EP-CM90G Water-Lubricated Oil-Free Screw Air Compressor for PET Bottle Blowing

EP-CM90G Water-Lubricated Oil-Free Screw Air Compressor for PET Bottle Blowing

The EP-CM90G is a 90 kW single-screw water-lubricated oil-free compressor delivering 8.2 m³/min (290 cfm) at up to 4.0 MPa (40 bar) — a high-capacity fixed-frequency solution engineered for large-scale PET bottle blowing lines requiring continuous, contamination-free compressed air with ISO 8573-1 Class 0 certification and over 25 years of design service life.

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EP-CM90G | 90 kW High-Capacity Water-Lubricated Oil-Free Compressor — 8.2 m³/min at 40 Bar

As PET bottle production lines scale toward higher cavitation counts and faster cycle speeds, the demand placed on compressed air systems grows in proportion. A high-speed rotary blowing machine producing 30,000–50,000 bottles per hour at 40 bar requires a compressor that can deliver consistent high-volume output without interruption, without oil contamination, and without the maintenance complexity that forces unplanned production halts. The EP-CM90G addresses this at the 90 kW power class.

Delivering 8.2 m³/min (290 cfm) of ISO 8573-1 Class 0 certified oil-free compressed air at pressures continuously adjustable between 2.0 and 4.0 MPa, the EP-CM90G is the largest single-motor fixed-frequency model in the CMG water-lubricated series — and the most productive single-unit option for facilities seeking maximum output simplicity without variable-speed complexity. Its single-screw compression geometry operates at approximately 3,000 rpm, roughly half the rotational speed of twin-screw designs, generating structurally lower bearing loads, reduced mechanical wear, and a design service life exceeding 25 years of continuous 7×24 operation.

For plant engineers evaluating compressed air infrastructure for new or expanded PET bottling lines, the EP-CM90G offers a straightforward value proposition: the highest single-motor water-lubricated output in the CMG fixed-frequency range, delivered with the inherent reliability of a design that contains no oil, no multi-stage intercoolers, and no valve assemblies that require periodic replacement. Browse the complete CMG series to compare all available configurations for your specific flow and pressure requirements.

EP-CM90G 90kW water-lubricated oil-free screw compressor high capacity PET bottle blowing 40 bar

Technical Specifications

Parameter Specification
Model EP-CM90G
Drive Type Fixed frequency (direct drive)
Motor Power 90 kW / 123 HP
Working Pressure 2.0 – 4.0 MPa (290 – 580 psi / up to 40 bar)
Free Air Delivery (FAD) 8.2 m³/min  |  290 cfm
Noise Level 72 dB(A)
Weight 2580 kg
Dimensions (L×W×H) 3000 × 1350 × 1540 mm
Compression Stage Single stage — single screw + star wheel
Lubrication Medium Pure water — zero oil in system
Compression Chamber Temp. Ambient + 15°C (≤ 45°C typical)
Air Quality ISO 8573-1 Class 0 (Oil: 0 ppm)
Certifications TUV (Germany) / ISO 9001 / ISO 14001
Design Service Life >25 years / 7×24 h continuous operation

Isothermal Compression: The Physics Behind Superior Efficiency

Conventional air compression is an adiabatic process — heat generated during compression is retained in the gas, raising its temperature dramatically and increasing the energy required to compress it further. At 40 bar, a dry oil-free screw compressor's compression chamber may reach 180–200°C, requiring significant intercooling infrastructure and accepting unavoidable thermodynamic losses at each stage boundary.

The EP-CM90G operates on a fundamentally different thermodynamic principle. Water injected continuously into the compression chamber absorbs compression heat at the instant it is generated — not after the fact through intercoolers — maintaining the chamber temperature within 15°C of ambient throughout the compression cycle. This near-isothermal process is thermodynamically closer to the theoretical minimum work required to compress a given volume of gas from atmospheric to 40 bar pressure. The practical result is energy consumption that is measurably lower than dry compression alternatives at equivalent output, with no multi-stage intercooler hardware to maintain.

Isothermal compression water lubrication internal circulation 40 bar oil-free PET compressor

Single-Screw Compression at 90 kW: Structural Reliability Advantages

Single screw compression technology 90kW star wheel balanced force zero net load

The single-screw compression geometry positions two star wheels symmetrically on opposite sides of the main screw. The radial forces each star wheel exerts on the screw are equal, opposite, and cancel each other — creating a theoretically balanced force condition with near-zero net radial load on the screw shaft. This balanced loading is the structural reason why the EP-CM90G's air end can operate for over 25 years without the bearing fatigue failures that limit the service life of twin-screw designs at equivalent pressure ratios.

Zero Net Screw Load

Symmetrical star wheel placement means axial and radial forces cancel, eliminating the net load on the main screw shaft that causes bearing fatigue in twin-screw designs. At 90 kW and 40 bar — conditions that would rapidly degrade conventional bearings — the EP-CM90G's air end maintains structural integrity throughout a 25-year service life.

Low Rotational Speed: ~3,000 rpm

Operating at approximately 3,000 rpm — compared to 6,000–25,000 rpm in dry oil-free twin-screw designs — the EP-CM90G's air end accumulates bearing cycles at a fraction of the rate of high-speed alternatives. This directly translates to extended service intervals, reduced mechanical wear, and lower vibration levels throughout the service life.

Aviation-Grade Star Wheel Material

Star wheel blades in the EP-CM90G are manufactured from confidential aviation-grade composite materials that fundamentally solve the wear challenge at the screw-star wheel interface. Every star wheel undergoes strict screening and testing before installation. The result is a compression element designed for multi-year continuous operation without replacement.

Patented No-Shaft-Sealing Design

Conventional screw compressors require shaft seals between the compression chamber and the motor side — a wear item that requires periodic replacement and is a common leak point. The EP-CM90G's patented no-shaft-sealing design eliminates this component entirely, removing both the maintenance task and the contamination risk associated with seal degradation.

Water-Cooled System Configuration

Water-cooled oil-free compressor flow chart system configuration PET blowing line 90kW

The EP-CM90G water-cooled configuration connects to a facility cooling water circuit or cooling tower. Cooling water enters the plate heat exchanger, removes compression heat from the lubricating water circuit, and returns to the cooling tower at temperatures below 55°C. The compressed air then passes through the water-and-air separation barrel, a refrigerated dryer, and downstream filters before reaching the blow molding machine at the required pressure and dew point.

High-Volume PET Application Reference

Blowing Line Type Cavities Output (BPH) Pressure Required EP-CM90G Coverage
Rotary (standard water bottles) 12 ~28,000 32–35 bar ✅ Single unit
Rotary (CSD bottles) 10 ~22,000 38–40 bar ✅ Single unit
Linear (edible oil, 5L) 4 ~4,000 35–38 bar ✅ Supports 2–3 lines
ISBM (injection stretch blow) 6–8 ~10,000 30–35 bar ✅ Single unit

ISBM stretch blow molding machine PET bottle output high volume production line

Maintenance: What the EP-CM90G Eliminates

Maintenance Item Piston Compressor EP-CM90G
Lubricating oil change Every 500–2,000 hours Never — no oil in system
Oil filter replacement Every 500–1,000 hours Not applicable
Piston ring replacement Every 4,000–8,000 hours Not applicable
Valve assembly service Every 2,000–4,000 hours Not applicable
Air filter replacement Per manufacturer schedule Per manufacturer schedule
Water filter replacement Not applicable Per manufacturer schedule

Manufacturing & Quality Assurance

The EP-CM90G is manufactured in Ever Power's 68,000 m² production facility operating under ISO 9001 and ISO 14001 certification. Each unit passes through pre-shipment testing that includes full-load performance measurement across the 2.0–4.0 MPa pressure range, acoustic measurement at rated load, and comprehensive leak testing of all water-circuit connections and compressed air pathways. TUV (Germany) certification documentation for ISO 8573-1 Class 0 is available for all units and can be supplied with delivery for quality system compliance purposes.

Ever Power oil-free compressor manufacturing facility quality control 90kW unit

Customer Case Studies

United States — Large-Format Beverage Bottler

Industry: Beverage  |  Application: 40 bar air for 12-cavity rotary PET blowing line producing 28,000 bottles/hour

"We evaluated three compressor technologies before selecting the EP-CM90G. The single-stage 40 bar capability was the deciding factor — our previous system required a primary screw compressor plus a high-pressure booster, two machines to maintain instead of one. Since installation, our compressed air system uptime has been 99.94%. The 8.2 m³/min output has headroom above our blowing line requirement, which provides a safety margin during production peaks."

★★★★★

Indonesia — Edible Oil Packaging Producer

Industry: Food Packaging  |  Application: 35 bar oil-free air for PET cooking oil bottle blowing — 3 linear lines simultaneously

"Our three bottle-blowing lines run 20 hours per day, six days per week. The EP-CM90G supplies all three simultaneously with stable pressure. The isothermal compression technology keeps our compressed air dry — we had persistent moisture problems with our previous piston units that caused rust inside our PET molds. Since switching to water lubrication technology, mold rust is no longer a production issue and our mold replacement frequency has dropped significantly."

★★★★★

United Kingdom — Contract Blow Molding Specialist

Industry: Contract Packaging  |  Application: 30–40 bar adjustable pressure for multi-client PET bottle production across 5 product categories

"As a contract blow molder, we run different bottle specifications for different clients — pressures vary from 30 to 40 bar depending on bottle geometry. The EP-CM90G's full pressure range adjustability means one machine covers all our client requirements. The Class 0 TUV certification satisfies every client's quality audit requirement without exception, including our pharmaceutical and food-grade packaging contracts."

★★★★★

Frequently Asked Questions

Why is 8.2 m³/min at 40 bar significant for PET bottle blowing?
At 8.2 m³/min (290 cfm) and 40 bar, the EP-CM90G serves high-speed rotary blowing lines producing tens of thousands of bottles per hour. Most medium-to-large rotary blow molding machines with 10–12 cavities operate within this flow range at full production speed. The fixed-frequency design ensures maximum output stability — critical at high production speeds where pressure fluctuations cause bottle wall thickness variations and mold damage.
What is isothermal compression and why does it save energy?
Isothermal compression means the process occurs at near-constant temperature. Water injected into the compression chamber continuously absorbs heat as air is compressed, keeping temperature within 15°C of ambient rather than the 150–200°C of dry compression. Because the energy required to compress a gas increases with temperature, this isothermal effect reduces power consumption by 10% or more versus adiabatic alternatives at equivalent pressure and flow — with no intercooler infrastructure required.
How many PET blow molding machines can the EP-CM90G support?
At 40 bar and 8.2 m³/min, the EP-CM90G can typically support one large-format rotary blowing machine (10–12 cavities at high speed) or two to three smaller linear blowing machines simultaneously. Exact sizing depends on machine type, cavity count, bottle volume, and production speed. Ever Power's engineering team can perform precise system sizing calculations based on your specific machine specifications and production schedule.
Does the EP-CM90G require a dedicated compressor room?
The EP-CM90G operates at 72 dB(A) — significantly quieter than equivalent piston compressors at the same capacity and pressure. A ventilated equipment room is recommended for optimal cooling and dust exclusion, but specialist acoustic construction is not required. The 3000×1350×1540 mm footprint fits within standard industrial equipment room dimensions.
What is the maintenance cost difference vs a piston compressor?
The EP-CM90G contains no oil, no oil filters, no oil separators, no piston rings, and no valve assemblies. Daily consumables are limited to air filter and water filter elements. Star wheel blades require replacement only at multi-year intervals. Maintenance cost per 1,000 operating hours is typically 60–80% lower than equivalent piston installations, while maintenance downtime is reduced proportionally.

Scale Your PET Line with Proven 90 kW Reliability

Beverage producers, food packagers, and contract blow molders in the US, Indonesia, UK, and 50+ markets run their highest-volume PET lines on Ever Power water-lubricated technology. Send us your blowing machine model, cavity count, and production speed — our engineering team will confirm EP-CM90G compatibility and provide a complete system configuration proposal within 48 hours.

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