The number of colours is one of the three inputs we will not quote without. It changes the valve stack, the paint supply, the flush system, the waste handling and the cycle time — and unlike reach or payload, it is a number the customer often gives from marketing intent rather than from production data.
How a colour-change stack is built
A colour-change valve block is a manifold with one circuit per colour plus circuits for solvent and air, all feeding a single line to the applicator. Every colour is a valve, a fitting and a supply line back to the mixing room, so the cost is close to linear in the number of colours.
We supply the CV3000 block for high-pressure circuits and the CV300 for low-pressure work. The choice follows the fluid pressure the applicator needs — an air-assisted airless line and an air-spray line are not the same duty.
What a colour change actually costs per event
- Solvent for the flush, and the paint left in the line from the valve to the gun — which is why the valve block sits as close to the applicator as the arm allows.
- Cycle time: every change is dead time on the line. On a 12-colour base-coat line with a moving conveyor, batching by colour is what makes the layout work at all.
- Waste: flush solvent and purged paint become hazardous waste with a disposal cost and a handling procedure.
Sizing it honestly
| Situation | Sensible stack | Why |
|---|---|---|
| One colour, occasional variant | Single-colour supply plus solvent | A diaphragm pump and a flush line; no manifold needed |
| 2–4 colours, batched production | 3-colour + solvent block | Batching absorbs the change time; a small stack keeps the cost down |
| Wide colour range, mixed sequence | 12-colour / 15-way block | The stack is priced once, but the paint supply and flush system grow with it |
| 2K topcoat over a colour range | Colour block plus 2K mixing at the arm | Hardener is added after the colour selection, so the mixed material is never in the stack |
The question to ask the production planner
Not "how many colours does the catalogue have" but "how many colour changes will there be per shift, and can they be sequenced". Twelve colours run in batches is a different machine from twelve colours run in random sequence — the second needs a faster change, more solvent capacity and, often, an extra robot to hold the cycle time.
That answer belongs in the specification, because it is the number that sets the quotation. We quote a stack against a stated change frequency, and the offer names the block, the number of circuits and the flush arrangement as separate lines.
Frequently asked questions
Can I add colours later?
To a point. A block has a fixed number of circuits; adding beyond that means a new block, new supply lines and revalidation of the flush. If growth is likely, buy the circuits now — spare circuits are cheap compared with a rebuild.
Where should the colour-change block be mounted?
As close to the applicator as the payload and the arm geometry allow. Every centimetre of line between the block and the gun is paint lost and solvent used at every change.
Does the block need to be explosion-proof?
The block is a fluid component inside the booth and is selected for the zone with the rest of the in-booth equipment. The robot certificate covers the manipulator, not the paint circuit — the two are assessed together in the installation.
Request a quote Send drawings and we check the selection before quoting.