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After October, winter arrives quickly. At present, the main method to prevent freezing in instruments is to rely on technicians carrying out inspections; when freezing or condensation occurs in certain circuits, steam is used to blow on them along with knocking on the pipes to resolve the issue. This is a very primitive method, and it’s tough and exhausting work. To reduce the workload associated with instrument maintenance, ensure smooth production, and help instrument equipment survive the winter safely, the following anti-freezing measures for instruments are provided for reference by instrument technicians. 1. Select appropriately suitable instruments for use in cold regions. ① Based on the category and purpose of the instruments as well as the location where they are to be installed, determine the requirements for frost protection, and then submit these requirements to the manufacturer for instrument selection. ②Remote transmitters and LCD display heads need to meet the requirements regarding environmental temperatures, while those equipped with isolation fluids must also satisfy the requirements related to the environmental tolerance of such fluids. ③In some areas in the north, the temperature difference between day and night is extremely large; temperatures can drop to -30°C at night. If this issue is not addressed during the product selection process, it results in a poor cost-performance ratio. Options include thermal insulation and heating, as well as maintenance solutions such as routine inspections and waste discharge. To ensure the safety of instruments during winter, these anti-freezing measures are essential. yunrun.com.cn/tech/2746.html 2. Insulation measures for instruments: Use insulating materials to cover those parts of the instruments that are prone to freezing, thereby preventing freezing damage to them. When winter arrives, inspections should be carried out and waste should be removed regularly to prevent damage to the insulation material of the packaging. 3. Instrument heating measures: The most important issue in winter is preventing instruments from freezing. Due to large temperature differences between seasons, operational conditions, and dirty media, many drain valves, including those with heating, often become sources of leakage problems. In the past, when instruments were in use during winter, reliance was placed on instrument technicians to conduct inspections; for circuits affected by freezing or condensation, methods such as using external steam to warm the pipes and knocking on them were employed – these were primitive and labor-intensive approaches with no effective solutions. Now, in order to reduce the workload associated with instrument maintenance and ensure smooth production, it is necessary to conduct a comprehensive inspection in advance, before winter arrives, to verify that all anti-freezing measures for the instruments have indeed been implemented. The first thing to consider is ensuring an adequate insulation layer and installing proper heat tracing. As for whether to use electric heat tracing, steam heat tracing, or low-temperature water heat tracing, the choice depends on the specific circumstances. ◆Insulation for steam heating systems: Before supplying steam, it is necessary to thoroughly check whether the insulation pipes are unobstructed. Additionally, during winter, regular inspections and cleaning are necessary to prevent the insulation pipes from becoming clogged. Sometimes it is also necessary to adjust the steam supply based on temperature changes, in order to prevent the condensate in the transmitter’s pressure tube from vaporizing due to high temperatures, which could affect the transmitter’s operation, or to prevent the condensate from freezing due to low temperatures, which could hinder proper functioning of the transmitter. ◆Measures for insulated protection boxes: ① Electric heating tube-based insulated protection boxes – their structural design is the same as that of regular protection boxes; the difference lies in the presence of an electrical heating device inside the box. This heating device consists of electric heating tubes and a temperature controller. There are sockets on the sides of the box, and once power is supplied, the temperature inside the box rises to the desired level. Once that temperature is reached, the temperature controller continues to supply power to keep the temperature high. Repetitive operation is used to keep the temperature inside the box within a certain range. The main parameters of its constant-temperature heater are: rated voltage 200V/50Hz ； Rated power 300-500W ； The control temperature can be set by the user ； Constant-temperature heaters can also be made explosion-proof ； There are three types of materials for electric heating tubes: copper tubes, carbon steel tubes, and stainless steel tubes. ②Steam pipe heating insulation box: The heating pipes are made of metal tubes in an S-shaped configuration. The top and bottom of the box are welded to these heating pipes using welded plate joints; the heating pipes are installed inside the box with steam entering from the top and exiting from the bottom, and heating is achieved through the circulation of steam within the pipe channels. ③Adding an additional layer of insulation material to the key instrument cabinets, and sealing the openings of these cabinets as well as the inlet and outlet pipelines with glue, can help prevent the instruments from freezing. ◆Electrical heating strip solutions: Electric heat tracing insulation technology is a new type of heating technique that converts electrical energy directly into thermal energy. Install insulated cables, winding the heating tape around the instruments or sticking it inside the instrument cabinet. However, as a clean energy source, electricity is relatively expensive, and it is difficult to ensure explosion safety for electric heat tracing. If the enterprise has its own heat exchange station, the waste heat can be used for heating and heat tracing. A single-phase constant-power electric heating tape suitable for heating, anti-freezing, and insulation of pipes, valves, and pump bodies, or for maintaining the process temperature of instrument pipelines. It features a constant heat generation per unit length; its output power does not change with variations in ambient temperature. The length required for use is proportional to the power level. It can be cut as needed during installation, but at least one heating section (i.e., 2.5 meters) must be retained. The outer woven layer serves to transfer and dissipate heat, and it also functions as a safe grounding element to prevent static electricity. It is mainly used for anti-freezing and insulation of various pipes and instruments, with a maximum maintainable temperature of 150°C. Note: Thermostats must be used for the heating and insulation of liquid pipelines where strict temperature control is required. It should also be noted that, aside from the temperature range required by the instruments themselves (note: electronic components are classified into military, industrial, and civilian types, with the vast majority of industrial-grade components functioning only at around -20°C), the most common form of heating/insulation used is that for sampling pipelines. Measuring pressure or differential pressure is dominated by the diaphragm box type; the shorter the sampling tube, the better. There should be a check valve, and it must be easy to maintain – it needs to be led from the pipeline rack to the ground level, at which point pipe heating is essential. Those with extensive experience in instrument maintenance know that the main piping for instrument heating branches off from the process main piping; monitoring instruments should be installed on this supply and return water/steam line in order to **reduce the risk of catastrophic damage to the instruments due to freezing. 4. Instrument maintenance measures ① Installation measures: Select an appropriate installation location; the instruments should be installed in a dry area free from rain, snow, and water leakage. ②Inspection measures: Whenever possible, a dedicated person shall conduct daily technical checks and take appropriate actions to ensure that the insulation materials are not damaged and that the steam pipelines are not blocked. ③Alarm measures: Where possible, install small audio-visual alarm devices that detect steam leaks or power outages, to facilitate the identification of potential issues related to insulation and anti-freezing measures and their prompt correction. ④Inspection measures: The person responsible for instrument maintenance in the area conducts regular inspections along the predetermined inspection routes. During inspections, it is necessary to check whether the valves of the insulated pipelines are functioning properly, whether the insulation boxes are in good condition, whether the drain devices are working correctly, whether the insulation material packaging is intact, and whether the components responsible for electric heating are functioning properly. Conduct thorough inspections of the instruments in freezing-prevention devices and keep records of these inspections; maintain the instruments and their insulation/anti-freezing measures in a dry, intact, and clean condition, and address any freezing-related issues that arise on site promptly. Related reading: Installation guide for electric heat tracing. Don’t think that heating and insulating instruments is only the responsibility of those who work with instruments. Here is the most comprehensive information on instrument heat tracing and insulation to help keep your instruments warm through the winter