NIST Calibration Services for Spinning Rotor Gauge Calibrations

Berg, Robert F.; Fedchak, James A.

doi:10.6028/nist.sp.250-93

Cited by 9 publications

(4 citation statements)

References 20 publications

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“…The SRG pressure measurement was absolute and SI traceable through a NIST calibration of the accommodation coefficient. 22 The outgassing rate q 0 of the measurement chamber was determined from

q_{0} false(T false) = Q_{0} false(T false) A_{0} = V_{0} \frac{{dp}_{0} false(T false)}{dt} .

Q 0 ( T ) is the outgassing flux from the measurement chamber of the volume V 0 with area A 0 at a temperature T .…”

Section: Methodsmentioning

confidence: 99%

Investigations of medium-temperature heat treatments to achieve low outgassing rates in stainless steel ultrahigh vacuum chambers

Sefa

Fedchak

Scherschligt

2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The authors investigated the outgassing rates and fluxes of vacuum chambers constructed from common 304L stainless steel vacuum components and subjected to heat treatments. Our goal was to obtain H2 outgassing flux on the order of 10−11 Pa l s−1cm−2 or better from standard stainless steel vacuum components readily available from a variety of manufacturers. The authors found that a medium-temperature bake in the range of 400 to 450°C, performed with the interior of the chamber under vacuum, was sufficient to produce the desired outgassing flux. The authors also found that identical vacuum components baked in air at the same temperature for the same amount of time did not produce the same low outgassing flux. In that case, the H2 outgassing flux was lower than that of a stainless-steel chamber with no heat treatment, but was still approximately 1 order of magnitude higher than that of the medium-temperature vacuum-bake. Additionally, the authors took the chamber that was subjected to the medium-temperature vacuum heat treatment and performed a 24-h air bake at 430°C. This additional heat treatment lowered the outgassing rate by nearly a factor of two, which strongly suggests that the air-bake created an oxide layer which reduced the hydrogen recombination rate on the surface. [http://dx.doi.org/10.1116/1.4983211]

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“…The SRG pressure measurement was absolute and SI traceable through a NIST calibration of the accommodation coefficient. 22 The outgassing rate q 0 of the measurement chamber was determined from

q_{0} false(T false) = Q_{0} false(T false) A_{0} = V_{0} \frac{{dp}_{0} false(T false)}{dt} .

Q 0 ( T ) is the outgassing flux from the measurement chamber of the volume V 0 with area A 0 at a temperature T .…”

Section: Methodsmentioning

confidence: 99%

Investigations of medium-temperature heat treatments to achieve low outgassing rates in stainless steel ultrahigh vacuum chambers

Sefa

Fedchak

Scherschligt

2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

Self Cite

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“…To support standards for vacuum pressure calibrations, piston provers with O-rings, sliding seals, or bellows seals have been used to measure flows as small as 8.6 × 10 −11 g s −1 (4 × 10 −6 cm 3 min −1 ) [20,[37][38][39]. Piston provers with seals of these types can accommodate a wider range of pressure differences across the seal.…”

Section: Piston Proversmentioning

confidence: 99%

Gas flow standards and their uncertainty

Wright¹,

Nakao²,

Johnson³

et al. 2022

Metrologia

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We review primary and working gas flow standards that are used to calibrate gas flow meters. For each type of primary standard, we describe the principles and practical considerations of its operation and describe one example implementation. We identify the practical limits of the example's performance, and, in many instances, we provide an uncertainty budget for a typical flow. The reviewed standards span the flow range 2.2 × 10-7 g/s to 520 kg/s. The references point to standards that operate at higher and at lower flows. The reviewed standards include volumetric flow standards (piston and bell provers, pressure-volume-temperature-time standards, rate of rise standards), static and dynamic gravimetric flow standards, and velocity × area standards such as critical flow venturis, laser doppler anemometer surveys, and multipath-ultrasonic meters. Finally, we describe working standard flow meters used in parallel to attain higher flows than economically practical via primary methods.

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“…Between 0.2 Pa and 2 Pa the effective accommodation coefficient is not constant but may be described by a simple linear model. 10,11 We did not use the SRG above 2 Pa in this work.…”

Section: Methodsmentioning

confidence: 99%

Gas uptake of 3D printed acrylonitrile butadiene styrene using a vacuum apparatus designed for absorption and desorption studies

Sefa

Ahmed

Fedchak

et al. 2016

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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We describe a vacuum apparatus for determining the outgassing rate into vacuum, the diffusion coefficient, and the amount of gas absorbed for various materials. The diffusion coefficient is determined from a model applied to time-dependent desorption data taken using a throughput method. We used this method to determine the diffusion coefficient, D, for H2O in 3-D printed acrylonitrile butadiene styrene (ABS). We found DH2O = 8.3 × 10−8 cm2/s ± 1.3 × 10−8 cm2/s (k = 1; 67% confidence interval) at 23.2 °C. This result was compared to the diffusion coefficient determined another by a gravimetric method, in which the sample weight was monitored as it absorbed gas from the atmosphere. The two methods agreed to within 3%, which is well within the uncertainty of the measurement. We also found that at least 80% of the atmospheric gas (air) absorbed by the ABS is water. The total amount of all atmospheric gas absorbed by ABS was about 0.35% by weight when exposed to ambient air in the laboratory, which was at a pressure of 101 kPa with a relative humidity of 57% at 22.2 °C.

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NIST Calibration Services for Spinning Rotor Gauge Calibrations

Cited by 9 publications

References 20 publications

Investigations of medium-temperature heat treatments to achieve low outgassing rates in stainless steel ultrahigh vacuum chambers

Investigations of medium-temperature heat treatments to achieve low outgassing rates in stainless steel ultrahigh vacuum chambers

Gas flow standards and their uncertainty

Gas uptake of 3D printed acrylonitrile butadiene styrene using a vacuum apparatus designed for absorption and desorption studies

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