.:: OPERATING INSTRUCTIONS FOR A BORATE DIP DIFFUSION TREATMENT PLANT::.



1. SCOPE

This works instruction describes the procedures to be followed during the different stages involved in treatment of timber with TOPRO 94 borate wood preservative solutions when using the immersion (dip diffusion) method.

2. OPERATING PROCEDURE FOR SOLUTION MIXING AND TRANSFER
2.1 Ensure that all valves are closed.
2.2

Add water to mixing/storage tank to ± 60% of the total working solution volume required.

Note: A sufficient volume of working solution should be prepared to ensure adequate overflow to the measuring tank, i.e. at least 50 percent of the measuring tank volume capacity.
2.3 Heat water in mixing/storage tank to ± 60°C and start mixer.
2.4 Slowly add the required mass of TOPRO 94 to the water in mixing/storage tank and continue mixing and heating until all salts have dissolved.
2.5 Stop mixer and add more water up to the required volume in mixing/storage tank to ensure that the required mass concentration in grams of boric acid equivalent (b.a.e) per litre of solution is obtained.
2.6 Start mixer and mix for a further 5 minutes an ensure solution temperature is maintained at ± 50°C.
2.7 Draw a solution sample and determine b.a.e. mass concentration by the hydrometer method. (See timber treatment manual, Works Instruction No. TL/W06)
2.8 Adjust solution mass concentration if necessary. (See timber treatment manual, Works Instruction No. TL/W07).
2.9 Open valve 1 and allow working solution to overflow from mixing/storage tank to measuring tank. (Level in sight glass on measuring tank should indicate at least 50 percent of the volume capacity. If not, prepare additional working solution).

3. OPERATING PROCEDURES DURING TREATMENT
3.1 Solution transfer to dip tank
3.1.1 Determine charge volume to be treated and fill in a treatment charge sheet (Report Form No. TL/R11).
3.1.2 Place timber to be treated in dip tank, and weigh down.
3.1.3 Record starting level in measuring tank after overflow from mixing/storage tank has stopped (Report Form No. TL/R11).
3.1.4 Open valve 2 and empty contents of measuring tank into dip tank by gravity feed.
3.1.5 Close valve 2.
3.1.6 Open valve 3 and transfer working solution from mixing/storage tank by gravity feed into dip tank to the required volume and start dip tank heating to maintain solution temperature at 50°C, ± 5°C.
3.1.7 Close valve 3 and proceed with dip treatment process. Keep timber completely submersed from the entire dip treatment period required.
3.2 Solution transfer to mixing/storage tank
3.2.1 On completion of dip treatment cycle, open valves 4 and 5, start transfer pump and transfer solution from dip tank to mixing/storage tank.
3.2.2 When dip tank is empty, close valves 4 and 5 and stop transfer pump.
3.2.3 Allow overflow from mixing/storage tank to settle and record final level in measuring tank (Report Form No. TL/R11).
3.2.4 Complete treatment charge sheet and accept or retreat charge.
3.2.5 Open valve 2 and empty contents of measuring tank into dip tank.
3.2.6 Close valves 1 and 2, open valves 4 and 5, start transfer pump and transfer solution from dip tank to mixing/storage tank. Close valves 4 and 5 and stop transfer pump.
3.2.7 Remove treated timber from dip tank, spray with anti-sapstain/mould solution and place in diffusion storage under complete cover.
3.2.8

Prepare new charge and repeat steps 3.1.1 through to 3.2.7.

Note:

1. Always ensure that working solution is well mixed and maintained at
± 50°C before treatment of a new charge.

2. Determine the solution b.a.e. mass concentration by the hydrometer
method before treatment of a new charge. (See timber treatment
manual, Works Instruction No. TL/W06).

4. OPERATING PROCEDURE FOR SOLUTION STORAGE
4.1 4.1 Transfer all working solution from measuring tank and dip tank to mixing/storage tank. (See steps 3.2.5 and 3.2.6)
4.2 Open valves 6 and 7 (ensure that rinse tank is filled with clean water).
4.3

Start transfer pump and flush pump system with clean water from rinse tank for at least 5 minutes. Close valves 6 and 7 and stop transfer pump.

Note: Flush water should be re-used for solution mixing.
5. OPERATING PROCEDURE FOR STRAT-UP AFTER EXTENDED SOLUTION STORAGE
5.1 Ensure that all valves remain closed.
5.2 Heat mixing/storage tank contents to at least 60°C.
5.3 Start mixer and continue mixing and heating at ± 60C until all salts and/or lumps have dissolved.
5.4 Rectify working solution concentration if necessary. (See steps 2.7 and 2.8)
5.5 Continue treatment as described under section 3.

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