In winter, when the measured medium is sent to the transmitter through the measuring pipeline, freezing, solidification, precipitation and crystallization often occur when the ambient temperature is too low, and the shock pressure gauge exceeds the instrument used because the ambient temperature is too low. The normal operating temperature range directly affects the accuracy of the meter's measurement display. For this purpose, the meter and meter measuring lines must be subjected to anti-freeze treatment. The objects that need to be heated and insulated are the transmitters installed in the instrument's incubator, the external buoyancy level transmitters or other forms of open-air installation. Transmitting unit, pressure, differential pressure, flow and other instrument detection and measurement pipelines. Avoid such accidents through selection or other methods.
The measures taken are usually: selection, heat tracing, maintenance (point inspection, sewage discharge), etc.
First, the selection measures Selected with insulation device type instrument. Differential pressure transmitter according to the type of instrument and intended installation location, proposed the instrument's insulation antifreeze needs, and then submitted to the manufacturers to deal with.
In some places in the north, there is a large temperature difference between day and night, which can reach more than -20 degrees at night. If the solution is selected, the cost is quite uneconomical. The choice of thermal insulation, maintenance (point inspection, sewage) and other methods is the solution to antifreeze.
Second, insulation measures
Insulation with insulation materials, that is, use of insulation materials to freeze the instrument or fear of frozen parts. During the winter, inspections should be carried out and the sewage should be drained regularly to prevent the insulation of the packaging from being damaged.
Third, heat tracing measures
1, steam heating measures
That is, the use of pipe steam heating insulation. Before steaming in winter, check whether the steam insulation pipe is open or blocked. The best steam is 24 hours, do not be too hot, sometimes according to the weather temperature changes to adjust the supply of steam insulation in order to prevent the temperature is too high so that the vaporization of the condenser condensate pressure transmitter affect the transmitter work or due to temperature Too low to freeze the condensate inside the transmitter pressure tube affects the smooth flow of the transmitter.
2, insulation protection measures
a. The electric heating pipe heat insulation box is composed of three parts: the box body, the heater, and the instrument bracket. The structure is the same as the protection box. The difference is that the electric heating device is installed in the box. The electric heating device is composed of an electric heating tube and a temperature controller. The side of the box body is equipped with a socket. When the power is turned on, when the box is heated to a desired temperature, the temperature controller is turned on to continue heating. Through repeated work so that the temperature inside the box can be maintained within a certain range.
b. The steam pipe with heat insulation box, heat tracing pipe is made of metal pipe S-shaped structure. The upper and lower parts of the box are welded with welding plate joints and heating pipe welding, with heat pipe installed in the box for the up and down, through the steam in The circulation within the lumen achieves the purpose of heating. Heating pipe material is generally divided into two types, namely, copper pipe, seamless steel pipe (carbon steel).
c. Add a layer of insulation cotton to the key instrument box, add plastic seal at the entrance of the insulation box and the inlet and outlet pipelines, and achieve the insulation and antifreeze effect of the instrument system.
3, electric heating belt measures
Electric heat tracing technology is a new type of heating technology that converts electricity directly into heat energy. Install insulation cables, wind the cable around the meter, or stick it inside the meter cabinet (but pay attention to the length of the heating cable used, to be economically modest).
Suitable for heating pipes, valves, pressure gauges, differential pressure transmitter body heating, antifreeze and insulation or single-phase constant power heating cable to maintain the process temperature of the instrumentation line, constant heat generation per unit length, output power is not affected by the ambient temperature Change and change, use the length and power is proportional to, can arbitrarily spliced ​​at the time of installation, but must keep a heating section (that is at least 2.5m), the outer layer of braid has heat transfer, heat dissipation, and can be used as anti-static safety Grounding. It is mainly used for antifreeze and heat preservation of various pipelines and meters. The maximum temperature is maintained at 150°C.
Note: Heating and insulation of liquid lines with tight temperature control (temperature controller must be used).
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