NZQA Expiring unit standard 21760 version 4 Page 1 of 10
Title Treat wood by the diffusion process
Level 4 Credits 10
Purpose People credited with this unit standard are able to: demonstrate and apply knowledge of the principles of diffusion treatment and NZS 3640 specification requirements; demonstrate knowledge of the operation of diffusion treatment plants; identify, explain and apply safety and security requirements for diffusion plants and storage sites; assess the treatment suitability of wood for diffusion treatment and prepare preservative solutions; operate the diffusion treatment plant and monitor plant performance and product treatment adequacy; maintain approved diffusion storage conditions; complete documentation and records for wood treatment by diffusion and analyse records to improve productivity; assess and confirm wood treatment performance and identify complying product; and apply maintenance requirements for diffusion treatment plants.
Classification Solid Wood Manufacturing > Timber Drying and Treatment
Available grade Achieved
Entry information
Recommended skills Unit 155, Demonstrate knowledge of the properties of wood; and knowledge Unit 156, Demonstrate knowledge of phytosanitary standards in the wood manufacturing industry; Unit 159, Demonstrate knowledge of environmental issues in wood manufacturing industries; Unit 736, Demonstrate knowledge of physical characteristics of wood; Unit 8339, Demonstrate knowledge of the principles of wood preservation and antisapstain treatment; and Unit 16240, Interpret legislative requirements and workplace compliance relating to wood preservation operations; Unit 21761, Treat wood with antisapstain chemicals.
Explanatory notes
1 Range diffusion – spray, dip, pressure; evidence is required of one process application.
Competenz Ó New Zealand Qualifications Authority 2018 SSB Code 101571 NZQA Expiring unit standard 21760 version 4 Page 2 of 10
2 Important: Personnel interpreting spot tests using boron compounds must not be colour blind.
3 All evidence requirements must be demonstrated and assessed in accordance with the reference text Demonstrate Knowledge of Wood Preservation, published by COMPETENZ and available from COMPETENZ at http://www.competenz.org.nz, or COMPETENZ, PO Box 137067, Parnell, Auckland 1151.
4 References Competence in this unit standard requires knowledge of the following: a NZS 3640:2003A1 Chemical Preservation of Round and Sawn Timber Amendment 1. This is referred to below as ‘NZS 3640’, and is available from Bennett’s Government Bookshops or online at http://www.standards.co.nz. b New Zealand Timber Preservation Council, Timber Preservation Quality Manual (Wellington, 2005). This is referred to below as the ‘TPQM’. c Best Practice Guideline for the Safe Use of Timber Preservatives and Anti- sapstain Chemicals (Wellington, 2005). This is referred to below as the ‘Guideline’. These last two references are available through the New Zealand Timber Preservation Council, Wellington or online at http://www.nztpc.co.nz.
5 The following apply to the performance of all outcomes of this unit standard: a All work practices must meet recognised codes of practice and documented worksite health and safety and environmental procedures (where these exceed the code) for personal, product and worksite health and safety, and must meet the obligations required under current legislation, including the Hazardous Substances and New Organisms Act 1996, the Health and Safety in Employment Act 1992, the Resource Management Act 1991, and their subsequent amendments. b All work practices must meet documented worksite operating procedures. This includes the recording (by electronic or non-electronic means) of activities, events, and decisions. c All evidence of communications gathered in relation to this unit standard must be in accordance with worksite procedures for content, recipient, timing and method.
6 Definitions Biological degradation refers to damage caused by insects, mould, sapstain, decay fungi, internal brown stain. Corrective action referred to in outcome 1 may include communication to management, communication to on-site technical person, communication to off-site technical support person, cleaning, communication with maintenance staff, recalibration, or changes made to the operating system in accordance with worksite documentation. Efficacy is defined as being capable of or successful in producing an intended result. Optimise refers to improving productivity and product quality. Worksite policies and procedures refer to documented policies and to documented or other directions provided to staff. These include, but are not limited to, ways of managing health and safety, environmental considerations, quality, and production, and must conform to legislation. Examples include standard operating procedures, company health and safety plans, on-site briefings, and supervisor’s instructions.
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Outcomes and evidence requirements
Outcome 1
Demonstrate and apply knowledge of the principles of diffusion treatment and NZS 3640 specification requirements.
Evidence requirements
1.1 Principles of the diffusion process and how preservatives diffuse into wood are explained.
1.2 Diffusion treatment application methods used in New Zealand are identified and the advantages and limitations of each method are explained.
Range dip, spray, pressure.
1.3 Factors which influence successful diffusion treatment are explained in terms of their effects.
Range factors may include but is not limited to – moisture content, species, wood source and density, surface condition, wood thickness, stock rotation, delays between cutting and treating, solution concentration and temperature, fungicidal additives, solution agitation, contamination, preservative coverage, weather factors, seasonal temperatures, strapping tightness, handling factors, diffusion storage, storage conditions, storage duration, compliance testing. Evidence of eight is required.
1.4 Preservative formulations used at the plant are identified and their properties and uses explained.
Range formulations – boron compounds, mouldicides and or anti- sapstains, dye additives; properties – solubility and permanence.
1.5 Preservative efficacy is explained.
Range preservatives may include but are not limited to – boron compounds, mouldicides and/or anti-sapstains.
1.6 The effects of contaminants on the efficacy of treatment solutions are described.
Range contaminants include but are not limited to – wood extractives, hydraulic fluid, sawdust.
1.7 Treatment specification requirements for diffusion processes are referenced and explained in accordance with NZS 3640, TPQM, and the Guideline.
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Outcome 2
Demonstrate knowledge of the operation of diffusion treatment plants.
Evidence requirements
2.1 The role, scope and responsibilities of the diffusion treatment plant operator are described in accordance with worksite policies and procedures.
2.2 Operating parameters, capability and capacity of the on-site treatment plant are explained.
Range may include but is not limited to – plant design and layout, proximity to diffusion storage area, preservative solution storage capacity, diffusion storage capacity, packet build and length, throughput capability.
2.3 Factors for consideration when scheduling diffusion treatment to improve productivity and quality are explained.
Range may include but is not limited to – species, process, product suitability, thickness and availability, preparation, treatment, storage times, preservative stock levels, diffusion storage availability and capacity, resources.
2.4 Operating components of the diffusion treatment plant and their function and sequence of operation are explained in accordance with the Guideline and worksite policies and procedures.
Range may include but is not limited to – control panels and mechanisms, automatic and manual control systems, preservative mixing, storage, treatment tanks, transfer pump(s), agitation mechanisms, valves, pipe work linkages, filters, temperature gauge(s), volume measuring devices, air compressor, spray nozzles, live conveyor systems and controls, heat sources and controls, solution containment safeguards, warning devices.
2.5 Plant control and product testing equipment is identified, its serviceability confirmed, and its use explained in accordance with the TPQM and worksite policies and procedures.
Range may include but is not limited to – hydrometer, refractometer, thermometer, indelible pencil, solution concentration determination references, titration, temperature gauge certification, spot test solutions (storage and viability requirements confirmed).
2.6 Storage and handling requirements before and after treatment are identified and explained in accordance with worksite policies and procedures.
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2.7 Documentation and charge sheet record requirements are identified and their use explained in accordance with the TPQM and worksite policies and procedures.
Range charge sheets, reconciliation statements, sampling summaries, production log books, analytical records.
Outcome 3
Identify, explain and apply safety and security requirements for diffusion plants and storage sites.
Evidence requirements
3.1 Hazardous areas on the treatment site and safety and security measures required are identified, and risks explained, in accordance with legislative requirements, the Guideline, and worksite policies and procedures.
Range may include but is not limited to – warning signs and symbols, authorised access areas, spray booths and/or dip tanks, chemical storage areas, chemical handling and mixing areas, fumes, operational mobile machinery, diffusion storage stacking, sample taking.
3.2 Risk factors associated with preservative formulations and fungicidal or insecticidal additives used on the worksite and the safeguards required are explained in accordance with Material Safety Data Sheets (MSDS), the Guideline, and worksite policies and procedures.
3.3 Environmental hazards associated with chemicals in the treating of wood by the diffusion process are identified and the management of risks are explained in accordance with the Guideline and worksite policies and procedures.
3.4 Safe operating and housekeeping requirements are explained in accordance with the Guideline, legislative requirements and worksite policies and procedures.
Range may include but is not limited to – safe operating practices, codes of conduct and personal hygiene, appropriate protective clothing and equipment, chemical and product handling, MSDS for each preservative, eye wash, emergency shower, first aid facilities, emergency procedures.
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Outcome 4
Assess the treatment suitability of wood for diffusion treatment and prepare preservative solutions.
Evidence requirements
4.1 Pre-treatment suitability of the product is assessed and confirmed in accordance with the TPQM requirements, and non-conforming product is removed, in accordance with worksite policies and procedures.
Range includes but is not limited to – approved species, product characteristics, surface condition, moisture content and moisture gradient, dimensional thickness, biological degradation, pre- cutting, machining, strapping tightness, packet build and length, product/unit identification.
4.2 Working tank solution is prepared for preservative concentration testing in accordance with worksite policies and procedures.
Range may include but is not limited to – agitation, operating temperature.
4.3 Representative solution samples are taken and tested in accordance with the TPQM and worksite policies and procedures.
Range may include but is not limited to – prior to, during and on completion of the treatment process.
4.4 Factors affecting the accuracy of solution concentration measurements are identified and corrective action is taken in accordance with worksite policies and procedures.
Range may include but is not limited to – operator technique, solution contaminants, aerated solution, inaccurate instruments, correction factors, equipment cleanliness, incorrect references.
4.5 Required solution concentration is calculated from test results and adjusted for seasonal, wood density, and surface condition factors.
4.6 Working tank is adjusted with required amounts of solution concentrate and water to meet production run requirements in accordance with worksite policies and procedures.
Range preservative, mouldicide/antisapstain, dye additives.
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Outcome 5
Operate the diffusion treatment plant and monitor plant performance and product treatment adequacy.
Evidence requirements
5.1 Operational factors influencing successful treatment performance are explained and applied.
Range includes but is not limited to – solution concentration, temperature, maintenance parameters, board coverage, immersion times and agitation, seasonal and weather factor adjustments and safeguards, handling factors, solution pick-up.
5.2 Process is operated and controlled, and plant control equipment is used, in accordance with manufacturer’s operating procedures and worksite policies and procedures.
5.3 Product and plant performance and weather influences are monitored, and corrective action taken, in accordance with the TPQM and worksite policies and procedures.
5.4 Equipment faults and malfunctions in the process cycle are identified, and corrective action is taken, in accordance with worksite policies and procedures.
Range includes but is not limited to – electrical, hydraulic, mechanical, spillage, temporary suspension of treatment, plant shutdown.
5.5 Treated product is held on the designated drip area for the prescribed time prior to removal to diffusion storage in accordance with the Guideline and worksite policies and procedures.
Outcome 6
Maintain approved diffusion storage conditions.
Evidence requirements
6.1 Factors affecting successful diffusion are identified, explained and applied.
Range may include but is not limited to – storage timeliness, air tightness, void spaces, wood density and growth factors, heartwood and sapwood, temperature, moisture content, seasonal factors.
6.2 Diffusion period is calculated with adjustments made for slow diffusing material in accordance with worksite policies and procedures.
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Outcome 7
Complete documentation and records for wood treatment by diffusion and analyse records to improve productivity.
Evidence requirements
7.1 Charge sheets are progressively completed, and charge performance comments entered and held, in accordance with the TPQM and worksite policies and procedures.
Range evidence is required of 12 recently completed charge sheets.
7.2 Reconciliations are completed and processed in accordance with the TPQM and worksite policies and procedures.
7.3 Records are completed in accordance with worksite policies and procedures.
Range may include but is not limited to – production log books, accident registers, production summaries, sampling summaries, analytical records.
7.4 Treatment documents and operations are analysed and corrective action taken to improve productivity.
Range may include but is not limited to – chemical usage, product factors, out of specification product, operator training or assistance, production scheduling, control factors, waste minimisation.
Outcome 8
Assess and confirm wood treatment performance and identify complying product.
Evidence requirements
8.1 Treatment compliance is determined from charge sheet results and product testing at the end of the diffusion period in accordance with NZS 3640 specifications and TPQM requirements.
Range may include but is not limited to – charge sheet details, correct product sampling prescription applied, valid test samples collected and prepared, correct application and interpretation of spot test results, accurate results recording, charge samples are batched, labelled and held for audit purposes as required.
8.2 Compliance branding or labelling is undertaken in accordance with NZS 3640 specifications.
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8.3 Non-conforming product is isolated and further options applied in accordance with TPQM and worksite policies and procedures.
Range non-complying product identification, extended diffusion period, drying, re-treatment, non-conformance investigation.
Outcome 9
Apply maintenance requirements for diffusion treatment plants.
Evidence requirements
9.1 Routine and preventative maintenance and cleaning requirements are explained and applied in accordance with the Guideline and worksite policies and procedures.
Range may include but is not limited to – plant maintenance log books, plant and equipment calibration, preservative storage and working tanks, belt drives, ball and roller bearings, gland packings, hydraulic systems, pump seals, impellors, filters, valves, gauges, plant operating equipment, compressors, lubrication, waste/sludge handling, removal and authorised disposal, anti-corrosion measures, safety and warning devices.
9.2 Product and material inventory levels are maintained to meet production and contingency requirements in accordance with worksite policies and procedures.
Range may include but is not limited to – preservative chemicals, chemical reagents, test equipment, solution containers, blank charge sheets, plant maintenance materials, protective clothing and first aid kits, strapping.
9.3 Preservative solutions and/or product samples for laboratory analysis are collected, tested, labelled and dispatched in accordance with the Guideline and worksite policies and procedures.
9.4 Laboratory analysis results for preservative solutions and treated products are correctly interpreted and matched against NZS 3640 specifications and operator check measurements, and corrective action is taken in accordance with worksite policies and procedures.
Range includes but is not limited to – product – penetration, retention zone, retention zone loadings; solution – active ingredients, solution concentration.
9.5 Procedures for varying or extending plant approvals are referenced and explained in accordance with the TPQM.
Range includes but is not limited to – species and/or process variations, branding dispensations.
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Replacement information This unit standard, unit standard 152, and unit standard 21759 have been replaced by unit standard 28016.
This unit standard replaced unit standard 149.
Status information and last date for assessment for superseded versions Process Version Date Last Date for Assessment Registration 1 18 December 2006 31 December 2015 Review 2 15 April 2011 31 December 2015 Review 3 18 April 2013 31 December 2018 Rollover 4 19 November 2015 31 December 2018
Consent and Moderation Requirements (CMR) reference 0173 This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Please note Providers must be granted consent to assess against standards (accredited) by NZQA, before they can report credits from assessment against unit standards or deliver courses of study leading to that assessment.
Industry Training Organisations must be granted consent to assess against standards by NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and which are assessing against unit standards must engage with the moderation system that applies to those standards.
Requirements for consent to assess and an outline of the moderation system that applies to this standard are outlined in the Consent and Moderation Requirements (CMR). The CMR also includes useful information about special requirements for organisations wishing to develop education and training programmes, such as minimum qualifications for tutors and assessors, and special resource requirements.
Competenz Ó New Zealand Qualifications Authority 2018 SSB Code 101571