Some South African inspection bodies are promoting the use of the hydrometer, which is not accepted in the national specifications for CCA timber treatment.
Dolphin Bay believes that using hydrometers would be a setback for the local timber treatment industry, as we have stated in a previous newsletter story, as there are more accurate methods available in South Africa for determining CCA solution strength.
The hydrometer is a scientifically valid tool and easier to use than the titration method, which is recommended in the national standards. However, the hydrometer produces less accurate results, and the local timber treatment industry has never motivated for its inclusion in the standards.
“We have noticed that many operators struggle with titrations, which seems to be the reason that some inspection bodies are promoting the use of a hydrometer,” observed Bertus. “However, the hydrometer is not a precision instrument, and using it can lead to both under- and over-treatment.”
Before using a hydrometer, the operator must take the temperature of the CCA chemical solution and ensure the equipment is very clean. The temperature is often read incorrectly, and residue left on the hydrometer equipment can cause an incorrect reading should the instrument not be cleaned properly.
When working with such low densities, the margin of error is very small.
Another issue is that the density of borehole water, often used by timber treaters, is higher than that of municipal water. Hydrometer charts do not take this into account, although it affects the readings.
“The hydrometer is not a precision instrument, and using it can lead to both under- and over-treatment.”
Dolphin Bay offers regular training to our customers’ operators in how to use the titration method and will provide beginner or refresher courses to any clients who ask for it. We also give our customers posters that provide clear instructions for the titration process.
“Titration is a relatively simple process and not as daunting as people might fear,” said Dolphin Bay’s Gareth Jantjies, who trains operators at our clients’ treatment plants.
Dolphin Bay does recommend the use of hydrometers to customers in countries where other methods are hard to come by. In many instances, we have seen that the XRF machine used in combination with the hydrometer results in accurate treatment.
For customers seeking greater accuracy than titration in determining solution strength, we provide an auto-titrator called Securus. This may seem an expensive option at first but can save treaters money in the long term as it prevents under- and over-treatment, ensuring a quality product and avoiding the overuse of valuable CCA.
Securus can also be useful for timber treatment plants that experience a high turnaround of operators, and where frequent training – and the lapse between operator appointments – becomes arduous.
“Dolphin Bay would be happy for the industry to have a discussion, if necessary, about whether the hydrometer should be included in the national standards or not,” said Bertus. “However, at this stage, we simply wish our customers to know it is not a method approved by the national standards and that more accurate options are available in South Africa.
“As things stand, there is no need to use the hydrometer, and doing so is not in the industry’s best interests as it undermines the specifications that have been set in place.”