That package includes:

• The procedure itself, in detail.
• The space, services, and environmental provisions required to support it.
• The risk control measures that will be in place.
• The reference equipment list and its own traceability documentation.
• The technician competency records and gowning qualifications.

The customer’s quality team then assesses the procedure against the risk it might pose to their production, their compliance position, and their facility reputation. We do that risk assessment with them. If anything raised by the customer’s quality system is unresolved, the onsite option is withdrawn and the laboratory route is used instead. The decision sits with the customer, not with us.

The customer chooses where the calibration is set up. The customer chooses when it happens. The customer chooses whether it happens at all. The customer’s representatives are welcome to remain in the room and watch the calibration being performed in front of them. The certificate, the data, the uncertainty calculation, and the as-found values are all visible in real time.

The power is with the customer because the procedure was built around solving the customer’s problem. That orientation has not shifted.

Timing and location — where the calibration is performed, and why

The timing of the onsite calibration is not arbitrary. It is scheduled to coincide with the customer’s planned cleanroom performance testing and safety cabinet performance testing — work the same Envirocal team is already on site to deliver, on a date the customer has scheduled, during a window the customer has nominated.

The location is equally deliberate. The calibration itself is performed in a customer-nominated lower-grade controlled space — typically a QC laboratory, an anteroom, or a CNC area — outside the classified production cleanroom. It is performed within a closed-loop HEPA-filtered arrangement (Figure 2) that contains the calibration aerosol at source. The classified production environment receives nothing from the calibration.

That positioning is deliberate, and it sits inside a wider point about how cleanrooms work in practice. Customers routinely and deliberately accept polydisperse oil aerosol — PAO, DEHS, DOS, DOP, mineral oil, paraffin oil, PEG — at challenge concentrations of 1 to 100 mg/m³ inside the classified cleanroom under accredited HEPA filter integrity testing (AS ISO 14644.3:2021 cl B.7, AS 1807:2021 cl 4.4), recovery testing (AS ISO 14644.3:2021 cl B.4.3.2 — cleanroom seeded to 10–100× the classified concentration), and airflow visualisation (cl B.3 — visible smoke or fog filling the workspace). These are routine annual or risk-based tests under the cleanroom’s own qualification programme. The full inventory is set out in Figure 1.

At completion of that testing programme, the cleanroom undergoes its scheduled three-stage cleaning and viable count programme, performed by the same accredited team. Any particulate residue from any source — integrity testing, operational activity, or any other release into the classified space — is removed, the cleanroom is returned to its qualified at-rest state, and viable counts are run as confirmation.

PIC/S PE-009-17, Annex 1 (Manufacture of Sterile Medicinal Products) clause 4.29(iii) explicitly recognises this design:

Recovery from deliberate disruption is part of how a cleanroom is qualified — it is not an exception.

To date, across every onsite calibration we have delivered under this procedure, no evidence has been produced that the calibration has impacted a customer’s cleanroom particle count, viable count, qualification status, or compliance position. That is consistent with the design: the calibration aerosol does not enter the classified production space, and the customer’s qualification programme accommodates far larger aerosol loads in that space anyway.

Figure 1 — Aerosol release: where it occurs, in the cleanroom test programme and in onsite OPC calibration

The table below itemises the accredited cleanroom and safety-cabinet tests that routinely and deliberately release aerosol into, or directly adjacent to, the classified production space — and contrasts them with the onsite OPC calibration. The point the table makes is across three columns: aerosol type and concentration, where the release occurs, and frequency.

Standards cited: AS 1807:2021 (cleanroom and safety-cabinet test methods); AS 2252.2:2025 / AS 2252.5:2017 (Class II BSC / Cytotoxic drug safety cabinet); AS ISO 14644.3:2021 (cleanroom test methods); ISO/IEC 17025:2017 (calibration laboratory accreditation); ISO 21501-4:2018 (light-scattering airborne particle counter calibration). Concentrations are typical operating ranges; refer to the cited standards for full method conditions.

Two facts emerge directly from the table. First, every accredited annual test in rows 1–9 deliberately releases aerosol either inside or directly adjacent to the classified production space — at concentrations measured in mg/m³ (HEPA challenges) or as visible smoke clouds (airflow visualisation). The customer’s qualification programme accommodates these releases by design, with documented recovery procedures that return the room to its qualified at-rest state. Second, the Envirocal onsite OPC calibration is structurally different: it is contained inside a closed-loop HEPA-filtered system, performed in a lower-grade controlled space outside the classified cleanroom, and releases nothing to the surrounding environment. The technical objection that calibration aerosol introduces unacceptable cleanroom risk does not survive contact with what the cleanroom is qualified to receive on a routine annual basis — and is moot in the first place, because the calibration does not enter the classified space.

The procedure was engineered, not improvised

Our calibration metrologist developed the procedure end-to-end: the methodology, the technician training programme, the proficiency testing regime, and the measurement uncertainty budget. Reproducibility and repeatability were not assumed — they were characterised, quantified, and built into the budget alongside reference instrument uncertainty, environmental contribution, and operator-specific contribution.

The procedure was developed in active partnership with a leading OPC manufacturer and their in-house calibration department. One of the deliverables of that collaboration was the engineered control of particle output during the calibration itself — the calibration arrangement is closed-loop where the methodology permits, captured at source where it does not, and every aerosol path is HEPA-filtered before it can interact with the surrounding environment. Figure 2 (below) shows the aerosol generation, conditioning, mixing and HEPA-filtered exhaust pathway in schematic, with equipment tags (P-001, F-001 through F-005, AG-001, DC-001, MC-001) and stream identifiers cross-referenced to the equipment and stream schedule on the drawing.

The procedure has subsequently been:

• Reviewed by recognised specialists in nano-particle measurement metrology.
• Audited under ISO/IEC 17025 (2017) by NATA, with on-site technical assessment by assessors holding the relevant domain expertise.
• Subject to the further independent panel review that is part of the NATA accreditation system.

This is not a procedure that exists because we said it works. It exists because each layer of the assessment system that examined it concluded, independently, that it works.

Figure 2 — Calibration equipment arrangement (drawing ECAL-CAL-SCH-001)

Click to open full-size schematic

Figure 2. Calibration equipment arrangement (drawing ECAL-CAL-SCH-001, Rev B). Both regulated outlets from F-001 (HEPA pre-filter) feed the drying column DC-001 — V-001 supplies the aerosol generator AG-001, V-002 supplies regulated dryer make-up. F-003 HEPA-filters the aerosol chamber relief. F-004 is a dedicated HEPA filter hard-piped directly to the mixing chamber MC-001, providing supplementary make-up air at sub-0.1 µm efficacy. F-005A and F-005B HEPA-filter the IUT and reference instrument exhausts before release. The arrangement releases no unfiltered aerosol to the surrounding environment under normal or upset operating conditions.

Who performs the calibration — and why that matters

The metrologist and the Quality team train the operators. The operators are not external calibration technicians who visit cleanrooms occasionally. They are accredited cleanroom performance testing professionals who spend their working week inside Grade A, B, C, and D environments, performing the AS 1807, AS ISO 14644, AS 2252, and AS 4273 testing listed in Figure 1.

Two things follow from that.

First, the operators are particle counter specialists by trade. The optical particle counter is the central instrument in their working life. They understand its behaviour, its failure modes, its quirks across manufacturers, and its operational limits better than most. When that operator is also trained and qualified to ISO 21501-4 calibration methodology by the metrologist, the result is a technician with deep instrument knowledge and formal calibration competence — not a calibration technician who has been briefed on cleanrooms.

Second, both the operator and the operator’s reference equipment are already gowning-qualified, induction-qualified, and equipment-validated for entry into the customer’s cleanroom. They are entering that cleanroom on the day of the visit regardless — to perform the cleanroom testing programme. The OPC calibration is added to that visit. The number of additional cleanroom entries created by the onsite calibration is zero.

That is worth pausing on. The most common objection to onsite calibration is that it introduces unnecessary cleanroom entry. In Envirocal’s model, the entry is not additional. It is consolidated. The technician is in the cleanroom for the cleanroom testing the customer has already scheduled. Adding the calibration to that same visit is an efficiency gain for the customer, not a risk introduction.

The risks of the post-and-calibrate model

Shipping a particle counter to a remote calibration facility is the alternative being implicitly defended whenever the onsite model is challenged. That alternative carries a real, documented risk profile. It is worth listing.

Transit damage. The originating case for this entire procedure was a $60,000 instrument lost on the return leg from an overseas calibration. We have since seen others. Shock, vibration, dropped pallets, customs handling, temperature exposure — the freight chain is hostile to optical metrology equipment.

Asset unavailability. A typical interstate or international post-and-calibrate cycle takes two to four weeks at best, longer when the freight chain or the calibration provider is congested. During that window the customer either operates without monitoring, runs at reduced confidence on a substitute, or pauses the operation that depends on the counter.

Substitute counter risk. A replacement counter rented for the calibration window may not match the original’s resolution, channel set, or 0.1 µm capability. Compliance gaps and data inconsistencies follow.

Lost production days. In pharmaceutical operations with same-day or next-day product release — radiopharmaceuticals especially — the cost of a counter being absent is measured in lost dose-days, not invoice value.

Insurance and freight cost. Carried by the customer, often not recovered.

Loss of visibility. The customer cannot see the calibration being performed. The customer cannot witness as-found values, cannot observe the reference setup, cannot ask questions in real time. The result is a certificate from a process the customer never observed.

International dependency. Time zone, customs, regulatory variation, and freight reliability outside Australia introduce variables the customer cannot control.

The onsite procedure is the customer’s option to remove these risks. It is not the only option. It is the option that solves the problem the original customer asked us to solve.

We are not pioneers

This is not a fringe methodology. One major optical particle counter manufacturer alone fields more than 600 trained service engineers globally, many of them performing onsite calibration to ISO 21501-4 in customer facilities every working day. Multiple OEM-operated facilities perform onsite calibration to ISO 21501-4 internationally. Onsite optical particle counter calibration is a recognised, established methodology in the OPC service industry.

What is rare — and currently unique to Envirocal in the Southern Hemisphere — is for that capability to be held by an independent provider, NATA-accredited to ISO/IEC 17025, with the on-site capability explicitly named on the scope, performing the work down to 0.1 µm. We did the work to occupy that position because the customer base needed it.

Transparency is the point

Our scope is public. Our accreditation number is public. Our methodology is documented. The customer chooses whether the procedure runs on their site. The customer chooses where it runs. The customer chooses when. The customer is welcome to stand in the room and watch every step. The as-found data is captured before any adjustment. The uncertainty is on the certificate. The reference traceability is on the certificate.

There is nowhere to hide and we have not built anywhere to hide. That is the design.

Closing

We are a small, accredited, technically grounded team doing demanding work for customers whose own work depends on it. We did not ask to be the only NATA-accredited onsite OPC calibration provider in this region — we became that because a customer, faced with the loss of a $60,000 asset, asked us to fix the problem rather than absorb it.

The procedure that came out of that request is on our scope, examined annually, performed in plain view of the customers it serves, and offered as an option — never a requirement. If that is the foundation you want under your cleanroom monitoring programme, we would like to do that work for you.

How Envirocal is redefining particle counter calibration for cleanrooms and controlled environments across Australia.

If you manage a cleanroom, laboratory, or any controlled environment, you already know how much depends on the accuracy of your particle counter. It is the instrument at the heart of your environmental monitoring programme — and its reliability is only as good as its last calibration.

At Envirocal, we have built our particle counter calibration service around a simple but important insight: the environment where you calibrate the instrument matters just as much as the calibration itself.

The problem with calibrating away from the operating environment

Most calibration providers require you to remove your particle counter from the facility, ship it to a laboratory, and wait for it to come back with a certificate. On the surface, this seems straightforward. In practice, it introduces a gap that is easy to overlook.

When a particle counter is removed from your cleanroom or controlled environment and calibrated on a workbench in a different facility, the results reflect performance under those conditions — not yours. Differences in temperature, humidity, airflow, and ambient particle load can all influence how the instrument behaves. You receive a certificate that tells you the instrument performed within specification in a controlled lab setting, but not necessarily in the environment where it actually counts.

For facilities operating under strict GMP, TGA, or ISO 14644 requirements, this distinction can matter during an audit.

The Envirocal difference: calibrated where it counts

Envirocal is the only NATA-accredited laboratory offering on-site particle counter calibration in Australia. Rather than requiring you to remove your instrument, our team comes to you — and calibrates your particle counter in situ, in its natural operating environment.

This means your calibration results reflect the real-world conditions your instrument experiences every day. Your certificate is more meaningful, your compliance position is stronger, and there is no disruption to your operations.

• Calibrated in your cleanroom or controlled environment, exactly as the instrument operates
• No need to remove equipment, reducing downtime and disruption to your workflow
• Results that reflect real environmental conditions, not a laboratory bench
• NATA-accredited certificates accepted by regulators, auditors, and certifying bodies

For facilities in pharmaceutical manufacturing, medical device production, biotechnology, and any ISO-classified environment, this approach provides a level of confidence that send-away calibration simply cannot match.

Flexible options to suit your situation

We understand that on-site calibration is not always practical for every customer. Some instruments are easier to transport, and some teams prefer the simplicity of a send-in service. That is why Envirocal offers both.

• On-site calibration — our team comes to your facility and calibrates your particle counter in its operating environment. This is the only service of its kind offered by a NATA-accredited laboratory in Australia.
• Send-in calibration — ship your instrument to us and we will return it with a NATA-accredited certificate and fast turnaround.

Not sure which option suits your facility? Our team is happy to talk through the options and help you make the right call.

Why NATA accreditation matters

NATA accreditation (National Association of Testing Authorities) is the benchmark for measurement confidence in Australia. When your calibration certificate is issued by a NATA-accredited laboratory, it carries formal recognition that the laboratory meets the requirements of ISO/IEC 17025 — the international standard for testing and calibration competence.

For regulated industries, this is not optional. NATA-accredited calibration certificates are required by the TGA, expected under GMP frameworks, and referenced in ISO 14644 cleanroom standards. They provide the traceability and confidence your quality system depends on.

Every particle counter calibration Envirocal performs — whether on-site or send-in — is issued under our NATA accreditation and traceable to national measurement standards.

Who we work with

Envirocal provides particle counter calibration for a wide range of industries and facility types across Australia, including:

• Radio/Pharmaceutical and biopharmaceutical manufacturing
• Medical device manufacturers
• Hospital and compounding pharmacies
• Biotechnology and research laboratories
• Microelectronics and semiconductor facilities
• Aerospace and defence
• Food and beverage production in controlled environments

Whether you are managing a Grade A filling suite, an ISO Class 5 cleanroom, or a general controlled environment, our team understands the compliance obligations your facility operates under.

Ready to book your particle counter calibration?

Talk to Envirocal about on-site or send-in particle counter calibration for your facility. Our team is ready to help you stay compliant, confident, and audit-ready.

Contact us: 1300 747 111   |   info@envirocal.com.au   |   www.envirocal.com.au

How Envirocal modernised calibration and environmental control for high-risk facilities.

Envirocal is a leader in environmental and calibration services across Australia’s most tightly regulated industries, from pharmaceutical manufacturing to nuclear medicine.

Our role is to make sure cleanrooms and controlled environments meet strict GMP and TGA standards for compliance, safety, and performance.

When legacy OEM systems began limiting flexibility, visibility, and value, Envirocal set out to modernise how critical data was captured, managed, and reported. Partnering with Bitpool as our technology platform, we implemented an open, AI-enabled monitoring solution that unlocked new levels of digital compliance and control for our clients.

The Challenge

For high-compliance radiopharmaceutical environments, small gaps in data can quickly turn into unnecessary cost, risk, and operational inefficiency.

Envirocal identified four key pain points across our customer base:

• OEM lock-in and control
  High licensing and exit costs were preventing upgrades, innovation, and supplier flexibility.
• Outdated integration
  Legacy systems were unable to interface with modern cloud or data architectures.
• Fragmented data
  Limited interoperability between temperature, humidity, radiation, and other critical sensors.
• No real-time visibility
  Poor access to live environmental metrics and compliance indicators made issues hard to detect early.

Our clients needed a way to take ownership of their data, reduce their dependence on OEM systems, and gain instant insight into environmental performance.

The Solution

Envirocal deployed an open-data monitoring platform, powered by Bitpool, to deliver visibility, flexibility, and AI-driven insight across our clients’ sites without the constraints of OEM systems.

• Rapid, non-disruptive integration
  Using MQTT data ingestion, Envirocal was able to connect directly with existing devices and loggers. The system was rolled out with no downtime or major infrastructure changes.
• Real-time customised data
  Visual dashboards provide live reporting for radiation, temperature, humidity, and other key environmental metrics, tailored to each site.
• AI-driven performance insights
  Intelligent anomaly detection highlights potential compliance risks instantly, giving engineers time to respond before issues escalate.
• Automated alerting
  Dynamic thresholds (warning, alert, alarm) trigger on-screen notifications and alarms, ensuring the right people are notified at the right time.
• Audit-ready compliance reporting
  The platform is designed to meet regulatory and GMP-aligned expectations, including user-level audit trails and historical reporting for inspections.
• Secure access and calibration records
  Role-based access and centralised calibration records ensure traceability and confidence across all users and locations.

The Outcome: control, compliance, and customer value

The Envirocal implementation in Wellington, New Zealand, has now become a model for how we deliver value across our client base.

Key outcomes include:

• OEM independence
  Open, scalable architecture that removes OEM lock-in and future-proofs system design.
• Regulatory and GMP-aligned compliance
  Data framework certified for GMP networks, supporting strict regulatory requirements.
• Non-disruptive roll-out
  No downtime or infrastructure overhaul for the client.
• Scalable success
  The model has been expanded across Australia and into other high-compliance environments.
• Instant visibility
  AI-powered dashboards detect environmental anomalies in seconds, improving response times and confidence.

Strategic value for Envirocal and our clients

Beyond immediate operational benefits, the project has delivered significant strategic value:

1. Higher-value contracts through expanded service capability and digital differentiation.
2. Lower deployment costs with flexible, reusable infrastructure that can be replicated across sites.
3. Broader market appeal as Envirocal is now positioned for growth in adjacent regulated sectors.
4. Improved client retention driven by transparency, data-driven optimisation, and stronger compliance outcomes.
5. Progressive industry profile with Envirocal recognised as an AI-enabled service provider and innovation partner.