# Dual-Dispense Airless Dual-Nozzle Geometry: Orifice Separation, Bulk Blending, and Viscosity Mismatch Limits
TL;DR — A dual-nozzle airless head pairs a divided chamber with two exit orifices: the separation between the orifices decides how the two phases meet, the blending happens in the bulk stream rather than in the pump, and the viscosity mismatch between the phases sets how far the pairing can be pushed. The catalog side is concrete — an airless family of 89 models with divided-chamber rows of 10+10, 15+3, and 30+3 ml, output in the 0.09–0.5 ml per stroke class, and verified components of outer and inner bottles, piston, and pump core. The dual-nozzle head itself is where the record goes quiet: no dual-nozzle airless model is recorded in the catalog; the geometry is a project-level configuration. Orifice separation, bulk blending, and viscosity mismatch limits are engineering guidance, with dosage/output and compatibility testing as the capability-level verification hooks.
Why: Two Chambers, Two Orifices, One Dose
A divided-chamber airless pump already keeps two phases apart until the stroke. The dual-nozzle head extends that idea to the exit: the phases leave through two orifices and meet on the way out, not inside the pump.
- Separation is the geometry. How far the orifices sit apart decides whether the two streams meet cleanly or interfere at the exit;
- Blending is the physics. With two separate channels, the mix happens in the bulk stream after both phases leave the head — and the order and intimacy of that meeting are set by the nozzle layout;
- Viscosity mismatch is the constraint. Two phases that flow at very different rates do not leave two identical orifices at the same speed, and the mismatch narrows the window the geometry can serve;
- The record is bounded. The airless family is catalog-verified; the dual-nozzle head falls outside the record, so the geometry below is project design.
How: From Divided Chambers to a Coordinated Exit
3.1 The record anchors the family, not the head
The airless family records 89 models with divided-chamber rows of 10+10, 15+3, and 30+3 ml, output in the 0.09–0.5 ml per stroke class, and material rows recorded for the family. The verified components of the family are the outer and inner bottles, the piston, and the pump core. These are the family anchors — chamber splits, an output class, a component set. On the dual-nozzle head itself the record is quiet: no dual-nozzle airless model is recorded in the catalog; the geometry is a project-level configuration.
3.2 Dual-nozzle geometry as a project-level configuration
Where a standard divided-chamber pump shares one exit, the dual-nozzle head gives each phase its own orifice. Nothing about that layering — the distance between the orifices, the angle of the two bores, the shape of the exit face — exists as a recorded catalog model. Each dual-nozzle build is configured per project and layered on the verified component base of the family.
3.3 Orifice separation and the bulk blend
The separation between the two orifices is the first design surface. Orifices close together let the two streams merge almost immediately into one ribbon, which favors a tight, homogeneous bulk blend; orifices set wider apart keep the streams distinct longer, which favors separation on the skin rather than in the stream. Which behavior the project wants — immediate blend or delayed contact — is decided by the geometry, and the separation distance in millimeters is not published; it is a per-project figure confirmed on the actual fill.
3.4 Bulk blending and the exit stream
The blend happens in the bulk, after both phases leave the head: the two streams collide or converge and the product lands as one stream even though it traveled in two channels. Because the mixing moment is outside the pump, the behavior is governed by the exit geometry and the flow rates — and a blend that looks homogeneous on one fill ratio can separate on another. The blend ratio and mixing behavior are per-project trial results, not catalog facts.
3.5 Viscosity mismatch limits
Two phases rarely flow alike. If the phases differ in viscosity, the thinner phase races through its orifice while the thicker lags in its channel, and the dual stream arrives unbalanced — one phase dominating early, the other catching up late. The viscosity mismatch a given geometry can tolerate is the real constraint of the format: it narrows or widens the acceptable formula window per project. No viscosity difference in centipoise is published; the mismatch limit is a per-project figure derived from the project's formula pairing.
3.6 The verification hooks: dosage/output and compatibility
Two capability-level capabilities anchor the family regardless of the head geometry. The dosage/output test answers whether each chamber's stroke still meets the output class. The compatibility test examines the formula–component pairing — including how the two phases behave at the interface with the nozzle and seal materials. Both are capability-level, parameter-free in the record, and judged against per-project criteria.
<pre class="language-mermaid"><code>flowchart LR
A[Airless family<br/>89 models] –> B[Divided-chamber rows<br/>10+10 / 15+3 / 30+3]
B –> C[Dual-nozzle geometry<br/>per project<br/>no recorded catalog model]
C –> D[Orifice separation + bulk blending<br/>guidance, per project]
D –> E[Viscosity mismatch limits<br/>per project]
E –> F{Dosage/output + compatibility verification}
F –> G[Release per project]
</code></pre>
What: Verified Program Data and the Verification Hooks
- Family scope: the airless family carries 89 catalog models;
- Divided-chamber rows: recorded splits of 10+10, 15+3, and 30+3 ml;
- Output class: output recorded in the 0.09–0.5 ml per stroke class — a family window, not a per-chamber spec;
- Components (verified): outer bottle, inner bottle, piston, and pump core;
- Material rows: material records exist for the airless family;
- Catalog boundary: no dual-nozzle airless model is recorded — the dual-nozzle geometry is a project-level configuration;
- Geometry boundary: orifice separation, bulk blending behavior, and viscosity mismatch limits are per-project figures — no separation distance in millimeters, blend ratio, or centipoise difference is published;
- Verification hooks (capability-level): dosage/output and compatibility tests — pass criteria configured per project.
Gotchas
- No dual-nozzle airless model exists in the catalog. The dual-nozzle head is a per-project configuration; do not cite a catalog model for a two-orifice build.
- Divided-chamber rows are family records, not geometry specs. 10+10, 15+3, and 30+3 are the recorded chamber splits; how the head meters either leg of the split is decided on the project.
- The blend is proved on the fill. A bulk mix that looks homogeneous on a bench formula can separate under a different ratio or viscosity; the exit behavior is a project test, not a catalog fact.
- Viscosity mismatch is measured per project. No centipoise difference is published; the mismatch limit a geometry can serve must be derived from the actual formula pairing.
- The output class is a family window. 0.09–0.5 ml per stroke is the recorded class; the delivered dose per chamber is confirmed on the project's own stroke.
- Capability is not a meter. Dosage/output and compatibility are recorded as capabilities; numbers and pass criteria are configured per project.
Related Resources
- Category: Bottles
- Related insights: Dual-Dispense Actuators: Orifice Divergence & Phase Mixing · Dual-Chamber Airless: Piston Sync & Viscosity Ratio · Dual-Piston Airless Stroke Balancing · Dual-Chamber Fresh-Mix Ampoules · The 12-Test Lab Matrix
- Quality & Testing Capabilities · Customization — dual-nozzle head configuration