In a tile factory, pulse cleaning a bag or cartridge dust collector uses around 150 to 250 l/min per unit, in pulses at 5 to 7 bar. With three or four dust collectors on the presses, the glazing lines and body preparation, that often comes to 0.5 to 1 m³/min on its own. The air must be dry: the slightest moisture turns clay dust into a crust on the filter bags that no pulse will shift.
The air needs of the whole factory, from glazing to pressing, are covered on our page compressor for ceramics and glazing. Here, we focus on pulse cleaning. The general principle of the bag filter is explained in our article compressor for bag filter pulse cleaning.
Where are the dust collectors in a tile factory?
A tile factory produces dust at almost every stage. The dust collectors are generally found:
- in body preparation: grinding, batching and conveying the raw materials;
- at the spray dryer, which turns the slip into pressing powder;
- at the presses, where the powder is loaded into the dies and then compacted;
- on the glazing lines, to capture glaze overspray and the dust from brushing the green tiles;
- at sorting and squaring of the fired tiles, where grinding the edges produces very fine dust.
Each of these units filters the extracted air through bags or cartridges. To keep them from blocking, a solenoid valve sends a reverse pulse of compressed air at regular intervals, which knocks the dust cake down into the hopper.
How much air does pulse cleaning use?
Consumption depends on the number of bags, the volume of each pulse and the frequency set on the sequencer. The dust collector manufacturer gives it in the manual, often in litres per pulse or as an average in l/min. As a guide:
| Dust collector | Consumption of around |
|---|---|
| Small local unit (booth, squaring machine) | 50 to 150 l/min |
| Press or glazing line dust collector | 150 to 250 l/min |
| Large body preparation or spray dryer dust collector | 300 l/min and more |
If the manual gives litres per pulse, multiply by the number of pulses per minute to get the average flow.
The step-by-step calculation for a tile factory
Example of a medium-sized tile plant (indicative figures, to be replaced with those from your manuals):
- 4 dust collectors (2 presses, 1 glazing line, 1 squaring) at 200 l/min: 800 l/min
- 2 presses, ejection and demoulding, at 150 l/min: 300 l/min
- 2 spray glazing booths or stations at 300 l/min: 600 l/min
- transfer line cylinders: 200 l/min
- 2 blow guns at 150 l/min, counted at 50%: 150 l/min
- total: 2,050 l/min
With the margins from our configurator: 2,050 × 1.25 = 2,563 l/min for safety, then 2,563 × 1.2 = 3,075 l/min with expansion, or about 3.1 m³/min at 8 bar (roughly 110 CFM).
The S 220 PM, a 22 kW permanent magnet screw compressor, delivers 3.6 m³/min at 8 bar: it covers this need. For a smaller unit, with two dust collectors and one press, the K 150 (2.2 m³/min, 4-in-1) or the S 150 (same flow, standalone compressor) is enough. Beyond that, the S series goes up to 132 kW on quotation.
Why must pulse cleaning air be dry?
This is the most important point in ceramics. Clay, grog and glaze dust absorbs water. If the pulse air contains droplets, it dampens the inside face of the bags with every pulse. The dust sticks to it, hardens and forms a crust. The pressure drop across the filter rises, extraction weakens at the presses and booths, and the bags have to be changed long before the end of their life.
Water causes other problems too: it builds up in the dust collector's pulse tank, makes the solenoid valve diaphragms stick and, in winter, can freeze in outdoor pipes.
The minimum treatment is a refrigerated dryer at the compressor outlet, with an automatic drain on the air receiver and at the low points. For a dust collector installed outdoors, where the pipe can drop below zero, a desiccant dryer on that line prevents freezing.
What pressure for pulse cleaning?
Most pulse-jet dust collectors work between 5 and 7 bar; the exact figure is on the rating plate or in the manual. Too low, and the pulse does not knock off the cake; too high, and it wears out the bags. Set the compressor between 7 and 8 bar to cover the network losses, and fit a regulator with a pressure gauge at the inlet of each dust collector.
The dust collector's pulse tank must refill between two pulses. If it is a long way from the compressor, supply it through a pipe of sufficient diameter so that the pressure does not collapse while it refills.
Pulse cleaning pitfalls in ceramics
- Pulse cleaning that runs overnight. Many sequencers carry on pulse cleaning after production has stopped. With a variable speed compressor, the flow adapts to this small demand instead of running off-load.
- A sequencer set too short. Pulses that are too frequent use air for nothing. Pulse cleaning controlled by the filter's pressure drop cuts consumption.
- Leaks on the solenoid valves. A split diaphragm blows continuously. Listen to the dust collectors once production has stopped, and put a figure on the leaks with our leak cost calculator.
- The compressor next to the dust collector. Its air intake would breathe the dust the filter has not caught. See our article on ceramic dust and the air intake.
- ATEX zones. Some organic dusts added to the body or present in binders can be combustible. If your dust collector is classified as an ATEX zone, the compressor stays outside that zone; have the layout approved by your safety manager.
To size the compressor for your factory, enter dust collectors, presses and booths in the configurator, or send us your dust collectors' manuals with a quote request. Our technicians can also measure actual consumption during a compressed air audit.
For your trade: Compressor for ceramics and glazing.