Description
The Atlas Copco 1616725691 is the OIS O-01 oil-injected screw element, the component that turns drive-shaft rotation into compressed air inside an Atlas Copco oil-injected rotary screw compressor. Two intermeshing helical rotors turn inside a machined housing, and the air leaving the discharge port carries the full output of the machine. Every figure printed on the compressor nameplate, from free air delivery to the power drawn per unit of air, is set by this one component.
Atlas Copco classifies the part under rate group S3K, oil-injected screw element. The element is manufactured in Belgium and is delivered as a sealed assembly containing the rotor pair, the housing, the bearings and the shaft sealing. Each unit carries its own serial number, which ties the element to the manufacturing and quality record behind it.
Product Overview
An oil-injected screw element performs a single task: it raises ambient air to a working pressure and delivers it at a steady rate. The 1616725691 OIS O-01 sits in the O-size class of the Atlas Copco oil-injected screw element range. Elements in that range are matched to a machine by displacement and pressure class, and Atlas Copco assigns the element to each individual compressor through the machine serial number.
The element is a long-life component rather than a consumable. Filters, lubricant and the separator element are renewed around it on a service schedule, while the element itself stays in the package. Its internal condition decides how much air the compressor delivers for each unit of energy taken from the supply. A compressor that loses output while the motor, the filters and the controls all test sound is losing it at the element.
Technical Specifications
Part Identification
| Parameter | Value |
|---|---|
| Service part number | 1616725691 |
| Production part number | 1616725681 |
| Element model | OIS O-01 |
| Product type | Oil-injected screw element |
| Rate group | S3K Oil injected screw, Element |
| Brand | Atlas Copco |
| Country of origin | Belgium |
| Customs tariff code | 8414900090 |
| Sales unit | Piece |
| Serialized | Yes |
| Stock policy | Stocked |
| Reference price | 46,958.58 EUR |
Dimensions and Shipping Data
| Parameter | Value |
|---|---|
| Item length | 88 cm |
| Item width | 62 cm |
| Item height | 58 cm |
| Item weight | 360 kg |
| Pallet quantity | 1 |
| Order pallet | No |
Production Number and Service Number
Atlas Copco lists this element under two numbers. The number 1616725681 is the production listing, the number that appears in the parts record of a compressor built with this element on the line. The number 1616725691 is the service listing used in the spare parts channel. Both numbers identify the same OIS O-01 element.
Ordering the service number returns the current revision of the genuine part, with no change to the mounting dimensions, the shaft interface, the oil port positions or the fitment. A maintenance team that reads 1616725681 from an existing machine can order 1616725691 and fit it without any adaptation work on the package. The dual numbering is standard practice for Atlas Copco rotating elements.
Construction and Operating Principle
Rotor Pair and Housing
The element 1616725691 holds a male rotor and a female rotor turning in opposite directions inside a cast and machined housing. The rotors do not touch each other or the housing wall at any point in the cycle. The clearance is held by the oil film that fills it during operation, and the rotor pair is kept in step by its own geometry rather than by contact.
Ambient air enters the element through the inlet port and fills the groove formed between the two rotors. As the rotors turn, the meshing point travels along the rotor length and closes the groove, which traps the air. Continued rotation shortens the trapped pocket and raises the pressure inside it. The pocket then reaches the discharge port and the air passes out of the element towards the separator vessel.
The action repeats many times each second, and each pocket follows the same path. That continuity is what gives a screw compressor its smooth, low-pulsation delivery, and it allows the element to be direct-driven at motor speed without the torsional vibration a reciprocating machine produces.
Bearings and Shaft Sealing
The rotors run on bearings carried in the element end covers. The bearings hold the rotor position under the gas load and the separating force generated during compression, and they hold it in both directions, because the pressure acting on a screw rotor loads the rotor ends as well as the flanks.
Shaft sealing keeps the two fluids on their own side of the rotor ends: oil stays in the bearing and injection circuit, and air stays in the compression chamber. The sealing arrangement holds a thin film between the sealing faces and the shaft, so the seal does not run in metal-to-metal contact.
The Role of the Injected Oil
Oil is injected into the compression chamber through a port in the housing. It does three jobs at the same time, and all three are necessary to the design.
First, it seals the clearance between the rotors and between each rotor and the housing wall. Without that film the compressed air would leak back towards the inlet through the same gaps, and the element would lose volumetric efficiency from the first hour of operation.
Second, it carries away the heat of compression. Air leaving the element stays within the temperature limit the compressor is designed for because the oil absorbs the heat as the pressure rises and releases it later in the cooler.
Third, it reaches the bearings and the rotor mesh and keeps a lubricating film on every moving surface inside the element. After discharge the oil is separated from the air, cooled, filtered and returned to the injection point, so the same charge circulates through the machine.
Traceability and Serialization
The 1616725691 is a serialized part. Each element leaves the factory with its own serial number, and that number links the unit to the record of the build it belongs to. For a plant running several machines of the same family, the serial number is what separates one element from another in the maintenance history and in the spare parts claim record.
Serialization also matters at the point of failure analysis. When an element is taken out of service, the readings taken from the removed unit can be logged against that specific serial number, so the trend is followed machine by machine rather than across a mixed fleet.
Confirming the Correct Element
Atlas Copco assigns elements by machine serial number, and the serial-number spare parts list is the record that names the element for a given compressor. Read the model and the serial number from the compressor nameplate and check the parts list for that machine. Where the machine is covered by a service agreement, the same number is held on the service record.
The element 1616725691 is one part of a matched set. The drive coupling, the oil circuit, the separator vessel, the cooler and the controller are all sized around the flow and pressure map of the element. Keeping the genuine element in that circuit keeps the oil injection rate, the discharge condition and the bearing load inside the design envelope of the package.
Installation and Service Planning
Handling and Installation
Store the element indoors with the inlet, discharge and oil ports closed until the moment of installation. Grit entering the chamber scores the rotor flanks on the first start, and the damage is permanent.
At 360 kg and 88 cm by 62 cm by 58 cm, this element is lifting work rather than a carry. Plan the lift with rated equipment and a clear route to the machine before the element leaves the pallet, and keep the unit on the pallet until it stands beside the compressor.
Seat the element on its mounting faces and fit the coupling. Re-torque the mounting bolts and the coupling bolts after the first running hours, at the interval the compressor manual states, because new joints settle during the first period of operation. Fill the machine with the specified lubricant, check the oil level and confirm the rotation direction before the first start.
Run the compressor unloaded first and watch the discharge temperature, the oil pressure and the vibration at the bearing housings before putting the machine on load. An element commissioned this way gives a clean baseline for every trend reading taken afterwards.
Wear Indication
An element wears gradually, and the change shows up in four readings. Free air delivery falls at the same rated pressure. Discharge temperature rises under the same load and ambient condition. Power drawn per unit of air delivered increases. Vibration and noise at the element housing grow at a steady load.
Taken once, any one of those readings means little. Recorded at a fixed interval and kept as a trend, they show the direction of change well before the element reaches the end of its service life, and the work can be planned into a scheduled stop instead of forced by a breakdown.
When an element does reach the end of its life, the choice is between a workshop rebuild and a new element. A rebuild keeps the original rotors and housing and renews the bearings, seals and gaskets, and it suits a unit whose rotors and housing show no scoring or pitting. A new 1616725691 returns the element to its original specification with new bearings and the current revision level in one step. The decision follows a teardown inspection and a clearance measurement by a qualified technician.
FAQ
What is the difference between 1616725691 and 1616725681?
Both numbers identify the same OIS O-01 oil-injected screw element. The number 1616725681 is the production listing used in original machine builds, and 1616725691 is the service listing used in the spare parts channel. Ordering the service number brings the current genuine revision with no change to fitment.
Which compressors use the 1616725691 OIS O-01 element?
The 1616725691 OIS O-01 sits in the O-size class of the Atlas Copco oil-injected screw element range and is matched to a machine by displacement and pressure class. Atlas Copco assigns elements by machine serial number, so the spare parts list for your compressor is the record that names the element. Send us the model and serial number from the nameplate and we will confirm the match before you order.
What is included with the 1616725691 element?
The part is supplied as a sealed element: the rotor pair, the housing, the internal bearings and the shaft sealing. The separator vessel, the oil cooler, the drive coupling and the controller stay on the host compressor and are reused at installation.
How do I know when the element needs attention?
Four readings show the condition of an element: free air delivery at rated pressure, discharge temperature, power drawn per unit of air delivered, and vibration or noise at the element housing. Recorded at a fixed interval, these readings form a trend that shows the direction of change and lets the work be planned into a scheduled stop.
Should the element be rebuilt or replaced?
A rebuild keeps the original rotors and housing and renews the bearings, seals and gaskets, and it suits a unit whose rotors and housing show no scoring or pitting. A new 1616725691 returns the element to its original specification with new bearings and the current revision level in one step. The decision follows a teardown inspection and a clearance measurement by a qualified technician.
How is the element shipped?
The element weighs 360 kg and measures 88 cm by 62 cm by 58 cm. It ships as one piece on a pallet with the ports closed, and it stays indoors and sealed until the moment of installation.
Genuine Atlas Copco Supply from Seadweer
Seadweer supplies genuine Atlas Copco products to customers worldwide. Send us the model and serial number from your compressor nameplate and our parts desk will confirm the correct element before you place the order.
Yousef Al-Mansouri –
We sent our nameplate details first and the parts desk came back with 1616725691 as the number for our machine. The element arrived on a pallet with the ports sealed and the serial plate in place. The mounting faces and the oil connections lined up with the existing pipework, so the swap went through inside one planned stop. Discharge temperature has held at the normal reading since the restart.