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Title / Kiln dry timber
Level / 4 / Credits / 25
Purpose / People credited with this unit standard are able to: demonstrate knowledge of kiln drying operations; demonstrate knowledge of dry and wet bulb reading and the factors affecting the drying of wood; describe factors that can influence timber defects and compare drying cycles; manage hazards associated with kiln drying wood products; load and operate a wood drying kiln; monitor the performance of kiln and charge; and explain and apply preventative maintenance requirements specific to an operating kiln.
Classification / Solid Wood Manufacturing > Timber Drying and Treatment
Available grade / Achieved
Entry information
Recommended skills and knowledge / Unit 143, Fillet timber for further processing; Unit 155, Demonstrate knowledge of the properties of wood; Unit 162, Describe knowledge of the principles of wood drying; and Unit 20759,Air dry timber or round wood; or demonstrate equivalent knowledge and skills.
Explanatory notes
1Range
evidence is required of one of the following – low temperature (below 60°C), conventional temperature (60°-80°), accelerated conventional temperature (ACT) (81°-100°C), high temperature (over 100°C);
evidence is required of 12 charges of varying schedules, product and/or time.
2References
Competence in this unit standard requires knowledge of the following:
aBest Practice Guideline for the Safe Use of Timber Preservatives and Antisapstain Chemicals (Wellington, 2005). This is referred to below as the ‘Guideline’, and is available through the New Zealand Timber Preservation Council, Wellington or online at
bApprovedCode of Practice for Training Operators and Instructors of Powered Industrial Lift Trucks (Wellington: Occupational Safety and Health Service of the Department of Labour, 1995), which is available from Bennett’s Government Bookshops or online at
cAS 1080.1 Timber – Methods of test – Method 1: Moisture content, which is available from Bennetts Government Bookshops or online at
3All evidence requirements must be demonstrated and assessed in accordance with the reference text: Kiln Dry Timber (Auckland: Competenz, 2000) and available from Competenz, PO Box 9005, Newmarket, Auckland 1149.
4The following apply to the performance of all outcomes of this unit standard:
aAll 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 Health and Safety in Employment Act 1992, the Resource Management Act 1991, and their subsequent amendments.
bAll work practices must meet documented worksite operating procedures. This includes the recording (by electronic or non-electronic means) of activities, events, and decisions.
cAll evidence of communications gathered in relation to this unit standard must be in accordance with worksite procedures for content, recipient, timing and method.
5Definitions
Corrective action may include actions such as communication to management, communication to on-site technical support 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.
MC refers to moisture content.
Optimise refers to the most efficient use of product and plant, taking into account raw material input, customer demands, and machine capability.
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.
Outcomes and evidence requirements
Outcome 1
Demonstrate knowledge of kiln drying operations.
Evidence requirements
1.1Role, scope and responsibilities of the kiln operator are described in accordance with worksite policies and procedures.
1.2Operating parameters, processing capability and capacity of kilns used in the workplace are defined.
1.3Energy systems and construction materials of kilns in use in New Zealand are described in accordance with the reference text.
Rangesystems – wood waste, coal, natural gas, electricity, fuel oil, gas, thermal steam;
materials – concrete block, brick, stainless steel, aluminium, steel.
1.4Energy sources of kilns used in the workplace are identified.
1.5Operating components of the kiln are identified and their function and operation are explained.
Rangeincludes but is not limited to – control panel, control valves, spray, vent, heat control, relief valves, wet and dual dry bulbs (thermometers), air circulation controls, water supply, overflow drains, door seal mechanisms, fans, ventilation and humidity controls, baffles, heating coils, spray lines, recording charts and mechanisms, pilot lights, computer monitoring, overload switches, re-set controls, kiln recording charts.
1.6Principles and purpose of drying are explained in terms of drying phases, cycles and sequences.
1.7Factors for consideration when scheduling charges to optimise production throughputs are explained in accordance with the reference text.
Rangefactors include but are not limited to – priority of orders, product suitability and availability by charge lots, end product specification requirements, drying time, steam availability.
Outcome 2
Demonstrate knowledge of dry and wet bulb reading and the factors affecting the drying of wood.
Evidence requirements
2.1Use of dry and wet bulb readings is explained in accordance with the reference text.
2.2Dry and wet bulb temperatures, drying time and start time are read and interpreted from kiln charts.
2.3Factors that are intrinsic to the wood and their effects on drying time are identified in accordance with the reference text.
Rangespecies, size, treatment, heart or sapwood, wood density, delay between cutting and drying, initial MC, target MC.
2.4Effects of sawn timber characteristics on drying quality are explained in accordance with the reference text.
Rangegrade; width; thickness; flat, quarter or mixed sawn, sawing accuracy, core and outer wood.
2.5Effects of temperature, humidity and airflow on speed of drying are explained in accordance with the reference text.
2.6Effects of altering processing variables are explained in terms of their effect on speed of drying.
Rangepacket build fillet placement, fillet width, and thickness, stack width, batching of timber sizes, baffling, initial moisture content variability of load, mixed species.
Outcome 3
Describe factors that can influence timber defects and compare drying cycles.
Evidence requirements
3.1Timber defects that can be caused by the drying process are identified and described.
Rangedefects – collapse, cup, spring (crook), bow, twist, case hardening, reverse case hardening, surface checking, end splitting, honeycombing.
3.2Methods of reducing defects during the drying process are described.
Rangemethods – correct schedules, uniform width and thickness of fillets, packet builds and fillet placement, restraining weights.
3.3Benefits of pre-steaming and reconditioning are explained in accordance with the reference text.
3.4Kiln types are compared in terms of operating temperatures, air velocity, ability or need to recondition, products dried, and drying time.
Rangekilns – low temperature, conventional temperature, accelerated conventional temperature (ACT), high temperature.
Outcome 4
Manage hazards associated with kiln drying wood products.
Evidence requirements
4.1Hazards associated with kiln drying wood products are identified and actions to be taken to isolate, minimise or eliminate the hazards are described in accordance with worksite policies and procedures.
Rangehazards may include but are not limited to – heat, mobile plant, noise, dust.
4.2Safe work practices associated with kiln drying wood products are used in accordance with worksite policies and procedures and legislative requirements.
Rangepractices may include but are not limited to – isolation procedures, lock-outs, emergency stops, machine guarding, wearing appropriate safety equipment, entry in kiln vault during drying operation, stacking, loading/unloading operations, steam handling procedures.
4.3Emergency procedures are described and carried out in accordance with worksite policies and procedures.
Outcome 5
Load and operate a wood drying kiln.
Evidence requirements
5.1Input material is checked against worksite specifications, timber packets are selected for uniformity of size, age, condition and species, and are loaded to optimise the air flows in the kiln.
5.2Kiln is operated to maximise kiln drying time and minimise turn around time according to worksite policies and procedures.
5.3Drying and final steam conditioning schedules are applied in accordance with worksite policies and procedures with regard to species, timber thickness, and customer requirements.
5.4Kiln charge data is entered into the kiln management system in accordance with worksite policies and procedures.
5.5Residue and waste are managed as required by legislative requirements and worksite policies and procedures.
Outcome 6
Monitor the performance of kiln and charge.
Evidence requirements
6.1Output data is monitored and used to determine the end point of drying.
6.2Operating faults that affect timber drying are recognised, and corrective action is taken in accordance with worksite policies and procedures.
6.3Equipment faults and malfunctions are identified and corrective action taken in accordance with manufacturer’s requirements and worksite policies and procedures.
6.4Drying schedule is amended in response to changing kiln conditions in accordance with manufacturer’s requirements and worksite policies and procedures.
6.5Kiln schedule specifications are adjusted to match product grade, species and end use in accordance with worksite policies and procedures.
6.6Characteristics of dry product are checked against specifications, and action taken in accordance with worksite policies and procedures.
Rangemoisture content, process defects, moisture gradient, stress.
6.7Appropriate cooling down period is observed before top weights are removed in accordance with worksite policies and procedures.
6.8Documentation is completed in accordance with worksite requirements.
6.9Kiln data is analysed, areas for improvement identified, and corrective action taken to optimise productivity in accordance with worksite policies and procedures.
Outcome 7
Explain and apply preventative maintenance requirements specific to an operating kiln.
Evidence requirements
7.1Preventative maintenance and cleaning schedule for the kiln is explained and carried out in accordance with worksite policies and procedures.
Planned review date / 31 December 2017Status information and last date for assessment for superseded versions
Process / Version / Date / Last Date for AssessmentRegistration / 1 / 27 January 1994 / 31 December 2014
Review / 2 / 24 October 1996 / 31 December 2014
Review / 3 / 10 February 1999 / 31 December 2014
Review / 4 / 18 December 2006 / 31 December 2014
Review / 5 / 18 April 2013 / N/A
Consent and Moderation Requirements (CMR) reference / 0173
This CMR can be accessed at
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 (CMRs). 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.
Comments on this unit standard
Please contact the Competenz at if you wish to suggest changes to the content of this unit standard.
CompetenzSSB Code 101571 / New Zealand Qualifications Authority 2018