🌿 Hydrogen chloride in workplace air — absorption in water, silver nitrate and turbidity measurement (turbidimetry), PN-Z-04225-03

Environment PN-93/Z-04225/03

Overview

WHAT THE STANDARD COVERS. The scope from the PKN catalogue card, quoted in full: "Hydrogen chloride is absorbed in a scrubber with water. Silver nitrate is added to the solution and the turbidity of the resulting silver chloride suspension is examined. The determination is interfered with by chlorine, bromine, hydrogen bromide, iodine, hydrogen iodide, sulphides and hydrogen sulphide. The method can be used in stationary measurements and in personal dosimetry. The determinability of the method is 1.25 mg in 1 cubic metre of air." The card's Polish text contains the typo "pochłaniania się".

STATUS (state of the card on 29 September 2026). The card carries the heading "Withdrawn" and the row "Date of withdrawal: 15-08-2014". There is no "Superseded by" field. Edition: published 26-03-1993, 2 pages, PKN technical committee KT 159 (Chemical and Dust Hazards in the Working Environment), ICS 13.040.30; "Supersedes: PN-Z-04049:1957 - Polish version". The PKN search for "PN-Z-04225" (29 September 2026) shows three sheets of the series — 01 (general provisions), 02 (turbidimetric method with sampling on filter papers) and 03 — all labelled "Withdrawn". Hydrogen chloride at workplaces is covered by the current PN-Z-04450:2014-08 "Air purity protection — Determination of hydrogen chloride at workplaces by the turbidimetric method with sampling on filters" (card without a withdrawal note; published 01-08-2014, 8 pages, KT 159; determinability 0.5 mg/m³; the method is not used in the presence of chlorine, bromine, hydrogen bromide, iodine, sulphides and hydrogen sulphide). The card of PN-Z-04225-03 does not indicate it as the successor — whether it is, WE HAVE NOT ESTABLISHED; PN-Z-04450 has a separate entry in this knowledge base.

LIMIT VALUES AND THE REGULATION ON THE METHOD. The NDS list — the annex to the regulation of 12 June 2018 as worded by the regulation of 26 March 2026 (Journal of Laws 2026 item 447), item 119 "Hydrogen chloride" [7647-01-0]: NDS (8-hour value) 5 mg/m³, NDSCh (short-term value) 10 mg/m³, without the "skin" notation. The determinability from the card (1.25 mg/m³) is one quarter of the NDS. The method is addressed by § 16 of the Regulation of the Minister of Health on tests and measurements of agents harmful to health in the working environment (consolidated text — Journal of Laws 2025 item 949): "Tests and measurements shall be carried out in accordance with the methods specified in Polish Standards and, where there are no such standards, with methods recommended and validated by the laboratories referred to in § 15(1) and (2)(1)" (our translation). The regulation does not name this standard; whether a standard withdrawn by PKN falls under § 16 when a current PN-Z-04450:2014-08 exists for hydrogen chloride — WE DO NOT DECIDE.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17 September 2026, read on 28 September 2026). All records of number 04225 with sheet 03: 15 entries at 13 laboratories. Forms: "PN-93/Z-04225/03" — 10 laboratories (at AB 719 with procedure PA-02; AB 949 in one entry "clause 7 and clause 10", in the other with a space "PN-93/Z- 04225/03 excluding clause 7"), "PN-93-Z-04225.03" — AB 552, "PN–93/Z–04225/03" with en dashes — AB 591, "PN-Z-04225-03:1993" — AB 877. The "Laboratories" tab searches for records BEGINNING with "PN-93/Z-04225/03" and will show 10 laboratories — checked with the tab query on the labcoda.pl production server on 29 September 2026: 10; AB 552, AB 591 and AB 877 remain outside it. AB 877 applies the standard outside the working environment — to "waste gas samples collected into scrubbers with an absorbing solution" (mass 0.025–5.00 mg in the sample); the card speaks of workplaces. Current scopes on the PCA website (read on 29 September 2026, issues from 29 October 2025 to 9 September 2026): all entries stand in the valid issues and every numerical range from the copy appears in the current document. Both entries of AB 949 (issue no. 22 of 9 September 2026) are suspended: footnote "*) Accreditation suspended at the request of the body in the part of the scope marked in bold italics from 09.09.2026 to 08.03.2027" (our translation).

TECHNIQUE AND RANGES. Nine laboratories record the technique as the "turbidimetric method", and four (AB 489, AB 591, AB 949, AB 964) as the "spectrophotometric method". Lower limits in mg/m³: from 0.4 (AB 591, AB 865) and 0.42 (AB 1287) through 0.5 (AB 489, AB 552, AB 581, AB 964, AB 1004) to 0.625 (AB 886) and 1.25 (AB 949 — exactly the determinability from the card); AB 886 and AB 949 start above one tenth of the NDS (0.5 mg/m³). Upper: from 12.5 (AB 552, AB 886, AB 949) to 125 mg/m³ (AB 1004) — at all of them above the NDSCh. AB 409 has an entry in a flexible scope, without a numerical range; AB 719 and AB 877 give only the mass of hydrogen chloride in the sample, and AB 719 describes the samples as collected "on filters or into scrubbers with an absorbing solution".

ALONGSIDE THIS STANDARD. For hydrogen chloride at workplaces the copy has, apart from this standard (full list): PN-Z-04450:2014-08 — 17 laboratories (AB 340, AB 418, AB 438, AB 481, AB 484, AB 647, AB 746, AB 782, AB 821, AB 849, AB 861, AB 882, AB 1226, AB 1261, AB 1642, while AB 886 and AB 935 write "PN-Z-04450:2014"); the NIOSH 7907 method (Issue 1, 2014) — AB 632 (with instruction IB-68), AB 802, AB 869 and AB 1302; ISO 21438-2:2024 with procedure PB-09A — AB 1207; procedure PB 089 — AB 875; the general records "Normy" (standards) (AB 412) and "Normy, Procedury badawcze" (standards, test procedures) (AB 934). AB 886 has both this standard and PN-Z-04450 in its scope.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN sells it (2 pages). We do not give the volume of water in the scrubber, the air flow and volume, the concentration of silver nitrate, the wavelength, the calibration curve, the formula or the precision; we do not know what clauses 7 and 10 contain, which AB 949 cites for the concentration and excludes for the mass in the sample.

Method principle

According to the card of the standard, hydrogen chloride from workplace air is absorbed in a scrubber with water, silver nitrate is added to the solution and the turbidity of the resulting silver chloride suspension is measured; chlorine, bromine, hydrogen bromide, iodine, hydrogen iodide, sulphides and hydrogen sulphide interfere. The method is suitable for stationary measurements and personal dosimetry, and its determinability is 1.25 mg/m³. The result is compared with the NDS of 5 mg/m³ and the NDSCh of 10 mg/m³ (Journal of Laws 2026 item 447, item 119). We DO NOT GIVE the volumes, reagent concentrations or measurement conditions — we did not have the text of the standard.

Applications

• Measurements of hydrogen chloride in workplace air — stationary and personal dosimetry (from the card); assessment against the NDS of 5 mg/m³ and the NDSCh of 10 mg/m³ (Journal of Laws 2026 item 447, item 119)
• In accreditation scopes: 13 laboratories; the current PN-Z-04450:2014-08 (sampling on filters) is cited by 17 laboratories

Key parameters

Standard

Standard number

PN-Z-04225-03:1993 (wersja polska)

Title (PL)

Ochrona czystości powietrza — Badania zawartości chlorowodoru — Oznaczanie chlorowodoru na stanowiskach pracy metodą turbidymetryczną z pobieraniem próbek do płuczek

Title (EN)

Air purity protection — Tests for hydrogen chloride content — Determination of hydrogen chloride at workplaces by the turbidimetric method with sampling into scrubbers

Step-by-step procedure

1. Status of the document

   PKN card: standard withdrawn on 15-08-2014, no successor indicated (state of the card on 29 September 2026); the current PN-Z-04450:2014-08 takes samples on filters.

2. Sampling

   Air is passed through a scrubber with water; stationary measurement or personal dosimetry (from the card).

3. Reaction

   Silver nitrate is added to the solution; a silver chloride suspension forms (from the card).

4. Measurement

   Measurement of the turbidity of the suspension; determinability 1.25 mg/m³ (from the card). Chlorine, bromine, hydrogen bromide, iodine, hydrogen iodide, sulphides and hydrogen sulphide interfere.

5. Result and assessment

   The concentration in mg/m³ is compared with the NDS of 5 mg/m³ and the NDSCh of 10 mg/m³.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Silver nitrate is corrosive and stains the skin — its safety data sheet applies
• SUBSTANTIVE NOTE: chlorine, bromine, iodine, their hydrides, sulphides and hydrogen sulphide in the air bias the result upwards — in their presence a result by this method does not distinguish hydrogen chloride from these substances

Frequently asked questions