Silicone Spoon Rest Made of 100% food grade silicone, Heat Resistant, non-toxic, BPA free, durable, flexible
Silicone Spoon Rest Use for kitchen utensils, gadget, table cutlery, to lay down your spoon, brush, utensils and so on, to keep your stove top, table top, counter clean
Silicone Spoon Rest Come with large size of 9.1 x 4.7 x 0.6 inches, big enough to put your kitchen utensil or other gadget on it
Silicone Spoon Rest Withstand high temperature up to 480° F, you can put your cooking utensils on it even you just took it out of the hot pan.
Silicone Spoon Rest Dishwasher safer, hand-wash recommended to extend product life
Material
100% food grade Silicone, BPA free
Size
length 23cm width 12cm
Color
Demand by Customers
Temperature
-40~230°C
Approved By
FDA/LFGB
Usage
Microware, Dishwashers and Freezer
Packing
PP bag or as your requirement
Feature
Green Products
Odorless&Non-Toxic&Stick
Easy Using and Cleaning
Durable
Anti-dust
Impermeable
Silicone Spoon Rest Silicone Spoon Rest,Kitchen Spoon Rest,Cooking Spoon Rest,Coffee Spoon Rest Shenzhen Feiaoda Technology Co.,Ltd , https://www.flysilicone.com
The thyristor phase-controlled DC speed regulation is a classic DC speed regulation scheme. The structure is simple and the technology is mature. It basically meets the needs of centrifuge speed regulation, so it is widely used in centrifuges at home and abroad. The main disadvantages are that the rectified waveform is poor, the current ripple is large, and the current cut-off phenomenon is prone to occur at light loads. In order to maintain the continuity of the DC motor current, a bulky smooth inductor needs to be added, which increases the volume and weight of the instrument. After the 1980s, with the development of fully controlled power devices, such as power transistors and field effect transistors, switching power conversion technology was gradually applied in the DC speed control system of centrifuges, such as the German eppendorf 5410 and 5402 centrifuges. The technology is mainly through high frequency DC chopping, adjusting the pulse width ratio, changing the auxiliary output voltage, and supplying power to the DC motor. Due to the high switching frequency, generally less than 50KHZ, the smooth DC current can be obtained only by the inductance filtering of the motor itself, which overcomes the shortcomings of thyristor phase-controlled DC speed regulation, so the speed is smoother and the speed regulation range is wider.
Switch speed control is the simplest speed control scheme. Even a dozen discrete devices or an integrated block can form a system, so some low-cost centrifuges in China still use this scheme. The main disadvantage is that they require manual operation. Speed ​​regulation, can not control the current of the motor, speed accuracy and technical added value are relatively low. In view of the limitations of open-loop speed regulation, most centrifuges at home and abroad generally adopt a dual closed-loop speed regulation scheme with both current feedback and speed feedback. Its main advantages are automatic speed regulation, fast speed increase, small speed overshoot, and precision High and current limit function to avoid motor over current damage.
Although the DC speed regulation has a long history and mature technology, the commutation of the DC motor mechanical commutator is its fatal weakness, which limits the speed of the motor, the commutator brings interference, and the carbon brush needs to be replaced. This made the early ultra-speed or high-speed centrifuges Indirect speed-increasing schemes such as gear shifting or other methods have to be adopted, which increases cost and volume, and reduces life and reliability. In the late 1970s, foreign ultra-speed centrifuges took the lead in adopting frequency conversion speed regulation technology, mainly by changing the power supply frequency of the induction motor to adjust the speed. Since the induction motor does not require a mechanical commutator, it not only eliminates the trouble of replacing the carbon brush, but also improves the motor speed, and even the ultra-speed centrifuge with more than 100,000 revolutions can also be directly driven, greatly simplifying the structure of the centrifuge. The technical key of variable frequency speed regulation: first, the development and application of fully controlled power devices, which simplifies the technical key of speed regulation: first, the development and application of fully controlled power devices, which simplifies the main circuit of the inverter; second, the SPWM technology The performance index of the inverter has been improved; the third is the development of control technology, such as vector control technology, etc., so that the control performance of the induction motor reaches or exceeds the level of the DC motor; the fourth is the large-scale integrated circuit and microprocessor dedicated for variable frequency speed regulation It greatly simplifies the frequency conversion circuit, such as Siemens three-phase programmable pulse width modulation integrated circuit SIH4520, Intel's SX196MC and TI's TMS 320C240 motor control microcontroller, etc. At present, the frequency conversion speed regulation can be comparable to DC speed regulation. After the 1990s, almost all the products of major foreign centrifuge manufacturers adopt the technology of frequency conversion speed regulation, whether it is overspeed, high speed, or low speed centrifuges, such as Germany Heraeus, Hettich, etc., China also lists the frequency conversion speed centrifuge as a key problem. It is planned that some manufacturers have already introduced variable frequency centrifuges, such as Shanghai Anting Scientific Instrument Factory and Institute of Biophysics, Chinese Academy of Sciences. According to the different AC motors, the frequency conversion speed regulation is also different. At present, there are three main types of motors used in frequency conversion speed regulation centrifuges: asynchronous induction motors, brushless DC motors and variable reluctance motors. In 1988, SORVALL applied the brushless DC motor for the first time to launch the RC-285 sub-speed centrifuge. Beckman applied a variable reluctance motor to produce the Avanti series centrifuge with a speed of up to 30,000 rpm. Doubled, but currently the most popular and mature application is asynchronous induction motors.
2. With the development of centrifuge manufacturing and application technology, centrifuges have not only made progress in speed regulation technology, but also made great progress in multifunction and automation, such as variable speed starting and braking, program speed change , Direct input of centrifugal force, storage and recall of operating procedures, automatic diagnosis of instrument status, requirements to display the parameters and status information of the centrifuge as much as possible, and more complete safety protection functions, etc. Some functions are not only icing on the cake, but also directly affect the centrifuge Effects, such as variable rate starting braking and program shifting can improve zone centrifugal effect and shorten centrifugation time. Early centrifuge control systems consisted of discrete components, with complex circuits, high costs, and many functions that were difficult to achieve. After adopting microcomputer technology, the functions of hardware can be replaced by software or functions that are difficult to realize by hardware, such as centrifuge program control, motor control, etc., not only greatly simplify the structure of hardware, but also become multi-functional and automated. The core of the general centrifuge microcomputer control system is a single-chip microcomputer. The hardware system includes: operation interface, motor control interface, temperature control interface, safety protection monitoring interface, system monitoring and so on. The operation interface manages the keyboard and display. In order to facilitate the user to operate and monitor the operating parameters, the operation interface should follow the principle of simplicity, strong logic, and clear parameters. The Biofugestratos centrifuge in Heraeus, Germany adopts the "EasyCon-trol" interface, which displays and processes operating parameters in a comprehensive manner, adopts an internationally recognized graphic language, and has as few single-function operation keys as possible. Can handle the operating parameters; the German Hermle new centrifuge inherits the operating characteristics of the traditional centrifuge, and still uses the knob to adjust the parameters. The input of the motor control interface is the motor current and speed signal, and the output is the motor speed control signal. The speed sensor generally has : Coaxial generator speed measurement, reluctance speed measurement, Hall device speed measurement, photoelectric projection and refraction type speed measurement, which is highly integrated, low cost, reliable and simple in application by Qianguang Optoelectronics and Hall speed measurement, so it has been widely used recently. Centrifuge The principle and structure of the temperature control system of the rotor cavity is roughly the same as that of ordinary refrigerators, but advanced and higher-precision inverter press temperature regulation technology has not yet been widely used: semiconductor (vehier) devices are also used for cooling, but it is not common; some centrifuges , Such as 16 and 30F of HettiCh, Germany, to reduce the heat conduction of the motor and the wind resistance of the rotor. Impact, using air-cooled cooling technology, the air duct design of the air-cooled centrifuge is the key. Generally, the air is sucked from the top and discharged from the bottom. The flowing gas will take away the heat of the rotor and the motor. The scientific air duct can both cool down. It can also reduce noise; some centrifuges control and display the temperature of the sample in the rotor (Sample Temperature), while some control and display the temperature of the rotor cavity, the former requires a lot of experiments, the technical content is high, and it is more popular with users. Welcome. Security protection monitoring interface mainly includes: overspeed, overtemperature, rotor unbalance, rotor identification and door lock monitoring, etc. System monitoring should monitor the status of the system itself, protect and give fault information in time to facilitate maintenance. Single chip It is better to choose a single-chip microcomputer with a high degree of integration, special purpose and internal bus. The high degree of integration can reduce the cost and improve reliability. The special purpose can simplify the design and improve the integration. The internal bus is isolated from the outside through the I / O port to reduce electromagnetic noise. Interference to the bus, the core of the eppendorf5415C control system consists only of a single-chip microcomputer with ADC (38ADP70) and a peripheral integrated block (ULN Composed of 2802A, the circuit is very simple.
3. Pay attention to safety, environmental protection and improper use of international standard centrifuges, such as rotating head overspeed, overload, imbalance, etc., may damage the instrument, or even blow the head, threatening personal safety, so manufacturers pay special attention to safety design, international and national regulations Corresponding safety standards, such as the German accident prevention regulations for centrifuges (UVV, VBG 7Z), industry standards for centrifuges and centrifuge tubes (DIN 58970, PARTI, 2, 3 and 4). The mechanical safety design mainly includes the following contents: ①Door lock protection system, adopts mechanical and electronic double-layer door locks, requires the centrifuge to start after the door lock is closed, and can only be opened after the motor stops. G ② Centrifuge chamber and cover The use of sturdy armor steel to prevent the unbalance detection of the rotor flyaway heart rotor is important. The unbalance of the rotor will cause the motor shaft to swing, affecting the life of the centrifuge. In severe cases, the motor shaft will be broken or even exploded. head. Generally, the unbalance is detected by detecting the vibration of the motor shaft. Common methods include: mechanical position switch, magneto-resistance (MSR), ultrasonic ranging, and acceleration sensing. The mechanical position switch is simple and practical and the most widely used. Heraeus Biofuge Stratos centrifuge uses an acceleration sensor and data processing software to develop an intelligent imbalance recognition system that can monitor the entire weight of the centrifuge for the specific weight of each rotor. , A change to the previous mechanical position imbalance identification system needs to hate the swing distance of the shaft, and it only works during the acceleration phase, so that it can detect even test tube rupture and samples at any speed, even at high speeds Unbalance caused by overflow; ④Improve the centrifuge's own anti-unbalance ability, not only can improve the robustness of the centrifuge, but also because the rotor does not need to be strictly balanced during the operation of the head, or even visual balance, it is convenient User actions. In general, small centrifuges place the entire motor on a shock-resistant elastic support, such as rubber pads, etc., and high-speed centrifuges often use a rubbing shaft for shock resistance. eppendorf5415C suspends the entire motor on a rubber support. Heraeus Biofuge Statos centrifuge uses the "Spindie Driver" anti-vibration drive system for the first time. The entire shaft is placed in an anti-vibration buffer container, which overcomes the fragility and breakage of the flexible shaft. Disadvantages, so it is stronger, more resistant to imbalances, and quicker to start and stop (about 305); ⑤The rotor identification system can automatically identify the rotor, limit the maximum speed of the rotor, and effectively prevent the user from misoperation. The basic principle of rotor identification is to set a unique code for each rotor, or inlay a certain number of small magnets at the bottom of each rotor, use Hall sensor, or use photoelectric refraction ring sensor. Ultrasonic and radio frequency rotor identification, the rotor can be identified without running, and even the rotor cover can be detected.
Environmental protection is mainly manifested in two aspects. First, the refrigeration system uses fluorine-free refrigerant or semiconductor (Peltier) refrigeration, but currently centrifuges that use semiconductor refrigeration are still rare; second, noise reduction, generally speaking, the voice is usually 60 minutes p, The driving sound of public gas cars is 70 to 80 decibels. Medical research has shown that noise above 70 decibels can interfere with conversation, cause upset, affect work, and even cause accidents. According to the technical evaluation standard for measurement certification of China's product quality inspection agency (fiG102 1 90), the noise of the test laboratory should not be greater than 70dBo. The noise reduction measures of the usual centrifuge moon mining are: the shell and the rotating head cavity are added with sound-absorbing coating; the sturdy and stable seismic base is used to isolate the mechanical frame from the elastic shock absorber ; Application of motor without commutator, etc. Generally, after the shock absorption treatment, the noise of the centrifuge can be limited to 60 decibels.
As electrical equipment, centrifuges must also meet the corresponding electrical safety and electromagnetic compatibility (EMC) standards, such as the International Electrotechnical Commission (IEC) "IEC General Safety Guidelines for Medical Electrical Equipment". The European Union's "EN61010-and and 61010-2-020", the electromagnetic compatibility standard has the European Union "EN55082-1" and so on. With reference to international standards, China has formulated electrical safety and electromagnetic compatibility standards suitable for China's national conditions, "General safety requirements for medical electrical equipment" and "Measurement methods and allowable values ​​of radio interference characteristics of power tools, household appliances and similar appliances (GM343- 84) "etc. The safety rules mainly stipulate four indexes, such as insulation resistance, leakage current, grounding wire resistance and grounding resistance, and require users to check these four indexes after overhaul or periodically. In January 1996, the European Union officially promulgated and implemented the electromagnetic compatibility index, which stipulates that all equipment that has passed the "EN55082-2" EMC certification will be issued with the CE mark, and stipulates that all products with the CE mark shall be allowed to transit through the EU member states Don't stay hard. Electromagnetic standards require that electrical equipment should not generate electromagnetic interference from the outside world, and must also have the ability to resist electromagnetic interference. Since the centrifuge has both an electric drive system that generates strong electromagnetic interference and a microcomputer weak current system that is sensitive to electromagnetic interference, both manufacturers and users should pay attention to the electromagnetic compatibility of the centrifuge. In short, the highconic of the mechanical and electrical centrifuge Heraeus meets the increasingly stringent requirements of quality and safety, and products with standard certification can gain more trust from users.
4. Rotating head improvements and increased variety
Rotors commonly used in the laboratory are: angle head, flat head, vertical head, and special and recently developed rotor heads, such as continuous flow head, elutriation head, zone head, enzyme plate head, capillary head, petroleum test head, The drum head and biological safety head, etc., have more types of rotors, improved the centrifugal method, and broadened the application field. In addition to the increased variety, the material and structure of the rotor have also made great progress. The material of the rotor is mainly aluminum alloy and titanium alloy. Aluminum alloy is light in weight, high in strength and low in cost, but it has poor corrosion resistance and high temperature resistance. In addition to the advantages of aluminum alloy, titanium alloy can also resist corrosion and high temperature resistance, and can be directly sterilized by high pressure and high temperature to work at high temperature. In order to reduce the load of the motor and increase the capacity of the samples, many manufacturers improved the material and structure of the rotor and introduced ultra-light rotors: Beckman and Hitachi launched carbon fiber rotors, which are only one-third the weight of aluminum alloy heads; Sorval series The weight of the ultra-light aluminum head is reduced by half; the anti-corrosion and temperature-resistant polypropylene head developed by IEC can be bleached for cleaning and disinfection, or it can be directly sterilized by high pressure and high temperature; Heraeus highconic (45 degree high-speed angle head) head uses a hollow cavity Structure, in a small centrifuge, load 6 X 50ml samples, high-speed operation; eppendorf uses a thin aluminum alloy plate, which is pressed into a hollow angle head with a mold; Hettich uses a method of slotting and hanging blue around the thin steel plate to make a flat head. In other respects, Heraeus has improved the material and structure of the biological head to solve the shortcomings of poor high-speed sealing of the biological head. The number of high-pressure and high-temperature sterilization is unlimited, and it has passed the CAMR test of the independent evaluation agency British Applied Microbiology Development Center.
When the rotor is running at high speed, centrifugal stress will be generated inside. When the centrifugal stress exceeds a certain limit, it will cause the rotor to fail prematurely, or even to explode, so users must pay attention to the correct use and proper storage of the rotor. After the rotor is used, it should be cleaned in time, and don't collide with scratches. If it is accidentally lost, the rotor should be X-rayed to confirm that there is no trauma inside before it can be used. In use, the use of the over-life rotor should be terminated in time. Usually, the manufacturer indicates the rotor hours and the number of centrifugation times. No matter which index comes first, it means that the rotor life has expired. The extension of the rotor life should be strictly in accordance with the manufacturer's instructions. Generally, the maximum speed of the rotor should be reduced under the following circumstances: â‘ The life of the rotor has expired, but the rotor is well preserved, and the speed is reduced to extend the use according to the manufacturer's instructions; â‘¡The rotor is partially damaged or slightly corroded; â‘¢When the average density of the sample using stainless steel centrifuge tube and casing core exceeds 1.2g / ml.
Item Name
food grade silicone spoon rest
Silicone Spoon Rest Pictures:
Desktop high-speed centrifuge
Desktop high-speed centrifuge
1. The AC frequency conversion speed regulation will gradually replace the DC speed regulation. The speed regulation system is the core part of the centrifuge, which is composed of three major elements of control, power drive and motor, mainly to control the speed of the motor. In the development process of centrifuges, DC speed regulation is indispensable. Its main characteristics are good starting and braking, wide speed range, simple structure, low cost, and relatively mature theory and practice. The centrifuge is widely used and mature, so it was widely used in the centrifuge before the 1980s, and it is still in use and continuous improvement, such as improving the wear resistance of the DC motor copper head and carbon brush to extend Motor life and carbon brush replacement cycle, etc.
Desktop high-speed centrifuge price / desktop high-speed centrifuge manufacturer / Shanghai desktop high-speed centrifuge
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