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This paper describes the novel concept of dual-type temperature sensors, that enables in-situ monitoring of thermocouple drift. The concept aims to provide users, who are performing temperature measurements by thermocouples, a relatively cheap and simple solution for monitoring its drift under conditions of typical use, including environments with varying temperatures. For industrial users, thermocouple drift causes many problems such as higher energy costs and lost time through process disruption due to the replacement or recalibration of failed thermocouples. This usually requires processes to be shut down when the measurement errors become too large. Such process disruptions can further lead to loss of raw material or the production of semi-finished products. For these reasons, users requiring high accuracy temperature measurements tend to replace thermocouples regularly as a precautionary measure, sometimes even if they have been used for only a few days. The main idea of the dual-type thermometers is that a drift of a thermocouple can be determined by monitoring the difference in its temperature readings and the readings of an additional (reference) thermometer if the reference sensor experiences a lower drift than the thermocouple under test. In many cases, the monitored thermocouple sensor cannot be simply replaced with a thermometer of lower drift, since it is connected to the electronic unit that is, in general, not suitable for measurement with a different type of temperature sensor. Even if changing the thermocouple type would be feasible, the replacement thermocouple would still experience drift that would be impossible to track in-situ. The concept of dual-type temperature sensors can solve this problem as a drift of a reference sensor can be estimated after every replacement of the monitored thermocouple. Also, in many industrial scenarios, thermocouples are not calibrated before being put in operation and users rely on their stated tolerance classes. In such cases, the methods described in this paper can be used for checking if a monitored thermocouple has departed outside the specified tolerance limits in time. Together with the description of the concept, this paper provides schematic diagrams of related measurement setups, drawings of dual-type temperature sensors (utilizing noble metal thermocouples and platinum resistance thermometers as the reference sensors) as well as an algorithm for drift determination. This work is performed within the framework of the European Metrology Programme for Innovation and Research (EMPIR) project 18RPT03 MetForTC. This project (18RPT03 MetForTC) has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme.

Within the work package one of the ongoing EMPIR project „Developing Traceable Measurement Capabilities for Monitoring Thermocouple Performance” (MetForTC), the novel concept of dual-type temperature probes was developed. By using dual-type temperature probes, users would be able to continuously monitor the thermocouple drift in-situ, including environments with varying temperatures. The concept is developed mainly for use in industry, where the drift of thermocouples can lead to various problems, such as increased energy consumption, loss of raw material, or decrease in quality of products. To mitigate the problems related to thermocouple drift, industrial users tend to replace thermocouples regularly, in some cases even after only a few days of usage. Using this approach, thermocouples can be occasionally replaced too early as well as too late. Dual-type temperature probe consists of a monitored thermocouple sensor and an additional temperature sensor, accommodated within the same protective sheath. The use of an additional (reference) sensor, which experiences a lower drift than the monitored thermocouple (e.g. higher grade thermocouple wires, platinum resistance sensors, or fiber-optic sensors), enables monitoring of thermocouple drift by continuous comparison of the differences in their temperature readings. While the drift of the monitored thermocouple can be tracked continuously, the concept also enables occasional tracking of drift of the reference sensor.

The measurement of relative humidity is complex and vitally important for many industrial, healthcare and meteorological applications. Therefore, establishment of traceable humidity measurements while simultaneously assuring traceability and providing dissemination is important activity of every national measurement institute (NMI). Ten European NMIs collaborate in the project HUMEA – Expansion of European research capabilities in humidity measurement financed in the scope of EURAMET EMPIR programme which kicked – off in 2016. One of the project's objectives are to improve the humidity measurement methods with manufacturing and characterisation of an inner chamber for calibration of relative humidity instruments. Intercomparison in relative humidity with the new sub-chamber will be organized between laboratories in the scope of the project. Expected outcomes of the HUMEA project are improvement of measurement capabilities in the participating NMIs with new or improved CMCs as well as better cooperation with industrial stakeholders in participating countries.

This paper presents the results of testing of the multi-entrance fixed point cell (MEFP) filled with aluminium. The MEFP cells aim to improve the performances of the zones of controlled temperature used for calibration of thermometers by comparison method. The improvements are achieved by using the phase transition of metals to reduce the uncertainties due to temporal instability and gradients in those zones. Since the MEFP itself does not represent the temperauture standard, the metals of modest purity are acceptable for its manufacture.

The simple laboratory model of dissipative fault was built. Two granite cubes were pressed together using a custom made device. When one of the blocks was knocked, the resulting vibration of the other was monitored in the form of local temperature change. The other experiment included the measurement of the friction coefficient for the rock with a smooth as well as a rough surface. In this way we tried to assess energy dissipation of solitary seismic wave crossing the fault.

It is common practice in thermometry to test the thermocouple which is to be calibrated for homogeneity of Seeback’ s coefficient. In order to facilitate that task and save time in calibration of thermocouples, 3 years ago a Thermocouple Inhomogeneity Testing Device was developed in Laboratory for Process Measurement (LPM), University of Zagreb. The device is primarily used for the testing of thermocouple inhomogeneity (either with moving heater or for gradual immersion of thermocouple into isothermal zone). It can be also used for estimation of axial gradients in isothermal zones and hydrostatic head effects in fixed points. The sled for mounting of the heater or the thermometer is translated by a threaded shaft and a step motor in horizontal axis, vertical axis or its sliding direction can be tilted in six steps between those two positions. Sled is mounted on shafts guides with precision linear ball bearing, which allow for smooth translation. The frame of the device is designed with adjustable height and distance between legs, which allows testing in most available metrological baths or furnaces. System is controlled by custom made program on LabView platform, with ability to automatically acquire, store and analyze data test data. This paper describes the design of the testing device. The example results are also presented.

The two-temperature (2-T) humidity generator developed at Laboratory for Process Measurement (LPM) is presently being modified to work in a single-temperature (1-T) dew point generator mode. It is designed to eventually operate in dew point range from -20°C to 60°C. The air flow through saturator is monitored and set to the desired levels with flow meters and valves. Gas saturation degree is determined by measuring the temperature differences between saturator gas outlet and liquid at the saturator inlet. Thermometers are connected to the resistance bridge, which is connected to the computer for monitoring and data acquisition on the custom designed, LabView based platform. The design features of the generator are presented. The generator is tested for stability and repeatability at 5°C and 15°C. The test results as well as example uncertainty estimates of the dew point generation are being presented.

As opposed to SPRTs, the IPRTs succumb to hysteresis when submitted to change of temperature. This uncertainty component, although acknowledged as omnipresent at many other types of sensors (pressure, electrical, magnetic, humidity, etc.) has often been disregarded in their calibration certificates’ uncertainty budgets in the past, its determination being costly, time-consuming and not appreciated by customers and manufacturers. In general, hysteresis is a phenomenon that results in a difference in an item’s behavior when approached from a different path. Thermal hysteresis results in a difference in resistance at a given temperature based on the thermal history to which the PRTs were exposed. The most prominent factor that contributes to the hysteresis error in an IPRT is a strain within the sensing element caused by the thermal expansion and contraction. The strains that cause hysteresis error are closely related to the strains that cause repeatability error. Therefore, it is typical that PRTs that exhibit small hysteresis also exhibit small repeatability error, and PRTs that exhibit large hysteresis have poor repeatability. Aim of this paper is to provide hysteresis characterization of a batch of IPRTs using the same type of thin-film sensor, encapsulated by same procedure and same company and to estimate to what extent the thermal hysteresis obtained by testing one single thermometer (or few thermometers) can serve as representative of other thermometers of the same type and manufacturer. This investigation should also indicate the range of hysteresis departure between IPRTs of the same type. Hysteresis was determined by cycling IPRTs temperature from 100 °C through intermediate points up to 600 °C and subsequently back to 100 °C. Within that range several typical sub-ranges are investigated: 100 °C to 400 °C, 100 °C to 500 °C, 100 °C to 600 °C, 300 °C to 500 °C and 300 °C to 600 °C . The hysteresis was determined at various temperatures by comparison calibration with SPRT. The results of investigation are presented in a graphical form for all IPRTs, ranges and calibration points.

Članak opisuje djelatnost i ustroj Hrvatskog mjeriteljskog instituta kao osnovnog dijela nacionalnog mjeriteljskog sustava. Čitatelj može saznati kako izgleda vrh mjeriteljske piramide za pojedinu fizikalnu veličinu u našoj zemlji ; tko je odgovoran za mjernu sljedivost prema SI sustavu, mogu li se neke fizikalne jedinice ostvariti u laboratorijima HMI-a ; da li su te realizacije globalno priznate, da li se te realizacije prenose do mjerenja koja su nam važna, te kako HMI pruža potporu gospodarstvu, znanosti i infrastrukturi kvalitete u Republici Hrvatskoj. Usput može naučiti/utvrditi značenje brojnih kratica u području mjeriteljstva.

This paper describes procedure and performance of the interlaboratory comparison (ILC) of pressure gauges calibration results in the range from 0 to 1 bar. ILC was organised by Croatian national pressure laboratory between four accredited Croatian pressure calibration laboratories. Transfer standard was pressure transducer with digital calibrator. Objective of this comparison was to assess calibration performance of participant laboratories compared to reference laboratory. Deviations for all measurement points will be listed in this paper. Assessment of the measurement results will be given by calculating En values.

In this paper, the advantages, design possibilities, performance of the Multi-Entrance Fixed Point (MEFP) concept are described. The purpose of MEFP is to replace equalizing blocks in any temperature-controlled zone with phase transition of matter during melting or freezing. The phase transition in such a calibration is not intended to be the temperature standard itself, but only provides for spatial thermal homogeneity and temporal stability during comparison calibration. Knowing that some of the main uncertainty components in the uncertainty budget of the comparison calibrated thermometer are the radial and axial gradients in the isothermal zone and knowing that comparisons comprise by far the majority of all calibrations, the improvement of speed and quality of calibration is of significant importance. The tin-filled MEFP with multiple entrance tubes, designed in the Laboratory for Process Measurements allows for simultaneous calibration of several thermometers against a standard thermometer. MEFP prototypes filled with other materials and with other design characteristics are pending production. This concept allows the use of modest purity materials to fill the cell, since a standard thermometer is used as the calibration reference. During this investigation, thermometers were calibrated against a standard in the same furnace, using both the standard equalizing block and the MEFP. The measurement results indicate that the use of MEFP decreases the uncertainty contributions from temperature gradients and the stability of the bath by an order of magnitude, compared to the standard equalizing block.

This paper presents results of the interlaboratory comparison organized by CROLAB-KUL (Calibration Laboratories Club) and Laboratory for Process Measurements (LPM) which is Croatian National Pressure Laboratory and part of Croatian Metrology Institute (HMI). Comparison was performed according to DKD-R6-1 (Type B) procedure for gas pressure measurements in the range from 0 up to 2 MPa using pressure transducer of high accuracy as transfer standard. Participating laboratories were: MARUS ATM d.o.o. ; Metron Instruments d.o.o., Ravnoteža, Petrokemija d.d., Inspekt Metrolab, BMB, CEI-IETA, STSI, all accredited by Croatian Accreditation Agency (HAA). Participants have reported deviations and measurement uncertainties in nine calibration points. Analysis of the measurement results are given by calculating the deviation, En, normalized with respect to the stated uncertainty for each participating laboratory.

Current practice in fixed-point calibration recommends usage of furnaces that provide best achievable uniform temperature distribution at the outer segment of the immersed portion of the fixed-point cell. The effect of any inhomogeneous temperature distribution is somewhat unrevealed, and its coverage in literature is insufficient. In order to establish some estimation of the influence of the inhomogeneous furnace temperature distribution to the calibrating process, a numerical study was conducted. The study was conducted using FLUENT software package employing finite volume method on non-structured grids. The problem was considered as axially symmetric. The domain of the calculation consisted of the whole cell volume and its geometry was modeled such to distinguish each of the individual elements of the fixed point cell assembly. The material properties of the assembly elements were treated as temperature dependent, while their surface properties were kept constant. The mathematical model employs transient conductive heat transfer along with solidification model for Zinc so as radiation heat transfer between surfaces in all argon - filled cavities. The effect of natural convection was assumed to be of minor importance and was therefore neglected thus saving significant amount of computational effort. The calculations covered the whole duration of Zinc solidification process. Several variants of boundary conditions at the fixed - point cell's outer surface were applied. The variants distinguish: the homogeneous temperature distribution at the outer skin of the immersed part of the fixed point cell, the plus and minus 1 K/m of gradient added to base temperature distribution in axial direction and the presence or absence of cold-roding. The base outer temperature was kept 1 K below the solidus temperature giving approximately 6 hours of calibration process. The study shows that such linear gradient of +/- 1 K/ m influences the process solely in its duration, prolonging it or shortening it for approximately 20minutes.

This paper investigates the scope of ND pressure monitoring in humanitarian safety and other safety systems. Possible applications include pressurized suits, vaults, ducts and apparatus which could be monitored for the reasons of humanitarian or other safety aspects. The theoretical basis is briefly explained. Then the safety systems are classified along the lines of pressure maintenance, behavior in time, spatial distribution and level of pressure as: active or passive, steady-state or dynamic, homogenous or non-homogenous and natural or forced. The scope of the method is presented by principle of operation and schematic drawings of ND pressure monitoring systems for several key configurations.

This paper describes characterization of 1-T dew point generator developed at Laboratory for Process Measurement (LPM) self-. Present operating range of generator is from -7°C to 18°C dew point range. The air flows through saturator in closed loop and is controlled with regulated flow meters. Air saturation degree is determined by measuring the temperature deviations between saturator air outlet and liquid in saturator. Thermometers are connected to the resistance bridge, which is in turn connected to the computer for data acquisition. The main design features of the 1-T generator are presented. The deviations between generated dew point temperature and LPM’ s dew point transfer standard hygrometer (recently calibrated in PTB) are discussed. The deviations between saturator air outlet and liquid in saturator are also examined. The test results are presented in graphical and tabular form together with an example of uncertainty estimates for various test dew points.

It is good calibration practice to test thermocouples for homogeneity of the Seeback’ s coefficient during calibration process. If change in homogeneity the coefficient, commonly known as inhomogeneity is not detected, thermometer although calibrated might not be able to measure temperature correctly. Several different testing techniques are developed, depending on type of the thermocouple and the equipment available. In order to automate process of thermocouple inhomogeneity testing for all applicable testing methods a Thermocouple Inhomogeneity Testing Device was developed in Laboratory for Process Measurement (LPM), University of Zagreb. The device is mostly used for the testing of thermocouple inhomogeneity in conjunction with heater moving along the thermocouple. The sled for mounting of the heater or the thermometer is translated by a threaded shaft and a step motor in horizontal axis, vertical axis or its sliding direction can be tilted in six steps between those two positions. Sled is mounted on shafts guides with precision linear ball bearing, which allow for smooth translation. The frame of the device is designed with adjustable height and distance between legs, which allows testing in most available metrological baths or furnaces. System is controlled by custom made program on LabView platform, with ability to automatically acquire, store and analyze data test data. Variation of the thermovoltage recorded during measurement is used in calculation of the uncertainty of the calibration. This paper describes the techniques for inhomogeneity testing and design of the testing device. Interpretation of the measurement results and calculation of inhomogeneity related component of the uncertainty budget is presented

Successful participation in proficiency testing (PT) has become a basic requirement for achieving and maintaining accreditation. This paper describes procedure and results of PT that was used in accreditation of two Croatian pressure calibration laboratories. Analysis of the tested laboratories measurement results will be given by calculating the deviation, En, normalized with respect to the stated uncertainty

This paper presents pressure calibration system in the absolute pressure range of 25 kPa to 2 MPa, which is being developing in Croatian national pressure laboratory- Laboratory for Process Measurement (LPM) at Faculty of Mechanical Engineering and Naval Architecture (FSB) in Zagreb. Design of the system, theoretical basis, main parameters influencing the effective pressure and the model for estimation of measurement uncertainty are described. The scope of the system is presented through absolute pressure uncertainty budget.

Recently, the Monte Carlo simulations (MCS) have been increasingly applied to estimations of measurement uncertainties for many physical quantities. This paper describes and directly compares two methods for estimation of measurement uncertainty in calibration of pressure balance effective area: ISO GUM approach and Monte Carlo simulation. Both methods are used in Croatian national pressure laboratory-Laboratory for Process Measurement (LPM) at Faculty for Mechanical Engineering and Naval Architecture. MCS is used for validation of the measurement uncertainties estimated by the GUM method. In MCS method, the probability density functions of the output values have been obtained by the convolution of distributions of input values with M=100000 simulations. Both approaches have been based on the same set of the cross-float calibration data. The scope of the procedure is illustrated by calibration example (oil-operated pressure balance, gauge pressure range up to 60 Mpa). Effective area calibration results and effective area uncertainty budgets obtained by both methods for one calibration point are given. The MCS and ISO GUM obtained uncertainties are in good agreement.

Ovaj rad opisuje osposobljenost Laboratorija za procesna mjerenja Fakulteta strojarstva i brodogradnje koji je prošle godine imenovan za nositelja državnih etalona jedinica temperature i tlaka. Laboratorij je prethodno uspješno prošao postupak ovlašćivanja od strane DAR/PTB/DKD (Deutscher Akkreditierungs Rat / Physikalisch-Technische Bundesanstalt / Deutsche Kalibrierdienst) službe za ovlašćivanje prema zahtjevima norme HRN EN ISO/IEC 17025 za mjerila tlaka i temperature. Opisan je ustroj laboratorija, područja umjeravanja te najbolje mjerne sposobnosti tlaka i temperature.

This paper describes the education program (named LAB3-V2) for setting up NDT, testing and calibration laboratories according ISO/IEC 17025 stan-dard. The three-day program has been taking place for several years at Edu-cation Center, which is the logistical part of National Accreditation Service and is located at Center for Transfer of Technology at Faculty of Mechani-cal Engineering and Naval Architecture - University of Zagreb. The broader education system providing for the educational needs of NSO, of which this seminar is a building block is briefly described. The seminar content and structure, which are fully compatible with EA guidelines and DAR programs in the Republic of Germany, are presented. The numbers and profiles of seminar attendees in previous years is analyzed and presented.

Laboratory for Process Measurements at the Faculty of Mechanical Engineering and Naval Architecture is assigned to be the holder of National standards for thermodynamic temperature and pressure. Beforehand Laboratory was successfully accredited by DAR/PTB/DKD (Deutscher Akkreditierungs Rat / Physikalisch-Technische Bundesanstalt / Deutsche Kalibrierdienst) accreditation service according to standard ISO/IEC 17025 for temperature and pressure measurands. In this paper, Laboratory temperature standards, temperature measurement systems and best measurement capabilities in the whole range from -20 to 1050°C are described with special emphasis on how the traceability of temperature in Croatia is assured. Future developments of the national laboratory related to independent realization of part of temperature scale are described.

This paper presents the modelling methodology for estimation of measurement uncertainties in comparison calibration of thermocouples used at Laboratory for Process Measurements (LPM). The methodology is applied for comparison calibration of noble and industrial base-metal thermocouples. The calibration standards used in examples are platinum resistance thermometers up to 660°C and standard/working standard thermocouples from 600°C to 1050°C

This paper describes iterative methodology for calculation of surface temperature measurement errors applied to symmetrically heated, vertical parallel plate channels. Heat transfer calculations within the channel (marching, control volume based, numerical procedure) are first based on initial raw and uncorrected surface temperature measurements. Those data are then utilized for determination of surface measurement errors modeled with emphasis on thermocouple induced local heat sink and convective stray looses. The new, corrected surface temperatures are then input to heat transfer calculations until satisfactory convergence. The scope of the methodology is investigated by it’ s application to surface measurement error estimation for several groups of channels, each group having different, but fixed height, and variable aspect ratio. The mutual influences of channel geometry and wall temperatures on surface measurement errors at various measurement locations along the channel height are analyzed with results presented in graphical form. It was found that close to the channel entrance errors tend to be significantly augmented due to thermo-siphon induced convective stray looses. As thermal boundary layers approach and meet, errors monotonically decrease and cease to exist in thermally saturated channel sections. It was also found that, because of the non-linearity, the channels with the same aspect ratio but different height, induce different convective stray looses to the sensors.

This paper presents a simplified model for the evaluation of the measurement uncertainty of pressure balance effective area calibrated by method of comparison which is being applied at Laboratory for Process Measurements (LPM). The methodology is applied for oil-operated industrial pressure balances in the gauge pressure range up to 60 MPa. The scope of the procedure is illustrated by calculation example.

This paper describes achievements of Laboratory for Process Measurements at Faculty of Mechanical Engineering and Naval Architecture in the field of pressure measurements. Laboratory is assigned to be holder of National standards for thermodynamic temperature and pressure. Beforehand Labo-ratory was successfully accredited by DAR/PTB/DKD (Deutscher Akkreditierungs Rat / Physikalisch-Technische Bundesanstalt / Deutsche Ka-librierdienst) accreditation service according to standard ISO/IEC 17025 for temperature and pressure measurands. In this paper, Laboratory pressure standards, pressure measurement systems and best measurement capabilities in whole range from 0 to 600 bar are described with special emphasis on how the traceability of pressure in Croatia is assured. Future developments of the national laboratory related to expansion of calibration range are pre-sented.

Ovaj rad opisuje program izobrazbe pod nazivom LAB3-V2 za ustroj ispitnih i umjernih laboratorija prema normi HRN ISO/IEC 17025. Trodnevni seminar održava se već nekoliko godina u Obrazovnom centru koji je logistički dio Nacionalne službe za ovlašćivanje i lociran je u Centru za transfer tehnologije (CTT) na Fakultetu strojarstva i brodogradnje Sveučilišta u Zagrebu. Ukratko je opisan prošireni sustav izobrazbe za potrebe NSO-a te sadržaj i struktura seminara LAB3-V2. Prezentirana je analiza broja i strukture polaznika proteklih seminara .

This paper presents the methodology for working space assessment in environmental and thermostatic test chambers. The temperature and humidity parameters including: rate of temperature and relative humidity rise, spatial temperature uniformity, spatial temperature-induced relative humidity gradients, short term temperature and humidity fluctuations, and deviations from the actual set points. The temperatures are treated on time-averaged basis. Assessment procedure uncertainties are described and applied to the case when the chamber is used for calibration of humidity sensors. The scope of the method is presented by example assessment of a humidity chamber with results presented in tabular and graphical form.

L'influence des impurites chimiques constitue generalement la composante d'incertitude preponderantedans les budgets d'incertitudes relatifis aux points fixes de temperature. Afin d'apporter des informations complementaires sur ce point particulier, le BNM-INM (France) at le LPM-FSB (Croatie) ont engage une cooperation scientifique.

This paper describes the education programme (named LAB3) for setting up NDT, testing and calibration laboratories according to EN45001 and ISO/IEC 17025 standards. The three-day programme has been taking place for several years at Education Centre which is the logistical part of National Accreditation Service and is located at Centre for Transfer of Technology (CTT) at Faculty of Mechanical Engineering and Naval Architecture - University of Zagreb. The broader education system providing for the educational needs of NSO, of which this seminar is a building block is briefly described. The seminar content and structure, which are fully compatible with EA guidelines and DAR programs in the Republic of Germany are presented. The numbers and profiles of seminar attendees in previous years is analyzed and presented in graphical form.

This paper presents the procedure for estimation of uncertainty budget in calibration of pressure transducers by method of comparison which is being applied in Laboratory for Process Measurements (LPM) at the Faculty of Mechanical Engineering and Naval Architecture (FSB). The methodology is applied for calibration with LPM pressure standards of pressure transducers having electrical output.

The objective of this paper is to present the methodology for estimation of measurement uncertainties in comparison calibration of thermocouples used at Laboratory for Process Measurements (LPM). The methodology is applied for comparison calibration of rare-metal and industrial base-metal thermocouples within temperature range from –20°C to 660°C with LPM standard/working standard platinum resistance thermometers and from 600°C to 1050°C with LPM standard/working standard thermocouples.

This paper presents calibration system in the gauge pressure range of 0,015 bar to 2 bar developed in Laboratory for Process Measurement (LPM) at Faculty of Mechanical Engineering and Naval Architecture (FSB) in Zagreb. Design of the system, theoretical basis, main parameters influencing the effective pressure and the model for estimation of measurement uncertainty are described. The scope of the system is presented through pressure sensor calibration with results presented in tabular form.

Ovaj rad opisuje metodologiju za ispitivanje radnog prostora peći za toplinsku obradu koja je razvijena u Laboratoriju za procesna mjerenja Fakulteta strojarstva i brodogradnje Sveučilišta u Zagrebu. Opisani su postupci odfređivanja dinamike zagrijanja, prostorne neujednačenosti temperature u radnom prostoru peći te određivanje kratkotrajne i dugotrajne vremenske nestalnosti temperature. Također je opisan prostorni raspored ispitnih termometara te način odabira ispitnih temperatura. Mogućnosti mjernog sustava ilustrirane su sa nekoliko primjera u grafičkoj formi.

This paper presents the test system and methodology for NDT and characterization of gas pressure sensors in the gauge pressure range of 0, 015 bar to 2 bar developed in Laboratory for Process Measurement (LPM) at Faculty of Mechanical Engineering and Naval Architecture (FSB) in Zagreb. The design of the system, theoretical basics, main parameters influencing the test pressure and the model for estimation of measurement uncertainty is described. The test pressure loading strategy is discussed having in mind the desired characterization data. The model for evaluation of basic short term static characteristics of the sensor is described. The scope of the test system and methodology is presented through detailed example evaluation of pressure sensor with results presented in graphical and tabular form.

This paper describes the methodology for design of network analogy models for estimation of steady state heat transfer in complex non-linear thermal systems. Simultaneous heat transfer by conduction, convection and radiation in complex geometrical arrangements is modeled by application of concentrated parameter network. The network design comprises of node clusters made up of individuals nodes which can be passive or with attached heat sources or sinks. The nodes are interconnected by resistances equivalent to arious modes of heat transfer. The scope of the method is presented by network design intended for calculation of steady state non-linear heat transfer in complex explosion proof transformer.

This paper presents the calibration system in the gauge pressure range of 15 mbar to 2000 mbar developed in Laboratory for Process Measurement at Faculty of Mechanical Engineering and Naval Architecture in Zagreb. The system is based on ceramic piston/cylinder assembly of 4 cm2 nominal effective area and custom designed pressure control and supply system filled with nitrogen. The system design, theoretical basis for calculation, main parameters influencing the effective pressure and device under test are described. The scope of the system is presented through calibration of pressure sensor with results presented in graphical form.

This paper describes the principle and design of two temperature humidity generator being developed at the Laboratory for Process Measurement. It is designed to eventually operate in dew point range from -15°C to 60°C and in test chamber range to 90°C, thus catering to most of the present demand for calibration in Croatia. The flow through saturator, test chamber and test chamber bypass loop is monitored and set to the desired levels with flow meters and valves. It can be adjusted from fully recirculating flow to fully open circuit flow. Gas saturation degree is determined by measuring the temperature differences between saturator gas outlet and liquid at the saturator inlet. Temperature controllers, thermometers and resistance bridge are connected to computer via digital interfaces and integrated into monitoring and control system on the custom designed, Labview based platform. The initial results of generator evaluation are presented for recirculating mode and for part of the operating range. They include saturator and test chamber responses to stepwise parameter changes and uncertainty estimates in terms of dew point and relative humidity.

Prihvaćanjem niza normi HRN EN45000 i uspostavom nacionalne službe za ovlašćivanje (NSO) u Državnom zavodu za normizaciju i mjeriteljstvo (DZNM) u Republici Hrvatskoj stvoreni su preduvjeti da ispitni i mjeriteljski laboratoriji, pristupe izgradnji sustava kakvo};e prema zahtjevima te norme i da se pripreme za postupak ovlašćivanja.

This paper describes the methodology for estimation of surface temperature measurement errors in complex apparata where simultaneous heat transfer by conduction, convection and radiation takes place. The complex thermal system is modeled by application of network analogy with surface measurement errors modeled with emphasis on thermocouple induced local heat sink and convective stray looses. The scope of the method is presented by calculation of surface measurement errors on inner surfaces of explosion proof transformer.

The developement of national temperature standard through realization of internationally traceable temperature scale ITS-90 in Croatia represents the foundation for developement of Croatian calibration service, product certification service, quality assurance systems, scientific and applied research, as well as other activities that require traceable temperature measurement. Laboratory for Process Measurement (LPM) at Faculty of Mechanical Engineering and Naval Architecture (FSB) is the Certified laboratory of Croatian State Office for Standardization and Metrology (DZNM) for temperature, pressure, humidity, heat energy.

Laboratory for Process Measurement (LPM) at Faculty of Mechanical Engineering and Naval Architecture (FSB) is the Certified laboratory of Croatian State Office for Standardization and Metrology (DZNM) for temperature, pressure, humidity, heat energy. LPM FSB is, together with DZNM, responsible for development and maintenance of Croatian National metrology standards for the above quantities.

This paper describes global education system for National Accreditation Service in Croatia resulting from extensive research of existing European systems. The resulting modular education system consists of two main groups of seminars: for assessors and tutors and for laboratories and physical quantities. The seminars for assessors and tutors are fully compatible with EAL guidelines as well as with DAR programs in Republic of Germany. The system is being implemented, researched and analyzed in Education center at Center for Transfer of Technology.

To respond to the increasing demand for traceable calibration of hygrometers in Croatia, a hygrometer calibration facility has been developed. It is based on two temperature recirculating humidity generator intended for operation in the 4°C to 60°C dew point range. The design of the facility is a compromise one, having to accomodate dew-point hygrometers, relative humidity meters and even chart recorders without remote sensors, i.e. the need for different calibration routines and levels of accuracy. The facility can , therefore, operate in three conceptualy different modes: as stand alone humidity generator, as a slave system directly controlled by transfer standard hygrometer and as an environmental chamber for comparison calibrations. The whole system is integrated and automated via the custom developed, graphycally interfaced software platform. The main design features of the facility are described as well as considerations regarding behaviour and the accuracy of the system.

Tema ovog rada je umjeravanje mjerila toplinske energije. U uvodu je opisan princip rada mjerila toplinske energije i ocjena njihove sukladnosti. Sljedeća poglavlja donose pregled teorijskih podloga i postojećih ispitnih regulativa te opis podsklopova mjerila toplinske energije i podjelu tipova mjerila. U kasnijim poglavljima opisan je korišteni mjerni sustav, sam postupak umjeravanja te postupak procjene mjerne nesigurnosti. Na kraju je prikazan primjer s rezultatima umjeravanja provedenih u Laboratoriju za procesna mjerenja na Fakultetu strojarstva i brodogradnje Sveučilišta u Zagrebu. The topic of this thesis is the calibration of heat meters. The introduction describes the principle of operation of thermal energy meters and the assessment of their compliance. The following chapters provide an overview of the theoretical basis and existing test regulations, as well as a description of the subassemblies of heat meters and the division of types of meters. Subsequent chapters describe the measurement system used, the calibration procedure itself, and the measurement uncertainty estimation method. Finally, an example with the results of calibration carried out in the Laboratory for Process Measurements at the Faculty of Mechanical Engineering and Naval Architecture is presented.