These are the ten questions most frequently asked during the selection stage for Depule vacuum pumps; the answers are based on datasheet parameters and actual operating-condition logic. Parameters are taken from the original factory technical specification sheets; matters involving 60Hz and customized configurations are answered according to the factory’s confirmation.
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Frequently asked questions
When selecting a vacuum pump, should I look at pumping speed first or ultimate vacuum first?
First clarify the ultimate vacuum required by the process, then calculate the pumping speed based on the gas load. The ultimate vacuum determines the pump type: for a level of 0.1 mbar, a single-stage oil-sealed rotary vane pump can be selected (V0040A to V0100 with gas ballast closed: 0.1 mbar); oil-free rotary vane pumps have a pumping speed range of 3.4 to 45 m³/h and are suitable for the rough vacuum range; if below 10⁻² mbar is required, then consider a two-stage or Roots pump set. Estimate the pumping speed as 'gas load ÷ allowable pressure rise' and then add a 20% margin.
How do I choose between an oil-free rotary vane pump and an oil-sealed rotary vane pump?
Look at the medium and the risk of contamination. For pumping water vapor, dust, easily condensable gases, or where oil mist and oil-change maintenance are unacceptable on site, choose an oil-free rotary vane pump; for clean gases and a lower ultimate vacuum requirement, choose an oil-sealed rotary vane pump, with periodic oil changes and oil mist separator element replacement. Oil-sealed pumps have a lower initial purchase cost; long-term cost depends on how well maintenance is carried out.
When should the gas ballast valve be opened?
Open the gas ballast when pumping condensable gases (water vapor, solvent vapor) to dilute the condensable gas before compression in the working chamber and reduce condensation into the oil. Taking V0040A to V0100 as an example, the ultimate vacuum with gas ballast closed is 0.1 mbar, and with it open it is 0.5 mbar—opening the gas ballast inevitably sacrifices some ultimate vacuum; this is normal. Close the gas ballast when pumping clean dry gas.
Does a Roots pump always need a backing pump?
Yes. A Roots pump is a booster pump and cannot exhaust to atmosphere on its own; it must be connected in series with a backing pump (rotary vane pump or Roots backing pump set). A common configuration is one backing pump with one Roots pump, with the pumping speed ratio controlled at 3 to 6 times; if the ratio is too high, pressure will build up and overheating will occur in the high-pressure stage. The LC series has a pumping speed of 250 to 4200 m³/h, a speed of 2900 r/min, a power of 2.2 to 11 kW, and inlet sizes from ISO63 to ISO250.
Can it be used directly in 60Hz regions?
Do not assume universal compatibility. The datasheet notes that some models are not suitable for 60Hz regions; before ordering, the motor and speed configuration of the corresponding model must be confirmed with the factory. When exporting to 60Hz markets, please state the country, voltage, and frequency in your inquiry.
How should a central vacuum system be configured?
First calculate the total flow of the points used simultaneously and the vacuum level required at each point, convert to total pumping speed according to the simultaneity factor, and then select the number of main units and the receiver tank volume. When multiple units are operated in parallel, independent backing and non-return measures are required to prevent backflow when a unit stops. Depule can provide a pump station configuration based on the list of points.
How should maintenance intervals be set?
For oil-sealed rotary vane pumps, pump oil every 500 to 2000 hours or every six months, and the oil mist separator element every 1000 to 2000 hours; oil-free rotary vane pumps have no oil, and the inlet filter should be checked monthly. For sites with heavy dust, high water vapor, or 24-hour continuous operation, follow half of the lower limit listed in the table.
How is vacuum pump evacuation time estimated?
Estimate according to t = (V / S) × ln(P0 / P1), where V is the volume (m³), S is the effective pumping speed (m³/h, which must be converted to m³/s), P0 is the starting pressure, and P1 is the target pressure. In practice, corrections must be added for pipeline flow resistance, leakage, and outgassing; rough estimates are generally optimistic, so allow an additional 1.3 to 1.5 times margin in engineering. The values can be entered directly on the site's 'Selection Calculator' page.
What information is needed for a quotation?
Six items: target vacuum level, pumping speed requirement or chamber volume, gas type (whether it contains water vapor/dust/corrosive components), continuous or intermittent operation, connection specifications and voltage/frequency, and delivery location. Inquiries with complete information can usually be given a model and price range on the same day.
How are spare parts and after-sales service arranged?
Commonly stocked parts include vanes, oil mist separator elements, inlet filters, seals, and coupling elastomers. The terms for whole-machine warranty and spare parts supply are executed according to the contract; the specific number of years and response method are confirmed at the quotation stage, and no unilateral commitments are made on this page.