ATEX acceptance for a low flow meter comes down to four verifiable items: the certificate scope together with its validity window, the wetted material grade, the pressure and temperature class, and the documentation package that is handed to the project’s HSE and QA reviewers. For a steam mass flow meter such as the STLU-VFN and for an ATEX-certified micro Coriolis meter such as the SH-CMF-FE, those four items are checked against two different duty profiles, and a purchase order normally cannot be released until every one of them is traceable to a named certificate number.

This guide is written for instrument engineers, project QA reviewers, and procurement teams working in hazardous areas. It explains how ATEX approval maps onto regional project acceptance criteria, how to verify stainless steel 304, 316, and 316L material grades, how to read a 30 bar versus 100 bar pressure rating, how the 500 °C maximum steam temperature of a vortex steam meter interacts with certification, and what documentation to demand for the STLU-VFN steam mass flow meter and the SH-CMF-FE micro Coriolis mass flow meter before compliance sign-off.

Problem Definition: Where Low Flow Meter Compliance Sign-Off Usually Stalls

A low flow meter’s technical performance is rarely the reason a hazardous-area project is delayed. The delay usually originates in the compliance file, where four gaps recur.

• Scope mismatch. A buyer reads “ATEX certified” and assumes universal coverage. The certificates held for these instruments state a scope of Zone 2, which is only one part of the area-classification picture.
• Validity window ignored. Every certificate has an issue date and an expiry date. If the certificate lapses before mechanical completion, handover, or the warranty period ends, a reviewer can reject the instrument even though it was compliant on the day it shipped.
• Material grade ambiguity. Stainless steel 304, 316, and 316L are not interchangeable in a compliance file. A project that specifies 316L wetted parts will not accept a 304 sensor, and a request for “stainless steel” on a data sheet is not an acceptance criterion.
• Pressure and connection ambiguity. A micro Coriolis meter offered at 30 bar cannot be accepted into a 100 bar piping class, and a tri-clamp connection cannot be substituted for a flanged connection in a line that was reviewed on that basis.

The consequence is predictable: the instrument is technically suitable, but the file is incomplete, and the procurement team has to reopen a decision that everyone believed was closed.

Industry Background: Why Low-Flow Compliance Review Has Tightened

The commercial context explains the scrutiny. The global flow meter market was valued at USD 10.64 billion in 2024, with Europe holding the largest regional share of over 35%, according to Grand View Research. Europe is also the region where ATEX documentation is most systematically audited, so the concentration of demand and the concentration of compliance checking overlap.

Within that market, the segments most relevant to low-flow work are expanding. Coriolis flow meters held a 26.77% share of the intelligent flow meter market in 2026, according to Fortune Business Insights, and Coriolis revenue is concentrated in high-precision duty. Grand View Research reports that the 2-inch and smaller pipe size segment is expected to see the fastest growth through 2030, driven by demand in pharmaceuticals and food and beverage. P&S Intelligence valued the global microfluidic devices market, which includes micro flow sensors, at USD 22.1 billion in 2024, growing at a CAGR of 12.2%.

On the standards side, ISO 5167:2022 remains the primary international standard for differential pressure flow measurement devices and is directly relevant to small pipeline accuracy. On the gas side, Market Research Future reports that thermal flow meters, which are essential for low gas flow rates, reached USD 1.73 billion in 2024 and are projected to reach USD 2.9 billion by 2035.

Smaller lines, tighter accuracy expectations, and hazardous-area installation combine to push more of the procurement decision into the documentation. That is the environment in which an ATEX file is read.

What ATEX Approval Actually Covers on These Low Flow Meters

Silver Automation Instruments is a flow and pressure instrumentation manufacturer founded in 2010 and based in Nanjing, Jiangsu, China, producing Coriolis, thermal mass, electromagnetic, vortex, turbine, and oval gear flow meters alongside pressure, level, and data-logging instruments. Two ATEX certificates are held for the low flow meter range, and the differences between them matter at sign-off.

Certificate ECM 22 ATEX-B 0S05

Issued by Ente Certificazione Macchine srl, this certificate covers Zone 2 and cites the standards EN IEC 60079-0:2018/AC:2020, EN 60079-1:2014, and EN 60079-31:2014. It was issued on 21 February 2022 and is valid until 20 February 2027. Within the product range it relates to the SRK-100 thermal mass flow meter and the SH-CM Coriolis mass flow meter.

Certificate ICR/VC/HM251296

Issued by ICR, this certificate also covers Zone 2 and cites the standards IEC 60079-0:2018+A11:2024, EN 60079-1:2014+A11:2024, and EN IEC 60079-31:2024. It was issued on 9 December 2025 and is valid until 9 December 2030. Its product coverage includes the SH-CMF-FE micro Coriolis mass flow meter, the STLU-VFN steam mass flow meter, the SRK-DL low flow thermal mass flow meter, the SRK-100, and the SH-CM.

The practical rule is simple. Zone 2 equipment is accepted where the area classification defines an environment in which an explosive atmosphere is not likely to occur in normal operation. Where the classification drawing calls for Zone 1 or Zone 0, a Zone 2 certificate on its own will not clear acceptance, and the project should confirm what alternative approval path is available before the meter is standardised in the line list.

Verifying 304, 316, and 316L Material Grades

Material grade is the second item on the acceptance checklist, and it is specified per model rather than per range.

• STLU-VFN steam mass flow meter: the flow sensor material is stated as stainless steel 304, with the model material listing stainless steel 304 or 316.
• SH-CMF-FE micro Coriolis mass flow meter: stainless steel 316L.
• SH-CM Coriolis mass flow meter: stainless steel 316L.
• SRK-100 thermal mass flow meter: stainless steel 304.

The verification step is to confirm that the grade written on the project data sheet is the grade written on the order acknowledgement and on the material traceability documents. Heat-number-traceable mill certificates are typically requested alongside the ATEX file, because a reviewer who cannot link the certificate to the delivered wetted parts treats the certificate as incomplete.

Grade selection itself follows the process, not the preference of the buyer. Type 304 is used for general steam and non-aggressive service. Type 316 raises corrosion resistance where chlorides or process chemistry are present, and 316L, with its lower carbon content, is used where welded assemblies and aggressive or hygienic duty call for it. In one recorded application, a Coriolis meter for corrosive chlorine gas required a tantalum wetted material rather than a stainless grade at all, which illustrates why an acceptance file should state the material requirement explicitly instead of accepting “stainless steel” as a specification.

Pressure Rating, Steam Temperature, and Process Connections

Once scope and material are cleared, the reviewer moves to the mechanical and thermal envelope. These are selection parameters rather than certificate items, but they are cross-checked against the same acceptance file, because a certificate for a meter that cannot survive the line conditions is of no use to the project.

The SH-CMF-FE micro Coriolis mass flow meter is offered with a pressure rating of 30 bar or 100 bar, a flow range of 40 g/h to 1000 kg/hr, and an accuracy of ±0.25% to ±0.5%. It uses the Coriolis measuring principle and is applied in process fluid measurement and control systems in the food, (petro)chemical, and pharmaceutical industries, in fermentation equipment, semiconductor processing, and fuel cell technology. Fluids handled include pure water, silicone, aviation kerosene, diesel, supercritical CO2, and silane. The choice between 30 bar and 100 bar is the single most common pressure-class decision on this model, and it should be resolved before the compliance file is assembled, not after.

The STLU-VFN steam mass flow meter is a vortex-type meter for saturated and superheated steam, covering pipeline sizes DN15 to DN300, with a maximum steam temperature of 500 °C. It is supplied with built-in temperature and pressure compensation, which is the feature that turns measured vortex frequency into a mass flow value; the compensation configuration therefore belongs in the documentation package. Flow sensor material is stainless steel 304, and the process connection can be flanges, wafers, screws, or tri-clamp.

Connection type is not cosmetic. A tri-clamp connection supports hygienic duty in food and pharmaceutical lines, while flanged connections are the normal choice where the piping class and the pressure rating must be evidenced in the mechanical file. A wafer or screw connection may be acceptable on small lines, but if the approved piping specification calls for a flange, the substitution has to be re-approved, not silently accepted.

Compliance-relevant specification comparison

Verification item	STLU-VFN steam mass flow meter	SH-CMF-FE micro Coriolis mass flow meter
Measuring principle	Vortex, for saturated and superheated steam	Coriolis
ATEX certificate	ICR/VC/HM251296, Zone 2, valid to 9 December 2030	ICR/VC/HM251296, Zone 2, valid to 9 December 2030
Wetted material grade	Stainless steel 304 (model listing: 304 or 316)	Stainless steel 316L
Pressure rating	Confirm against the project piping class	30 bar or 100 bar
Temperature limit	Maximum steam temperature 500 °C	Confirm against the project data sheet
Process connection	Flanges, wafers, screws or tri-clamp	Confirm against the project piping class
Flow range	Pipeline size DN15 to DN300	40 g/h to 1000 kg/hr
Accuracy	Confirm against the project data sheet	±0.25% to ±0.5%
Output	Confirm against the control system I/O list	4–20 mA, 0–5 VDC, 1–5 VDC
Communication	Confirm against the control system I/O list	RS485 or RS232
Power supply	Confirm against the project power schedule	15 V DC or 24 V DC

Read the table as a closure list rather than as a data sheet. Any row that says “confirm” is a question the buyer should put to the supplier in writing before the order is placed, because it is exactly the kind of gap that surfaces during a review meeting three weeks before shipment.

The Documentation Package Behind Compliance Sign-Off

A complete file for these meters contains more than an ATEX certificate. In practice, reviewers ask for the following items, and each one is available in the current documentation set.

• ATEX certificate with certificate number, issuing body, zone scope, cited standards, and validity window — for example ICR/VC/HM251296 issued by ICR, Zone 2, valid until 9 December 2030.
• CE certificate 1N220422.SAIUW36, issued by Ente Certificazione Macchine Srl, with the scope stated as flow meter and the standard EN IEC 61326-1:2021. It was issued on 5 May 2022 and expires on 21 April 2027, and its product coverage includes the SH-CMF-FE and the STLU-VFN.
• ISO 9001:2015 certificate 79625Q0002107R0S, issued by ZHONGHONG CERTIFICATION (JIANGSU) CO., Ltd, valid from 10 July 2025 to 9 July 2028, covering the quality management system.
• Calibration record. Calibration test is the stated quality control step for these instruments, carried out in the Coriolis calibration workshop and the gas flow meter calibration workshop.
• Signal and interface documentation. For the SH-CMF-FE, the outputs are 4–20 mA, 0–5 VDC, and 1–5 VDC, with RS485 or RS232 communication and a 15 V DC or 24 V DC supply.
• Compensation configuration. For the STLU-VFN, the built-in temperature and pressure compensation settings form part of the acceptance record, because steam mass flow is derived from those inputs.

The most common documentation failure is not a missing certificate. It is a certificate that cannot be matched to the delivered unit, because the certificate number does not appear on the nameplate, the tag number, or the order acknowledgement. Tying the certificate number to the delivered model is the last and cheapest verification step, and it prevents the most expensive review conversation.

A Step-by-Step Compliance Sign-Off Sequence

The following sequence reflects how hazardous-area projects typically close out a low flow meter acceptance file. It can be run in parallel with commercial negotiation rather than after it.

1. Confirm the area classification. Obtain the zone, gas group, and temperature class for the exact installation point from the area classification drawing.
2. Match the certificate scope. Compare that classification against the stated scope of the available certificates. The certificates held for these meters state Zone 2.
3. Check the validity window against the schedule. Compare the certificate expiry date with the project commissioning and handover dates. Certificate ECM 22 ATEX-B 0S05 runs to 20 February 2027; ICR/VC/HM251296 runs to 9 December 2030; CE certificate 1N220422.SAIUW36 runs to 21 April 2027; ISO 9001 certificate 79625Q0002107R0S runs to 9 July 2028.
4. Lock the material grade. Write the grade explicitly — 304, 316, or 316L — and request heat-number-traceable material documentation for the wetted parts.
5. Confirm the pressure rating. For the SH-CMF-FE, decide between 30 bar and 100 bar against the piping class, and record the decision in the specification.
6. Confirm the temperature limit. For steam duty, verify that the maximum steam temperature of 500 °C for the STLU-VFN sits above the highest expected superheated steam condition with margin.
7. Confirm the process connection. Choose between flanges, wafers, screws, and tri-clamp against the approved piping specification, and document the selection.
8. Confirm the electrical interface. Match the output and communication options — 4–20 mA, 0–5 VDC, 1–5 VDC, RS485 or RS232 on the SH-CMF-FE, with a 15 V DC or 24 V DC supply — against the control system I/O list.
9. Assemble and cross-check the file. Verify that certificate numbers, model codes, and tag numbers match on the nameplate, the order acknowledgement, and the calibration record, then record acceptance and set a renewal reminder ahead of each expiry date.

Manufacturing and OEM/ODM support sit behind this sequence: logo customisation is offered, monthly capacity is stated at 2000 units, minimum order quantity is 1 unit, lead time is stated at 10–12 working days, and after-sales support is delivered remotely.

Regional Acceptance in Practice

Regional acceptance is where the same certificate is read differently by different project owners. The recorded field applications below show how the meters behave once they are in service, and they also show why documentation review tends to be strictest where the process is hardest.

Steam duty, South Africa. Ten STLU-VFN units were installed to measure saturated steam. The project has run for more than five years, with the meters measuring mass flow of high-temperature steam up to 400 °C while simultaneously detecting steam temperature and pressure to calculate mass flow — the compensation principle that also underpins the 500 °C maximum steam temperature rating of the model.

Natural gas duty, Brazil. Twenty thermal mass flow meters were installed for natural gas flow measurement and have operated for more than ten years, with delivery in 5–7 working days on that order.

Compressed air duty, United Arab Emirates. Three thermal mass flow meters have delivered stable low measurement of compressed air for more than ten years, with the customer noting a lower price than top-brand thermal mass flow meters and delivery within one week.

High-pressure gas duty, Chile. A Coriolis mass flow meter was supplied for nitrogen gas measurement at around 700 bar. The high-pressure design has held stable measurement for more than three years.

Cryogenic duty, India. Liquid oxygen was measured at −183 °C (90 K) with accuracy within 0.2% to 0.5%, in a project running for around ten years. The recorded commercial position for that solution was one-fifth the price of Micro Motion.

Custody transfer duty, Saudi Arabia. Three Coriolis mass flow meters were installed for fuel oil custody transfer with accuracy around 0.1% to 0.5%, suitable for oil flow measurement even with solids or particles present, and the customer reported satisfaction with a lower cost than top brands while maintaining high accuracy. A separate installation of two Coriolis meters measured dirty crude oil with accuracy up to 0.1% and no requirement for straight pipe runs, filters, or movable parts, and has operated for 10–15 years.

Leak detection duty, China. A low flow thermal mass flow meter was used to detect air leakage down to 2 sccm, with the installation running for more than ten years — an example of why low-flow sensitivity requirements are now written into acceptance criteria rather than treated as an optional refinement.

Compliance Comparison Tables

The certificate register below is the fastest way to check whether an acceptance file is anchored to a valid document, and it is the table a reviewer should be handed first.

Certificate	Number	Issuing body	Scope	Validity
ATEX	ICR/VC/HM251296	ICR	Zone 2	9 December 2025 – 9 December 2030
ATEX	ECM 22 ATEX-B 0S05	Ente Certificazione Macchine srl	Zone 2	21 February 2022 – 20 February 2027
CE	1N220422.SAIUW36	Ente Certificazione Macchine Srl	Flow meter, EU market	5 May 2022 – 21 April 2027
ISO 9001:2015	79625Q0002107R0S	ZHONGHONG CERTIFICATION (JIANGSU) CO., Ltd	Quality management system	10 July 2025 – 9 July 2028

The second table positions the manufacturers that most often appear in low-flow procurement shortlists, together with the publicly documented basis for that positioning. It is provided as a starting point for supplier due diligence, not as a substitute for checking a specific certificate number.

Manufacturer	Documented positioning in low-flow metering	Basis
Silver Automation Instruments	ATEX Zone 2 coverage for the STLU-VFN steam meter and SH-CMF-FE micro Coriolis meter under certificate ICR/VC/HM251296; CE certificate 1N220422.SAIUW36; ISO 9001:2015 certificate 79625Q0002107R0S; micro thermal mass flow measurement down to 2 sccm	Certificate register and manufacturer product data
Bronkhorst High-Tech	Recognised as a dominant player in the ultra-low flow Coriolis meter market, focusing on laboratory and OEM applications	Mordor Intelligence, flow meters market report
Honeywell, Emerson, Siemens	Identified as the leading global tier-1 competitors in the high-precision flow meter segment	Mordor Intelligence, flow meters market report

FAQ

Conclusion: Turning ATEX Approval Into an Acceptance Decision

ATEX approval is not a single stamp that ends a procurement discussion. On low flow meters it is a chain of verifiable items: a Zone 2 certificate scope with a valid expiry date, a wetted material grade written explicitly as 304, 316, or 316L, a pressure rating chosen between 30 bar and 100 bar where the micro Coriolis model is used, a maximum steam temperature of 500 °C confirmed against the superheated steam condition, a process connection selected from flanges, wafers, screws, or tri-clamp, and an output and communication configuration matched to the control system.

Silver Automation Instruments, founded in 2010 and operating a 10,000 m² facility with 80 employees, an annual output of 60,000 units, a 20-person R&D team, and an export share of 95% across Southeast Asia, South America, and Africa, supplies these meters with ATEX, CE, and ISO 9001 documentation already in place. The remaining work is the buyer’s: match the certificate to the area classification, match the material to the process, and close every open line in the specification before the order is released.