2026-09-22 · AmmoniaEquip Engineering
Google already shows AmmoniaEquip for “ammonia compressor overhauls,” but the people typing it are not looking for a slogan. They want to know whether the machine on the pad is due, whether a knock is a valve plate or a rod, and whether they should spend the shutdown on an overhaul or a replacement. This note answers those questions the way we answer them on site.
Hour meters are useful and incomplete. Reciprocating ammonia compressors commonly see a major strip in the 15,000–25,000 hour band. Oil-injected screws are often quoted at 30,000–50,000 hours for a full bearing and seal intervention. Those ranges assume clean oil, a working separator, and no liquid slugging. A machine that has run wet, dirty, or misaligned can be due far earlier. A machine with oil analysis and vibration trending can run longer with a lighter intervention.
The signs that beat the calendar: lost capacity at the same slide or unload position; rising discharge temperature at the same condensing pressure; metallic or ammonia-diluted oil; shaft-seal weep; a new knock; coupling heat after a motor change; or a slide valve that hunts. One symptom is a watch list. Two or three is a planned overhaul before the weekend breakdown.
Overhaul versus rebuild versus replace is vocabulary until money is on the table. We use overhaul for a full inspection and renewal of wear parts to documented clearances. Rebuild is selected failed items plus the seals you must remove to reach them. Replace is for cracked housings, rotors past grind limits, or a quote that crosses roughly half the cost of a sound remanufactured frame. If you searched “compressor overhauling” or “ammonia compressor rebuild,” you are in this decision — not a different trade.
Cost is almost never a single number. It is parts lead time, crane access, a second machine covering the room, and whether valve plates and bearings are on the shelf. A planned piston overhaul with kits ready is days. A surprise screw rotor job is weeks if the frame is unusual. That is why we ask for nameplate photos and hours before we talk price.
Safety sits in the same plan. IIAR 6 (which replaced older bulletin-style inspection language) expects condition-based mechanical integrity, not a calendar sticker. Isolate, evacuate, and lock out before the casing opens. A leak that appeared after the last alignment is part of the overhaul scope, not a separate argument with the safety officer.
If the plant cannot stop, a refurbished or remanufactured compressor can cover the duty while the installed machine comes to the bench. That is often cheaper than a failed room. It is not cheaper than ignoring oil colour for another season.
Send make, model, serial, hours, and the symptom. We will say overhaul, parts-only, refurbished drop-in, or “this is a condenser problem.” The dedicated overhaul page is the service home; this article is the decision you make before you book the window.
Questions we hear
How often should an ammonia compressor be overhauled?
Use OEM hours as a window, then let oil, vibration, capacity, and leaks decide. Reciprocating machines often land at 15,000–25,000 hours; screws at 30,000–50,000 — sooner after slugging or dirty oil.
Is an overhaul cheaper than a new compressor?
Usually, when the housing and rotors or crank are sound. When the rebuild quote approaches half a replacement, we recommend a remanufactured or new frame instead of spending twice.
Can you overhaul without a full plant shutdown?
If a parallel machine can hold the room, yes. Otherwise we stage a refurbished compressor or a short, planned window with parts already on site.