Atlas Copco 1616585181 OFS G-21 Oil-Free Screw Element

Description

The 1616585181 is the OFS G-21 oil-free screw element, the compression stage Atlas Copco builds for oil-free rotary screw compressors. It converts drive power into compressed air with nothing added to the compression chamber, and the air leaving its discharge port carries no oil from the stage itself.

Packed, the stage measures 40 × 28 × 28 cm and weighs 52.20 kg, and Belgium is recorded as the country of origin. The item record carries the rate group S3L Oil free screw, Element and lists the 1616585181 as a serialized unit, which means each stage is identified on its own rather than by the family it belongs to.

What the 1616585181 OFS G-21 Element Is

An element is the core compression stage of a screw compressor, and the 1616585181 is the OFS G-21 stage in that role. It turns shaft power into air flow at pressure, and it is a long-life component rather than a consumable filter or a charge of lubricant. When a stage reaches the end of its working life, the renewal arrives as a complete factory assembly, with the rotor pair, the housing and the bearings built as one unit.

Those interfaces are set by the machine the stage was built for, so the match is confirmed against the compressor record rather than from the designation on its own. Two stages that share a designation can still fill different positions on different builds.

The item record for the 1616585181 also carries the material group S1 and the customs tariff code 8414900090. Those entries describe how the part is classified in the parts programme, and they are the reference a workshop reads against its own documentation for the machine.

The OFS G-21 Designation

OFS is the oil-free screw designation, and G-21 is the stage code Atlas Copco records for this element. The designation is quoted in the parts records exactly as it stands here, and it is the first reference to check when a renewal is being confirmed. It separates the G-21 stage from the other stages in the same oil-free family.

Serialization and Unit-Level Traceability

The item record lists the 1616585181 as serialized, and that carries practical weight in a compressor room. Each stage is marked with its own unit number rather than being identified only by the part number, so a stage on a machine can be traced back to the record it was built under and matched to the compressor it was fitted to.

That trace matters most where a plant runs several machines of the same model. Two compressors side by side can carry the same stage number and still hold different service histories, and the unit number is what separates them in the file. A record written with the unit number names one stage on one machine, while a record written with the part number alone names every 1616585181 unit in the plant.

What the Unit Number Carries

The unit number is read from the plate on the 1616585181 and written into the machine file. From then on it links three things that are otherwise separate: the stage, the compressor it sits in, and the service history built around them. On the next renewal the file states which unit was fitted where and when.

Plants that keep that record find the ordering step shorter. The parts desk receives a unit number and a machine, works from the record rather than from a description of the part, and confirms the match in a single pass. The 1616585181 is quoted against that number, and the new unit number is logged beside it when the stage is changed.

Oil-Free Compression with Nothing Added to the Air

Oil-free compression starts from a simple difference: nothing in the compression chamber of the 1616585181 lubricates the rotors. The rotor pair turns inside a precision-bored housing with the running gap held small enough to seal the compression pocket, and the surfaces stay apart rather than riding on each other.

With no oil film carrying the load, timing gears at the drive end hold the rotor pair in phase. The rotor surfaces run with an anti-friction coating that protects them in that non-contact gap, precision rolling bearings take the radial and thrust loads of the shafts, and a shaft seal keeps gear-end lubrication on the gear side of the 1616585181.

The result is an air path with no lubricant to remove. Plants that run oil-free screw units such as the ZR and ZT ranges work to air-quality classes where oil must not enter the air at all, and the compression stage is the point where that condition is set. Everything downstream of the discharge port of the 1616585181 inherits the quality the stage delivers.

The Stage Position the G-21 Fills

An oil-free package can compress in one stage or in two, with intercooling between them, and the position the 1616585181 fills is fixed by the build of the machine. On a two-stage unit the low pressure and high pressure positions take different stages, and each of them is ordered by its own number.

That is the reason the compressor record matters more than the family name. A stage built for one position carries the port arrangement, the drive interface and the mounting faces of that position, so it does not move to another position unless the parts list for the serial number says it does.

The interfaces on the 1616585181 are what a renewal has to match: the shaft end that takes the drive, the faces of the inlet and discharge ports, and the mounting faces that set its position in the frame. Air reaches the inlet after the filter and leaves the discharge towards the aftercooler and the air treatment line, so the stage sits at the centre of the air path through the package.

Condition Reading and the Renewal Decision

Renewal of the 1616585181 is decided on condition rather than on a fixed hour count. The rotor coating is what changes first: as it wears, the running gap opens and the stage delivers less air at the same shaft power. Free air delivery measured at the rated pressure is the reading that follows it, and discharge temperature at a steady load moves with it.

Vibration at the bearing housings and the noise level around the 1616585181 form a second line of evidence. Bearing fatigue develops slowly, and a single measurement says little on its own. Taken at a fixed interval, the same reading becomes a trend, and the trend is what turns an unplanned stop into a planned one.

Left unchecked, bearing fatigue can end with the rotors touching and seizing, and at that point the stage is written off rather than repaired. A planned renewal avoids that outcome, because the stage is changed while the frame, the drive and the pipework are still in good order. The unit number logged in the machine file is what makes the timing judgement easier when the next 1616585181 renewal comes up.

Handling, Mounting and the First Run

At 52.20 kg in a 40 × 28 × 28 cm package, the 1616585181 moves with ordinary workshop equipment. A pallet truck brings it to the machine, and a light hoist or a second pair of hands sets it on its mounting faces. The stage is carried on its faces rather than rolled onto its shaft, and the port caps stay in place until the moment of fitment.

The machine side of the job follows the same discipline. The mounting faces are cleaned and checked for burrs, the coupling or belt layout is inspected for wear, and alignment and direction of rotation are confirmed before the 1616585181 is turned. Seals and gaskets are renewed with the stage rather than carried over from the one being removed.

Once the machine is closed up, it is run unloaded under observation. Discharge temperature, pressure and vibration at the bearing housings are watched through the first running period, and the coupling and mounting fasteners are re-torqued after the first hours. A short log of those readings becomes the baseline for every later check on the 1616585181.

Technical Specifications

The tables below collect the identification data and the physical figures recorded for the 1616585181.

Part Identification

Dimensions and Weight

The 52.20 kg weight and the 40 × 28 × 28 cm package describe the 1616585181 as it is supplied, and they set the handling plan for the fitting day. Seadweer confirms the current package details with the quotation.

Ordering the OFS G-21 Through Seadweer

Two pieces of information lock the order down: the number on the stage being replaced, which reads 1616585181 or 1616 5851 81 in the printed form, and the model and serial number from the compressor nameplate. The nameplate matters because stage position and port arrangement differ across the builds that use this element family.

Send both to Seadweer and the parts desk checks the number against the machine record and confirms the 1616585181 in one pass. Where the number on the old stage has worn away, the nameplate is enough on its own, because the parts list for the machine names the stage it was built with.

Plants that run several compressors keep a short record for each machine: model, serial number and stage number. That record turns the next enquiry into a single message with a confirmed answer, and it is the same record the parts desk works from when the 1616585181 is quoted.

FAQ

What does the unit number on the 1616585181 record?

The item record lists the stage as serialized, so each 1616585181 carries its own unit number on the plate. That number links the stage to the build record and to the machine it was fitted to, and it is the reference to log in the machine file after a renewal.

Which compressors take the OFS G-21 stage?

The OFS G-21 belongs to the oil-free rotary screw family, which covers stationary oil-free compressors such as the ZR and ZT ranges. Stage position and port arrangement differ across those builds, so the parts list for your machine serial number is the record that confirms the 1616585181 for your position.

How is the 1616585181 handled at 52.20 kg?

The item data lists 52.20 kg and a packed size of 40 × 28 × 28 cm, with three units to a pallet. A pallet truck and a light hoist cover the move, and the stage is set down on its mounting faces rather than on its shaft.

Does an oil-free element ever need oil?

No oil enters the compression chamber of the 1616585181. The rotor pair runs in a non-contact gap held by timing gears, and gear-end lubrication stays on the gear side behind the shaft seal, away from the air path.

What readings show that the stage is due for renewal?

Possible signs can include falling free air delivery at the rated pressure, rising discharge temperature at a steady load, more power for each unit of air, and growing vibration at the bearing housings. Recorded at a fixed interval, those readings form the trend the decision is based on.

How do I confirm the right stage for my machine?

Read the number on the stage being replaced and note the model and serial number from the compressor nameplate. Send both to Seadweer and the fitment is confirmed against the machine record before the order is placed.

More Atlas Copco Parts List

If you are looking for other Atlas Copco air compressor parts, further models are listed in the table below. Have a look, or get in touch with us for details.