Short answer: A low-pressure air compressor for the ceramic industry feeds the plant’s atomisation, conveying and filter-cleaning air at 3–5 bar rather than the 7–8 bar a general-purpose compressor room supplies. On a 25 m³/min ceramic duty that band typically cuts air energy by around 32% — about 200,000 kWh and 16,100 USD a year (based on 0.08 USD/kWh · 6,000 h/yr · 80% average load · site-logged 25 m³/min at 4 bar versus an 8 bar incumbent).
By Johnny Wayne, General Manager, AirSpace Machinery Co., Ltd. — 20 years in industrial compressed air systems. Reviewed by our engineering team.
Ceramic plants are unusual among industrial air users: almost nothing they do with compressed air requires high pressure. The air atomises slip inside a spray dryer, drives the cylinders that keep a press running, conveys glaze and body powder, and pulses the dust filters — and every one of those jobs is comfortable in a 3–5 bar band. Yet most plants we visit are supplied from an 8 bar compressor room, because that is the pressure the general-purpose market sells.
Across textile, ceramic, glass and cement, that mismatch is the largest avoidable item in a compressed air bill. We have measured it often enough in the field to say where it comes from: pressure is chosen once, at specification time, to cover every possible consumer, and never revisited.
What does a low-pressure air compressor for the ceramic industry actually do?
It supplies the four continuous air users that keep a ceramic line moving at the pressure those users need, rather than the pressure the compressor was designed for. Same air, narrower band, less energy per cubic metre.
The difference shows up in running hours: a ceramic plant’s dryer, presses and conveying lines generally run 16–24 hours a day, putting annual running hours in the 6,000–8,000 range (based on duty-point submissions from ceramic and building-material plants in Vietnam, Indonesia and Uzbekistan, 2025–2026). A 32% cut in specific power repeats six thousand times a year.
Where does the air go inside a ceramic plant?
A typical plant draws from four consumers, and only one is anywhere near the 8 bar a general-purpose machine supplies:
| Plant consumer | Typical pressure window | Pattern of demand |
|---|---|---|
| Spray-dryer slip atomisation | typically 3–5 bar | continuous while the dryer runs |
| Press and mould-support cylinders | typically 5–6 bar | short, frequent bursts |
| Pneumatic conveying of body and glaze | typically 3–5 bar | batch peaks with quiet periods between |
| Bag-filter and dust-collector pulse cleaning | typically 4–6 bar | short high-energy pulses on a timer |
Confirm these windows against the spray-dryer and press manuals and your own logged profile. In our experience the atomisation and conveying groups carry the bulk of the volume, and both sit comfortably in the low-pressure band.
Why is 8 bar the wrong band for a spray dryer?
Because the nozzles set the requirement, and nozzles are far less demanding than compressors. An atomisation nozzle needs enough pressure to break slip into droplets of the right size distribution; above that threshold, extra pressure buys nothing but a different wear pattern, while the compressor pays a higher compression ratio on every cubic metre for the life of the machine.
The flow consequence is measurable: a 90 kW (125 HP) airend delivering roughly 16 m³/min at 8 bar typically delivers 24–26 m³/min at 4 bar (based on manufacturer flow curves across the 3–8 bar band). A plant that “needs a bigger compressor” often needs a smaller one at a lower band instead.
What does the sizing look like on a real ceramic duty point?
Take a plant logging 25 m³/min at 4 bar across dryer, presses and conveying, 6,000 hours a year, at 0.08 USD/kWh and 80% average load:
- Air actually needed: 25 m³/min at 4 bar, from a site log covering one representative week.
- 8 bar incumbent sized for that flow: a 132 kW (180 HP) general-purpose package, average input 132 × 0.80 = 105.6 kW.
- Specific power of the incumbent: 105.6 kW ÷ 25 m³/min = 4.22 kW/m³.
- Low-pressure unit on the same flow: a 90 kW (125 HP) low-pressure screw package delivering 25 m³/min at 4 bar, average input 90 × 0.80 = 72 kW.
- Specific power of the low-pressure unit: 72 kW ÷ 25 m³/min = 2.88 kW/m³.
- Difference: 4.22 → 2.88 kW/m³, about 32% less energy per cubic metre at identical delivered flow.
- Annual energy: 633,600 kWh vs 432,000 kWh → 201,600 kWh saved, which at 0.08 USD/kWh is 16,128 USD a year.
Our planning benchmark for this family is a ~35% saving against a fixed-speed machine sized for the same duty — a screening figure, not a guarantee. Here the arithmetic landed at 32%.
What did the numbers look like in a real installation?
We publish measured data rather than only method, and neither installation we point to is a ceramic plant — deliberately, because the mechanism is a property of the pressure band rather than of one industry.
Our 75 kW PMV VSD installation case study documents an iron processing and fabrication plant in Ho Chi Minh City: a 15,000 m² facility with more than 200 employees running 16 hours a day, where compressed air had been costing over 3,200 USD a month in electricity, with pressure swinging ±0.5 bar and maintenance at 850 USD a month on the old fixed-speed unit. In the field, that ±0.5 bar swing is what forces every downstream consumer to be sized with a margin nobody budgets for.
A second case study, 34% annual energy savings against a European-tech brand, replaced a 75 kW machine and held plant pressure to ±0.1 bar with a 14-month payback. We describe the same system-side pattern in our note on system-wide energy savings of air compressor stations, and keep a longer sector reference on the role of air compressors in the building-material industry.
How do ceramic, textile, glass and cement plants compare on low-pressure air?
A low-pressure air compressor for the textile / ceramic / glass / cement industry is specified with one shared rule: find the pressure each process genuinely needs, set the discharge band to match it (15–300 HP at 3–5 bar on our low-pressure screw series), and stop paying compression ratio for headroom nobody consumes.
| Industry | What the air does | Typical pressure band | What drives the sizing |
|---|---|---|---|
| Ceramic | spray-dryer atomisation, press support, conveying of body and glaze | typically 3–5 bar | continuous dryer load plus batch conveying peaks |
| Textile | air-jet insertion and relay nozzles, yarn texturing, blow-off | typically 3–5 bar | flat 16–24 h demand, so the delta repeats all year |
| Glass | forming and blow-off, annealing-line cooling air, mould support | typically 3–5 bar | steady clean supply; pressure spikes damage ware |
| Cement | pneumatic conveying, bag-filter pulse cleaning, silo air cannons | typically 3–5 bar | duty cycle rather than average flow sets the size |
The differences are in duty cycle, not principle. A ceramic dryer wants volume at a steady band; a cement silo wants short hard pulses with storage behind them. Both are poor matches for a general-purpose 8 bar package.
AirSpace Machinery Co., Ltd. builds and exports that low-pressure family — 15–300 HP at 3–5 bar — alongside its PMV variable-speed and Class 0 oil-free ranges, covering 2–540 HP (1.5–400 kW) in total, with CE marking and ISO 9001:2015 quality certification, selling through distributors rather than around them.
How do you handle the intermittent peaks in a ceramic plant?
Peaks are a storage problem before they are a compressor problem: conveying batches and filter pulses both draw far above the plant average for seconds at a time.
- Size the receiver on the pulse: a 45 m³/min batch lasting 3 seconds needs about 2.3 m³ of usable storage at 4 bar (based on 45 m³/min × 3 s with a 1 bar usable differential).
- Keep the machine on base load: a variable-speed low-pressure package follows the band at part load and avoids the unload losses a fixed-speed unit runs into between batches.
- Separate the bands: feed press support and filter cleaning from a small dedicated unit rather than raising the whole plant band.
Key takeaways
- Ceramic air users live in a 3–5 bar band — atomisation, conveying and filter cleaning — while most plants supply them at 7–8 bar.
- That gap is worth about 32% less energy per cubic metre on a 25 m³/min duty: 201,600 kWh and 16,128 USD a year at 0.08 USD/kWh · 6,000 h/yr · 80% load.
- The same airend gives 24–26 m³/min at 4 bar where it gave 16 m³/min at 8 bar, so “we need a bigger compressor” is often a pressure decision in disguise.
- Serve peaks with storage, not headroom. Size the receiver on the batch and keep the machine on base load.
- Measure the demand first. Leakage is typically 20–30% of it (based on compressed air audit practice under ISO 11011:2013), and no pressure change repairs pipework that was already marginal.
Frequently asked questions
Does a spray dryer really run on 3–5 bar air?
Usually, yes — atomisation nozzles are typically rated in that window, and the exact figure comes from the nozzle manufacturer rather than from us. If a dryer genuinely needs 6 bar or more, feed that consumer separately and drop the rest of the plant to the lower band.
Can one low-pressure compressor serve the whole ceramic plant?
Often it serves the bulk of the volume — atomisation and conveying — while a small higher-pressure unit covers press support and filter cleaning at 5–6 bar. Splitting by band is usually cheaper than holding the whole plant at 8 bar for the smallest consumer.
How do you verify a low-pressure saving claim before buying?
Ask for the airend flow curve at your actual discharge pressure, a specific power figure in kW/m³ at your duty, and a named installation you can call. A quotation listing only motor power and FAD at 8 bar cannot support a low-pressure claim.
How long is the payback on a ceramic plant conversion?
Commonly 12–24 months where the plant runs 6,000 hours or more a year and the incumbent is a fixed-speed 8 bar machine. At 8,000 hours the payback shortens noticeably; below 4,000 hours it can stretch past three years, and fixing leakage comes first.
Sources and standards
- ISO 11011:2013 — Compressed air — Energy efficiency — Assessment. The method behind the baseline measurement and the leakage share quoted above.
- ISO 1217:2009 — Displacement compressors — Acceptance tests. Defines how delivered flow (FAD) is verified, which makes a 4 bar flow curve comparable with an 8 bar one.
- ISO 8573-1:2010 — Compressed air — Contaminants and purity classes. The purity classes that govern glaze-handling and instrument air in a ceramic plant.
- ISO 9001:2015 — quality management certification held by AirSpace Machinery Co., Ltd., with CE marking applied under Machinery Directive 2006/42/EC.
- Our published references — low-pressure compressor series, air compressors in the building-material industry and system-wide energy savings of air compressor stations.
About the author
Johnny Wayne (Wei Zhuang) is General Manager of AirSpace Machinery Co., Ltd., the Shanghai manufacturer behind ChinaCompressor.org. The company builds oil-injected and Class 0 oil-free screw compressors from 2 to 540 HP (1.5–400 kW), including the low-pressure series at 15–300 HP for 3–5 bar duty, on a 4,000 m² production facility with 20 years of engineering history behind it. Products carry CE marking and ISO 9001:2015 quality certification, and we sell through distributors rather than around them.
If you have a ceramic duty point, send the atomisation nozzle pressure, logged flow and hours, plus your tariff, to sales@chinacompressor.org, or start with the free compressed air kWh forecast and system review.
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