Pump, step 4 of 8
What pumping speed actually reaches the chamber?
The system, laid piece by piece
What changed on this machine
read read from the base typed entered by hand, outside the base
A Bill of Vacuum is what a vacuum engineer leaves behind: what the machine will reach, and which document every number came from.
The chamber at temperature
| Gas | Gas load, warm walls | Pumping at the chamber | Pressure in the cold |
|---|
What this design raises
What to do about it
Branch by branch
| Branch | Line | Conductance | At flange | At chamber | Delivered | Wall | In the total | Actions |
|---|
Every wall the gas sees counts, from the chamber inclusive to the pumps exclusive. A compact chamber stays a single node. A longitudinal profile requires L/D ≥ 10, a declared uniform lateral source and explicit physical boundary conditions. Profile V1 is modeled with a 1D long-tube approximation. Unsupported domains refuse a profile. The 0.3 cm of gasket face the gas sees at each joint and the 2 diameters a tee or a cross is counted as remain declared modeling conventions.
Full record
| Quantity | Value | Face | Read at |
|---|
What nothing covers
What these figures rest on
The chamber is the node. A branch starts at its pump: put a pump on a port, then lay its line back toward the chamber, section by section, until it reaches. Click the dashed section to lay a piece, press Enter, lay the next. Drag the drawing to turn it. Proportions are representative, only the typed dimensions are computed, and the molecular regime is the only one these formulas hold in.
P. Chiggiato, Vacuum Technology for Ion Sources, CERN, Geneva, arXiv:1404.0960. Read here: Eq. 20 C = C′ A₁ τ. Eq. 21 the Santeler equation for the transmission probability of a uniform circular tube, stated to better than 0.7 per cent. Eq. 22 its long tube limit. Eq. 23 C ≈ 12.3 D³/L for N₂. Table 8 unit area conductances at 293 K. F-CHIGGIATO-IONSOURCES
E. Al-Dmour, Fundamentals of Vacuum Physics and Technology, Proceedings of the 2017 CERN Accelerator School course on Vacuum for Particle Accelerators, Glumslov, arXiv:2006.01464. Read here: Eq. 47 C = 3.64 A √(T/M) for a thick orifice. Eq. 48 C = 11.6 A for air at 23 C. Eq. 49 C = 3.81 (d³/L) √(T/M) for a long circular tube. Eq. 50 C = 12.1 d³/L for air at 23 C. Eq. 51 1/S_eff = 1/C + 1/S_nom. F-ALDMOUR-CAS2017
V. Baglin, Cryopumping and Vacuum Systems, Proceedings of the 2017 CERN Accelerator School course on Vacuum for Particle Accelerators, Glumslov, Sweden, arXiv:2006.01574. Read here: Eq. 4 S = (1/4) σ (1 - P/P_vap) A V̄ ≈ (1/4) σ A V̄, a cold surface as a pump. Eq. 5 S = 3.64 σ √(T/M) in L s⁻¹ cm⁻², with the published control that at 4.2 K the maximum pumping speed of hydrogen and carbon monoxide equals 5.3 and 1.4 L s⁻¹ cm⁻². Eq. 7 P₁/P₂ = √(T₁/T₂) and n₁/n₂ = √(T₂/T₁), thermal transpiration, with the published controls that a vessel at 4.2 K reads the measured pressure divided by 8 and one at 77 K divided by 2. Table 2, peak desorption temperatures H2 18 K, CH4 60 K, H2O 285 K, CO 45 K, CO2 95 K. Section 2.1, cooling a metallic surface to 77 K will only pump water molecules. Section 3.4, one shall operate below 4 K to reach a low vapour pressure of helium. F-BAGLIN-CAS2017
V. Parma, Cryostat Design, Proceedings of the CAS-CERN Accelerator School course on Superconductivity for Accelerators, Erice, Italy, 2013, CERN-2014-005 pp. 353-399, arXiv:1501.07154. Read here: Eq. 18, Kennard law, Q̇ = A₁ · α(T) · Ω · p · (T₂ - T₁) in the molecular regime, with p in Pa, temperatures in K, and Ω = 2.13 W m⁻² Pa⁻¹ K⁻¹ published for helium. Eq. 19 for the combined accommodation coefficient of two surfaces. Table 4, accommodation coefficients, helium 0.3 at 300 K, 0.4 at 80 K, 0.6 at 20 K, 1 at 4 K, air 0.8 at 300 K and 1 at 80 K. Section 3.2, at 4.2 K most gas species except H2 and He can be cryo-condensed on the cold surfaces. F-PARMA-CAS2013
Edwards, nXDS Scroll Pump Instruction Manual, A735-01-880 Issue B, Original Instructions, mirrored at mmrc.caltech.edu. Read here: Table 6, General mechanical data, section 2.3.1, overall dimensions L x W x H 432 x 282 x 302 mm, nominal rotational speed 1800 rpm at 30 Hz, inlet connection NW25 and outlet connection NW25. Figure 1 and its item list, lifting eye, NW25 inlet port, gas ballast control, cooling fan, NW25 exhaust port, rubber feet, user interface panel. S-EDWARDS-NXDS
Caburn-MDC Europe Limited, catalogue section 2, Valves, gate valves Million cycle line MC+, angle valves Million cycle line MC, all-metal valves and butterfly valves, www.caburn.co.uk. Read here: Section 2.1, gate valves, one page per port size, CF port connections, giving the face to face of the body, 38 mm at DN16, 50.8 at DN40, 70 at DN63, 80 at DN160, 85 at DN200 and 102 at DN250, with the bore, the flange outer diameter, the bolt circle and the number of bolts on each. Section 2.3, angle valves, axis to face equal on both ports, 38 mm at DN16, 63 at DN40, 105 at DN63, 135 at DN100, 165 at DN160 and 216 at DN200. Section 2.5, all-metal angle valve DN16, legs of 38 mm on a 34 mm flange with a 14.5 mm bore, stainless steel bellows sealed actuator and a formed bellows. Section 2.5, butterfly valves, table giving flange outer diameter, knob height, through bore and thickness, 19.1 mm thick at DN16CF and 25.4 at DN40CF. S-CABURN-MDC-VALVES
Nor-Cal Products, Inc., Products Online Catalog 2019, CF fittings and CF flanges, www.n-c.com. Read here: CF fittings tables, flange outer diameter column, reading 6.00 inches on the fittings whose tube outer diameter is 4 inches, which is the DN100 CF bore. 152.4 millimetres exactly, one inch being 25.4 millimetres by definition. The same flange is printed 6 inches by the Pfeiffer Vacuum catalogue, part 3.3 page 50, table Primary dimensions of CF flanges, to the same ISO 3669 standard, which reads 152.0 millimetres. That reading carries no page number. Section 2.4, CF Flanges, one table per nominal outer diameter, columns BOLT HOLES and DIAMETER OR THREAD, with the metric option named at the foot of each page. Page 50 carries CF Flanges - 3 3/8 Inch (86mm) Nominal OD, which is the DN50 CF bore, reading 8 bolt holes, thread 5/16-24, clearance .332 inch, and Add -M8 = Metric tapped bolt holes. Page 48 carries CF Flanges - 2 1/8 Inch (54mm) Nominal OD, which is the DN25 CF bore, reading 4 bolt holes, thread 1/4-28, clearance .265 inch, and Add -M6. The two table names this registry entry answers for, as the fiche prints them: "CF Fittings, flange OD column" and "CF Flanges, BOLT HOLES column and the metric tapped option of the page". S-NORCAL-CATALOGUE-2019
K. Jousten, Vacuum gauges for the fine and high vacuum, CERN Accelerator School, Vacuum in Accelerators, Platja d’Aro, 16-24 May 2006. Read here: Slide 9, overview of the principles: the capacitance/piezo/piezoresistive/membrane group is labeled "Gas independent, total pressure, p = F/A", the thermal-conduction group (Pirani, thermocouple) is labeled "Gas dependent, difficult to interpret". Slide 30, Helium/Nitrogen correction factor measured on four commercial Pirani gauges (Pfeiffer, Thyracont, MKS, Leybold), from 0.95-1.20 below 0.1 mbar to near 0 above 10 mbar. Slide 44, table "Relative measurement uncertainty of commercially available vacuum gauges": Pirani gauges, measurement range 1e-1 to 1e4 Pa. Capacitance diaphragm gauges, measurement range 1e-4 to 1e5 Pa. S-JOUSTEN-CAS2006-FINE
K. Jousten, Ultrahigh vacuum gauges, CERN Accelerator School, Vacuum in Accelerators, Platja d’Aro, 16-24 May 2006. Read here: Slides 8 to 17, the Penning gauge: crossed electric and magnetic field diagram (vector B named on the diagram), the magnetic field is constitutive of the principle. Slides 19 to 22, effects in the Bayard-Alpert gauge: 1 the intended ionization, 2 electron-stimulated desorption (ESD), 3 the X-ray effect, 4 the inverse X-ray effect: effects 2 and 3 cap the reading at low pressure, the extractor gauge reduces this residual current through a geometry that moves the collector away from the ionization volume rather than through an added field. Slide 44, same table as S-JOUSTEN-CAS2006-FINE: Penning gauges, measurement range 1e-7 to 1 Pa. Ionization gauges (emission cathodes, Bayard-Alpert and extractor), measurement range 1e-10 to 1e-2 Pa. S-JOUSTEN-CAS2006-UHV
INFICON, IE414 and IE514 Sensors, High-end Hot Ion Gauges, Passive, datasheet tiba70e1-b, 2024. Read here: Specifications table, row "Measurement range (N2)": IE414, Bayard-Alpert gauge system, 2e-11 to 1e-2 mbar. IE514, extractor gauge system, 2e-12 to 1e-4 mbar. Cover page, stated X-ray limit: IE414 below 1e-11 mbar, IE514 below 1e-12 mbar. S-INFICON-IE414-IE514
MKS Instruments, 631F, Heated Absolute Baratron Capacitance Manometer, datasheet 631F_11/21, 2021. Read here: Specifications table, row "Full Scale Pressure Ranges": 1, 2, 10, 30, 100 and 1000 Torr (mmHg). Ordering code table, page 4, the 1000 Torr range carries code "13", a configuration actually sold. S-MKS-631F
Outgassing rates are read from the outgassing base by material and surface state, and the key of each reading travels with the result into the dossier.
Flange, tube and bellows dimensions come from VACOM Vakuum Komponenten und Messtechnik GmbH, Vacuum Components, chapter 1, KF Components, ISO Components, CF Components, www.vacom-vacuum.com, read in its dimension tables. Every drawn dimension comes from those tables, and a bore no table carries is marked typed. S-VACOM-COMPONENTS
- Dimensions of CF Flanges, to ISO 3669 and its pre-norm ISO/TS 3669-2, DN10 to DN250, 12 bores. Read here: outer diameter, thickness, copper gasket diameter, bolt circle, number and size of bolts.
- Dimensions of KF flanges / KF centering rings, to DIN 28403 and ISO 2861, DN10 to DN50, 5 bores. Read here: outer diameter, centring ring diameter, clamp diameter, flange height.
- Dimensions of ISO-K flanges and centering rings, to DIN 28404 and ISO 1609, DN63 to DN400, 8 bores. Read here: outer diameter, centring ring diameter, thickness, number of clamps and of claw clamps with their size.
- CF Tube, 1 m length, KF Tube, 1 m length, ISO Tube, 1 m length, to DIN 11850, DN16 to DN200, 9 bores. Read here: outer diameter and wall thickness, the wall you see at the cut end of a drawn tube, DN25 read at the KF table because the CF one leaves it out as an auxiliary bore.
- Dimensions of ISO-K flanges and centering rings, rows D2 and RA, the tube inner and outer diameter, DN250. Read here: the only place in the catalogue that carries a tube at this bore, 250 inside and 254 outside.
- CF Hydroformed bellows, 1 flange rotatable, KF Hydroformed bellows connectors, ISO-K Hydroformed bellows connectors, under no norm the catalogue names, DN16 to DN250, 10 bores. Read here: free length and compressed length by bore, and nothing about the shape of the convolutions.
Not in the base yet
The elbow, the bellows and the gate valve are shop rules. No document opened for this page publishes a formula for them: they are drawn dashed and counted as unsourced in the table.
A tee carries 3 openings and a cross 4, all of them equal. The one the line arrives by is taken, and every other one is a port of its own: it takes the line onward, a blank flange with its gasket, a gauge, or a pump. A tee or a cross conducts like a tube 2 diameters long with its side ports ignored, which is a shop rule and no published result, so it is drawn dashed like the elbow and the valve.
The face a gasket shows the gas is a ring, pi times the bore times 0.3 cm of exposed height. That height is a convention of this page: no opened document publishes it, and it depends on the torque, the crush and the flange standard. The outgassing rate of the gasket material is read from the base with its key.
While a piece is being laid, the bore one step up is drawn as a dashed ghost at the same place. It shows the room that bore would take, for comparison.
- unsourced No pump is in the data. The conductance chain on this page computes what a pumping speed becomes behind a line, and the pumping speed itself has to be typed in from the pump datasheet.
- unsourced The bellows conductance has no source in the corpus. A bellows is computed here as a straight tube of the same bore and length, which UNDERSTATES its resistance, and the field is marked as such.
- unsourced The elbow correction of 1.3 diameters per bend is a shop rule, carried in formulas.ts under the flag COUDE_ILLUSTRATIF. No source in this corpus publishes it.
What already answers this
Each line links a page of this site and says what it carries for this step.
- /tools/regime-abacus/ names the pump families that work at the target pressure
- /stack/pumps/ holds what each pump family does and where it stops
- /academy/vent-physics/ carries the flow regimes the conductance formulas depend on
Your machines
kept in this browser, never sent anywhereNothing here yet. Open an archetype, change one thing, and save it here.
All eight steps
- 01 Specify What pressure do I actually need, and by when?
- 02 Materials What can the chamber be made of?
- 03 Join How do these two materials become one vacuum wall?
- 04 Pump What pumping speed actually reaches the chamber?
- 05 Clean and bake How clean is clean enough, and how do I prove it?
- 06 Verify Does the chamber hold, and how would I know?
- 07 Commission How long until it reaches the number I specified?
- 08 Operate It was fine yesterday. What changed?
From a target pressure to a machine in service. Every step opens on a question an engineer actually asks, then points at what this site already carries to answer it. The cards, the tools and the modules stay where they are, and each step links to them. Each step ends on what it cannot answer, in a block derived from the corpus at build.
The dossier
A Bill of Vacuum is the document these steps produce: the result you calculated, the source keys it read, and the list of what it had to take on trust. It lives in this browser, with no account, and it leaves as versioned JSON or as a printable sheet carrying its keys and its licence.
The 8 steps point at 26 places across 19 distinct pages of this site, and declare 17 things the base does not carry yet. Both counts are read from the data at build.