Cast iron piston compressor WK900-7-5/270P Input power 5.5 kW, suction capacity 880 l/min, pressure 10 bar, air receiver 270 l, voltage 400/50 V/Hz
Code: WK900-7-5/270P
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Product detailed description
WALTER WK900-7.5/270P Cast Iron Piston Compressor - 5.5 kW, 270 l
The WK900-7.5/270P is a horizontal cast-iron compressor with a 3W three-cylinder unit, a power input of 5.5 kW, suction of 880 l/min and an effective delivery of 740 l/min at 10 bar. The unit operates at 902 rpm – for a machine with a 5.5 kW input, this is the range where compression occurs smoothly, without undue stress. Power supply 400 V / 50 Hz, noise level approx. 80 dB(A), 3 years warranty after registration at waltercesko.cz.
This machine is not intended for a single operator with an impact wrench. It is designed for workshops where two people are at two permanent consumption points and a smaller compressor has begun to drop below the required working pressure. The 270 l horizontal air tank on wheels is a deliberate compromise: the machine delivers 190 l/min more than the 4.0 kW class, while remaining dimensionally manageable and movable within the workshop, rather than permanently cementing one corner.
Configuration of this machine
Why choose this model
The 3W design means three cylinders arranged in a W configuration. The 880 l/min suction is divided between three compression chambers instead of two, meaning a smaller volume per stroke. The practical impact is threefold: shorter and denser pulses in the delivery instead of two large shocks, a better-balanced crankshaft mechanism, and more uniform tension on the V-belts. This platform shares the 3W three-cylinder unit with the 3.0 kW class – but here it runs slower and with a larger transferred volume.
Compared to the 550 l/min of the 4.0 kW class, this is 190 l/min more. It sounds like a one-third increase, but in practice, it is a turning point: 550 l/min can handle one permanent draw and peaks of a second, whereas 740 l/min covers two truly permanent draws – for example, an orbital sander (300 to 450 l/min) and a chipping hammer simultaneously, with a reserve for distribution leaks.
A unit of the same design in the 3.0 kW class rotates at 1 202 rpm; this one rotates at 902 rpm. Given a comparable piston stroke, this means approximately a quarter shorter sliding path of the piston ring per hour of operation. This figure is not compared in catalogues because it does not look like performance – but it is precisely the metric that determines how many thousand hours the unit lasts before needing rings.
With a typical pressure differential between cut-in and cut-out of 2 bar, a 270 l tank delivers approximately 540 l of free air per cycle. At a continuous draw of 300 l/min, this results in roughly 20 motor starts per hour. The version with a 500 l tank has about 11 starts under the same conditions, but it is a machine that is positioned and stays put. This variant remains a horizontal tank on wheels – you move it to the work, not just to a corner.
Design and technology
Piston, rings and cast-iron liner
The cast-iron cylinder liner and piston rings are standard service parts — the unit can be refurbished after years of use rather than discarded.
Intake filter with steel mesh
The new generation metal insert withstands repeated blowing out with compressed air, whereas a paper insert would tear after a few cleanings.
Head gaskets and valves
The redesigned cylinder head gaskets maintain pressure even after thermal cycles; valve plates are stocked as spare parts.
Inspection on a 3D measuring machine
Key dimensions of the unit are verified on a coordinate measuring machine — this ensures that parts from different series fit together perfectly.
Technical data WK900-7,5/270P
What the data sheet doesn't tell you — calculated values
Values are calculated from manufacturer parameters and serve for comparing models with each other, not as a guaranteed figure.
Who is it for
The typical buyer is a locksmith's workshop or a smaller metal fabrication plant with two permanent workstations – one person grinding, another using a chipping hammer or impact wrench – and an auto repair shop with three bays, where the simultaneous use of tools cannot be scheduled. It is also suitable for a joinery with grinders and pneumatic clamping, where it is not just about the volume of air, but ensuring that the pressure in the distribution system does not fluctuate and tools do not slow down. If the machine only runs for a few hours a week and never more than one tool at a time, this class is unnecessarily large.
Typical applications
- Two simultaneous permanent draws: an orbital sander and a chipping hammer in a body shop
- Pneumatic angle grinder (400 to 600 l/min) in continuous operation, with reserve for a second tool
- 1/2" impact wrench across several auto repair shop bays without waiting for repressurisation
- Pneumatic clamping, drills, and ratchets in metal fabrication with short but frequent draws
- HVLP spray gun simultaneously with air blow-off – pressure in the distribution system remains stable
- Sandblasting with a 3 mm nozzle in shorter bursts; for continuous sandblasting, choose the 7.5 kW class
Where to choose a different model
Opt for the same pump unit on a 500 l tank. The free air reserve per cycle increases from 540 to 1,000 litres, the number of motor starts at a draw of 300 l/min drops from approximately 20 to 11 per hour, and the distribution system can handle short draws exceeding 740 l/min.
View recommended model →740 l/min is not enough for this – a sandblasting gun with a 3 mm nozzle consumes 500 to 1,000 l/min on its own. Go for the four-cylinder 7.5 kW class with a displacement of 1,100 l/min and a 500 l air tank.
View recommended model →Do not overpay for power. The 4.0 kW class with the same 270 l tank delivers 550 l/min, runs at 993 rpm, and is a correctly dimensioned machine for one permanent draw plus the peaks of a second one.
View recommended model →Service and maintenance to maintain the warranty
Inspections may be carried out by an authorised WALTER service centre or by yourself — provided that original parts and fluids are used and proof of purchase is retained.
3 year WALTER warranty
36 months after registration at waltercesko.cz
The warranty is provided by Walter Kompressortechnik Česko s.r.o. (Ostrava). Machine registration extends the warranty to 36 months from the date of purchase; proof of purchase is required to claim the warranty.
- Claim assessment within 14 working days, approved repairs free of charge and completed within 30 days
- After 4 repairs and a further defect, you are entitled to a replacement of the machine with a fault-free one
- You may perform the prescribed inspections yourself — using original parts and providing proof of purchase
Transport and Commissioning
The machine is delivered on a pallet. Before the first start, check the oil level, direction of rotation, and the tightness of connections; after the first 8 hours of operation, tighten the cylinder head bolts to a torque of 25 Nm. Leave the electrical connection to a professional — for three-phase machines, it is necessary to verify the correct phase sequence.
Related models and alternatives
The same 5.5 kW three-cylinder pump unit on a 500 l tank: double the reserve, roughly half the number of motor starts.
View model →Vertical version of the same pump unit with a 270 l air tank – same air reserve on approximately half the footprint.
View model →One class higher: four-cylinder 7.5 kW, 1,100 l/min and 768 rpm – for continuous sandblasting and three draws.
View model →The pump unit alone on a base frame without a pressure vessel – for replacing a worn-out unit on your own tank.
View model →Frequently asked questions
Why does this machine with a 5.5 kW power input have three cylinders, while the smaller 4.0 kW model has only two?
Is a 270 l tank sufficient for a delivery rate of 740 l/min?
Can it run two pneumatic angle grinders simultaneously?
What electrical connection does the machine require?
Is it louder than the smaller models in the range?
Additional parameters
| Category: | Compressors for all applications - hobby and industrial |
|---|---|
| Warranty: | 3 years |
| EAN: | 5905122000141 |
| Compressor type: | Piston compressor |
| Pressure: | 10 bars |
| Suction power: | 880 l/min |
| Displacement: | 740 l/min |
| Pressure vessel volume: | 270 L |
| Design of pressure vessel: | Lying down |
| Connecting: | Quick coupling DN 7.2, Ball valve 1/2" |
| Motor power: | 5.5 kW |
| Mains voltage: | 400/50 V/Hz |
| Speeds: | 902 rpm |
| Number of cylinders: | 3 |
| Number of grades: | 1 – single-stage compressor |
| Lubrication: | Oleic |
| Noise: | 80dB(A) |
| Dimensions: | 1650 × 510 × 1150 mm |
| Weight: | 178 kg |
| Accessories: | Pressure regulator, Wheels, Handle, Quick coupler, Ball cock |
| Engine: | Electric |
| Soundproofed: | No |
| Drive: | V-belts |
| Air dryer: | No |
| Retrieved from: | Professional |
| Development: | Mobile |
| In stock: | External warehouse |
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