Why idle and transported compressors fail
Compressors are often damaged not while running but while standing or travelling. A screw compressor left in a damp shed through the monsoon can develop rust inside the airend inlet and bearings. A portable diesel unit towed over rough roads can loosen hose clamps, crack a cooler bracket or shift a battery. A stored electric package can draw in moisture through its motor windings and trip on insulation failure at the first start.
The risks fall into a few groups:
- Corrosion: humid air and condensation inside airends, coolers, separator vessels, receivers and pipework.
- Fluids: oil degrading or absorbing moisture, coolant on diesel engines, fuel ageing, and water left in drains.
- Mechanical: bearing marks from vibration in transport, belts and seals taking a set, loose fasteners.
- Electrical: moisture in motors, controllers and cable entries; battery discharge on diesel units.
- Contamination: dust, insects and rodents entering through open inlets, cooler faces and cable glands.
- Pressure: residual pressure trapped in separator vessels and receivers.
Preparing a compressor for storage
- Record the condition: running hours, last service, any known faults, and nameplate details.
- Run the machine to normal temperature, if it is serviceable, so the oil is warm and moisture is driven out.
- Stop, isolate electrically and vent all pressure from the separator, receiver and lines; confirm on a gauge.
- Drain condensate from the receiver, separators, filters and drain traps.
- Change the oil or leave it, according to the manufacturer’s storage instructions and the oil’s condition.
- Seal the air inlet, cooler faces where appropriate, discharge connections and cable entries against dust and moisture.
- Protect bare metal with a suitable preservative where the maker recommends it.
- On diesel units, follow the engine maker’s storage procedure for fuel, coolant and battery, and disconnect the battery.
- Label the machine clearly as preserved, with the date and who did it, and tag any items removed.
Where and how to store it
| Storage situation | Main risk | Good practice |
|---|---|---|
| Indoor, dry, ventilated store | Dust, slow moisture ingress | Cover loosely, keep openings sealed, inspect periodically |
| Open yard or site | Rain, sun, heat, dust | Weatherproof cover that still lets air circulate, raised off the ground, drains closed |
| Coastal site | Salt-laden air and corrosion | Better sealing, preservative on exposed metal, more frequent checks |
| Container or closed shed in summer | High temperature, condensation on cooling at night | Ventilation, keep electronics and rubber parts away from hot walls |
| Long-term standby inside a plant | Neglect, moisture in motor windings | Periodic run or rotation as the maker advises, anti-condensation heater where fitted |
In Telangana and Andhra Pradesh, the change from dry summer heat to monsoon humidity is when stored machines suffer most. Daily temperature swings create condensation inside closed vessels and panels. A cover that traps moisture against the canopy can do more harm than good, so choose one that sheds rain but breathes.
Periodic checks while in storage
- Look for water, rust, rodent damage and broken seals at the inlet, cooler and panel.
- Check the receiver and separator drains for water.
- Turn the airend or engine by hand where the manufacturer recommends, to move bearings and spread oil.
- Check battery charge on diesel units.
- Check the motor and controller for signs of moisture.
- Record each check: date, findings and action taken.
Transporting a compressor safely
Static packages and portable units need different handling, but the principles are the same: nothing pressurised, nothing loose, and lifting and lashing only at the points the manufacturer provides.
- Confirm the weight and centre of gravity from the nameplate or manual, and use only the marked lifting points or forklift pockets.
- Vent all pressure and drain condensate before moving.
- Secure loose items: hoses, doors, panels, filters and tools.
- Restrain the package on the vehicle using chains or straps on the designated points, never over coolers, pipes or the canopy.
- For portable units being towed, check the tow bar, coupling, tyre pressures, wheel nuts, lights and safety chain, and keep to safe towing speeds for the road surface.
- For long journeys over rough roads, consider transport locks or packing where the maker specifies them for airend, motor or engine mounts.
- Record the condition at dispatch and at arrival, with photographs, so any damage in transit can be identified.
Crane lift planning, vehicle selection and road-transport rules are specialist matters. Use qualified riggers and transporters for heavy or difficult lifts.
Recommissioning after storage or transport
Do not simply press start. A short, structured check prevents most damage at restart.
- Remove all preservation covers, plugs and tags, and confirm nothing is left in the inlet or coolers.
- Inspect for transport damage: cracked brackets, loose pipes, damaged coolers, dented vessels.
- Check oil level and condition; change the oil if it is cloudy, contaminated or past its storage limit.
- Check the air filter, belts or coupling, and all hose connections.
- On electric units, have the motor insulation checked before energising if the machine has been stored in damp conditions.
- On diesel units, check engine oil, coolant, fuel, battery and the engine maker’s recommissioning steps.
- Confirm the safety valve, high discharge temperature protection and, on diesel units, low engine oil pressure and high coolant temperature shutdowns are in place and working.
- Start unloaded where possible, check rotation direction on electric machines, then load gradually while watching pressure, temperature and leaks.
- Monitor closely for the first hours. Discharge temperature on an oil-injected screw compressor normally settles at about 75–95 °C.
- Record the recommissioning results and any parts replaced.
Signs that something went wrong during storage or transport
- High discharge temperature after restart: blocked cooler, wrong oil level, or a stuck thermostatic valve.
- Unusual noise from the airend: bearing damage from vibration or corrosion.
- Oil carry-over: damaged separator element or seal, or wrong oil level.
- Earth fault or insulation trip on starting: moisture in the motor or panel.
- Diesel engine hard to start or smoking: aged fuel, water in fuel, or a weak battery.
- Leaks at hoses and joints: connections loosened in transit or seals that have taken a set.
Rental and project machines
Our rental compressors move between sites all the time, so preparation, transport and recommissioning are routine work for us. Each machine is checked before dispatch and on arrival, and on hire jobs we service at 300 running hours with an oil change. For large temporary air projects we have supplied, erected and commissioned complete packages, including transport, for example an air and power package for a natural-gas development at Kakinada in Andhra Pradesh. The same discipline applies to any compressor that leaves one site and starts at another.
Keeping a preservation and recommissioning record
Write down what was done to the machine before storage, what was found at each check, and what was done before restart. The record should name who did each step and list any items removed or plugged. It protects the next engineer from starting a machine with a blanked inlet, and it shows the owner or buyer that the compressor was cared for while idle.
How Reddy Compressors helps
We are an independent multi-brand compressor specialist at Tarnaka, Secunderabad, serving industry since 2002. We sell new and used/refurbished compressors, rent from our own fleet, and service and supply spares for ELGi, Atlas Copco, Ingersoll Rand, KAESER, Chicago Pneumatic, Sullair, Doosan, Kirloskar and other brands. We are not an authorised dealer of any brand. We have tie-ups with all major and reputed brands.
- We prepare compressors for storage and recommission machines that have been idle or relocated.
- We inspect and test used compressors after transport before they go into service.
- Our 20+ service engineers and technicians cover all of Telangana and Andhra Pradesh, and we supply machines and spares across India.
- Where a stored machine needs repair before restart, we can provide a rental compressor as temporary cover.
What to send us
- Make, model, serial and nameplate photographs.
- How long the machine has been idle and where it was stored.
- Last service date and running hours.
- Photographs of its present condition, including the inlet, coolers and panel.
- Where it is going and when it needs to run.
Frequently asked questions
How do I store an air compressor that will not be used for months?
Run it warm if it is serviceable, then stop, isolate and vent all pressure. Drain condensate, check or change the oil according to the manufacturer’s instructions, and seal the inlet, discharge and cable entries against dust and moisture. Store it indoors or under a breathable cover, off the ground, and check it periodically for water, rust and rodents. Label it as preserved with the date.
Is it safe to start a compressor that has been idle for a long time?
Not without checks. Inspect oil level and condition, filters, belts, hoses and coolers, and remove any preservation plugs. Have motor insulation checked if it was stored in damp conditions. On diesel units check engine oil, coolant, fuel and battery. Confirm protections work, start unloaded, and watch temperature, pressure and leaks closely during the first hours of running.
How should a portable diesel compressor be towed safely?
Check the tow bar, coupling, safety chain, tyres, wheel nuts and lights before moving. Make sure all pressure is vented, doors are latched and hoses are stowed. Keep to a speed suited to the road and the trailer’s design, and take care on rough or uneven site roads. Inspect the unit on arrival for loosened fittings or damage before starting it.
Why does my compressor overheat after being moved to a new site?
Common causes are a cooler blocked by dust or packing, an oil level that changed during transport, a stuck thermostatic valve, or a new location with poor ventilation where hot air recirculates to the intake. Check the cooler faces, oil level and room airflow first. Discharge temperature on an oil-injected screw compressor normally runs at about 75–95 °C; consistently higher readings need investigation.
Should I change the oil before storing a compressor?
Often, yes, because used oil contains moisture and acids that can attack internal surfaces during a long idle period. Some manufacturers recommend fresh oil or a specific preservation oil before storage, while others recommend changing on recommissioning. Follow the manufacturer’s instructions for your machine. If the oil is near its change interval anyway, changing it before storage is usually sensible.
What damage can happen to a compressor during transport?
Vibration and shocks can mark bearings, loosen fasteners and pipe connections, crack cooler brackets and damage canopies or vessels. Poor lashing over coolers or pipework can crush them. Residual pressure left in a vessel adds a stored-energy hazard. Inspect and photograph the machine before dispatch and on arrival, and check it carefully before the first start.
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Technical content reviewed by D. Srinivas Reddy, Managing Partner and service engineer, Reddy Compressors. Last updated 17 October 2026. How our engineering content is reviewed.