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In winter, when the medium to be measured is conveyed through the measurement pipeline to the transmitter, freezing, solidification, and crystal formation can occur when the ambient temperature is too low. Since such low temperatures exceed the normal operating temperature range of the instruments used, it directly affects the accuracy of the measurements displayed by these instruments. To this end, it is necessary to take anti-freezing measures for the instruments and their measurement pipelines. The components that require heating for insulation mainly include differential pressure transmitters installed in instrument enclosures, external float-type level transmitters or other types of level transduction units installed outdoors, as well as the detection and measurement pipelines for instruments such as pressure, differential pressure, and flow rate. Below is a detailed explanation of the key points for the maintenance of differential pressure transmitters. 1. Criteria for selecting differential pressure transmitters: Choose instruments equipped with insulation devices. Based on the category and purpose of the instrument, as well as the location where it is intended to be installed, the insulation and anti-freezing requirements for that instrument are determined, and then submitted to the manufacturer for handling. In some areas in the north, the temperature difference between day and night is extremely large; at night, temperatures can drop below -20 degrees. If this issue is not addressed through proper product selection, it results in a poor cost-performance ratio, making it uneconomical. Choosing insulation and heat tracing, along with maintenance methods such as routine inspections and waste discharge, are the best solutions to prevent freezing. II. Insulation measures for differential pressure transmitters: Use insulating materials to provide insulation, that is, wrap the parts of the instrument that are prone to freezing or sensitive to cold with such materials. When winter arrives, inspections should be carried out and waste should be removed regularly to prevent damage to the insulation material of the packaging. III. Heating measures for differential pressure transmitters: 1. Steam heating measures – That is, using steam from pipes for insulation. Before supplying steam for insulation in winter, check whether the steam insulation pipeline is unobstructed or blocked. It is best to keep the steam flowing 24 hours a day, but not at too high a temperature. Sometimes it is also necessary to adjust the amount of steam supplied based on changes in weather and temperature, in order to prevent condensation inside the pressure transducer tubes from vaporizing due to high temperatures, which could affect the operation of the transducer; or to prevent the condensation from freezing due to low temperatures, which could hinder the proper functioning of the transducer. 2. Insulation protection box measures (1) The electric heating tube type insulation box consists of three main components: the box body, the heater, and the instrument bracket. Its structural format is the same as that of a regular protection box; the difference lies in the presence of an electrical heating device inside the box. This heating device is made up of electric heating tubes and a temperature controller. There are sockets on the sides of the box body, 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 as follows: Rated voltage: 200V, 50Hz; Rated power: 300–500W. The control temperature can be set by the user. The constant temperature heater can also be designed as an explosion-proof version. There are three types of materials for the heating elements: copper tubes, carbon steel tubes, and stainless steel tubes. (2) Steam pipe heating insulation box: The heating tube is made of metal in an S-shaped structure. The top and bottom of the box are welded to the heating tube using welded plate joints; the heating tube is 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 tube cavity. Heating tube materials are generally divided into two types: copper tubes and seamless steel tubes (carbon steel). (3) Adding another layer of insulation material to the key instrument box, and sealing the entrance to the insulated box as well as the inlet and outlet pipelines with glue, can achieve a better insulation and anti-freezing effect for the instrument system. 3. Measures for differential pressure transmitter electric heating strips Electric heat tracing insulation technology is a new type of heating technology that converts electrical energy directly into thermal energy. Install insulated cables; wrap the heating tape around the instruments or stick it inside the instrument cabinet (be careful to choose a length for the heating tape that is appropriate and cost-effective). 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 at will 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: Heat tracing and insulation for liquid pipelines where strict temperature control is required (a temperature controller must be used). IV. Maintenance measures for differential pressure transmitters: 1. Proper installation methods: Select an installation location that is dry and free from rain, snow, or water leakage. 2. When conditions permit, a dedicated person shall conduct daily technical checks and take necessary actions to determine whether the insulation materials are damaged or whether the steam pipelines are blocked. 3. The inspection measures are carried out regularly by the regional instrument maintenance responsible person 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 the freeze-proofing equipment and keep records of these inspections; maintain the instruments as well as the insulation and freeze-protection measures in a dry, intact, and clean condition, and address any issues related to insulation and heating that arise on site promptly. 4. Where conditions permit, small audio-visual alarm devices for steam leaks or power outages can be installed as a means to facilitate the detection of potential issues related to insulation and anti-freezing measures, as well as their timely correction.