Gauge Head Research Articles

Experimental hydraulic parameters of drainage grate inlets with a horizontal outflow in the broad-crested weir mode.

The accurate assessment of discharge coefficients for different types of water inlets is crucial for minimizing modelling errors in drainage systems thus reducing the risk of flooding in adjacent areas. This study experimentally investigated the hydraulic characteristics of gully grate inlets with water seal and horizontal outflow, with nominal outlet pipe diameters of 100 and 150 mm, using a laboratory setup that meets the requirements of a special European regulation. Transition depths from the weir to the orifice mode were determined, and it was found that the perforated grates significantly increased the hydraulic resistance compared to the bar grates, resulting in a corresponding decrease in the discharge capacity of gully inlets. Power-law relationships between the weir discharge coefficient and gauge head were obtained for both bar and perforated grate inlets, as well as between the discharge coefficient and Froude number at the perimeter of grate inlets. These findings provide important insights for optimizing the design and performance of water inlets, particularly in the weir mode, which is critical for the proper functioning of drainage systems.

Fast and Precise Non-Contact Measurement of Cylindrical Surfaces with Air Gauges.

In this paper, the results of an investigation on the application of air gauges in the measurement of out-of-roundness parameters are presented. The principle of the measuring system is explained, in particular the novel design of the floating gauge head. An algorithm for fully automated measurement and data processing is described. The results from a series of initial measurements provided the data for further simulations, which revealed possible sources of errors. The simulations helped to evaluate the influence of some of the parameters on the final measurement results. After various accuracy tests, the method accuracy (MA) parameter was calculated in relation to the dedicated reference form tester. The result MA = 9.29% was judged to be highly satisfactory considering the short measurement time and non-contact method.

On measuring techniques of pore pressure in concrete at elevated temperature

Entrapment of water vapor pressure is a major reason leading to explosive spalling of concrete subjected to elevated temperature. However, the measurement techniques for pore pressure inside concrete specimens were not consistent from different studies. This paper presents an extensive review of pore pressure measurement techniques first. Three main differences (viz., medium to transfer pore pressure, type of pressure gage head, and placement of thermocouples) were found in previous studies. An experimental program comprising twelve pore pressure gages was designed to evaluate effectiveness of all the combinations of factors by conducting one-dimensional heating test of concrete slabs. The test results showed that heat transfer properties and temperature measurements were not influenced by the different measurement techniques. Filling steel tubes with rods or leaving the tubes empty would impair build-up of vapor pressure. On the contrary, filling it with silicon oil will create extra hydraulic pressure due to thermal expansion of the oil itself. The use of sintered metal as a gage head could compensate additional pressure by introducing free volume and collect pore pressure evenly. Placing thermocouples outside the steel tube would not compromise accuracy of temperature measurement and the complexity of the measurement system could be greatly reduced. At last, two requirements are proposed for correctly measuring vapor pressure: (1) expansion of oil must be compensated by free volume; (2) free volume should not interfere with moisture accumulation and vapor pressure build-up.

The data acquisition and control system for the operation of ASDEX pressure gauge for the measurement of neutral pressure in ADITYA Tokamak

Bayard-Alpert (BA) type hot cathode ionisation gauge is widely used to measure neutral pressure precisely in vacuum system below 10−3 Torr pressure. Neutral pressure measurement in magnetic confinement fusion experiments is quite challenging for standard BA type gauge due to higher pressure limitation and its ionisation is affected by strong magnetic and electrical fields. To overcome the above limitations, a special hot cathode ionisation gauge, named ASDEX Pressure Gauge (APG) system was developed by G. Haas at the Max-Planck-Institute, Germany. The APG system can work in high magnetic field up to 6 T and high temperature plasma environment with broad pressure measurement range from 10−1 to 10−6 mbar with fast response (<10 msec) and good noise immunity.In the present work, we report the design and development of control and data acquisition of ASDEX Pressure Gauge (APG) for ADITYA Tokamak to measure real time neutral pressure during the high temperature plasma. The developed system can achieve synchronous control of gauge controller using General Purpose Interface Bus (GPIB) and data acquisition of ion emission current of gauge head using Peripheral Component Interconnect (PCI) based data acquisition module. Initially, the APG calibration with standard BA type hot cathode ionization gauge had been carried out using the test set-up of low magnetic field and ultrahigh vacuum system with gases like H2, Ar, He. For APG calibration for various pressure ranges of these gases, precise gas feed control system has been developed using controller based hardware and LabVIEW based software. After testing and calibration, the APG was installed on ADITYA tokamak and calibrated under high magnetic field of ADITYA. The developed APG control system is configurable for presenting the gauge parameters before the plasma discharge. During plasma discharge, the analog signal equivalent to neutral pressure is acquired in real-time using simultaneous sampling analog to digital converter (ADC) module. The acquired raw data and processed real time pressure can provide valuable neutral pressure/density information of Tokamak plasma.

Focus on materials, semiconductors, vacuum, and cryogenics

Focus on materials, semiconductors, vacuum, and cryogenics

Status of the development of diagnostic pressure gauges for the operation in ITER

The ITER Diagnostic Pressure Gauges (DPG) shall provide the measurement of the neutral gas pressure, which is an important parameter for basic control of the operation of the ITER machine as well as for input to physics models of the plasma boundary. The reference sensor is a hot cathode ionization gauge, which is able to operate in an environment with strong magnetic fields (up to 8T), strong and noisy background signals and fast pressure changes. In total 52 DPG sensor heads will be installed in 4 lower ports, 4 divertor cassettes and 2 equatorial ports. The DPG system is currently being developed by IPP in collaboration with F4E and Sgenia within the Framework Partnership Agreement FPA-364. As part of the system level design activities several different architectures of the DPG system, including gauge head and supporting electronic equipment, have been evaluated in detail with the aim to fulfil technical requirements imposed by the integration in ITER. Most important steps made towards the currently defined baseline design of the DPG system, which is based on ASDEX Pressure Gauge (APG) technology, are discussed in the present paper.

Static Characteristics of Air Gauges Applied in the Roundness Assessment

Abstract In the article, analysis of the work conditions and the metrological characteristics of the air gauges dedicated for the roundness assessment is described. To reach the required accuracy of the acquired data, the phenomena of gas dynamics had to be analyzed in the whole flow through elements of the air gauge. A model based on the second critical parameters was used, because it reflects the true processes of the air flow. As a result, fast and accurate simulations provided series of the characteristics to be considered. Nevertheless, the chosen air gauge configuration underwent the experimental verification of its metrological characteristics. Finally, the entire measurement system Geoform with the gauge head based on the chosen air gauges underwent the accuracy test in order to make sure of its overall measurement quality.

Study on Vacuum Materials Outgassing Rate Using the Method of Switching Between Two Pumping Paths

A new measurement apparatus for vacuum materials outgassing rate was developed, which is mainly composed of three systems, including ultra-high vacuum system, high vacuum system, switching between two pumping paths (SPP) measurement system. The test principle of the modified SPP method is described in details, and the newly-developed technique has two main advantages over the conventional one. Firstly, the errors due to the use of two gauges with different physical properties are avoided by using only one gauge during data processing. Secondly, the outgassing rate of sample chamber, the test chamber and the outgassing or pumping effect of the gauge head can be eliminated enormously. Based on the SPP method, this paper gives the details of the experiments and the results on specific outgassing rate of the 7075 aluminum alloy sample in different conditions, namely, at different times and at different temperatures generated by infrared light irradiation heating.

Measurement of the Femoral Head Diameter at Hemiarthroplasty of the Hip

This paper is focusing on the measurement methods of the femoral head at the hip hemiarthroplasty surgery. The measurement result of 10 femoral head specimens using four different methods of Vernier calliper, ring gauge, CT scan and X-ray were compared. It is generally believed that under sizing of the implant may cover the errors of the measurement methods, but the result of this study shows that the callipers and ring gauge measurements are more reliable than the CT and X-ray methods. Conclusively, the full-circle ring gauge or femoral head template is the recommendation for measurement of the femoral head diameter in the hip hemiarthroplasty surgery.

Advantages of the experimental animal hollow organ mechanical testing system for the rat colon rupture pressure test

BackgroundMany studies have been conducted on colorectal anastomotic leakage to reduce the incidence of anastomotic leakage. However, how to precisely determine if the bowel can withstand the pressure of a colorectal anastomosis experiment, which is called anastomotic bursting pressure, has not been determined. MethodA task force developed the experimental animal hollow organ mechanical testing system to provide precise measurement of the maximum pressure that an anastomotic colon can withstand, and to compare it with the commonly used method such as the mercury and air bag pressure manometer in a rat colon rupture pressure test. Forty-five male Sprague–Dawley rats were randomly divided into the manual ball manometry (H) group, the tracing machine manometry pressure gauge head (MP) group, and the experimental animal hollow organ mechanical testing system (ME) group. The rats in each group were subjected to a cut colon rupture pressure test after injecting anesthesia in the tail vein. Colonic end-to-end anastomosis was performed, and the rats were rested for 1 week before anastomotic bursting pressure was determined by one of the three methods. ResultsNo differences were observed between the normal colon rupture pressure and colonic anastomotic bursting pressure, which were determined using the three manometry methods. However, several advantages, such as reduction in errors, were identified in the ME group. ConclusionDifferent types of manometry methods can be applied to the normal rat colon, but the colonic anastomotic bursting pressure test using the experimental animal hollow organ mechanical testing system is superior to traditional methods.

A Size-Shifting Measuring Method for Multi-Diameter Shaft Grinding

A novel size-shifting measuring method for multi-diameter shaft grinding is presented. The principle of size-shifting measuring method is to automatically switch the zero positions of multi-diameter shaft in grinding process. Each steps zero position of the sample part and magnification of the gage head are measured before grinding. The measured values of all these steps are controlled within the gage head measuring range by auto-compensation, so that the grinding process of multi-diameter shaft can be accomplished with only one-step installation and non-stop. The size-shifting software of the function is programmed, and the hardware circuit is designed for active measuring instrument. The experimental measurement on the basis of active measuring instrument is carried out to demonstrate the validity of this suggested method. This method has such advantages as operational simplicity, high efficiency and reasonable accuracy. At the same time, the research result is beneficial to further improving the active measuring instrument.

Development of CMM Auxiliary Equipment for Tiny Hole Measuring

According to the limited measurement range of specific coordinate measuring machine (CMM), a reverse test method was put forward, and an auxiliary measuring equipment for tiny hole was developed. A measuring method for tiny hole was formulated, which using gauge head trigger signal of CMM as the test signal. The principle which was the tiny hole moving but not moving gauge head was used and the corresponding measurement software was designed so that the small measurement range was expanded. The measurement precision influence factors were analyzed and the measurement scheme was optimized. The results indicate that: then the measurement range of tiny hole is expanded to 1.0mm based on the combination of auxiliary equipment and CMM. The precision error is 0.004 mm which meets the measurement requirements.

Design and accuracy analysis of pneumatic gauging for form error of spool valve inner hole

The inner hole of a spool valve is a slender hole required to have high precision form, and the form error is generally not allowed to exceed 1 μm in servo valve production. Aiming at ultra-precision measurement for the spool valve inner hole in situ, this paper proposes a novel non-contact measurement method based on the differential pressure pneumatic measuring principle and develops a form error pneumatic gauge system for the spool valve inner hole. The pneumatic measuring circuit, gauge head and precise driving mechanism have been designed. The factors that influence the accuracy of the pneumatic gauge system have been thoroughly analyzed and tested to evaluate the measuring uncertainty. The system calibration and measurement experiments have been carried out. Results show that the measuring error does not exceed 0.3 μm, which can be further improved by the error separation and compensation technique.

Research on High Efficient Virtual Measuring Method for Globoidal Cam Machining Error

Current methods for measuring Globoidal cam exist these problems: difficulty of measurement of profile machining error, heavy dependency on expensive measuring equipment and low measuring efficiency. In order to solve them, this paper established a high efficient virtual measuring method for globoidal cam machining errors. Based on virtual measuring theory and globoidal cam space engagement theory, and by taking the three-dimensional machining simulation models of the globoidal cam profile as the measured object, the virtual gauge head can do measurement along the planned measuring path. The machining error calculation method was determined according to the degree of geometric interference between virtual gauge head and the surface of machined models. And a virtual measuring system on UG platform for globoidal cam profile machining errors was built by use of Visual C++ 6.0 and UG/Open API secondary development tools. Finally, a virtual measuring experiment was performed for the two kind of machining simulation models generated by generating method and one-side machining method. The experimental results show that the high efficient virtual measuring method for globoidal cam machining error is correct and the virtual measuring system is reliable. On the one hand, an effective method is provided to achieve an efficient, low-cost measurement for globoidal cam profile machining errors in this paper. On the other hand, it has great engineering guiding significance for the actual production and processing of globoidal cam.

A Pirani gauge in a high-intensity proton accelerator

We have developed a Pirani-type vacuum gauge for monitoring the back pressure of a turbo-molecular pump (TMP), which is employed as the main pump for the 3-GeV Rapid Cycling Synchrotron (RCS) at the Japan Proton Accelerator Complex (J-PARC).As vacuum components are subjected to high levels of radiation in these devices, the TMP and the vacuum gauge used for monitoring the TMP’s back pressure should have high reliability and a long life so as to minimize exposure to radiation during maintenance. Moreover, to ascertain the vacuum conditions of the ring and to monitor the back pressure, the gauge should preferably be capable of measuring pressures from 0.1 Pa to 103 Pa. To satisfy these requirements, the following measures were taken: All the components around the sensor head, including the connector and cables, were replaced with components that were guaranteed to perform satisfactorily even with a radiation dose greater than 30 MGy. Then, the semiconductor devices used in the measuring circuits were checked by using the four-point probe method and found to work satisfactorily at a distance of 150 m from the sensor. To measure higher pressures, the current control circuit was modified in such a way that the set value of the current increased in stages as the pressure increased. Further, it was ensured that the gauge showed high resistance to vibration and to an abrupt air intake as well as high radioactive resistance. The newly designed gauge head comprised a series of twelve Pt wires, each with a diameter of 100 μm. It was confirmed that pressures from 5 × 10−2 Pa to atmospheric pressure were measurable with an accuracy of less than 30%.This Pt Pirani gauge has shown good performance in monitoring the back pressure of the TMP at the J-PARC RCS, where it has been in use since Oct. 2009.

Design of the Precision Detection Device for the Key Dimension of Bending Mold

The key to guarantee bending mold interchangeability is the precise detection of the cutting edge angle, symmetry and the distance from its center to the fitting surface of CNC bending mold. According to the features of the Key Dimension of the Bending Mold (KDBM), it is detected using a 3-DOF mechanical arm connected in series. The mechanical arm has a horizontal DOF, a vertical DOF, and a rotational freedom of the gauge head which is placed at the end of the mechanical arm. The Precision Detection Device (PDD) for KDBM that we have designed has high accuracy, good stability and rapid response.

Deep-hole inner diameter measuring system based on non-contact capacitance sensor

A precise aperture measuring system of small deep holes with capacitance sensors is presented. Based on the working principle of non-contact capacitance sensors, influence of the edge effect of gauge head is studied, and one capacitance sensor for measuring the aperture of the small blind holes or through holes is introduced. The system is composed of one positioning device, one aperture measuring capacitance sensor, one measuring circuit, and software. This system employs visual CCD and two-dimensional micro-adjusting mechanism to realize the precise positioning. By LabView software this system is controlled to run automatically, to carry out calibration and automatic data collection, and to make data import into the database directly. Experiments proved that the diameter measurement range of the system can be 1.8 mm–7 mm, the resolution can be up to 5 nm–10 nm, the repeatability measurement standard deviation can be 0.05 μm–0.1 μm, and the measurement uncertainty can achieve 0.15 μm–0.3 μm. So the measuring system can realize the nanometer-level measurement.

The Development of a Pirani Vacuum Gauge with a Platinum Wire in the J-PARC 3-GeV Rapid Cycling Synchrotron

The back pressure of Turbo-Molecular Pumps (TMPs) is constantly monitored using Pirani gauges at J-PARC (Japan Proton Accelerator Complex) RCS (3-GeV Rapid Cycling Synchrotron) where they are used not only in rough pumping but also evacuations during beam operations. The gauge head needs to be very resistant to vibration and abrupt air inlet etc. in minimizing exposure to radiation during maintenance and hence a 50 μm in diameter W wire was adopted as the filament. This type of Pirani gauge has worked well in monitoring the back pressure of the TMP but it has become difficult to measure the low pressure of less than several Pa with the gauge, which may have been due to changes in the emissivity of the W surface. An attempt was therefore made to develop a gauge head made of Pt wire in allowing pressures as low as 0.1 Pa to be measured. Platinum is one of the best possible materials to use because it is very stable against oxidization. However, ordinary Pt gauge heads are rather weak when it comes to vibrations and abrupt air inlet due to its low tensile strength. In order to improve its toughness the filament was composed of twelve 100 μm in diameter Pt wires that were 65 mm long, resulting in it being capable of enduring a force of 25 N. All the wires were welded in series on metal poles in two separate glass plates, with the poles being electrically insulated. This resulted in the filament, 78 cm long and about 10 Ω at room temperature, being containable in a 5 cm in diameter and 10 cm long cylindrical envelope. The output from the gauge head was then examined as a function of pressure under constant current as the plan was for it to be controlled using the constant current method. Confirmation then took place that the pressures of 0.1 Pa up to 103 Pa were measurable with the gauge using current control in such way that the set value increased with pressure increases in three stages.

Development of SPring-8 vacuum system

SPring-8 storage ring has been available for user operation with low emittance and extreme stability for over 10 years. However there occurred some problems in the components of the storage ring due to high-brightness synchrotron radiation (SR) and low-emittance operation. On the vacuum system of the storage ring, an accurate pressure could not be measured near the photon absorber due to scattered high-energy SR to the gauge head. High-energy SR activated dissolved oxygen in cooling water, and the activated dissolved oxygen corroded the inside of the photon absorbers in SR irradiation part. Air leakage occurred at an injection chamber due to impact by a small-size electron beam produced by low-emittance operation. We investigated the cause of the aforementioned difficulties with the vacuum system and prescribed the treatments described in this paper. In addition, we are making continual efforts at further system upgrades such as developing an RF shield that suppresses temperature increase in the shield in possible high-current operation.

放射線による圧力測定異常の実験的研究

In the SPring-8 storage ring, we could not make an accurate measurement of pressure using a Bayard-Alpert vacuum gauge near the photon-absorber due to the irradiation of the scattered X-ray to a gauge head. Therefore the effect of X-ray irradiation to a gauge head has been investigated experimentally. As the results, the ion current of the collector electrode was detected without emission current from the filament. It was confirmed that the causes of the ion current were photoelectric effect and Compton scattering to the collector electrode and the ionization of gases. Especially, the ion current caused by ionization of air between the gauge head and the connector was extremely large. With these experiments, we identified main cause and its mechanism.