5.5 kW / 7.5 HP 3‑in‑1 Tank‑Mounted Screw Air Compressor, 200 L, Air‑Cooled, AC Powered — Spec, Sizing & Export Guide

A 5.5 kW (7.5 hp) integrated screw package with a 200 L receiver is a small fixed‑speed or optional VSD industrial unit for workshops, garages, woodworking, textiles, packaging, pneumatic tools, small automation and light process air. “3‑in‑1” usually means the screw air‑end, electric motor and air tank are combined in one cabinet; many suppliers also include an integrated refrigerated dryer as the third element. Confirm the exact “3‑in‑1” definition before quoting, because it changes price, footprint and air‑quality scope.

1. Positioning and likely configuration

Important: if the buyer needs oil‑free air, a standard 5.5 kW oil‑injected screw is not suitable. Use oil‑free scroll, water/dry oil‑free screw or diaphragm/piston with proper dryer/filtration.

2. Realistic FAD vs pressure

Fixed‑speed oil‑injected screw, 5.5 kW class:

These are package FAD estimates, not displacement. Always request ISO 1217 Annex C FAD at the proposed working pressure, inlet 20 °C/1 bar a/0% RH. If the unit is VSD, FAD scales with speed; at 50% speed a 5.5 kW nameplate may deliver roughly 50% flow but not 50% power because fixed losses remain.

A 200 L tank does not increase FAD—it only buffers peak demand and reduces motor start/stop cycling.

3. “3‑in‑1” variants to confirm

A. Host + motor + tank only​

Smallest footprint, lowest cost. Buyer must add external dryer/filters if clean/dry air is needed. Suitable for general pneumatic tools, inflation, blowing, light automation.

B. Host + motor + tank + refrigerated dryer​

Most common “all‑in‑one” small screw. Dryer gives roughly +3 °C pressure dew point, good for workshops, packaging, woodworking, garages. Add line filters separately.

C. Host + motor + tank + dryer + filters​

Ready clean‑air package. Specify coalescing, particulate, optional carbon. Still oil‑bearing downstream unless oil‑free air‑end is used; for food/pharma/lab define ISO 8573‑1 classes.

D. Host + motor + tank + VSD controller​

Intelligent version: inverter, pressure setpoint, soft start, energy reporting. “AC powered” does not imply VSD; if the inquiry wants variable speed, state VSD/PM VSD separately.

4. 200 L tank — how much buffer?

Rule of thumb for stored free air:

• Gauge pressure 8 bar, 200 L tank. Marketing “storage equivalent” ≈ 200 L × 8 ≈ 1,600 L free air if ignoring thermodynamics; actual usable energy recovery is less because you cannot drain to zero and temperature changes during charge/discharge.

• Practical usable buffer between 6 and 8 bar: 200 L × (8−6) ≈ 400 L simple gauge estimate, again before thermal and pressure‑switch losses; useful only for short peaks.

• For steady tool demand near the compressor’s FAD, the 200 L tank mainly smooths pulsation and short peaks; it will not compensate for an undersized air‑end.

Sizing example:

• If total tool demand at 7 bar = 0.6 m³/min and compressor FAD = 0.75 m³/min, 200 L is adequate for moderate peaks.

• If demand frequently exceeds 0.75–0.80 m³/min at 8 bar, either upsize to 7.5–11 kW screw or add a second unit; a bigger tank only delays starvation.

5. Air‑cooled design requirements

For a 5.5 kW air‑cooled screw:

• Ambient operating range commonly 0–45 °C; ideal 5–40 °C. High ambient reduces FAD and shortens oil life.

• Install in ventilated plant room; exhaust air must not recirculate into the intake.

• Aftercooler should reduce discharge air toward ambient +10–15 °C before the tank/dryer.

• Fan power is part of total package power; confirm total input kW, not only motor nameplate.

• Dusty environments: uprate intake filter, add pre‑filter, plan shorter service intervals.

• Altitude correction: above ~1000 m, derate FAD/cooling; request altitude rating.

6. AC electrical specification

5.5 kW screw, 3‑phase AC:

*Based on input 5.5–6.2 kW, PF 0.85, motor efficiency 0.9. Confirm nameplate.

Requirements:

• Dedicated branch circuit, proper breaker and overload; DOL start inrush 5–7× FLA; star‑delta or soft starter reduces inrush; VSD gives lowest starting current.

• Cable sized for continuous current, ambient and conduit; typical 4–6 mm² copper at 380–415 V for short runs, larger for long runs—verify local code.

• Grounding, EMC filtering if VSD, motor protection IP55/IP54, insulation class F or H.

• Generator use: DOL 5.5 kW may need 20–30 kVA transient capacity; VSD/soft‑start can lower required generator kVA but VFD harmonics and voltage stability must be checked.

7. Screw system components and service

Even an integrated 3‑in‑1 unit contains the same core screw subsystems:

• Air‑end: male/female rotors, oil injection for sealing/cooling, shaft seal, bearings.

• Motor: IE3/IE4 AC, direct or coupling/belt.

• Oil system: oil separator tank, separator element, oil filter, thermostat/valve, cooler, sight glass.

• Air system: intake filter, minimum pressure valve, safety relief, aftercooler, tank, drain.

• Control: pressure switch/controller/PLC, sensors, unloader, VSD if fitted.

• Optional dryer/filters if 3‑in‑1 extended.

Maintenance intervals (typical oil‑injected screw, confirm OEM):

• Oil: 2000–4000 h standard, 1000–2000 h first fill, longer for synthetic/extended‑life oils.

• Oil separator: 4000–8000 h or pressure differential alarm.

• Oil filter: 2000–4000 h.

• Intake filter: inspect 500–1000 h, replace 1000–2000 h in dusty sites.

• Drains: automatic or manual; check weekly.

• Belts/coupling: belt tension every 500–1000 h if belt‑drive; coupling inspection per schedule.

• Integrated units need enough panel clearance—ask for service access dimensions before purchase.

8. Air quality and dryer/filter train

Standard oil‑injected 5.5 kW screw output contains oil aerosol, water vapor and particles. Define the train:

1. Aftercooler → moisture separator with drain.

2. Refrigerated dryer: +3 °C pressure dew point, suitable for workshops, packaging, wood, garages, general plant.

3. Desiccant dryer: −20 to −40 °C or lower for paints, labs, pharma, food, electronics.

4. Filtration:

   • Coalescing 1 µm/0.1 mg/m³ oil for general clean air

   • 0.01 µm/0.01 mg/m³ for sensitive paint/lab/food

   • Particulate after dryer

   • Activated carbon if odor/oil vapor must be removed

5. Purity class: specify ISO 8573‑1 solid/water/oil classes, e.g., Class 1.4.1 or 1.2.1 for cleaner plant air; Class 0 only if oil‑free air‑end plus validated train.

If the listing says “3‑in‑1 with dryer,” confirm dryer capacity at 5.5 kW FAD and working pressure; an undersized integrated dryer will raise dew point under summer load.

9. Application sizing worksheet

1. List all tools/devices with consumption at working pressure (m³/min or cfm at bar/psi).

   • Small impact wrench: ~0.1–0.3 m³/min

   • Angle grinder/sander: ~0.2–0.6 m³/min depending size

   • HVLP spray gun: ~0.2–0.6 m³/min at regulated low pressure, but compressor must supply dried oil‑free‑grade air if paint quality matters

   • Packaging/pneumatic cylinders: intermittent, low average CFM

   • Plasma/laser/automation: define by equipment maker

2. Use compressor FAD at working pressure, not displacement.

3. Apply simultaneity: single‑user garage 0.7–0.9; multi‑worker plant 0.6–0.8; continuous automation 0.9–1.0.

4. Add 10–15% margin for filters/dryer drop and leaks.

5. 5.5 kW/200 L screw is generally good for total average demand ~0.5–0.7 m³/min at 7–8 bar with occasional peaks; if sustained demand >0.8 m³/min at 8 bar, consider 7.5–11 kW or twin units.

6. If dry air is required, include dryer performance at site ambient and pressure.

10. Factory/RFQ checklist

Request in writing:

1. Air‑end type: oil‑injected screw, fixed or VSD; direct/belt; rotor profile/service interval.

2. FAD at 7/8/10/13 bar per ISO 1217; package input power; specific power kWh/m³.

3. Motor: 5.5 kW, IE3/IE4 certificate, voltage/frequency, IP, insulation, starting method.

4. 3‑in‑1 scope: host+motor+tank only, or with dryer/filters; dryer type, PDP, capacity.

5. Tank: 200 L material, code PED/ASME/local, coating, relief valve, auto/manual drain.

6. Cooling: air‑cooled fan power, ambient range, aftercooler outlet temp, oil cooler specs.

7. Controls: pressure switch/PLC, remote/modbus, VSD option, alarms, maintenance timer.

8. Filters: grades supplied, replacement hours, oil‑separator specs.

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

10. Certificates: CE, ISO 9001, PED/ASME, motor IE, electrical compliance, optional ATEX if explosive area.

11. Commercial: EXW/FOB/CIF, MOQ, lead time, OEM logo, manuals, warranty, spares (separator, oil, filters, valve kit).

11. Sample English listing copy

5.5 kW / 7.5 HP 3‑in‑1 Tank‑Mounted Screw Air Compressor, 200 L, Air‑Cooled, AC​

Integrated rotary screw package combining screw air‑end, AC motor and 200 L receiver in one cabinet; optional all‑in‑one version adds built‑in refrigerated dryer and line filters. Designed for workshops, auto repair, woodworking, packaging, textiles and light industrial pneumatic systems. Direct‑coupled 5.5 kW IE3/IE4 motor delivers stable 7–8 bar air with low vibration and automatic load/unload control; air‑cooled aftercooler, oil separation and automatic drain support continuous duty.

Specifications: 5.5 kW / 7.5 hp • 200 L receiver • 7/8 bar standard, 10/13 bar optional • FAD 0.60–0.85 m³/min at 7–8 bar (confirm ISO 1217) • 380–440 V 3‑phase 50/60 Hz • air‑cooled • IP55 motor • optional VSD, dryer and filters • auto start/stop, overload and overtemp protection • CE/ISO/PED options, OEM voltage and tank code customizable.

Replace FAD, noise and dryer PDP with tested package data; if the client needs oil‑free, do not quote this oil‑injected screw without an external oil‑free air‑end and certified treatment.

12. Common mistakes to avoid

• Calling it “oil‑free” because it is a screw — standard 5.5 kW tank‑mount screw is oil‑injected unless explicitly oil‑free.

• Quoting displacement instead of FAD at working pressure.

• Assuming “3‑in‑1” always includes dryer — some suppliers mean only host+motor+tank.

• Undersizing ventilation for air‑cooled units in small rooms; high ambient reduces output and oil life.

• Using 200 L tank to compensate for insufficient kW; tank only buffers, it does not create flow.

• Single‑phase 5.5 kW — impractical for most sites; use 3‑phase AC or downsize to piston if only single‑phase is available.

• Ignoring separator/filter service — integrated units can be cheap to buy but costly if service access is poor.

If you tell me the target pressure, duty hours, altitude/ambient, voltage, whether “3‑in‑1” must include dryer, and the main tools or process, I can fix one BOM: fixed‑speed vs VSD, 200 vs 300 L tank, dryer PDP, filter grades and estimated running cost per kWh.