ISO/TC 112 - Vacuum technology

This document specifies three methods for measuring the volume flow rate and one method each for measuring the base pressure, the compression ratio, and the critical backing pressure of a vacuum pump. The first method for measuring the volume flow rate (the throughput method) is the basic concept, in which a steady gas flow is injected into the pump while the inlet pressure is measured. In practice, the measurement of gas throughput may be complicated or inexact. For this reason, two other methods are specified which avoid the direct measurement of throughput. The second method for measuring the volume flow rate (the orifice method) is used when there is very small throughput at very small inlet pressures (under a high or ultra-high vacuum). It is based on measuring the ratio of pressures in a two-chamber test dome in which the two chambers are separated by a wall with a circular orifice. The third method for measuring the volume flow rate (the pump-down method) is well suited for automated measurement. It is based on the evacuation of a large vessel. The volume flow rate is calculated from two pressures, before and after a pumping interval, and from the volume of the test dome. Different effects, such as leak and desorption rates, gas cooling by nearly isentropic expansion during the pumping interval, and increasing flow resistance in the connection line between test dome and pump caused by molecular flow at low pressures, influence the results of the pressure measurement and the resulting volume flow rate. The choice of the required measurement methods depends on the properties of the specific kinds of vacuum pump, e.g. the measurement of the critical backing pressure is only necessary for vacuum pumps which need a backing pump. All data that are measured on a vacuum pump, but not specified in this document (e.g. measurement of power consumption), are defined in the specific pump standard.

This document specifies methods for measuring the volume flow rate, base pressure, water vapour tolerance, power consumption, and the lowest start-up temperature of positive displacement vacuum pumps, which discharge gas against atmospheric pressure and with a usual base pressure In this document, it is necessary to use the determinations of volume flow rate and base pressure specified in ISO 21360‑1. This document also applies to the testing of other types of pumps which can discharge gas against atmospheric pressure, e.g. drag pumps.

This document gives definitions of vacuum pumps and related terms. It is a continuation of ISO 3529‑1 which defines general terms used in vacuum technology.

This document specifies the dimensions of the clamped-type quick-release couplings used in vacuum technology, as well as those of the O-rings and their carriers associated with these couplings, used to ensure vacuum tightness. NOTE The dimensions retained for the coupling diameter ensure the compatibility of the quick-release coupling with the corresponding vacuum flanges specified in ISO 1609[1].

This document specifies the dimensions of fixed or rotatable bolted knife-edge flanges used in vacuum systems for pressures ranging from atmospheric to as low as 10−11 Pa.

This document specifies the dimensions of non-knife-edge flanges and collars used in vacuum technology. The dimensions ensure interchangeability between bolted, clamped and rotatable flanges: a) whether the assembly be homogeneous (for example, bolted flanges or clamped flanges) or heterogeneous (for example, bolted flanges assembled with clamped flanges either by means of bolts or clamps or by means of bolts and rotatable flanges). b) whether the sealing rings used with the flanges be elastomer O-rings or metal sealing rings, provided that they are compatible with the linear sealing loads given in Annex A.

This document specifies mounting dimensions for vacuum pipeline fittings (elbows, tees and crosses) of knife-edge flanges for nominal bores from 16 mm to 200 mm.

This document defines dimensions of right-angle valves that are compatible with the mounting dimensions of elbows defined in ISO 9803-1 and ISO 9803-2. This document covers right-angle valves with flanges defined in ISO 2861, ISO 1609 and ISO 3669.

This document specifies mounting dimensions for vacuum pipeline fittings (elbows, tees and crosses) of non knife-edge flange for nominal bores from 10 mm to 250 mm of the R5 series.

This document defines general terms used in vacuum technology. It gives theoretical definitions as precise as possible, bearing in mind the need for use of the concept in practice.

This document defines terms related to capacitance diaphragm gauges (CDGs), specifies which parameters have to be given for CDGs, details their calibration procedure and describes which measurement uncertainties have to be considered when operating these gauges. This document complements ISO 3567 and ISO 27893 when calibrating CDGs and using them as reference standards.

This document specifies methods and special requirements for measuring the maximum tolerable pressure difference, effective compression ratio, compression ratio with zero throughput and overflow valve pressure difference of mechanical booster vacuum pumps. It applies to mechanical booster vacuum pumps employed for medium vacuum or rough vacuum applications including gas-cooled mechanical booster vacuum pump and multiple mechanical booster vacuum pump systems. It covers particular characteristics of mechanical boosters that are different from those of the usual positive displacement vacuum pumps. Maximum tolerable pressure difference Δpmax, effective compression ratio Keff, compression ratio with zero throughput K0 and overflow valve pressure difference Δp1 are special characteristics of the performance of mechanical booster vacuum pumps.

This document, in conjunction with ISO 21360-1, specifies methods for the measurement of performance characteristics of turbomolecular vacuum pumps. It is applicable to all sizes and all types of turbomolecular vacuum pumps, including those — with mechanical or magnetic bearings; — with or without an additional drag stage(s) or other pumping stages on the shaft; — with one or more inlet ports. Since turbomolecular vacuum pumps are backed by primary pumps, their performance cannot be completely defined by the volume flow rate curve. Also, the driving device and the backing pressure of the turbomolecular vacuum pump is important to the performance. The following completes the performance characteristics: — information about throughputs and backing pressure of the turbomolecular vacuum pump; — the compression ratio curve (compression ratio vs backing pressure of turbomolecular vacuum pump).

This document describes procedures to measure outgassing rates from components designed for vacuum chambers and of vacuum chambers as a whole. The outgassing rates are expected to be lower than 10−5 Pa m3 s−1 (10−2 Pa L s−1) at 23 °C and to emerge from devices that are suitable for high or ultra-high vacuum applications. The molecular mass of the outgassing species or vapour is below 300 u. The upper limit 10−5 Pa m3 s−1 of total outgassing rate is specified independent of the size, the total surface area and texture or state of the outgassing material. If a specific outgassing rate (outgassing rate per area) is determined, the area is not a specific surface area including the surface roughness, but the nominal geometrical one. When it is difficult to determine the nominal geometrical surface area of the sample, such as powders, porous materials, very rough surfaces, or complex devices, mass specific outgassing rate (e.g. outgassing rate per gram) is used. For many practical applications, it is sufficient to determine the total outgassing rate. If a measuring instrument, which sensitivity is gas species dependent, is used, the total outgassing rate are given in nitrogen equivalent. In cases, however, where the total outgassing rate is too high, the disturbing gas species is identified, and its outgassing rate is measured in order to improve the sample material. This document covers both cases. Some outgassing molecules can adsorb on a surface with a residence time that is much longer than the total time of measurement. Such molecules cannot be detected by a detecting instrument when there is no direct line of sight. This is considered as a surface effect and surface analytical investigations are more useful than general outgassing rate measurements considered here. Also, molecules that are released from the surface by irradiation of UV light or X-rays, are out of the scope of this document. This document is written to standardize the measurement of outgassing rates in such a way that values obtained at different laboratories and by different methods are comparable. To this end, for any of the described methods, traceability is provided to the System International (SI) for the most important parameters of each method and according to the metrological level. Outgassing rate measurements by mass loss, which were mainly developed for testing of spacecraft and satellite materials, are not gas specific. For acceptable measurement times, mass loss measurements require significantly higher outgassing rates (>10−5 Pa m3 s−1) than typical for high and ultrahigh vacuum components. Also, it is not possible to measure the sample in situ due to the weight of the vacuum chamber, since the balances are not vacuum compatible. For these reasons, mass loss measurements are not considered in this document. It is assumed that the user of this document is familiar with high and ultra-high vacuum technology and the corresponding measuring instrumentation such as ionization gauges and quadrupole mass spectrometers.

This document describes procedures to characterize quadrupole mass spectrometers (QMSs) with an ion source of electron impact ionization and which are designed for the measurement of atomic mass-to-charge ratios m/z This document is not applicable to QMSs with other ion sources, such as chemical ionization, photo-ionization or field ionization sources and for the measurements of higher m/z, which are mainly used to specify organic materials. It is well known from published investigations on the metrological characteristics of quadrupole mass spectrometers that their indications of partial pressures depend significantly on the settings of the instrument, the total pressure, and the composition of the gas mixture. For this reason, it is not possible to calibrate a quadrupole mass spectrometer for all possible kinds of use. The characterization procedures described in this document cover the applications of continuous leak monitoring of a vacuum system, leak rate measurement with tracer gas, residual gas analysis and outgassing rate measurements. The user can select that characterization procedure that best suits his or her needs. These characterization procedures can also be useful for other applications. It is also well known that the stability of several parameters of quadrupole mass spectrometers, in particular sensitivity, are rather poor. Therefore, when a parameter has been calibrated, it needs frequent recalibration when accuracy is required. For practical reasons this can only be accomplished by in situ calibrations. To this end, this document not only describes how a quadrupole mass spectrometer can be calibrated by a calibration laboratory or a National Metrological Institute with direct traceability to the System International (SI), but also how calibrated parameters can be frequently checked and maintained in situ. By their physical principle, quadrupole mass spectrometers need high vacuum within the instrument. By reducing dimensions or by special ion sources combined with differential pumping the operational range can be extended to higher pressures, up to atmospheric pressure. This document, however, does not include quadrupole mass spectrometers with differential pumping technology. Therefore, it does not cover pressures exceeding 1 Pa on the inlet flange of the quadrupole mass spectrometer. This document does not describe how the initial adjustment of a quadrupole mass spectrometer by the manufacturer or by a service given order by the manufacturer should be made. The purpose of such an initial adjustment is mainly to provide a correct m/z scale, constant mass resolution or constant transmission, and is very specific to the instrument. Instead, it is assumed for this document that a manufacturer's readjustment procedure exists which can be carried on-site by a user. This procedure is intended to ensure that the quadrupole mass spectrometer is in a well-defined condition for the characterization. It is the intention of this document that the user gets the best possible metrological quality from his quadrupole mass spectrometer. From investigations it is known that in most cases this can be achieved in the so called "scan mode". The bar graph may also be of an adequate quality depending on the software used for evaluation of the data taken by the quadrupole mass spectrometer. The trend mode, however, often involves the additional uncertainty that a shift of the peak value position on the mass scale causes a shift in ion current. For this reason, the scan mode is preferable for most of the measurement procedures of this document. It is not the intent of this document that all the parameters described be determined for each quadrupole mass spectrometer. However, it is intended that the value of a parameter addressed in this document be determined according to the procedure described in this document if it is given or measured (e.g. for an inspection test). It is assumed for this document that the applicant

ISO 19685:2017 identifies parameters of Pirani gauges, their calibration procedure, and describes measurement uncertainties to be considered when operating these gauges. ISO 19685:2017 applies to Pirani vacuum gauges operating over a pressure range of 0,01 Pa to 150 kPa. ISO 19685:2017 complements ISO 3567 and ISO 27893 when calibrating Pirani gauges and using them as reference standards. In addition, ISO 19685:2017 defines procedures to characterize Pirani gauges for response time and hysteresis.

ISO 3529-3:2014 gives definitions of total and partial pressure vacuum gauges. lt is a continuation of ISO 3529‑1, which defines general terms used in vacuum technology, and of ISO 3529‑2, which gives definitions of vacuum pumps and related terms.

ISO 14291:2012 defines terms relevant to quadrupole mass spectrometers (QMSs) and specifies the parameters required for specification by QMS manufacturers necessary for proper calibration and for maintaining the quality of partial pressure measurement. ISO 14291:2012 applies to QMSs with an ion source of the electron impact ionization type. Such QMSs are designed for the measurement of atomic mass-to-charge ratios m/z typically /z above 300, which are mainly used to specify organic materials, lie outside the scope of ISO 14291:2012.

ISO 27893:2011 gives guidelines for the determination and reporting of measurement uncertainties arising during vacuum gauge calibration by direct comparison with a reference gauge carried out in accordance with ISO/TS 3567. ISO 27893:2011 describes methods for uniform reporting of uncertainties in vacuum gauge certificates. Uncertainties reported in accordance with the guidelines given in ISO 27893:2011 are transferable in the sense that the uncertainty evaluated for one result can be used as a component in the uncertainty evaluation of another measurement or calibration in which the first result is used. ISO 27893:2011 defines two measurement models that are sufficient to cover most practical cases. However, it is possible that the models given cannot be applied to newly developed vacuum gauges.

ISO 27892:2010 specifies a method for the measurement of rapid shutdown torque (destructive torque) of turbomolecular pumps in which gas momentum is produced by axial flow type blades and/or helical channels. The main forces leading to failure of turbomolecular pumps are torques around the rotational axis. Other insignificant forces and moments that can occur lie outside the scope of ISO 27892:2010. There are two kinds of failure: rapid shutdown by whole burst and softer crash of rotor. ISO 27892:2010 applies to both. The same measurement method can be used for turbomolecular pumps and molecular drag pumps.

ISO 27895:2009 specifies methods for the leak testing of vacuum valves used for control of gas flow or vacuum pressure in a vacuum system.It is applicable to vacuum valves that can be closed to leak rates less than 1 x 10-5 Pa m3/s for trace gas. The methods employ a sealing arrangement for the valve body, which is also specified in ISO 27895:2009. The methods are suitable for the verification of valve specifications. A valve leak rate less than the nominal leak rate specified by the manufacturer during and after the operation enables the specification of such valve operating conditions as operating pressure range, permissible pressure difference between ports, bake-out temperature or operating temperature, and life cycle.

ISO 27894:2009 defines terms relating to hot cathode ionization vacuum gauges, and specifies which parameters are given by manufacturers of hot cathode ionization gauges and which measurement uncertainties have to be considered when operating these gauges.

The measurements deal with diffusion pumps, ejector pumps, and booster pumps, i.e. pumps capable of operation in both the molecular and laminar flow regions.

The considered method of measurement deals with vapours jet vacuum pumps, diffusions pumps and diffusion-ejector pumps. The dependence of the performance of these pumps on the backing pressure can only be completely described be means of a curve relating the inlet and backing pressure over the range of operation. The recommended test dome and the principle of the test equipment are illustrated.

 ISO 3669:2017 specifies the dimensions of fixed or rotatable bolted knife-edge flanges used in vacuum systems for pressures ranging from atmospheric to as low as 10−11 Pa.

ISO 2861:2013 specifies the dimensions of the clamped-type quick-release couplings used in vacuum technology, as well as those of the O-rings and their carriers associated with these couplings, used to ensure vacuum tightness.

This part of ISO 21360 specifies methods for measuring the volume flow rate, base pressure, water vapour tolerance, power consumption, and the lowest start-up temperature of positive displacement vacuum pumps, which discharge gas against atmospheric pressure and with a usual base pressure In this part of ISO 21360, it is necessary to use the determinations of volume flow rate and base pressure specified in ISO 21360‑1. This part of ISO 21360 also applies to the testing of other types of pumps which can discharge gas against atmospheric pressure, e.g. drag pumps.

ISO/TS 27893:2009 gives guidelines for the determination and reporting of measurement uncertainties arising during vacuum gauge calibration by direct comparison with a reference gauge in accordance with ISO/TS 3567. It describes methods for uniform reporting of uncertainties in vacuum gauge certificates. Uncertainties reported in accordance with ISO/TS 27893:2009 are transferable in the sense that the uncertainty evaluated for one result can be used as a component in the uncertainty evaluation of another measurement or calibration in which the first result is used. This specification defines two measurement models that are sufficient to cover most practical cases. However, it is possible that the models given cannot be applied to newly developed vacuum gauges. The final uncertainty to be reported in a certificate is evaluated from the uncertainties of the input quantities and influence quantities. The principal quantities that may affect the result of a vacuum calibration are described; however, a complete list of the possible quantities that may have an influence on the final result lies outside the scope of ISO/TS 27893:2009.

ISO/TS 3669-2:2007 specifies the dimensions of fixed or rotatable bolted knife-edge style bakable flanges used in vacuum systems for pressures ranging from atmospheric to as low as 10-13 Pa.

ISO 21360:2007 is a basic standard which defines three different methods for measuring the volume flow rate and one method each for measuring the base pressure, the compression ratio and the critical backing pressure of a vacuum pump. The choice of the required measurement methods depends on the properties of the specific kinds of vacuum pump, e.g. the measurement of the critical backing pressure is only necessary for vacuum pumps which need a backing pump. All data that is measured on a vacuum pump but not described in ISO 21360:2007 (e.g. measurement of power consumption) is defined in the specific pump standard.

ISO 9803-2:2007 specifies mounting dimensions for vacuum pipeline fittings (elbows, tees and crosses) of knife-edge flanges for nominal bores from 16 mm to 200 mm.

ISO 9803-1:2007 specifies mounting dimensions for vacuum pipeline fittings (elbows, tees and crosses) of non-bakable and non knife-edge flange for nominal bores from 10 mm to 250 mm of the R5 series.

ISO 21358:2007 defines dimensions of right-angle valves that are compatible with the mounting dimensions of elbows defined in ISO 9803-1 and ISO 9803-2. ISO 21358:2007 covers right-angle valves with flanges defined in ISO 2861-1, ISO 1609 and ISO 3669. ISO 3669 lists two flange series: preferred series, and secondary series. ISO 21358:2007 covers only the valves with flanges of the secondary series.

ISO/TS 3567:2005 lays down the physical, technical and metrological conditions to be fulfilled when calibrations of vacuum gauges are performed by direct comparison with a reference gauge.

ISO 5302:2003 specifies methods for the measurements of performance characteristics of turbomolecular pumps. It is applicable to all sizes and all types of turbomolecular pumps, with mechanical or magnetic bearings, and with or without an additional drag stage.

The method of determining the volume of gas which flows in unit time through the pump inlet are specified. The considered pumps discharge the gas against atmosphere pressure and achieve a limiting inlet pressure less than 100 pa in one stage.

Specifies the dimensions for vacuum pipeline fittings (elbows, tees and crosses) for nominal bores from 10 mm to 250 mm of the R5 series.

The considered pumps discharge the gas against atmosphere pressure and achieve a limiting inlet pressure of less than 100 Pa in one stage. The method adopted is that the ultimate pressure is measured at a specified temperature in a specified form of test dome attached to the inlet of the pump.

The specified dimensions ensure interchangeability between bolted, clamped and rotable flanges under special conditions. The main dimensions are tabled; linear sealing loads, bores for vacuum flanges and required outside tube diameters are specified.

Deals with flanges rigidly or rotatably bolted which are used in vacuum systems. Two series of flanges are specified: a preferred one, the main dimensions of which ensure compatibility with already standardized, non-bakable flanges (see ISO 1609) and a secondary series concerning flanges in common use.

ISO 2861-2:1980 specifies the dimensions of quick-release couplings of the screwed type as used in vacuum technology, as well as those of the “O” rings and the insert which are associated with these tailpieces to ensure coupling tightness. General information is also included which refers to the clamped quick-release coupling standardized internationally in ISO 2861-1, with which the screwed quick-release coupling specified in ISO 2861-2:1980 is compatible.

The graphical symbols of vaccum pumps, baffles, traps, pressure measuring apparatus, flowliness, valves and vaccum chambers are described and illustrated. In the annex an example of the use of the recommended symbols is shown.

ISO 2861-1:1974 specifies the dimensions of quick-release couplings of the clamped type as used in vacuum technology, as well as those of the “O” rings and their carriers which are associated with these couplings to ensure vacuum tightness.