การศึกษาการสอบกลับมวลแห่งชาติ

The Study of Traceability of Mass in Thailand

Name: วีระ ตุลาสมบัติ

Name: Veera Tulasombut

Organization : มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

keyword: ตุ้มน้ำหนัก

Abstract: This research is a study of various factors influencing mass determination using theory and principle of force comparison, in which the sample mass (weight) and the reference standard mass (weight) are weighed with a mass comparator. The aforementioned method is used in the traceability system. Traceability is calibrating the sample weight with a higher-level reference standard weight until it can be traced to the International Prototype of the kilogram (K). This study begins by calibration the reference level or EO class 1-kg weight (S102) with the National Prototype of the kilogram No.80 (P80), which is traced to the International Prototype of the kilogram (K). After that the calibration El-class 1-kg weight (Sl), with the reference level or EO class 1-kg weight (S102) is performed. In this level the El class set of weights ranging fiom 1 mg to 1 kg and from 1 kg to 10 kg are calibrated against El class 1-kg weight (Sl) by mass scale method. In case of calibration of E2 class set of weights ranging fiom 1 mg to 10 kg with the El class set of weights ranging from 1 mg to 10 kg by direct comparing method which is normal practiced by the calibration laboratories, therefore it is not included in this research. The weights were calibrated by weighing in air, therefore the air buoyancy difference between the two objects must be considered. The key point of this research is when comparing the EO class 1 kg weight (S 102) with the National Prototype of the kilogram No.80 (P80), which has the volume difference at the temperature 22 degree celsius about 80 cm3 (126.9384-46.4145) cm3 an indicated value of 1-kg, the difference in air buoyancy is approximately 0.096 g (9.6*10^-5). The uncertainty of comparison results must be less than 0.025 mg (2.5*10^-8) at a confidence level of 68 percent. In case of calibration El class 1 kg weight (S1) with EO class 1 kg weight (S102) the volume difference between two weights at the temperature 22 degree celsius is about 2 cm3 (124.8866-126.9384) cm3, the difference in air buoyancy is about - 0.0025 g (-2.5X 10^-6). Results show that the major influences in mass measurement in air are temperature, air pressure and relative humidity, respectively. If the temperature changes 1 degree celsius, the air density will change, making the 1-kg camparison result change approximately -0.350 mg (-3.5* l0^-7). A 1-mbar change in air pressure will change the air density and effect the 1-kg comparison result change approximately 0.096 mg (9.6* l0^-8). As for relative humidity, if there is a change of 1 percent RH, the effect will be approximately -0.008 mg (-8.OX l0^-9).Therefore, in calibrating the EO class weight (P102) with the National Prototype of the kilogram No.80 (P80) in order to obtain an uncertainty less than 0.025 mg (2.5X l0^-8) at a confidence level of 68 percent or coverage factor, k =1, stable environmental conditions must be controlled as much as possible. The mass comparator and all equipments must be kept separate fiom other instruments. Maintain the air control sensor, construct a separate chamber for mass comparator, operate the mass comparator at night and calibrate the temperature, ambient pressure and relative humidity sensors according to their validity period. Finally the environmental conditions temperature, air pressure and relative humidity can be controlled within the limit of +- 0.03 degree celsius, +- 0.1 mbar and +- 1 percent RH, respectively.

มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

Address: กรุงเทพมหานคร

Email: info.lib@mail.kmutt.ac.th

Name: เอก ไชยสวัสดิ์

Role: อาจารย์ที่ปรึกษา

Name: วชิระ มีทอง

Role: อาจารย์ที่ปรึกษา

Created: 2546

Issued: 2007-02-09

Modified: 2558-12-28

วิทยานิพนธ์/Thesis

ISBN: 9741832974

CallNumber: INC126

tha

DegreeName: วิศวกรรมศาสตรมหาบัณฑิต

Level: ปริญญาโท

Descipline: วิศวกรรมระบบควบคุมและเครื่องมือวัด

Grantor: มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

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ลำดับที่.	ชื่อแฟ้มข้อมูล	ขนาดแฟ้มข้อมูล	จำนวนเข้าถึง	วัน-เวลาเข้าถึงล่าสุด
1	INC126.pdf	3.44 MB	37	2024-01-11 00:15:40
2	INC126ab.pdf	66.02 KB	18	2020-10-19 02:26:34
3	INC126ab.txt	3.78 KB	8	2018-05-10 17:33:24

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