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
and knowledge
Unit 155, Demonstrate knowledge of the properties of wood;
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
SSB Code 101571
 New Zealand Qualifications Authority 2016
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 Antisapstain 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.
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
21760 version 4
Page 3 of 10
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
1.3
Factors which influence successful diffusion treatment are explained in terms of
their effects.
Range
1.4
preservatives may include but are not limited to – boron
compounds, mouldicides and/or anti-sapstains.
The effects of contaminants on the efficacy of treatment solutions are
described.
Range
1.7
formulations – boron compounds, mouldicides and or antisapstains, dye additives;
properties – solubility and permanence.
Preservative efficacy is explained.
Range
1.6
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.
Preservative formulations used at the plant are identified and their properties
and uses explained.
Range
1.5
dip, spray, pressure.
contaminants include but are not limited to – wood extractives,
hydraulic fluid, sawdust.
Treatment specification requirements for diffusion processes are referenced
and explained in accordance with NZS 3640, TPQM, and the Guideline.
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
21760 version 4
Page 4 of 10
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
2.3
Factors for consideration when scheduling diffusion treatment to improve
productivity and quality are explained.
Range
2.4
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.
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
2.6
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.
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
2.5
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.
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).
Storage and handling requirements before and after treatment are identified and
explained in accordance with worksite policies and procedures.
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
2.7
21760 version 4
Page 5 of 10
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
Competenz
SSB Code 101571
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.
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
21760 version 4
Page 6 of 10
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
4.2
Working tank solution is prepared for preservative concentration testing in
accordance with worksite policies and procedures.
Range
4.3
may include but is not limited to – agitation, operating temperature.
Representative solution samples are taken and tested in accordance with the
TPQM and worksite policies and procedures.
Range
4.4
includes but is not limited to – approved species, product
characteristics, surface condition, moisture content and moisture
gradient, dimensional thickness, biological degradation, precutting, machining, strapping tightness, packet build and length,
product/unit identification.
may include but is not limited to – prior to, during and on
completion of the treatment process.
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
Competenz
SSB Code 101571
preservative, mouldicide/antisapstain, dye additives.
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
21760 version 4
Page 7 of 10
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
5.5
includes but is not limited to – electrical, hydraulic, mechanical,
spillage, temporary suspension of treatment, plant shutdown.
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
6.2
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.
Diffusion period is calculated with adjustments made for slow diffusing material
in accordance with worksite policies and procedures.
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
21760 version 4
Page 8 of 10
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
7.4
may include but is not limited to – production log books, accident
registers, production summaries, sampling summaries, analytical
records.
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
8.2
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.
Compliance branding or labelling is undertaken in accordance with NZS 3640
specifications.
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
8.3
21760 version 4
Page 9 of 10
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
9.2
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.
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
9.5
includes but is not limited to –
product – penetration, retention zone, retention zone loadings;
solution – active ingredients, solution concentration.
Procedures for varying or extending plant approvals are referenced and
explained in accordance with the TPQM.
Range
Competenz
SSB Code 101571
includes but is not limited to – species and/or process variations,
branding dispensations.
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
Replacement information
21760 version 4
Page 10 of 10
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
SSB Code 101571
 New Zealand Qualifications Authority 2016