Andy Burns explains why companies should never take any chances, especially where testing and analysis are concerned
What would you think if you saw someone using a shopping trolley as a car jack? Or a newspaper and sunglasses as an improvised welding mask? You’d probably ask yourself why anyone would put themselves in that kind of danger.
In a nutshell, the dangers caused by the lack of preventative maintenance are rooted in the degradation of thermal fluid. Over time, heat transfer fluid breaks down through a process called ‘thermal cracking’. The fluid’s molecules are broken down into smaller particles and several types of fractions are released from this chemical reaction. The first side products of thermal cracking are light ends that have a low boiling point and are very volatile.
The second category of thermal cracking decomposition products are heavy ends, which recombine to form heavy polyaromatic molecules that usually cause fouling of the heat transfer system.
Hot, closed and circulating
Sample methodology is crucial – incorrect sampling gives inaccurate flash point results, which can have very dangerous consequences. Unless the fluid samples are collected when the oil is hot and circulating, they will reveal artificially high flash point values. This incorrect sampling will lead to the conclusion that the system is safe, when in reality it might not be.
The sample also needs to be ‘closed’ so that no potential atmospheric particles can contaminate it or distort the results. An open sample would also allow light ends to flash off to the atmosphere, instead of remaining in the sample, which produces unreliable readings.
Test often and well
Global Heat Transfer recommends testing thermal fluids quarterly to help mitigate health and safety risks and manage regulatory compliance. It can also result in cost savings of up to 75 per cent. The easiest way to manage quarterly testing is to use a preventative maintenance plan, supplied by a trusted thermal fluid provider.
Global Heat Transfer's maintenance plan, Thermocare, is a proactive, preventative approach to fluid management. The plan is especially designed to avoid unexpected maintenance costs and expensive downtime. It also ensures legislative compliance and helps minimise a company's environmental impact.
Best practice sampling
As opposed to most companies, that only provide a seven point test, GHT looks in detail at key data to ensure the results completely reflect reality.
The Ramsbottom carbon residue test (RCR) is a method of calculating the carbon residue in a fluid. If the carbon level (heavy ends) is too high, build-ups can occur, which will reduce the efficiency of the system, make pumps work harder and result in higher running costs for the company.
Global Heat Transfer performs both types of flash point measurement: open and closed cup. The Pensky-Martens closed flash test involves the heating of test specimens in a covered brass cup at regular intervals until a flash point that spreads throughout the inside of the cup is identified. A Seta open cup flash test is also performed on the fluid sample.
An acidity level test identifies the amount of additive depletion, oxidation or acidic contamination, in a thermal fluid sample. The acid number is determined by the amount of potassium hydroxide (KOH) base required to neutralise the acid in one gram of an oil sample.
These three main areas of testing are complemented by additional checks, including appearance, viscosity, water and ferrous content, particulate quantities and fire point testing. The data from the eleven tests forms the basis of a holistic analysis based on trend data, which results in an accurate thermal fluid evaluation.
The complexity of thermal fluid testing might seem intimidating, but the importance of the process cannot be stressed enough. Respecting legal regulations, performing preventative maintenance and frequent testing are the best ways to ensure your company is not taking any unnecessary risks.
Andy Burns is technical business manager at thermal fluid specialist Global Heat Transfer.