Portable Inverter Rotary Screw Air Compressor for Pneumatic Tools — Spec, Sizing & Export/Quotation Guide

A portable inverter/PM‑VSD rotary screw is the “no‑three‑phase, low‑noise, continuous‑duty” alternative to a jobsite piston. It suits mobile mechanics, tire vans, small garages, woodworking, light fabrication, workshops, and sites where tools run intermittently but you still want steady pressure without piston cycling. “Portable” can mean wheeled mini‑package with a small receiver, truck‑mounted skid, or a larger diesel screw for remote blasting—this guide focuses on electric AC portable screw packages for pneumatic tools, including 220V single‑phase inverter versions.

1. What the configuration means

For pneumatic‑tool duty, screw wins over piston when runtime is long, multiple tools run together, or stable pressure/noise matters; piston still wins for very intermittent DIY, tight budget, or where only single‑tool bursts are needed .

2. Typical portable inverter screw ranges

Small electric AC, tank‑mount, air‑cooled:

*Indicative only. Always quote package FAD per ISO 1217 at working pressure; displacement overstates delivered air.

Large “portable screw” for construction/blasting is a different category: diesel, 100–900+ cfm, 7–14+ bar, tow‑behind; not covered in detail here except as “if no AC power, use diesel piston/diesel screw” .

3. Pneumatic‑tool air demand — sizing method

1. List every pneumatic tool, its required pressure (psi/bar) and consumption (cfm/Lpm at that pressure). Most general tools are sized around 90 psi/≈6.2 bar, but impacts/sanders/spray vary .

   • Impact wrench (std): ~3–6 cfm @90–120 psi

   • Heavy impact/1" drive: ~6–10+ cfm @120–150 psi

   • Ratchet/air drill: ~3–5 cfm @90 psi

   • Die/angle sander: ~6–12 cfm @90 psi

   • Orbital/DA sander: ~6–10 cfm

   • Grinder (5"–7"): ~6–12 cfm @90 psi, larger 12–20+

   • Blowgun: ~2–4 cfm

   • Tire inflator/manifold: intermittent 1–3 cfm; bead seat peak much higher

   • Nailer/staple: low average, bursty

   • HVLP spot repair: 6–12+ cfm at regulated spray pressure; compressor main should be 7–10 bar with dry/clean treatment

   • Full spray booth: often multiple guns → usually beyond small portable screw

2. Sum tools used simultaneously; apply simultaneity 0.6–0.9 by crew size.

3. Add margin: many buyer guides add 25–30% for leaks/growth; some portable guides use up to 50% safety margin for mixed tool use . For variable VSD screw, 10–25% is often enough because VSD trims part‑load; for piston replacement, 25–30% is safer.

4. Set compressor pressure = tool pressure + dryer/filter/pipe loss. For 90 psi tools, a 7–8 bar screw is usually enough; for 120–150 psi heavy impact/some blast prep, choose 10–12.5 bar.

5. Pick FAD, not HP. Example: two mid impacts 2×5 cfm + DA sander 9 cfm + blowgun 3 cfm = 22 cfm peak; simultaneity 0.8 → 17.6 cfm + 20% → ~21 cfm. A 3.7 kW single‑phase VSD screw (~21–23 cfm @8–10 bar depending model) or 5.5 kW 3‑phase screw fits; a 2.2 kW mini will not .

6. Tank buffers bursts; it does not increase FAD. Portable mini screw 70–130 L is fine for tool bursts; if tool demand exceeds screw FAD continuously, upsize power or go 3‑phase.

4. Inverter/VSD benefits for tool duty

• Stable pressure​ — VSD holds a set band (e.g., 6.5–8.0 bar) so impact torque and sander speed stay consistent; piston cut‑in/cut‑out swings more .

• Soft start on 220V​ — inverter ramps current, avoids DOL inrush that can trip small workshop/single‑phase breakers .

• Part‑load saving​ — tool shops are rarely flat‑out all day; VSD reduces motor speed at idle/light load. Variable demand is exactly where VSD pays back versus fixed screw/piston .

• Quieter​ — enclosed portable VSD screw packages commonly 60–68 dB(A) for small units; pistons are often 75–85+ dB(A) . Good for indoor workshops, vans, occupied sites.

• Continuous duty​ — screw runs 100% duty; piston portable units are often 50–75% duty and need cool‑down on heavy use .

5. Single‑phase 220V vs three‑phase vs gas/diesel

Portable electric screw options:

• 220/230V single‑phase VSD: best where no 3‑phase. Small/very quiet units from 2.2 kW up; 3.7 kW single‑phase VSD examples include 130 L tank, 470 LPM @10 bar, 12.8 A full load, 68 dB(A) ; other 3.7 kW single‑phase screws quote 21 cfm @8 bar / 23 cfm @10 bar with 250 L option . 5.5 kW single‑phase is possible but current is high—confirm panel/cable; many suppliers offer 2.2–7.5 kW single‑phase screw .

• 380/400/415V three‑phase: preferred for 5.5–11 kW+ portable screw, lower current, better for busy garages/fabrication/multiple sanders.

• 120/240V split single‑phase: 120V portable electric is only for very small CFM (≈up to 6 cfm guides); 240V dedicated 20–30A supports bigger single‑phase tools/compressors .

• Gasoline/diesel portable: use when no grid power on site. Gasoline piston up to ~30 cfm portable; diesel screw 100–900+ cfm for remote blasting/pipeline/road . Inverter electric screw is not a substitute for high‑cfm off‑grid blasting.

Single‑phase current planning (inverter PF/efficiency dependent; not a substitute for nameplate):

• 2.2 kW ≈ 10–14 A at 220V simple estimate; a 2.2 kW VSD product may differ

• 3.7 kW ≈ 12–18 A; one 220V VSD 3.7 kW unit is published at 12.8 A full load

• 5.5 kW ≈ 25–35 A estimate; verify inverter input and starting method

• 7.5 kW single‑phase ≈ 35–50+ A; often better as 3‑phase

Always request full‑load amps, max inrush/soft‑start curve, breaker size, cable size by run length, and voltage tolerance.

6. Portable package components

Even a mini portable inverter screw contains:

• Screw air‑end: oil‑injected twin rotor (common), direct or belt; oil‑free scroll/screw if clean‑air tools required.

• Motor: IE3/IE4 AC or PM synchronous; PM VSD common in small portable screw for efficiency .

• Inverter/VSD: compressor‑rated vector drive, pressure PID, ramp/soft start, fault logging.

• Receiver: 70–200 L for mini/mobile; 30 gal (≈114 L) in some portable VSD shop units; larger skids for diesel .

• Cooling: air‑cooled aftercooler + oil cooler, fan; ambient rating commonly up to 40–45 °C (confirm).

• Oil system (lubricated): separator, oil filter, thermostat, drain; 3‑stage separation can be quoted at low ppm for screw packages .

• Controls: touch/LED controller, pressure setpoint, maintenance timer, alarms (overtemp/overpress/filter/sep differential), IoT optional.

• Mobility: casters/handle for shop units; skid/frame/anti‑vibration mounts for van/truck; weather enclosure for outdoor.

• Options: built‑in refrigerant dryer, coalescing/particulate/carbon filters, automatic drains, hose reel, multiple outlets.

7. Air quality for pneumatic tools

Not all tools need the same air:

• General impact/ratch/blow/tire: aftercooler + moisture separator + basic coalescing/particulate filter. Refrigerated dryer recommended in humid shops .

• Sanding/finishing/light spray: refrigerated dryer (~+3 °C PDP) + 1 µm coalescing + 0.01 µm option + particulate after dryer. For quality paint, desiccant and/or oil‑free upstream may be required .

• Food/pharma/electronics/medical‑support: oil‑free air‑end + desiccant dryer + validated ISO 8573‑1 Class 0/low particulate/low dew point; portable oil‑injected screw alone is not enough .

• Dirty sites/blast: aftercooler, moisture separator, heavy‑duty intake pre‑filter; diesel screw with proper filtration.

ISO 8573‑1 example classes:

• General tools: 1.4.2 or 1.4.1 (solid/water/oil)

• Clean workshop/spray prep: 1.2.1 or 1.1.1 depending paint OEM

• Desiccant/dry instrument: 1.2.0 or lower dew point class

Request oil carryover data (separator outlet ppm and point‑of‑use after filters), dryer PDP at rated FAD/pressure, and filter micron/grade.

8. Example configurations

A. 2.2 kW portable PM VSD, 220V, 70–90 L — solo mobile mechanic​

~240–350 L/min @7–8 bar (model‑dependent), 8–10 bar option, direct‑drive PM, touch controller, wheels. One impact + tire fill + blowgun; not for continuous sander/spray. Quiet, plug‑and‑go .

B. 3.7 kW portable VSD, 220V single‑phase, 130 L — tire shop/small garage​

~360 L/min @8 bar in one PM line, 470 LPM @10 bar in a published 220V VSD unit, 12.8 A, 68 dB(A); alternatively 21 cfm @8 bar / 23 cfm @10 bar with 250 L option . Two impacts alternately, balancer, light sander; add refrigerant dryer for humid sites.

C. 5.5 kW portable VSD, 3‑phase or 220V inverter, 120–200 L — 2–3 bays​

Use 3‑phase if available; single‑phase only if panel amps permit. Covers multiple impacts + one sander + blowguns; spray spot‑repair only with dryer/fine filters. Supplier single‑phase screw tables list 5.5 kW variants with different FAD by pressure—confirm ISO 1217 .

D. 7.5–10 hp portable VSD, 230V single‑phase or 3‑phase, 30 gal/larger — busy shop​

Published 7.5 hp VSD portable ~33 cfm @120 psi with 30‑gal tank/casters; 10 hp VSD ~38–39 cfm @116–120 psi . Multiple sanders/spray/impact rotations; single‑phase 230V needs dedicated heavy circuit, 3‑phase preferred for 10 hp.

E. Off‑grid/site portable — gasoline piston or diesel screw​

Piston gasoline up to ~30 cfm for light tools; diesel screw 100+ cfm for jackhammers/blast/continuous crew air . Inverter electric mini screw is not for remote high‑CFM.

9. Maintenance (portable oil‑injected VSD screw)

• Compressor oil: standard 2000–4000 h; synthetic/extended longer; first fill earlier. Portable/vans with short hours still age oil by moisture/time—follow OEM.

• Oil separator: 4000–8000 h or differential alarm; affects oil carryover and pressure drop .

• Oil filter: with oil change or 2000–4000 h.

• Intake filter: dusty sites/jobsites inspect monthly, replace 1000–2000 h; dirty intake cuts FAD.

• Receiver drain: auto preferred on portable units; manual daily if humid.

• VSD cabinet: keep out of dust/overspray/rain; check fan/filter, log faults.

• Wheels/casters/hoses: check before moving; drain condensate from tank and dryers.

• Service access: integrated mini screws save space but confirm filter/separator/cooler access before install on a van/skid.

10. RFQ / factory spec sheet — portable inverter screw for pneumatic tools

Request in writing:

1. Air‑end: oil‑injected/single/twin, direct/belt, rotor profile, rated duty, oil spec.

2. Motor/drive: kW/hp, PM/IE3/IE4, 220V 1‑ph / 380–415V 3‑ph, 50/60 Hz, IP grade, insulation, VSD brand/turndown (e.g., 25–100%).

3. FAD: ISO 1217 at 7/8/10/12.5 bar; displacement separately; specific power kWh/m³.

4. Pressure setpoint range, control band, soft‑start/ramp, remote/Modbus/IoT.

5. Tank: volume, steel code PED/ASME/local, coating, relief, auto/manual drain, portable frame/wheels/weight.

6. Electrical: full‑load amps, starting current, breaker/cable recommendation, voltage tolerance, EMC, phase‑loss protection.

7. Cooling: air‑cooled fan power, ambient range, aftercooler outlet rise, oil/air cooler.

8. Dryer/filter options: refrigerant/desiccant PDP, micron grades, carbon, ISO 8573‑1 class achievable.

9. Noise: dB(A) at 1 m loaded per ISO 3744/2151.

10. Outlets/fittings: G3/4/DN/1/2″, number of tool connections, hose kit.

11. Mobility/enclosure: casters/handle/skid/truck‑mount, IP for outdoor, vibration isolation.

12. Certificates: CE/ISO 9001, tank pressure code, motor efficiency, electrical compliance, optional ATEX for solvent areas.

13. Commercial: EXW/FOB/CIF, MOQ, lead time, OEM logo/manuals (EN/ES/FR/AR), warranty (whole/VSD/air‑end separate), spares (oil, separator, filters, drain, sensors).

11. Sample English listing copy

Portable Inverter Rotary Screw Air Compressor for Pneumatic Tools​

Compact oil‑injected screw package with PM VSD/inverter drive, designed for mobile mechanics, tire shops, workshops, woodworking and light industrial tool air. Available 2.2–7.5 kW in 220V single‑phase or 380–415V three‑phase, 7–12.5 bar, with 70–200 L wheeled receiver or skid/truck mount. Inverter control gives soft start, stable pressure band and automatic load matching for impact wrenches, ratchets, sanders, grinders, drills, blowguns and tire equipment. Direct‑drive screw air‑end, IE3/IE4 or permanent‑magnet motor, air‑cooled aftercooler, automatic tank drain and optional built‑in refrigerant dryer plus coalescing/particulate/carbon filters.

Specifications (example 3.7 kW class): 220V 1‑ph • 3.7 kW/5 hp • 7–10 bar • FAD approx. 360 L/min @8 bar / 470 LPM @10 bar depending model (confirm ISO 1217) • 90–130 L receiver • PM VSD soft start • full‑load current approx. 12.8 A for selected 220V unit • air‑cooled • 60–68 dB(A) enclosed • G3/4 outlet • optional dryer/filters to ISO 8573‑1 • CE/ISO/PED options, OEM voltage/tank/mobility customizable.

Replace FAD, amps, tank, noise and dryer PDP with tested package data; for 5.5–7.5 kW single‑phase, publish verified full‑load current and starting method, not only kW.

12. Common mistakes to avoid

• Sizing by HP or tank gallons instead of tool CFM at working pressure; a big tank cannot fix low screw FAD .

• Calling a portable oil‑injected screw “paint‑ready” or “food/medical” without dryer/filters and, where needed, oil‑free air‑end + ISO 8573‑1 report .

• Specifying 220V single‑phase 5.5–7.5 kW without checking panel amps/cable; if service is marginal, quote 3‑phase or smaller VSD .

• Using a mini 2.2 kW screw for continuous sanding/spray multiple bays; upsize or use 3‑phase.

• Assuming “portable” means hand‑carry; many portable screws are 150–400+ kg with tank/VSD—confirm weight, wheels, van/trailer handling .

• Skipping aftercooler/dryer on humid sites; pneumatic tools clog/rust and paint fails from moisture/oil aerosol .

• Running piston in 8–24 h continuous tool duty; screw/VSD is usually better despite higher upfront .

If you give me tool list with cfm/psi, simultaneous bays, daily hours, site power (220V single‑phase amps available vs 380–415V three‑phase), required pressure, and whether air touches paint/food/medical, I can return one fixed BOM: 2.2/3.7/5.5/7.5 kW, tank size, VSD turndown, dryer PDP, filter grades, estimated current and running cost.