Piston-cylinder Assembly Research Articles

Final report on regional key comparison COOMET.M.P-K2: Hydraulic gauge pressure in the range 10 MPa to 100 MPa

This report describes a COOMET key comparison of hydraulic pressure standards of seven national metrology institutes that was carried out in the period from June 2005 to July 2008 in order to determine their degrees of equivalence in the range 10 MPa to 100 MPa of the gauge pressure. The pilot laboratory was VMT/VMC. The pressure standards of the participating NMIs were pressure balances of different design, equipped with piston–cylinder assemblies. The transfer standard was a pressure balance, equipped with a 9.8 mm2 piston–cylinder assembly, manufactured by SMU. The participants reported the pressure-dependent effective areas of the transfer standard at specified pressures. The reference values were calculated as the weighted means of PTB, NPL, SMU and VNIIM, which have primary pressure standards. The results by all participants agree with the reference values and with each other within the expanded uncertainties calculated with a coverage factor (k = 2). At the level of standard uncertainties there is a full agreement between 10 MPa and 100 MPa. The results of this comparison were linked to those of key comparison CCM.P-K7. Degrees of equivalence and expanded (k = 2) uncertainties between the COOMET and laboratories having participated in other KCs: CCM.P-K7, APMP.M.P-K7, EUROMET.M.P-K4 and APM.M.P-K7.1 at measured pressure points are presented in the final report. The results of the comparison demonstrate equivalence of the laboratory standards and, for laboratories the CMCs of which are not yet presented in the KCDB, this comparison provides a basis for submission in the range from 10 MPa to 100 MPa of hydraulic gauge pressure.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Large-Eddy Simulation for an Axisymmetric Piston-Cylinder Assembly With and Without Swirl

Large-eddy simulation (LES) has been performed for an axisymmetric piston-cylinder assembly with and without swirl. For both cases, the LES mean and rms velocity profiles show better agreement with experimental data than profiles obtained using a Reynolds-averaged Navier–Stokes (RANS) approach with a standard k − e turbulence model. The sum of the resolved and modeled contributions to turbulence kinetic energy (TKE) approaches grid independence for the meshes used in this study. The sensitivity of LES to key numerical and physical model parameters has been investigated. Results are especially sensitive to mesh and to the subfilter-scale (SFS) turbulence models. Satisfactory results can be obtained using simple viscosity-based SFS turbulence models, although there is room for improvement. No single model gives uniformly best agreement between model and measurements at all spatial locations and at all times. The strong sensitivity of computed mean and rms velocity profiles to variations in the SFS turbulence model suggests that better results might be obtained using more sophisticated models.

The effect of cylinder liner surface topography on abrasive wear of piston–cylinder assembly in combustion engine

Abstract Reciprocating piston engines are the major propulsion devices for light aircrafts, helicopters and mostly all automotive vehicles. They are expected to fulfill the present and future strains on the engine performance and durability including fuel economy and exhaust emission legislation. One of the key issues for these demands is the limitation of thermomechanical internal losses, wear, and lubricating oil consumption. Such phenomena are conditioned all together by tribological behavior of a piston–cylinder assembly. Apart from various advanced technologies, a conventional plateau-honing operation is still the standard technology for shaping cylinder liner surface microstructure. This paper describes the distinctions between piston–cylinder assembly wear of the engines varied by cylinder liner roughness parameters due to different honing settings made. Research was performed on the test-bed where the wear was forced by grinding flour precisely dosed into the engine inlet manifold. After 10 h of running-in operation the high correlation of the maximum valley depth of the profile Rv with the piston–cylinder assembly wear was noticed. After 21 h of full load operation a similar strong relationship, but referring to the maximum peak height of the cylinder liner profile Rp occurred as well. Both these parameters have a physical interpretation on a surface material ratio diagram, where Rv corresponds to the material fraction of the surface layer, and Rp – to the oil retention volume.

Final Results of the Geometrical Calibration of the Pressure Balances to be Used for the new Determination of the Boltzmann Constant

This paper presents results of the dimensional calibration of piston-cylinder assemblies to be used for the joint NMI project “Re-determination of the Boltzmann constant”. Several measurements optimization strategies are described. For the first time 3D uncertainties in the range of 8 nm (piston) and 16 nm (cylinder) could be achieved.

Liquid composition-dependence of calcium isotope fractionation during diffusion in molten silicates

Liquid phase diffusion experiments were carried out to determine whether diffusive isotopic fractionation of a major chemical element (Ca) varies with chemical composition in high-temperature molten silicates. The objective was to determine how differences in silicate liquid structure, such as the ratio of bridging to non-bridging oxygen atoms, as well as bulk transport properties such as viscosity, relate to isotope discrimination during diffusion. This information, in turn, may relate to the lifetimes and sizes of multi-atom structures in the liquid. Diffusion couples consisting of juxtaposed natural mafic and felsic liquids were held at T = 1450 °C and P = 1.0 GPa for durations of 12–24 h in a standard piston–cylinder assembly. Experiments were done using different mafic endmember compositions (two tholeiitic basalts and a ugandite) and a single rhyolite composition. Major-element diffusion profiles and Ca isotope profiles were measured on the recovered quenched glasses. The starting materials were isotopically indistinguishable, but 44Ca/ 40Ca variations of ca. 5‰ arose due to a mass dependence of the Ca diffusion coefficients. Results indicate that the mass dependence of Ca diffusion coefficients varies with the magnitude and direction of aluminum gradients and the viscosity of the liquid. Some Ca fractionations result mainly from Al gradients. A simplified multicomponent diffusion model was used to model the experimental results. The model allows for diffusion of Ca in response to gradients in the concentrations of both CaO as well as Al 2O 3, and the model results are consistent with the inferred existence of at least two distinct species of Ca. The magnitude of isotopic discrimination during diffusion also appears to be stronger on the rhyolite versus the basalt/ugandite side of diffusion couples. The results can largely be accounted for by an adaptation of the model of Dingwell (1990), whereby in high silica liquids, Ca diffuses largely by site hopping through a quasi-stationary aluminosilicate matrix, producing strong isotopic effects because the Ca diffusion is not strongly correlated with the movement of the framework atoms. In low-silica liquids, Ca diffusion is correlated with the movement of the other components and there is less mass discrimination. Combining our Ca results with Ca, Mg, and Li data from previous studies, we show that this model can explain most of the cation- and composition-dependence of diffusive isotopic fractionations observed thus far. A key parameter controlling isotopic discrimination is the ratio of the elemental (Ca, Mg, Li) diffusivity to the Eyring (or Si) diffusivity. However, all experiments done so far also exhibit isotopic features that are not yet fully explained; some of these may relate to small temperature gradients in the capsules, or to more complex coupling effects that are not captured in simplified diffusion models.

The development of novel interchangeable pistons for pressure performance optimization in a gas-operated dead weight pressure balance

The texture of surfaces within a piston–cylinder assembly (PCA) can influence the pressure performance of gas-operated dead weight pressure balances (DWPBs). In order to systematically study this response, it has been necessary to design, develop and manufacture uniquely interchangeable 35 mm diameter PCAs for use in a novel hybrid gas-operated DWPB with high mechanical, thermal and pressure stability. This work reports the development of the PCAs and the validation of the DWPB design, allowing the performance characteristics of the interchangeable PCAs to be understood, in terms of variations of effective area calculations. This is achieved by investigating the pressure responses of the DWPBs by changing the speed and direction of rotation. The results demonstrate the stability of the gas-operated DWPB design when used in gauge mode, and importantly allow the verification of the performance of the interchangeable PCAs.

Final report on APMP.M.P-K6.1 pneumatic key comparison from 20 kPa to 105 kPa in gauge mode

This report describes the key comparison APMP.M.P-K6.1 among the three national metrology institutes, Center for Measurement Standards–ITRI (CMS-ITRI, Taiwan), SPRING Singapore and National Institute of Metrology (NIMT), in the pressure range from 20 kPa to 105 kPa in gas media and gauge mode executed during the period April 2003 to April 2004. This comparison was conducted by CMS-ITRI and was based on the calibration procedure of APMP pneumatic pressure comparison APMP.M.P-K6. We intended to link to the CCM.P-K6 key comparison through the APMP.M.P-K6 key comparison by using the proposed linkage method in the APMP.M.P-K6 key comparison to determine a linking factor that can transform the quantities measured in the APMP.M.P-K6.1 key comparison. All three participating institutes used pneumatic piston gauges as their pressure standards. The Ruska 2465 gas-operated piston–cylinder assembly TL-1409 used as transfer standard offered by CMS-ITRI was calibrated three times by the pilot institute during the comparison period and showed that it was very stable after evaluation. The comparison was conducted on the basis of cross-float experiments to determine the effective area of transfer standards from the national standards of three institutes.The comparison results (as shown in Table 6) were equivalent to the CCM.P-K6 comparison and the relative bilateral degrees of equivalence between two laboratories were smaller than 39.7 × 10-6 from 20 kPa to 105 kPa. These results showed all participating institutes measuring the same quantity in the whole pressure range lay within their expanded uncertainty with confidence level 95%.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Experimental Investigation of a Novel Blast Wave Mitigation Device

A novel blast wave mitigation device was investigated experimentally in this paper. The device consists of a piston-cylinder assembly. A shock wave is induced within the cylinder when a blast wave impacts on the piston. The shock wave propagates inside the device and is reflected repeatedly. The shock wave propagation process inside the device lengthens the duration of the force on the base of the device to several orders of magnitude of the duration of the blast wave, while it decreases the maximum pressure over an order of magnitude. Two types of experiments were carried out to study the blast wave mitigation device. The first type of experiments was done with honeycomb structures protected by the blast wave mitigation device. Experimental results show that the device can adequately protect the honeycomb structure. A second type of experiments was done using a Hopkinson bar to measure the pressure transmitted through the blast wave mitigation device. The experimental results agree well with results from a theoretical model.

Cryogenic gas loading in a Mao–Bell-type diamond anvil cell for high pressure-high temperature investigations

A simple system for loading argon fluid at cryogenic temperatures in a Mao-Bell-type diamond anvil cell (DAC) has been developed. It is done in a two step process in which the piston-cylinder assembly alone is submerged in the cryogenic chamber for trapping the liquefied inert gas. Liquid nitrogen is used for condensing the argon gas. This system is now being efficiently used for loading liquid argon in the DAC for high pressure-high temperature experiments. The success rate of trapping liquefied argon in the sample chamber is about 75%. The performance of the gas loading system is successfully tested by carrying out direct conversion of pyrolitic graphite to diamond under high pressure-high temperature using laser heated DAC facility.

Heat Transfer During Compression and Expansion of Gas

Abstract Heat transfer during compression and expansion of gas is investigated to obtain a correlation that is easy to use in the design of the reciprocating energy conversion machines. We carried out experiments to measure the heat transfer characteristics to̸from gas during compression and expansion to obtain the correlation. These measurements were performed using a piston-cylinder assembly over a range of volume ratios, frequencies, mean pressures, gases, and internal extended surface areas. The heat transfer was estimated thermodynamically from experimental pressure-volume data. Dimensionless groups for heat transfer are discussed in order to correlate the data. The product of the dimensionless heat transfer and specific heat ratio was found to be optimal and was correlated with only the Peclet number for a wide range of conditions, even for gases having different specific heat ratios. The temperature amplitude of the center of the test space was obtained, and it is found that the penetration depth reached the center when the Peclet number is in the range from 20 to 30.

Final report on CCM key comparison CCM.P-K2: Pressure (10 kPa to 120 kPa) absolute mode

The results are presented of key comparison CCM.P-K2 that covered the pressure range 10 kPa to 120 kPa in absolute mode. Nine national measurement institutes participated in the comparison, which used a piston–cylinder assembly of 335 mm2 nominal effective area as a transfer standard.Whilst not all laboratories were found to be equivalent at all pressures, the larger-than-expected instabilities in the transfer standard precluded the ability to discriminate between participants' standards at a level needed to fully support the Calibration Measurement Capabilities table in the BIPM key comparison database.Main text.To reach the main text of this Paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Report on a comparison of pressure standards in the range 10 MPa to 100 MPa

A comparison in the hydraulic pressure range between 10 MPa and 100 MPa was undertaken as EUROMET Project 389. The comparison was originally between five national metrology laboratories but was subsequently expanded to include a further ten participants. The pilot laboratory was the National Physical Laboratory. This report presents the results obtained by each laboratory for the effective area of the piston–cylinder assembly used in the comparison. The results of all participants were found to be consistent with each other and with the calculated reference value, within their claimed uncertainties, at all pressures. The results are therefore considered to be very satisfactory.Main text.To reach the main text of this Paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Final report on key comparison COOMET.M.P-K1 in the range 0.05 MPa to 0.5 MPa of pneumatic gauge pressure

This report describes a COOMET key comparison of pneumatic pressure standards of six national metrology institutes (NMIs) that was carried out in the period from September 2004 to June 2006 in order to determine their degrees of equivalence in the range 50 kPa to 500 kPa of the gauge pressure. The pilot laboratory was VNIIM. The pressure standards of the participating NMIs were pressure balances of different design. The transfer standard was a 5 cm2 piston–cylinder assembly accompanied by a mounting post and a weight carrier supplied by VNIIM. The pressure-dependent effective areas of the transfer standard at specified pressures were reported by the participants. The reference values were calculated as the weighted means of the results of VNIIM and PTB, which were primary and independent laboratories in this comparison. The results of this comparison were linked to the 1 MPa comparison CCM.P-K1.b using the results of the PTB obtained in both comparisons. Results by all but one participant agree with the reference values and with each other within the expanded uncertainties calculated with a coverage factor 2; roughly a half of the reported results demonstrate agreement within their standard uncertainties. With the exception of one laboratory, the results of the comparison demonstrate the equivalence of the laboratory standards and support their measurement capability statements. For laboratories whose CMCs are not presented in the KCDB yet, this comparison provides a basis for submissions for the range 50 kPa to 500 kPa of pneumatic gauge pressure.Main text.To reach the main text of this Paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Final report on APMP.M.P-K1.c.1: Pneumatic key comparison from 0.4 MPa to 4.0 MPa in gauge mode

This report describes the key comparison APMP.M.P-K1.c.1 among the three national metrology institutes, Center for Measurement Standards-ITRI (CMS-ITRI, Chinese Taipei), SPRING Singapore and National Institute of Metrology (NIMT) in the pressure range from 0.4 MPa to 4.0 MPa in gas media and gauge mode executed during the period April 2003 to April 2004. This comparison was conducted by CMS-ITRI and was based on the calibration procedure of APMP Pneumatic Pressure Comparison APMP.M.P-K1.c. We intended to link to the key Comparison APMP.M.P-K1.c via the results of SPRING Singapore. All three participating institutes used pneumatic piston gauges as their pressure standards. The Ruska 2465 gas-operated piston-cylinder assembly V-1215 used as a transfer standard offered by CMS-ITRI was calibrated three times by the pilot institute during the comparison period and showed that it was very stable after evaluation. The comparison was conducted on the basis of cross-float experiments to determine the effective area of the transfer standard from the national standards of three institutes. The mean value of the results obtained by all participating institutes measuring the same quantity from 0.4 MPa to 4.0 MPa in gas media and gauge mode lay within their expanded uncertainty with a confidence level of 95%. Linking key comparison APMP.M.P-K1.c to key comparison APMP.M.P-K1.c.1 at two nominal pressures near 1 MPa and 4 MPa was established.Main text.To reach the main text of this Paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Multiple Cylinder Free-Piston Stirling Machinery

In order to improve the specific power of piston-cylinder type machinery, there is a point in capacity or power where an advantage accrues with increasing number of piston-cylinder assemblies. In the case of Stirling machinery where primary energy is transferred across the casing wall of the machine, this consideration is even more important. This is due primarily to the difference in scaling of basic power and the required heat transfer. Heat transfer is found to be progressively limited as the size of the machine increases. Multiple cylinder machines tend to preserve the surface area to volume ratio at more favorable levels. In addition, the spring effect of the working gas in the so-called alpha configuration is often sufficient to provide a high frequency resonance point that improves the specific power. There are a number of possible multiple cylinder configurations. The simplest is an opposed pair of piston-displacer machines (beta configuration). A three-cylinder machine requires stepped pistons to obtain proper volume phase relationships. Four to six cylinder configurations are also possible. A small demonstrator inline four cylinder alpha machine has been built to demonstrate both cooling operation and power generation. Data from this machine verifies theoretical expectations and is used to extrapolate the performance of future machines. Vibration levels are discussed and it is argued that some multiple cylinder machines have no linear component to the casing vibration but may have a nutating couple. Example applications are discussed ranging from general purpose coolers, computer cooling, exhaust heat power extraction and some high power engines.

Final report of APMP pressure key comparison (APMP.M.P-K6) in gas media and gauge mode from 20 kPa to 105 kPa

This report summarizes the results of a regional key comparison (APMP-IC-2-97) under the aegis ofAsia Pacific Metrology Program (APMP) for pressure measurements in gas media and in gaugemode from 20 kPa to 105 kPa. The transfer standard was a pressure-balance with a piston–cylinderassembly with nominal effective area 335.7 mm2 (TL-391) and was supplied by the NationalMetrology Institute of Japan [NMIJ]. Nine standards laboratories from the APMP region with onespecially invited laboratory from the EUROMET region, namely Physikalisch-TechnischeBundesanstalt (PTB), Germany, participated in this comparison. The comparison started inOctober 1998 and was completed in May 2001. The pilot laboratory prepared the calibrationprocedure as per the guidelines of APMP and International Bureau of Weights and Measures(BIPM) [1–4]. Detailed instructions for performing this key comparison were provided in thecalibration protocol and the required data were described in: (1) Annex 3 – characteristics of thelaboratory standards, (2) Annex 4 – the effective area (A′p′/mm2) (where the prime indicates values based on measured quantities) at 23 °C of the travelling standardas a function of nominal pressure (p′/kPa) (five cycles both increasing and decreasing pressures atfive predetermined pressure points) and (3) Annex 5 – the average effective area at 23 °C (A′p′/mm2)obtained for each pressure p′/kPa with all uncertainty statements. The pilot laboratory processedthe information and the data provided by the participants for these three annexes, starting with theinformation about the standards as provided in Annex 3. Based on this information, the participatinglaboratories are classified into two categories: (I) laboratories that are maintaining primary standards,and (II) laboratories that are maintaining standards loosely classified as secondary standards with aclear traceability from other established national metrology institutes (NMI) as per norm of theBIPM. It is observed that out of these ten laboratories, six laboratories have primary standards[Category (I)]; the remaining four laboratories are placed in Category (II).During the process of comparison, there was a loss of mass of the piston TL-391 by an amount ofroughly 23.4 mg in two instances, originally noticed at NMIJ and then at NMISA within the firstyear of circulation. Unfortunately, we do not have any information where it had happened and when.But after that, there was no change of mass of the piston for nearly two years till the end of thiscomparison. NMIJ reported that it happened due to the damage of the pin attached to the piston.Interestingly, loss of mass of the piston by an amount of 7.6 mg was reported in the transit fromNMIJ to NMISA and within one month. Since the damage and subsequent loss of mass occursinstantaneously, we believe that the first damage had happened close to NMIJ and the second at NMISAwhere the necessary corrections have been already made. Therefore, we have not introduced anycorrection to any datum provided by the participating laboratories in both the phase A and phase B loops.The obtained data were compiled and processed under the same program as per theConsultative Committee for Mass and Related Quantities (CCM)/BIPM guidelines [5]. Following theapproach of Elster et al [6], we have evaluated these results and establish a link with CCM.P-K6through the link laboratory PTB (Germany). From the CCM.P-K6 key comparison reference value(KCRV), we have estimated the relative deviation of A′0/mm2 from the reference value for all tenlaboratories and compared this with their estimated expanded uncertainties at k = 2. The bilateraldegree of equivalence of the participating laboratories in the APMP.M.P-K6 comparison has beenestimated from the degree of equivalence between two laboratories. These results show an excellentagreement of all participating laboratories within the estimated expanded uncertainties using acoverage factor k = 2.Main text.To reach the main text of this Paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Numerical simulation of a novel blast wave mitigation device

This paper proposes a novel blast wave mitigation device, consisting of a piston–cylinder assembly. A shock wave is induced inside the device when it is subject to a blast wave. The shock wave propagates inside the device and is reflected repeatedly. The physical processes within the blast wave mitigation device are simulated numerically. Numerical predictions are in excellent agreement with analytical solutions for special cases of the investigated problem that are available in the literature. The peak pressure on the base of the device caused by the blast wave is studied using a number of design parameters. The numerical simulation shows that, although the transmitted impulse remains practically unchanged, the peak pressure of the blast wave can be reduced by as much as 98%, or even higher, depending on the design parameters chosen.

Liquid and gas in dead-weight pressure-gauge testers

It is demonstrated that the density and viscosity of liquids and gases exert different effects on the effective area of piston-cylinder assemblies even at comparatively low pressures, as a consequence of which a change in the working medium in the piston-cylinder assemblies of high-precision dead-weight pressure-gauge standards may be accompanied by a marked change in the reproducible pressure. The feasibility of creating a system for assuring the correctness of pressure measurements in gas media, including a state standard, is evaluated.

Final report on key comparison EUROMET.M.P-K3.a in the gauge pressure range 50 kPa to 1000 kPa

The standards of seven European laboratories in the pressure range from 100 to 1000 kPa, with an option at 50 kPa, have been compared in the period 2000–2001. The transfer standard was a pressure balance equipped with a gas-lubricated piston–cylinder assembly of nominal effective area 980 mm2. This assembly was formerly used as transfer standard for the key comparison CCM.P-K1.b. At the time of the comparison, the results relating to the effective area were not published. The link of the EUROMET.M.P-K3a comparison to CCM.P-K1.b will be established through the results of LNE, acting as the pilot laboratory.The comparison protocol for the EUROMET comparison was the same as for the CCM one. As the difference between the CCM reference value and the EUROMET reference value was not significant, the CCM reference value has been used to establish the equivalence statements of the participants to the EUROMET.M.P-K3a comparison to CCM.P-K1.b. The deviations from the reference value of all the laboratories but one are less than their estimated expanded uncertainty. Over 21 combinations of pairs of European laboratories, 18 demonstrate equivalence of the results at 1 MPa.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Grain boundary mobility of siderophile elements in MgO

Siderophile elements are key in understanding the Earth’s history, particularly the platinum group elements and their longlived isotopes. These elements are highly concentrated in the core relative to the silicate mantle, and a mechanism for core-mantle communication is of great interest to those interested in both the Earth’s segregation history as well as the identification of a unique chemical fingerprint that is characteristic of the deep mantle. Elements such as the highly and moderately siderophile elements (HSE and MSE) that are quite incompatible in the lattices of mantle rocks may be present and mobile in the grain boundaries of these phases, thus providing a reservoir for the storage and transport of these important elements. The grain boundary mobility of several HSE and MSE has been investigated in polycrystalline MgO, a deep mantle analog. The experimental strategy required the presynthesis of MgO wafers to obtain an equilibrium microstructure. Powdered metal particles were smeared on each side of the wafer; the upper horizon with the diffusing element of interest or ‘source’ (Ir, Os, Rh, Au, Pt, Ru, Re, W, Mo, Cu) and the lower horizon with the ‘sink’ element, usually Pt. Since the source elements are highly incompatible in the lattice (and likely have very low lattice diffusivities), alloying of the source element with the initially pure Pt particles implies a grain boundary diffusion pathway. The wafers were placed in a piston-cylinder assembly and held at 1600 C and 2.5 GPa for 5–50 h. The run products were analyzed by electron microprobe (EMP) by measuring the concentration of the source element in the Pt particles. The results indicate that all of the elements studied are mobile in the polycrystalline MgO. Grain boundary transport caused 0.07–95% alloying with the Pt layer. The cumulative fluxes of source atoms through the MgO layer were estimated and these values span nearly three orders of magnitude: Pt, Os and Re display the smallest; W is about an order of magnitude greater; Au, Ir, Ru, Mo, and Cu all have similar values 6 times that of W; and Rh has the largest flux with 25 times that of W. It is worth noting that not all of the Pt blebs of a given experiment had the same amount of source element: Ir levels range from 3-18% across the sample and Rh levels range from 25–95%. This indicates that not all grain boundaries are equally conductive pathways for diffusion, but that grain boundary diffusion may present a fast pathway for core-mantle transfer of trace siderophile elements.