How to calibrate the greenhouse parameters in the use of electric constant temperature incubator

With the continuous development and improvement of the detection methods for industrial production, medicine, medical and health, and engineering quality inspection industries, the requirements for temperature indicators are getting higher and higher. For electric constant temperature incubators, the temperature field is not only required to be even, but also the fluctuation is reasonable. The temperature deviation requirement is extremely strict. This requires us not only to guide companies to properly use the electric constant temperature incubator, to ensure its accuracy, but also to improve its accuracy. In the actual on-site temperature field test process, in order to eliminate the error brought about by the measurement results, and also a true and reliable measurement result, we will talk about how to reduce the error of the measurement of the temperature field in the following points.

1, the correct use of electric constant temperature incubator

(1) In strict accordance with the instructions for use, the correct use of electric constant temperature incubator; (2) Select a reasonable temperature field within the working area of ​​the warm field; (3) When using a constant temperature incubator, ensure that the constant temperature time is long enough to make it warm The field is kept constant; (4) In the steady state, the accuracy of its temperature field is guaranteed.

2, how to improve the use of temperature field accuracy

Before the measurement, we introduce several concepts about the temperature field.

● Incubator work area: In a stable state, the area is consistent with the temperature uniformity of the incubator and the temperature fluctuations.

Incubator temperature uniformity: In the steady state, the difference between the highest temperature and the lowest temperature in the constant temperature incubator working area.

● Incubator temperature fluctuation: In the steady state, the incubator working area within a certain time interval, the range of temperature changes.

• Incubator temperature deviation: In the steady state, the incubator shows the difference between the temperature and the actual temperature at the geometric center of the workspace.

Here's a step-by-step how to improve the accuracy of the use of its temperature field.

1 First, check the temperature of the primary temperature incubator and the temperature display instrument, and give the correction value of the corresponding measurement temperature point. This eliminates the combined errors introduced by the primary and secondary temperature instruments.

2 Because of the difference between the position of the temperature measuring element and the working geometric center of the working field in the temperature field, the system error naturally occurs. We measured and corrected the difference between the temperature at the geometric center of the workspace and the temperature at which the primary element was located, thus avoiding errors due to the temperature measurement element not being in the geometric center.

3 When conducting the temperature field test, the error caused by the standard device should also be taken into account, ie the error caused by the standard device should also be corrected.

4 The electrothermal incubator is mainly a temperature indicator, so the accuracy of temperature control also directly affects the accuracy of the temperature field. Even if the temperature indicating error of the temperature indicating instrument in the incubator is 0, if the temperature control accuracy is not high, the temperature control point deviates from the actual temperature also causes the temperature field to run out of control. Therefore, setpoint errors for each temperature control point should be given and corrected.

5 In summary, to improve the accuracy of the use of electrothermal incubators, the above error sources should be corrected. The actual temperature of its temperature field is calculated according to the following formula:

t real = t + x + x + x + x + x + x + standard + x control type: t real - constant temperature incubator test point actual temperature, °C; t shows - constant temperature incubator temperature display instrument Display temperature, °C; x yuan - temperature correction value of the primary component of the constant temperature incubator at this point, °C; x table - temperature correction value of the secondary temperature instrument of the constant temperature incubator at this point, °C; x position - ——Deviation of temperature correction from the geometrical center, °C; x-standard—The temperature correction value of the standard device, °C; x-control—Temperature incubator temperature control point temperature correction value, °C.

6 Based on JJF1030-2010 "Constant Temperature Bath Technical Performance Test Specification", JJF1101-2003 "Environmental Test Equipment Temperature, Humidity Calibration Standard", JJF (Liao) 118-2011 "Electric Thermostatic Water Bath Calibration Standard" on the temperature of the electric constant temperature incubator Field temperature uniformity, fluctuations, and temperature deviations are calibrated.

3, the calibration of temperature parameters

(1) The calibration temperature point generally selects the upper limit, lower limit and intermediate point of the equipment use range, and can also select actual commonly used 1, 2 temperature points according to user needs.

(2) The location of the test points is distributed on the three calibration surfaces of the equipment working chamber, referred to as the upper, middle and lower layers. The middle layer is the calibration working surface parallel to the bottom surface through the geometric center of the studio, the test points and the working room. The distance between the walls is not less than 1/10 of the length of each side. If the device has a sample holder, the lower test point can be placed 10 mm above the sample holder.

(3) The number of test points, the general electric constant temperature incubator's volume is less than 2m3, temperature test point is 9, including 4 points on the upper and lower layers, 1 point on the middle layer, located in the middle geometric center. (4) temperature calibration, according to the provisions of the temperature sensor layout, the temperature controller of the electric constant temperature incubator set to the required nominal temperature, so that the device works. The reading was started after stabilization, and the temperature of all test points was recorded every 2 minutes, and 10 tests were performed in 20 minutes.

(5) Data processing

1 temperature deviation calculation △td = td-to type: △td - - temperature deviation, °C; td - - constant temperature incubator display temperature, °C; to - - the actual geometric center O point of the work area Temperature, °C.

2 Temperature uniformity calculation △ t = tpmax-tpmin where: △ t uniform - temperature uniformity, °C; tpmax - each temperature (continued) Actual temperature maximum, °C; tpmin - The actual temperature of each temperature measurement point is minimum, °C.

3 Calculation of temperature fluctuation △tb=±(toh-tot)/2 Where: △tb―—Temperature fluctuation, °C;toh―——Maximum temperature at point O of the working geometric center, °C;tot― The minimum temperature at point O in the center of the work geometry, °C.

After the calibration of the electrothermal incubator, not only the precision of the constant temperature incubator but also the accuracy of its use is greatly improved.

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