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How to keep instruments and instruments warm in winter?

How to keep instruments and instruments warm in winter?

  • September 14,2018.

In winter, as the temperature decreases, when the measured medium by measuring the pipeline for a transmitter, often appear to freeze occurs, when the environment temperature is too low, the phenomenon such as coagulation, precipitation crystallization, due to environment temperature is too low and beyond the normal working temperature range of instrument used, directly affect the accuracy of the meter display.As for pressure, flow, liquid level, temperature and other various instrument points, their measuring medium is mostly liquid. Affected by low temperature, it is more likely to cause measurement error, which may cause poisoning, fire, explosion and other safety accidents.

To sum up, the cold and frost-proofing of instruments is particularly important.Some users of large instruments and meters have made early response measures, such as power plants, water plants, oil and chemical industries, etc., have developed cold and cold prevention work systems suitable for their own enterprises.Next, let's discuss how users of winter meters should work to prevent freezing.

For the anti-freezing treatment of the instrument and the measuring pipeline of the instrument, the objects requiring thermal insulation shall mainly include the transmitter installed in the thermal insulation box of the instrument, the liquid level transformer unit of external pontoon type liquid level transmitter or other forms of open-air installation, the testing pipeline and measuring pipeline of the instrument such as pressure, differential pressure and flow rate.Avoid such accidents by type selection or other means.The following measures are usually taken: type selection, thermal insulation, maintenance (point inspection, discharge), etc.

Ⅰ、Selection of measures

(1) Select thermal insulation device type instrument.According to the type and use of the instrument and the location of the instrument to be installed, propose the thermal insulation requirements of the instrument, and then submit to the manufacturer for processing.

(2) The signal remote transmission instrument and display gauge head shall take environmental temperature resistance into account, and the isolation liquid shall take environmental temperature resistance into account.

(3) Metal rotor flowmeter, electric target type flowmeter, volumetric type flowmeter and mass flowmeter generally do not need separate heating.

(4) When selecting the type, the first consideration is the utility and economy of the instrument. The utility refers to the convenience of maintenance and the accuracy of measurement, while the economy is simply cheap.They should be combined with each other instead of mass flowmeters, metal rotors, electric targets and so on for convenience and maintenance free.Therefore, correct selection is also a measure of antifreezing and anticoagulation.In addition, the installation of the instrument should fully consider the anti-freezing and anti-coagulation of the instrument, such as the pressure pipe as short as possible, regular inspection of sewage discharge, to facilitate heating, and so on, otherwise good selection is also useless.

(5) in some places, the temperature difference between day and night is too large, and it can reach -20 degrees at night. If it is solved from model selection, it is not cost-effective.The best way to prevent freezing is to choose thermal insulation and maintenance (point inspection, discharge).

Ⅱ、Heat preservation measures

Use thermal insulation materials, use thermal insulation materials to the instrument easy to freeze or do not freeze parts wrapped up.Winter comes to check, often sewage, to prevent packaging insulation materials damaged.

Ⅲ、Heat tracing measures

1. Steam heat tracing measures

Even if the pipe steam heating insulation.Check whether the steam insulation pipe is unblocked or not before delivering steam in winter.The best steam is 24 hours through, not too hot, and sometimes adjust the heat preservation capacity according to the change of weather temperature to prevent the temperature is too high so that the condensation vaporization in the pressure tube of the transmitter can affect the work of the transmitter or because the temperature is too low so that the condensation liquid in the pressure tube of the transmitter can affect the work of the transmitter.

2.Measures of heat preservation and protection box

a. Electric heat pipe thermal insulation box, the box body, a heater, instrument bracket three major components, such as its structure form and protection case is the same, the difference is in the box is equipped with electric heating device, the structure as shown in figure, electric heating device is composed of electric heat pipe, temperature controller, body side with socket, when switched on, the heat in the oven to the required temperature, then by the temperature controller connected to the power supply continues to heat up.The temperature in the box can be kept within a certain range through repeated work.Main parameters of the thermostatic heater:

(1)Rated voltage: 200v. 50Hz;

(2)Rated power: 300 ~ 500W;

(3)Temperature control can be set by the user;

(4)Constant temperature heater can also be made into explosion-proof type;

(5)There are three types of electric heat pipe materials: copper pipe, carbon steel pipe and stainless steel pipe.

b. Steam pipe with thermal insulation box, the heat pipe is made of s-type structure with metal pipe. The box body is made of welded plate connector and the heat pipe.There are two types of heating pipe materials, namely copper pipe and seamless steel pipe (carbon steel).

c. Add another layer of insulating cotton for the key instrument box, and add adhesive seal at the door of the incubator and the inlet and outlet pipeline, to achieve better insulation and antifreeze effect of the instrument system.

3.Electric heating belt measure

Electric thermal insulation technology is a new kind of heating technology, which is directly transformed from electric energy to thermal energy.Add thermal insulation cable, which will be tropical, wrapped around the instrument, or glued in the instrument cabinet (but pay attention to the length of the tropical, to be economically appropriate).

Are applicable for pipe, valve, pump body heat, antifreeze, and insulation or maintain the instrument temperature of single-phase constant power electric heating pipeline technology, the unit length of calorific value is constant, the output power is not affected by environmental temperature change and change, use is proportional to the length and the power, can arbitrarily splicing when installation, but you must keep a fever (that is, at least 2.5 m), the outer braid have heat transfer and heat dissipation effect, and can be used as the security of the anti-static grounding.Mainly used for all kinds of pipes, the frost, heat preservation, maintain highest temperature 150 ℃.Note: temperature requirements for the strict control of the liquid pipeline heating and insulation (with a temperature controller).

There is also a kind of product on the market, is the flexible packaging of electric heat tracing protective cover, is specially used for the instrument with small space heat tracing, explosion-proof, mainly installed in the instrument's pressure tube section and valve.

Ⅳ.Safeguard measures

1. Installation measures

Reasonable installation site: dry, no rain or snow drips.

2. Inspection measures

When the conditions are available, a special person shall carry out technical confirmation and technical disposal on whether the insulation material is damaged or not and whether the steam pipeline is blocked.

3. Alarm measures

Conditional can be installed steam leakage or power off state of the sound and light alarm small device to facilitate thermal insulation and anti-freezing measures hidden dangers and timely remediation.

4. Inspection measures

By the regional instrument maintenance responsible person according to the scheduled inspection route regular inspection.During the inspection, check whether the heat preservation pipeline valve is normal, whether the heat preservation box is normal, whether the trap device is normal, whether the heat preservation material package is intact, whether the electrical heating power supply components are normal, etc.Carry out key inspection on the instrument of easy freezing equipment and make inspection records, carry out the maintenance of the instrument and its thermal insulation and anti-freezing measures to dry, complete and clean, and timely solve the problem of thermal insulation and thermal insulation.

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