Principle and application of the hottest temperatu

The principle and application of temperature and humidity recorder

I. preface

temperature and humidity measurement is a newly developed field of modern measurement, especially humidity measurement. Through the process of electrical measurement from length method, dry and wet method to today, the humidity measurement technology is becoming more and more mature. Today, because we are no longer satisfied with the measurement of humidity, especially the monitoring of some places, it is directly required to record the changes of temperature and humidity in the whole process in real time, and determine the safety of the storage and transportation process based on these changes, leading to the birth of a new temperature and humidity measurement instrument - temperature and humidity recorder

the temperature and humidity recorder is an instrument that measures the temperature and humidity parameters and stores them in the internal memory according to the predetermined time interval, connects them to the PC after completing the recording function, and uses the adaptation software to put forward the stored data and analyze it according to its value and time. Using this instrument, it can be determined that there is no event endangering product safety in the storage and transportation process, experimental process and other related processes

the principle and application of hygrolog temperature and humidity recorder produced by Swiss rotronic company are introduced as an example

II. Principle of temperature and humidity recorder

temperature and humidity recorder is composed of three parts: measurement part, instrument body and PC interface

Figure 1 the structure block diagram of the recorder

the following three parts are introduced respectively:

(I) the measurement part

is composed of Hygroclip series probes that are completely interchangeable. Different probes complete different functions:

hygroclip s universal probe, which is applied to general measurement, including plant, laboratory, container space and other space measurements

hygroclip sc04/sc05 probe for narrow space is used in places requiring narrow space and causing little damage to products. For example, museums preserve sculptures, sculptures and other works of art; Some fossils; Engineering construction, bridge construction monitoring concrete drying and other applications

hygroclip SP05 small space insertion probe, applied to the insertion measurement of granular stacking materials

hygroclip hk25/40 high temperature probe, up to 200 ℃. For high temperature environment

hygroclip hs28 sword probe is used in papermaking, printing, roll deposits and other places

the above probes are completely interchangeable and can be connected with hygrolog. And complete different functions

(II) the instrument body

hygrolog recorder measures through the probe, stores and transmits the data to the PC. its storage capacity is 10000 data points (5000 points for temperature and humidity respectively), and the recording interval is adjustable from 15s to 2H: it is adjusted by the PC, and the recording time can be determined according to its set value for up to 416 days. The working temperature of the recorder is limited by the battery, that is, lithium battery: -20 to 70 ℃; Alkaline battery: -10 to 50 ℃. Range and accuracy are determined by the probe. Range: up to -50 to 200 ℃, 0 to 100% RH; Accuracy: ± 1.5% RH, ± 0.3 ℃; Protection grade: IP65

Figure 2 record curve and analysis chart generated on computer

(III) PC interface

hw3 software. Software support is an indispensable part of the recorder. Its main functions are: setting units, setting storage cycles, setting sampling cycles, reading data and displaying measured data, historical curves, etc., which are an integral part of the data recorder. A good host computer software can provide the widest support for the recorder. Through the support of the host computer, unnecessary parts such as the keyboard are liberated, and more resources are provided for use

all recorders generally follow such a mode, the difference is: make the car more energy-saving. Some recorders place the measurement part inside the recorder, and some recorders use separate and completely interchangeable probes. Using the former method, its characteristics are: it can reduce the volume of the product, but it brings problems such as occupying storage resources, inconvenient calibration, etc., and it can't be transported at the same time. What people consider more before is the technology and method to complete multiple functions with standard products. At the same time, it also brings problems such as narrowing the monitoring range due to the limitation of the battery; Using the latter circuit, because the traditional probe adopts analog output, it also brings: 1. A/d conversion is required; 2. It is required to carry out different circuit or parameter transformation corresponding to different ranges and different inputs

based on the above reasons, a new design task has been put forward for us. In this regard, Swiss rotonic company has taken the lead. Their probe adopts digital technology, conforms to the consistent protocol, and eliminates the problem of a/d conversion. At the same time, due to the separation of measurement and recording parts, the application scope is widened to the greatest extent. Due to the adoption of single bus protocol and DIO bus technology, its resources are greatly saved. In this way, the power consumption components are reduced, and the high transmission accuracy and longer working time of the battery are ensured. For example, with a 750mah battery, the sampling interval is 5 minutes, which can be recorded continuously for 6 months

rotonic recorders have a wide range of applications, covering almost all places where temperature and humidity data archiving is required. Due to the use of a variety of characteristic probes, applications in many fields are possible

III. typical applications

(I) food storage and transportation

because the time of food storage and transportation is not a short-term problem, but the relative equilibrium humidity in food preservation is an important index to ensure food safety, and the relative equilibrium humidity directly affects the growth of colonies. For example, in the range of equilibrium relative humidity from 95% RH to 91% RH, the colonies that are easy to breed are Salmonella, Pauline bacteria, lactic acid bacteria, mold and yeast. The food preservation cycle is also related to temperature and balanced relative humidity. The cake with balanced relative humidity of 81% RH has a shelf life of 14 days at 27 ℃ and 24 days at 21 ℃. If the balanced relative humidity is increased to 85% RH, these indicators will be reduced to 8 days at 27 ℃ and 12 days at 21 ℃. The equilibrium relative humidity of hygroscopic substances plays a decisive role. The equilibrium relative humidity is defined as the humidity value obtained from the surrounding air without the exchange of water between the substance and the air. This definition is very clear. In order to successfully store and maintain these products, the environmental climate control and packaging must be carefully specified. At the same time, the taste of many foods will deteriorate if they are kept too dry. In view of this situation, it is required to record the changes of temperature and humidity in real time to ensure that food can enter the mouth of consumers safely

when long-distance transportation or sea transportation of frozen and refrigerated food, it is very important to prove that the goods have been in the specified temperature and humidity conditions at the time of receipt. The way to solve the dispute is to put a recorder in the cargo hold at the time of delivery and start it. The temperature and humidity recorder has a precise internal clock to faithfully record the temperature and humidity data at the specified time interval. When taking it out, you can easily use the computer to view the graphic files and alarm values, judge whether it exceeds the allowable value, when and duration can be easily obtained, and the carrier will immediately know whether it has

(II) management of cultural relics and archives in museums

this is another large field of application of temperature and humidity products, in which recorder is a very distinctive product. The paper of archives can be stored for more time under suitable temperature and humidity conditions, and once the temperature and humidity conditions are damaged, the paper will become brittle, and the important data will disappear. It is necessary to record the temperature and humidity of archives, which can prevent the occurrence of malignant accidents. The use of temperature and humidity recorder will simplify the work of temperature and humidity recording, save the cost of cultural relics storage, and make this work scientific without too many human factors. At the same time, the use of tiny probes such as Hygroclip sc04 ensures that the cultural relics, including their colors and shapes, will not be damaged on the premise of minimum damage to the works of art

(III) building materials experiment

in the drying process of building materials, especially concrete, we should pay attention to its drying trend, which is one of the indicators to evaluate products and also provides reliable data for construction parties. The application of temperature and humidity recorder can record this data and provide it to building materials researchers, which will provide useful help for construction. Especially in military buildings, time is life. Accurately grasping the drying time of concrete provides a guarantee for effectively providing effective forces to the battlefield. This function is completed by hygrolog+hygroclip sc04

(IV) agriculture and animal husbandry

the temperature and humidity values should be recorded in detail in the seedling stage of agriculture and animal husbandry production, especially the production of some cash crops. In agricultural applications, the acid-base environment caused by the harsh environment - fertilizers, feces, etc. makes the humidity products drift more than other environments, which requires that the humidity sensitive capacitance drift is small and the whole machine calibration is convenient

climate record: hygrolog temperature recorder is of great significance for agricultural and meteorological analysis

(V) building acceptance

is mainly reflected in the acceptance of intelligent buildings. Due to the large number of acceptance projects in the construction industry, in addition to HVAC indicators, other indicators such as radiation intensity, formaldehyde concentration and other requirements of the Ministry of construction to meet human health indicators should also be monitored, which are directly related to human health. If the testers rush into these places and keep records for a long time when these indicators are unknown, it is not responsible for the personal health of the testers, The application of recorders will ensure the maximum protection of the personal safety of testers while obtaining reliable data

(VI) important medical and health places

according to the requirements of the exposure draft of the technical code for the construction of hospital clean operating department, the temperature and humidity of the operating room must be controlled within a certain range: that is, the temperature is 22... 25 ℃; Relative humidity 45% RH... 60% RH. Appropriate environmental temperature and humidity are very important for both operators and patients. When the room temperature exceeds 28 ℃ and the humidity is greater than 70%rh, it is easy to have muggy, sweating after the experiment, irritability, fatigue and other reactions, which is easy to affect the stable mood and agile thinking, so that the operator's technical level can not be brought into full play. At the same time, patients will also have symptoms such as rapid heart rate and sweating, which will increase the difficulty of surgery; When the room temperature is lower than 20 ℃, the operator who only wears the surgical suit will feel cold, which is easy to affect the sensitivity and accuracy of the operation, especially the subtle movements of the fingers. Exposed patients are at a low level of body resistance due to trauma, and are more likely to have complications such as colds. The indoor humidity is low, and the floating dust on the surface of the object is suspended in the air with the change of air flow caused by some actions, such as laying sheets, opening and closing doors, etc. The temperature difference inside and outside the operating room is large, and the air in some areas forms a cochlear flow after the door is opened. The wind speed increases to about 4 times the original wind speed in the operating room. At this time, the attachments on the surface of the object quickly float in the air. According to the investigation of CDC in the United States, there is a risk of airborne infection when the number of floating bacteria in the air of the operating room is cfu/m3. It can be seen from the results that the air pollution is the most serious from the time of placing the sheet to 2 hours after placing the sheet during the operation, which is the stage of operation. Due to the effect of gravity, indoor dust can directly settle on the surgical wound, or the operator's hand or surgical instruments. Therefore, it is important to strengthen the control of air pollution in this period to prevent postoperative incision infection. These require the health and epidemic prevention departments to confirm the compliance of the operating rooms of each hospital through their own monitoring. The recorder is a good method to reduce personnel waste and ensure the fairness of law enforcement

(VII) pipeline maintenance

moisture in the pipeline will promote micro