Work / Mass Production

Design the
Competition In

How making a safety-critical subsystem supplier-agnostic drove a 35% cost reduction — and why procurement strategy is an engineering discipline.

Client
Hydrogen electrolyser manufacturer
Scale
7,500+ units in mass production
Disciplines
Mechanical Design Fluid Systems Mass Production Supply Chain Leak Testing Safety Systems

When a hydrogen electrolyser company decided to redesign their single-core electrolyser for mass production, every subsystem needed to be rethought — not just for performance, but for manufacturability, cost, testability, and supply chain resilience at scale.

The gas block is a safety-critical subsystem at the heart of the electrolyser. It takes hydrogen directly from the stack and manages everything that happens to it before it leaves the unit: filtering aerosol water and chemical impurities from the gas stream, regulating upstream stack pressure, and providing multiple independent layers of safety protection against dangerous pressure excursions.

In the original design, this system was assembled inside the electrolyser frame — component costs alone exceeded the eventual target for the fully assembled, tested, and delivered subsystem. The brief was clear: redesign for mass production, reduce cost, improve performance, and make it manufacturable and testable as a standalone modular unit.

The modular architecture and supplier competition strategy were not part of the original brief — both emerged from the engineering process itself. The decision to make the subsystem fully testable as a standalone unit before it ever reached the production line, and to structure the component specification to allow genuine supplier competition, were defining choices that shaped everything that followed.

The gas block was redesigned as a self-contained modular unit — fully assembled, leak tested, and validated by the supplier before delivery. On the production line, installation is a single clip-in operation.

The gas management system handles the full hydrogen conditioning sequence in a compact package:

1
Coalescing filter — captures aerosol water generated during electrolysis
2
Dual-chamber amine filtration — removes chemical impurities from the gas stream (subject of a patent application)
3
Pressure regulator — maintains upstream stack pressure at 30 bar
4
Bulkhead pressure sensor — monitors downstream pressure for blockage detection
5
Solenoid valve — triggers on dangerous pressure rise, connects to purge reservoir
6
Mechanical safety relief valve — final independent protection layer if solenoid valve fails

The design was made deliberately agnostic to component supplier — fittings, tubing, sensors, and CNC parts were all specified to allow multiple suppliers to compete for the mass production contract. Two suppliers — Voss and Serto, both established industrial fluid system specialists — were selected for the initial production period to maintain competitive pressure and dual-source security. A single final supplier was selected based on long-term performance and consolidation efficiencies.

Pass/fail leak test thresholds were established through a dedicated experimental campaign conducted in collaboration with Pfeiffer Vacuum. Those thresholds remain in use today.

Supplier acceptance meeting with Serto in Switzerland, 2021, with gas block components on the workbench
Supplier acceptance meeting with Serto, Switzerland — 2021. Gas block components on the bench. Photo: Ralph Caldecott
A patent application has been filed on the dual-chamber amine filtration design. A separate blog post examines the trade-offs between single and double ferrule fittings — a key decision in the sealing architecture of this subsystem.
>35%
Cost reduction per subsystem — from components-only (no assembly, no test) to a fully assembled, leak-tested, and validated delivered unit at a lower absolute price
Only one
Subsystem across the entire electrolyser redesign programme to meet and exceed every original target
7,500+
Units in mass production — <1% leak test failure rate; failures attributable to assembly error, always detected before leaving the supplier
Clip-in
Installation on the production line — fully validated subsystem arrives ready to use, zero assembly required
Patent
Application filed on the dual-chamber amine filtration design
Mechanical Design CAD Fluid Systems Hydrogen Safety Leak Testing Mass Spectrometry Supply Chain Management Supplier Competition Production Engineering Modular Design Pressure Regulation Safety Architecture

The most underrated engineering skill is knowing how to use a procurement process as a design tool. Making the subsystem supplier-agnostic wasn't just good engineering practice — it created real commercial leverage. Suppliers who know they can be replaced perform differently from those who know they can't. The price reductions were significant, but the improvement in supplier focus and quality commitment was equally valuable and harder to quantify. Good design and good procurement strategy are not separate disciplines.

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