For an independent glazier with a cutting table and an edging machine, a 7.5 kW 4-in-1 screw compressor such as the K 75 (1.1 m³/min at 8 bar) is enough. A glass workshop that adds a second edger, a washing machine and vacuum lifters moves up to a K 110 (1.7 m³/min). A processor with an insulating glass line aims for a K 150 (2.2 m³/min) or more. The choice comes down to a simple calculation, set out below.
The air demand of the whole trade, from the toughening furnace to the sandblaster, is covered on our page on the compressor for glass processing and glazing. Here, we start from the workshops.
Which machines use air in a glass workshop?
Walk round the workshop and note every machine with an air supply. In a glass and glazing workshop, you will almost always find:
- the cutting table, which applies the cutting wheel, breaks out the cuts and sometimes lifts the glass on an air cushion;
- one or more edging or arrissing machines, driven by cylinders;
- the glass washing machine, with its pneumatic valves and blow-off nozzles;
- vacuum lifters and suction cups, when they work by venturi;
- cleaning blow guns, at the cutting station and at edging;
- sometimes a glass drilling machine, a sandblaster or an insulating glass line.
For each one, take from the manual the consumption in l/min (or CFM, or litres per cycle) and the pressure required. Failing that, the indicative values in this article give an order of magnitude, but they do not replace the manual.
How do you work out the air flow you need?
The method is the one our configurator uses:
- Add up the machines that work at the same time. A machine in continuous use (edger in production, sandblaster) counts at 100%.
- Count tools used in bursts at 50%. A blow gun or a vacuum lifter does not draw air all the time; the air receiver absorbs their peaks.
- Add 25% for safety, to cover leaks, wear and network losses.
- Add 20% for expansion, for the machine you will buy in two years' time.
Taken together, the two margins bring the base total to 1.5 times its value.
Workshop 1: the independent glazier
A manual cutting table with pneumatic breaking, an arrissing machine and a blow gun.
- cutting table: 200 l/min
- arrissing machine: 120 l/min
- blow gun, counted at 50%: 75 l/min
- base total: 395 l/min
With the margins: 395 × 1.25 = 494 l/min, then 494 × 1.2 = 593 l/min, or about 0.6 m³/min.
The K 75 gives 1,100 l/min at 8 bar. It covers this workshop with spare capacity, and brings together the compressor, a 420 L air receiver, a refrigerated dryer and filtration on a single frame. The S 55, at 0.6 m³/min, would be tight: with no built-in dryer, you would also have to add air treatment. For an independent glazier, the 4-in-1 is the simplest solution.
Workshop 2: the glass shop that edges and washes
An automatic cutting table, two edging machines, a washing machine, two vacuum lifters and two blow guns.
| Station | Indicative value | Counted |
|---|---|---|
| Cutting table | 250 l/min | 250 l/min |
| Two edging machines | 2 × 150 l/min | 300 l/min |
| Washing machine | 100 l/min | 100 l/min |
| Two vacuum lifters (50%) | 2 × 120 l/min | 120 l/min |
| Two blow guns (50%) | 2 × 150 l/min | 150 l/min |
| Base total | 920 l/min |
With the margins: 920 × 1.25 = 1,150 l/min, then 1,150 × 1.2 = 1,380 l/min.
The K 75 is no longer enough. The K 110 delivers 1,700 l/min at 8 bar, with a 340 L receiver. Our configurator recommends about one litre of receiver for every 3 l/min of demand, so around 460 L here: an additional air receiver placed near the cutting table smooths the peaks from breaking and the lifters. The air receiver size calculator refines this volume.
Workshop 3: the processor with insulating glass
Workshop 2, plus an insulating glass line (press and conveyors) at 400 l/min and a second edging station at 150 l/min.
- base total: 920 + 400 + 150 = 1,470 l/min
- with 25% safety: 1,838 l/min
- with 20% expansion: 2,205 l/min
That lands right at the limit of the K 150, which gives 2,200 l/min at 8 bar. Two options are reasonable: the K 150 if the planned expansion is uncertain, or the S 220 PM, 3.6 m³/min at 8 bar, with a separate dryer and filters, if a sandblaster or a second line is on the cards. When losing air stops the line, two compressors taking turns are also a good answer: see backup compressor and redundancy.
What pressure should you set?
Glass machines generally need around 6 bar at their inlet. Allowing for the dryer, filters and pipework, set the compressor between 7 and 8 bar. Going up to 10 bar "to be on the safe side" costs electricity and makes the network leak more, without giving the machines anything. If a machine shows a low pressure alarm, first look for a drop in the network: a clogged filter, a pipe that is too narrow or an undersized quick coupling. The pressure drop calculator helps you check the pipe diameter.
Common mistakes in glass workshops
- Choosing on the average. Breaking and suction cups draw air in bursts. Without a big enough receiver, the pressure drops just as the table breaks.
- Forgetting the dryer. A compressor without a dryer sends water into the suction cups and blow guns, and the water ends up on the glass.
- Neglecting filters at the station. Treatment at the compressor outlet is not always enough for a face that will be bonded or silvered. See oil in compressed air.
- Installing the compressor in the workshop. Glass dust is abrasive for the intake filter and the cooler.
The S and K series are variable speed and run on 380 V three-phase. Between two cuts, the compressor slows down instead of running idle.
For your own workshop, enter your machines in the configurator, or send us the list of your stations with a quote request.
For your trade: Compressor for glass processing, glaziers and double glazing.