Tips for preventing the degradation of heat transfer oil
Regardless of the size and design of your heat transfer oil system, there are a few basic procedures you can follow to maximize the life of your heat transfer oil. Heat transfer oil can become degraded over time, and while it's impossible to recommend exact operation and maintenance procedures without knowing the specific features of your operating system, the following are some general tips you can follow to maximize your investment, regardless of what type of system you use.
How to Properly Start Up and Shut Down a Heat Transfer Oil System
Although starting up a heat transfer oil system is a simple process, many heat transfer oil system operators are not always doing it properly. In order to start up a heat transfer oil system properly, start the system pump and wait till the fluid starts flowing throughout the system. Next, apply heat in incremental steps until the heat transfer oil reaches a viscosity of 10 centipoise or less. Once this level of viscosity is reached, dial the heater to the operating temperature.
In order to shut down a heat transfer oil system, avoid shutting down the heater and pump at the same time to prevent thermal cracking. To shut down a heat transfer oil system properly, turn off the heater first and then let the pump circulate the heat transfer oil to remove residual heat throughout the system. Once the temperature has dropped to under 200°F (93°C) or less and the residual heat has been removed, the system is safe for shut down.
Factors That Lead to the Degradation of Your Heat Transfer Oil and How to Avoid Them
Factors that lead to the degradation of heat transfer oil include thermal cracking, oxidation, and contamination. Thermal cracking, also referred to as thermal degradation, occurs when large oil molecules decompose and form into solid coke. Excessive thermal cracking can lead to premature fluid and system failure. By following sound operating practices, you can prevent thermal cracking. Recommended operating practices include properly starting up and shutting down the heat transfer oil system, maintaining your system's instrumentation, and performing regular heat transfer oil analysis.
Oxidation, which happens most commonly in open heat transfer oil systems, refers to when oxygen reacts with the heat transfer oil by a free radical mechanism. This reaction leads to the formation of larger molecules, which then turn into polymers or solids. These polymers increase the heat transfer oil's viscosity, making it more difficult to pump. Eventually, oxidation can lead to the fouling of the expansion tank and sludge formation in the system. To prevent oxidation, be sure to keep the temperature of the expansion tank below 140°F (60°C) and maintain a positive net pump suction head.
Contamination of a heat transfer oil system occurs when contaminants enter your heat transfer oil system. Contamination can not only lead to a degradation of the heat transfer oil, it can cause operational problems. In order to prevent contaminants from entering your heat transfer oil system, always use fresh fluid to top off the system during daily operation and drain the system completely during regular cleanings so that it operates more efficiently. Never use water to flush out your heat transfer oil, and use a flushing fluid instead. After all, the contaminant most commonly found in heat transfer oil system is water. Tests can be conducted regularly to check for the presence of water in your heat transfer oil system.
In sum, to prevent the rapid degradation of heat transfer oil, clean out your heat transfer oil system on a regular basis with a flushing fluid, perform regular analysis of the heat transfer oil, and start up and shut down the system properly. Following these basic operation and maintenance procedures will help to prevent oxidation, contamination, and thermal cracking, thus extending the life of the heat transfer oil and improving the operational efficiency of your heat transfer oil system.
