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KENYA STANDARD KS 2255: 2010 ICS ....

Mixtures of copper-chromium-arsenic compounds for wood preservation

PUBLIC REVIEW DRAFT, JULY 2010

KEBS 2010 First Edition 2010

KS 2255: 2010

ii KEBS 2010 All rights reserved

TECHNICAL COMMITTEE REPRESENTATION

The following organizations were represented on the Technical Committee:

Howard Humphreys Pest Control and Products Board Mangat I.B Patel & Partners Moi University Timber Treatment Institute Jomo Kenyatta University of Agriculture and Technology Timsales Ltd Kenya Power and Lighting Company Ltd. Harley Timber Engineering Services Ltd Ministry of Roads (Materials Branch) Cabro E.A Ltd Kenya Institute of Highways and Building Technology Ministry of Public Works Kenya Bureau of Standards Secretariat

REVISION OF KENYA STANDARDS

In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed. Suggestions for improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are welcome.

Kenya Bureau of Standards, 2009

Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 12 of 2001 of the Laws of Kenya, copyright subsists in all Kenya Standards and except as provided under Section 26 of this Act, no Kenya Standard produced by Kenya Bureau of Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing from the Managing Director.

KENYA STANDARD KS 2255: 2010 ICS .

KEBS 2010 All rights reserved iii


KENYA BUREAU OF STANDARDS (KEBS)

Head Office: P.O. Box 54974, Nairobi-00200, Tel.: (+254 020) 605490, 602350, Fax: (+254 020) 604031 E-Mail: [email protected], Web:http://www.kebs.org

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KS 2255: 2010

iv KEBS 2010 All rights reserved

Foreword

This Kenya Standard was prepared by the Timber and Wood poles Technical Committee under the guidance of the Standards Projects Committee, and it is in accordance with the procedures of the Kenya Bureau of Standards.

This standard calls for the use of substances that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage.

Attention is drawn especially to the hazardous nature of the formulations and their solutions. Particular care and the use of appropriate protective clothing is necessary. Special precautions are required for the disposal of solutions

During the preparation of this standard, reference was made to the following documents:

SANS 673 Mixtures of copper-chromium-arsenic compounds for timber preservation

BS 4072: 1999 copper/chromium/arsenic preparations for wood preservation

Acknowledgement is hereby made for the assistance derived from these sources.

KENYA STANDARD KS 2255: 2010

KEBS 2010 All rights reserved 1


1 Scope

This Kenya Standard specifies requirements for two types of waterbone preservatives containing mixtures of compounds of copper (II), chromium (VI) and arsenic (V) for application to timber to protect it against attack in service by wood - destroying organisms

2 Normative references

The following referenced documents are indispensable for the application of this Kenya Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

KS 09 1084-1 pH measurement - Part 1: Specification for laboratory pH meters KS 09 1084-2 Kenya Standard pH measurement - Part 2: Specification for pH scale ISO 4793 Laboratory sintered (fritted) filters -- Porosity grading, classification and designation ISO 1042 Laboratory glassware -- One-mark volumetric flasks KS 09 1084-4 Specification for glass and reference electrodes for the measurement of pH BS 2648 performance requirements for electrically-heated laboratory drying ovens BS EN 212 Wood preservatives. General guidance on sampling and preparation for analysis of wood

preservatives and treated timber BS 5666-3 Methods of analysis of wood preservatives and treated timber. Quantitative analysis of

preservatives and treated timber containing copper/chromium/arsenic formulations KS ISO 3696 Water for analytical laboratory use - Specification and test methods

3 Definitions

For the purposes of this standard, the following definitions shall apply:

3.1 batch the material from a single mix or, in the case of a continuous production process, the material from a single day's production

4 composition

4.1 raw materials The preservatives shall consist of a mixture of compounds of copper (II), chromium (VI) and arsenic (V)

Note 1 The preferred mixtures of compounds are as follows

a) copper (II) sulphate, sodium dichromate and hydrated arsenic (V) oxide; b) copper (II) oxide, chromium (VI) oxide and arsenic (V) oxide

Note 2 minor additives are permitted

4.2 Formulations

Two formulations are specified (designated type 1 and type 2, respectively) The nominal proportion and the minimum proportion of each component in the preservative formulation shall be as specified in Table 1

The sum of the proportions of the individual components shall be not less than 95 %( m/m)

Note 1 variations in composition from the nominal composition can arise because of variations in the purity of the ingredients of the mixture

The preservatives shall be supplied as mixtures

KS 2255: 2010


Note 2 the usual forms are as a paste or as a concentrated solution for subsequent dilution Note 3 preservatives as supplied can vary in concentration as a result of variations in water content

The containers in which the preservatives are supplied shall carry information on the mass of the preservative mixture equivalent to unit mass of the preservative formulation as specified in Table 1, as applicable.

Table 1 nominal and minimum proportions of compounds of components in formulations based on metal oxides

component Type 1 preservatives Type 2 preservatives Nominal % m/m Minimum % m/m Nominal % m/m Minimum % m/m

Copper (as CuO) 17.10 15.5 19.10 17.20 Chromium (as CrO3)

45.3 40.9 51.40 46.30

Arsenic (as As2O5) 37.6 33.5 29.50 26.60

5. Sampling

the preservative mixture shall be sampled in accordance with BS EN 212

6. Insoluble matter

when tested in accordance with annex A, the content of insoluble matter in the preservative mixture shall not be more than 0.1% (m/m)

7. pH value of solution

When tested in accordance with annex B the pH value of a solution containing the equivalent of 12g/L of the oxide based preservative formulation , shall be in the range of 1.8 2.8

8. Analysis

The copper, chromium and arsenic contents of th preservative mixture shall be determined in accordance with BS 5666-3 on a sample prepared in accordance with BS EN 212

9 Packing and marking 9.1 Packing

Only material from the same batch shall be packed in a container.

9.2 Marking

Each container shall bear in prominent, legible and indelible marking, the following information and any additional information required in terms of the relevant national and statutory regulations: a) The manufacturer's name or trade mark or both; b) the form that the mixture is supplied in; c) the net mass or net volume (or both) as applicable, of the contents; d) the concentrations of the active elements; e) the chemical form of each constituent; f) instructions for dilution; g) the batch identification; h) the date of manufacture.

KS 2255: 2010

KEBS 2010 All rights reserved

3

Annex A (normative)

Determination of insoluble matter

A.1 Reagent

A.1.1 Water, conforming to grade 3 as specified in KS ISO 3696: 1995.

A.2 Apparatus

Ordinary laboratory apparatus, together with the following.

A.2.1 Sintered glass filter, pore size index P40 conforming to ISO 4793

A.2.2 Laboratory drying oven, capable of being adjusted to (105 5) oC, conforming to BS 2648.

A.2.3 One-mark volumetric flask, 500 ml capacity, conforming to ISO 1042.

A.2.4 Analytical balance.

A.3 Preparation of test portion

Place a sintered glass filter (A.2.1) in the drying oven (A.2.2) previously adjusted to (105 5) oC. Dry for a period of 1 h, transfer to a desiccator and allow to cool to room temperature. Weigh the filter then repeat the drying, cooling and weighing operations until the difference between two successive weighings is not greater than 0.5 mg.

Take a mass of the preservative sample which contains the equivalent of (6 0.1) g of the oxide based formulation and weigh it to the nearest 0.001 g. Transfer this test portion to a beaker and dissolve it in 250 ml of warm water (not exceeding 40 oC), stirring continuously. Allow the solution to cool to room temperature and filter it though the pre-weighed sintered glass filter into a 500 ml one-mark volumetric flask (A.2.3). Wash the beaker and the residue five times with (10 1) ml portions of warm water (not exceeding 40 oC), collecting the washings in a clean beaker. Allow the washings to cool to room temperature and then quantitatively transfer the washings to the 500 ml flask. Dilute to the mark with water (A.1.1) and reserve for the determination of the pH value (see annex B).

A.4 Determination

Transfer the sintered glass filter containing the residue from A.3 to the drying oven (A.2.2) previously adjusted to (105 5) oC. Dry for a period of 1 h, transfer to a desiccator and allow to cool in the desiccator to room temperature. Weigh the filter then repeat the drying, cooling and weighing operations until the difference between two successive weighings is not greater than 0.5 mg.

A.5 Calculation

Calculate the quantity of insoluble matter in the preservative mixture (M) as a percentage by mass (% m/m) using the following equation:

1003

12

=

m

mmM

where m1 is the mass of the dried sintered glass filter in grams (g);

m2 is the mass of the sintered glass filter and residue after drying in grams (g);

m3 is the mass of the test portion (see A.3) in grams (g).

KS 2255: 2010


Annex B (normative)

Determination of pH

B.1 Reagent

B.1.1 Water, conforming to grade 3 as specified in KS ISO 3696: 1995.

B.2 Apparatus

Ordinary laboratory apparatus, together with the following:

B.2.1 Sintered glass filter, pore size index P40 conforming to ISO 4793

B.2.2 pH meter, conforming to KS 09 1084-1, fitted with electrodes conforming to KS 09 1084-4

B.2.3 One-mark volumetric flask, 500 ml capacity, conforming to ISO 1042.

B.2.4 Analytical balance.

B.3 Preparaiton of test solution

Follow the procedure described in A.3 to obtain a test solution of the preservative in a 500 ml one-mark volumetric flask.

NOTE If the pH value alone is to be determined, there is no necessity to dry and weigh the sintered glass filter.

B.4 Determination

Determine the pH of the test solution prepared in accordance with A.3 at (20 1) oC using the pH meter (B.2.2) in accordance with the procedure described for accuracy class 0.3 given in KS 09 1084-2, B.4.

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