Atlas Copco GA 75 Parts List: The Purchasing Checklist I Use Before Ordering Parts or Service

Who this checklist is for

I'm an office administrator for a 160-person building products company. I manage parts and service ordering for our plant equipment—roughly $140,000 a year across five vendors. I report to operations and finance, which means I'm the one who gets questions when a part is wrong, an invoice is unclear, or a maintenance visit has to be rescheduled.

One piece of equipment gets most of my attention: the Atlas Copco GA 75 air compressor. As the compressor goes, so goes most of the plant. I'm not a mechanic. My job is to make sure the mechanics and outside service technicians have the right Atlas Copco parts and service information on the day they arrive. This is the checklist I now follow, built from mistakes made since I took over purchasing in 2020.

Step 1: Start with the nameplate—not the model number

The first time someone asked for a GA 75 parts list, I did what most people would do: I searched atlas copco ga 75 parts list, found a parts diagram that looked correct, and passed it along. It was close. Close isn't good enough.

Now I walk out to the unit and photograph the nameplate before I do anything else. I need the full model line, the serial number, and ideally the configuration or order number. The GA 75 family includes fixed-speed and VSD versions, and the machine may have an integrated dryer, different cooling options, or voltage variants. The nameplate is the only record that ties all of that together.

My own five-minute check: confirm the complete model line, serial number, installation year, and whether there is a dryer sitting on top or after the compressor. If you are looking for parts online, you will need the serial number anyway. Getting it first prevents about half of the ordering mistakes I have seen from my side of the desk.

Step 2: Request the official parts list for that serial number

Generic drawings are useful for orientation, but the atlas copco parts and service document you order from should match your machine. Atlas Copco's parts and service portal (atlascopco.com, accessed April 2025) lets an authorized distributor generate a spare parts list from the serial number. The parts list produced for the machine is more reliable than a manual found through a search.

The first time a distributor asked for the serial number, I thought they were being overly cautious. They were doing their job. The wrong part we received later came from a supplier who did not ask for the serial number and sold me a part number that was close to—but not identical with—the one listed.

Step 3: Separate service parts from repair parts

Once you have the official parts list, split it into two categories. The regular service category includes the parts most people mean when they say compressor maintenance: the intake air filter, oil filter, oil separator cartridge, and approved compressor oil or coolant. Repair parts—such as the inlet valve, minimum pressure valve, safety valve, seals, and gaskets—live in different sections of the parts list.

This separation sounds basic, but it is where the process breaks down. I once called our supplier and asked for a new filter for the GA75. In my office, filter meant the intake air filter. Maintenance meant the oil separator, because it separates oil from air inside the compressor. Both of us used the same word and meant different things.

The air filter arrived. The oil separator did not. The service tech discovered the gap after starting the job, which turned a one-visit service into two visits and an expedited parts order. Now I confirm each part number out loud with the maintenance lead before sending a purchase order. It feels like over-communication until the moment it saves you a second truck call.

Step 4: Know whether you are dealing with a single-stage or two-stage air compressor

This next item is the reason I did not buy just by model number. Our GA75 is a single-stage oil-injected rotary screw compressor. Our backup piston compressor is two-stage. Their service parts are not interchangeable, and their parts lists look very different.

If you are comparing compressors, the single stage vs two stage air compressor question is mostly about pressure and efficiency. A single-stage compressor compresses air once before it enters the tank or system. A two-stage compressor compresses air, cools it, then compresses it again. Two-stage piston designs are typically how you reach around 175 psi and above without the air getting too hot. Most plant screw compressors, including the GA75, are single-stage because the facility air is usually in the 100–150 psi range.

How does this affect parts? Two-stage machines have additional components between stages—most commonly an intercooler and associated valving—so their parts list includes items that a single-stage GA75 list will never show. If someone quotes you an intercooler or an interstage valve for a GA75, stop the conversation. That alone tells you they are looking at the wrong equipment or the wrong system.

Step 5: Order with part numbers, purchase order numbers, and invoice compliance in mind

By now, you should have a short list of genuine part numbers and the serial number. The next step is getting quotes. I ask three questions of any supplier before ordering: Can you quote genuine Atlas Copco parts? Do the line items show the original part number? Can you invoice against our purchase order with that same part number?

Question three was a hard lesson. A lower-cost quote did not fail on the part itself; it failed on documentation. The invoice showed a description like 'GA75 filter kit' without the part number or our purchase order reference. Finance rejected the expense, the payment run was delayed, and I spent more time fixing the paperwork than the part would have cost.

I am not saying every non-genuine part is bad. I am saying my purchasing process needs traceability, especially on a compressor that supplies air to the production line. Ordering from an authorized distributor makes that traceability much simpler. If you use another source, verify their invoice format before ordering, not after.

Step 6: Open the box before the box goes to stock

The last step sounds too simple to matter, which is exactly why it matters. When the parts arrive, compare the part number on the box with the part number on the purchase order and the part removed from the compressor—or with a photograph of the old part taken before removal.

I skipped that check once because the delivery arrived while we were busy, and I thought what are the odds the supplier sent the wrong item. The odds caught up with me. The cartridge looked like the right filter, so it went straight into the parts cabinet. It was not the right part. We found out during the next service, and the rushed replacement shipping cost nearly as much as the part.

If you are not comfortable opening compressor packages, ask the maintenance lead to do the check. Just make sure someone does it before the delivery driver leaves the site. That one verification step has saved me more times than anything else on this list.

Two errors I still watch for

The first is assuming that a previous purchase order is correct just because it exists. People reorder a wrong part number for years. After we had a mislabeled oil separator incident, I started checking every repeat order against the current parts list—not against last year's invoice.

The second is scheduling service before confirming stock. An outside technician costs more per hour than almost any filter we buy. It makes no sense to book a technician, then discover the part is backordered. I now check stock status before confirming the date, and I keep a small inventory of the high-wear items for the GA75.

This checklist is not about becoming a mechanic. It is about making sure the people who fix the equipment have the right part, the right paperwork, and the right information when they arrive. A few minutes of verification on my side has prevented more than one rescheduled service visit—and that is a good thing, because my boss counts those too.