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Sizing guide and report.
Size compressors, vacuum pumps, transformers and machine guarding from your own numbers, then keep every result in one report you can print or send for approval.
How to size it, in four steps
- Start from what the process needs, not the old nameplate. Measured air demand and pressure, the vacuum level and what is in the gas, the motor brake horsepower, the machine stopping time.
- Run the matching tool below. Each one shows the working, so you can check it or hand it to your electrician or engineer.
- Pick the size it points to. Results link straight to the matching product with its list price, or to a quote when it has to be built to your site.
- Save each result to your report. It stays in this browser, so you can come back, add to it, print it or send it to your manager for sign off.
Sizing tools
Sizing questions, answered
What size air compressor do I need?
Size the compressor to your measured peak demand in cfm at the lowest pressure your equipment needs, not to the old machine's nameplate. A rotary screw compressor delivers about 4 to 4.5 cfm per horsepower at 100 psig, so a 200 cfm peak needs about 50 hp. Each 2 psi of extra pressure costs about 1% more energy. The compressor room planner sizes the compressors, dryer and tanks and links to matching models.
How do I choose the right vacuum pump?
The vacuum level you need and what is in the gas choose the technology. Oil sealed rotary vane pumps suit clean, dry air to about 0.1 mbar; dry claw pumps suit oil free work to about 100 mbar; liquid ring pumps handle wet loads and liquid carryover; rotary piston and dry screw pumps reach deep vacuum for drying and furnaces. The vacuum selector ranks them for your process.
How long will a vacuum pump take to pump down a tank?
Pump down time is t = V / S × ln(P1 / P2), where V is the tank volume, S the effective pumping speed and P1 and P2 the start and end pressures. Add about 25% below 10 mbar and 50% below 1 mbar for leaks and outgassing, and pick a pump whose ultimate pressure is ten times lower than your target.
What size transformer do I need to run 480 V equipment on a 600 V plant?
Multiply 1.732 × the equipment voltage × its full load amps and divide by 1000 to get kVA, add about 25% for motor starting, then pick the next standard size up. A 51 A machine at 460 V needs 40.6 kVA, or 50.8 kVA with starting allowance, so a 75 kVA transformer. The electrical sizing tools do the maths and link to matching transformers.
Do I need a drive isolation transformer for a variable speed drive?
Use a drive isolation transformer when a variable speed drive needs a voltage change or isolation from the plant supply. It is built for the harmonic current and DC offset a drive draws, which a standard transformer is not. Size it from the motor brake horsepower.
How are freight and installation handled on large equipment?
Compressors, vacuum pumps, blowers and transformers ship by freight, quoted to your site after you order. Rigging, electrical connection by a licensed electrician and start-up are quoted separately, so every price you see is the equipment list price before tax. Orders over $10,000 are paid on invoice.
Your sizing report
Results you saved from the tools, with the matching products. Print it, save it as a PDF, or send it to your manager.
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Sizing methods on this page are developed and checked by a licensed professional engineer in Ontario. Results are planning numbers; we confirm every size against your site before anything is ordered.