Vacuum technology · Buyer's guide
Follow the gas from the vacuum chamber through a turbomolecular pump to its backing pump. Compare gas-specific performance, understand the components, and check the flange and cooling details before specifying the system.
01
High vacuum describes a pressure range, not one machine design. This guide concentrates on turbomolecular systems; cryopumps and sputter-ion pumps use different gas-capture mechanisms. The table is a functional component reference, not a manufacturing BOM for the Baosi model. [3] [6] [7]
| Component / pump family | Function | Material and configuration boundary |
|---|---|---|
| Rotor · turbomolecular | Moving blades transfer momentum to gas molecules. [3] | The Baosi page does not identify rotor alloy, coating or replacement part number. [5] |
| Stator · turbomolecular | Stationary blades alternate with the rotor stages; Holweck designs use helical stator channels. [3] | No stator material or drag-stage configuration is stated for FFZ250/2000PM-W. [5] |
| Bearing system · turbomolecular | Supports the rotating assembly. ISO 21360-4 covers both mechanical- and magnetic-bearing designs. [2] | Baosi states grease lubrication, but does not specify bearing material or service interval. Do not infer magnetic levitation from the category name. [5] |
| Cold surface / cryopanel · cryopump | Retains gas by condensation or adsorption; regeneration releases the accumulated gas. [6] | Leybold describes activated charcoal on inner cryosorption panels. This is a cryopump construction example, not a Baosi turbopump material specification. [6] |
| Cathode · sputter-ion pump | Ion bombardment sputters getter material; ions can also be implanted in the cathode. [7] | Leybold describes titanium cathodes and stainless-steel anodes. These belong to an ion-pump electrode system. [7] |
In a turbomolecular pump, fast-moving rotor blades transfer momentum to gas molecules. Stationary blades alternate with the rotor stages; the combined stages move gas toward the foreline, where the backing pump takes over. Molecular flow is essential to this pumping action. A Holweck stage, where fitted, adds a rotating sleeve and helical stator channels downstream. Its presence must be checked for the offered model. [3]
A cryopump instead holds gas on cold panels, including adsorbent-coated surfaces for gases that are difficult to condense. A sputter-ion pump uses ion bombardment, sputtered getter material and implantation to retain gas. A cryopanel or cathode therefore is not an optional component of the rotor assembly in the turbopump described below. [6] [7]
For a replacement-parts order, request the manufacturer’s exploded drawing, part numbers and material list for the exact pump serial number. The component functions above do not establish interchangeable parts.
02
Range names are conventions. One leading supplier divides the scale as below and notes that the division is somewhat arbitrary [1].
| Range | Pressure (mbar = hPa) | What to tell the supplier |
|---|---|---|
| Rough vacuum | 1000 to 1 [1] | Within reach of a backing pump alone |
| Medium vacuum | 1 to 10⁻³ [1] | Pump-down time and gas load at changeover to the high-vacuum pump |
| High vacuum | 10⁻³ to 10⁻⁷ [1] | Base pressure, working pressure during the process, and the main gases |
| Ultra-high vacuum | 10⁻⁷ to about 10⁻¹⁴ [1] | Bakeout, all-metal sealing and hydrogen performance become deciding factors |
Give pressures with units. Datasheets mix Pa, hPa and mbar: 1 hPa equals 1 mbar, and 1 Pa is 0.01 mbar.
03
ISO 21360-4:2018 says a turbomolecular pump's performance cannot be fully defined by its pumping-speed curve, because it is backed by a primary pump; backing pressure and the drive also matter [2]. ISO lists the 2018 edition as current, confirmed in 2024, with a replacement under development; confirm the contractual edition when ordering. [2]
Pure rotor–stator turbopumps need a fore-vacuum of about 10⁻² hPa to keep molecular flow. Designs with added Holweck (drag) stages can discharge against 0.5 to 5 hPa, which lets a diaphragm pump do the backing [3]. Ask which type you are being offered and its maximum backing pressure.
Pfeiffer identifies an oil-backflow risk when a turbopump backed by an oil-sealed rotary vane pump is switched off, especially with incorrect operation. Its comparison discusses dry alternatives, but is not a current price quotation. Specify your contamination limit before choosing the backing pump. [3]
A Chinese turbomolecular pump page specifies a backing pump of 15 L/s for its 2000 L/s model, without naming a pump type [5]. Ask for the backing pump type, pumping speed and the backing pressure behind every quoted ultimate pressure.
| Backing pump (one published test) | Fore-vacuum pressure | Ultimate pressure reached |
|---|---|---|
| Duo 6 · two-stage rotary vane | 0.003 hPa | 2.47 × 10⁻¹¹ hPa [3] |
| MVP 015-2 · two-stage diaphragm | 3 hPa | 2.75 × 10⁻¹¹ hPa [3] |
| MVP 020-3 · three-stage diaphragm | 1.3 hPa | 2.65 × 10⁻¹¹ hPa [3] |
| ACP 15 · multi-stage Roots | 0.032 hPa | 2.56 × 10⁻¹¹ hPa [3] |
Pfeiffer measured these results with its HiPace 300 H (February 2022 publication, Table 1, p. 10). They are not FFZ250/2000PM-W test results. The same publication notes the gas-load limitation of compression-optimized pumps. [3]
04
A turbopump's compression ratio rises with the molecular mass of the gas, so it is much higher for nitrogen than for hydrogen [3].
05
Pfeiffer’s connection guide gives the pressure capabilities below for particular flange and seal arrangements. They are connection capabilities, not a guarantee of the pressure a complete chamber will reach. [4]
| Flange | Standard and sizes | Pressure and temperature |
|---|---|---|
| ISO-KF (small, clamped) | DIN 28403 and ISO 2861, DN 10 to DN 50 [4] | Down to 1 × 10⁻⁸ hPa with O-rings; below 1 × 10⁻⁹ hPa with metal seals and special clamps [4] |
| ISO-K / ISO-F (clamped or bolted) | DIN 28404 and ISO 1609; ISO-K DN 10 to DN 630, ISO-F up to DN 1000 [4] | Down to 1 × 10⁻⁸ hPa with O-rings; below 1 × 10⁻⁹ hPa with metal seals [4] |
| CF (copper gasket) | ISO 3669:2026 is the current knife-edge flange dimensional standard. Pfeiffer’s older size discussion cites ISO/TS 3669-2; compare the actual mating dimensions rather than relying on that superseded reference. [8] [4] | Pfeiffer describes CF connections for below 1 × 10⁻¹² hPa and bakeout up to 450°C. This does not authorize baking the pump, controller or every gasket to 450°C. Used copper gaskets must be replaced. [4] |
Baosi offers CF250 or LF250 inlet and KF40 outlet. Its “LF250” designation needs a mating drawing; do not silently convert it to an ISO-K or ISO-F specification. Request bolt/clamp details, seal type and the pump’s own inlet bakeout limit. [5]
06
This is one Baosi water-cooled turbomolecular model, not a specification range for all high-vacuum pumps. Values are manufacturer claims from the linked page. Unpublished fields remain questions for the quotation. [5]
| Parameter | Published value or evidence gap | What the quotation needs to resolve |
|---|---|---|
| Ultimate pressure · Pa | Summary and parameter table disagree; exact values are compared above. [5] | One corrected value for each flange, with backing pump, gas and measurement conditions. |
| Pumping speed · L/s | 2000 for N₂ in the summary. [5] | Gas-specific curves and working pressure; do not treat this as chamber evacuation time. |
| Power · W | Maximum power ≤750. [5] | Whether this covers pump and controller; no separate motor-power rating is published. |
| Electrical supply · V / Hz | 220 V; supply frequency is not stated. [5] | AC/DC, acceptable voltage range, frequency and the exact drive/controller. |
| Temperature limits · °C | Cooling-water field reads “≤25” without a unit; ambient range is absent. [5] | Separate water, ambient, process-gas and inlet-bakeout limits. |
| Ingress protection · IP code | Not stated. [5] | Pump and controller enclosure ratings separately. |
| Noise · dB(A) | Not stated; vibration ≤0.15 μm is a different measurement. [5] | Sound metric and measurement conditions, including the backing pump. |
| Mass · kg | 40 kg. [5] | Supplied assembly boundary and mounting/support requirements. |
| Envelope / service space · mm | No dimensioned installation envelope is given in the text table. [5] | A dimensioned drawing with connector and service clearances. |
| Gas-contact materials | Not stated. [5] | Rotor/stator/housing/seal materials and compatibility with the actual process gases. |
| Connections | Inlet CF250 or LF250; outlet KF40. [5] | Mating dimensions, seal and hardware—not just a nominal diameter. |
The published rotational speed is 24,000 rpm. This is rotor speed, not the incoming supply frequency. Baosi does not identify the associated controller model. [5]
07
Values below are from one Chinese turbopump page and show what to ask for, not a general rule.
08
For FFZ250/2000PM-W, obtain the manufacturer’s shutdown, venting and bearing-service procedure before commissioning. The public product page gives neither a venting sequence nor a grease specification or replacement interval. Its run-up time is not a rotor-stop time. Request the conditions for safe access, power-loss behavior and cooling-failure response in the operating manual. [5]
For removable CF joints, Pfeiffer requires a new copper gasket after disassembly and controlled, even heating and cooling during bakeout. Keep flange maintenance separate from servicing the rotating pump; the flange’s temperature capability is not the pump’s allowable temperature. [4]
For a cryopump, a service plan must include regeneration: retained gases are released when the cryopanels are warmed. Leybold distinguishes full and partial regeneration. That process is specific to gas-capture pumps and is not a turbopump bearing-maintenance instruction. [6]
09
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Product: high-vacuum pump, type [turbomolecular / turbodrag; other capture-pump requirement separately], quantity [units] Chamber: volume [L], target base pressure [value] mbar, working pressure [value] mbar Gases pumped: [N2 / H2 / He / process gases], gas load [mbar·L/s] Required data: pumping speed for [N2/He/H2], compression ratio for [N2/H2], compression ratio vs backing pressure curve (ISO 21360-4 if available) Inlet flange: [ISO-KF / ISO-K / ISO-F / CF] DN [size]; outlet flange: [type, size] Backing pump: [existing model and speed / please propose: rotary vane / diaphragm / Roots], maximum backing pressure accepted Cooling: [water / air], available water [°C, L/min]; power supply [AC/DC, V, Hz]; pump/controller enclosure [IP requirement] Controller, cables and venting valve: [included / not needed] Orientation: [vertical / horizontal / any]; bakeout required: [yes °C / no] Documents: data sheet tying ultimate pressure to flange and backing pump, test report for the supplied unit, dimensioned installation drawing, gas-contact materials, venting/power-loss instructions and bearing service interval Delivery to [country], target date [date]
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1 company lists this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.
Baosi lists FFZ250/2000PM-W with water cooling, 2000 L/s N₂ pumping speed and CF250/LF250 inlet options. Its pressure and lubrication conflicts are explained in this guide. The public listing supports the model offering; it does not independently verify unit performance or model certification.
Product scope checked 2026-10-09
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Yes, for a compatible turbodrag design and gas load. Pfeiffer reports 0.5–5 hPa for diaphragm-backed arrangements with Holweck stages, while classic rotor–stator designs need about 10⁻² hPa. Its HiPace 300 H test with an MVP 015-2 backing pump reached 2.75 × 10⁻¹¹ hPa at 3 hPa fore-vacuum; that result does not establish compatibility with a different pump. [3]
A turbopump's compression ratio grows with the gas's molecular mass, so it is much lower for hydrogen than for nitrogen. Ask for hydrogen compression and pumping speed separately. [3] [5]
Pfeiffer describes CF metal-sealed connections for below 1 × 10⁻¹² hPa, whereas its O-ring ISO-KF and ISO-K/F examples extend to 1 × 10⁻⁸ hPa. Confirm the complete system and seal selection. The guide’s 450°C CF bakeout figure applies to the connection, not to every attached pump or controller. [4]
One convention is 10⁻³ to 10⁻⁷ mbar, with ultra-high vacuum below that; the boundaries are a convention, so state your target pressure in numbers. [1]
Pfeiffer says used CF copper gaskets must be replaced. Its guide separately allows repeated use of suitable FKM seals around 1 × 10⁻⁸ hPa; that is a different seal arrangement and pressure capability, not permission to reuse a copper gasket. [4]
Sources checked 2026-10-12. Standards bodies and regulations define the requirements; manufacturer pages show published ranges for those models only. CNFX does not certify products or suppliers.
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