Bipolar plates, gaskets and end plates for stack assembly
Parts reordered by customers who assemble or maintain our stacks themselves. Orderable individually, or as a set matched to your stack configuration and cell count.
If this is your first stack, the stack itself is what you want, not the parts. This page is for reordering and servicing a stack you already run.
What this part does and what decides it
Building a stack is not only about the membrane and the electrodes. The gasket needs a material and a thickness, the bipolar plate and the end plates need a material, the compression bolts and nuts need a specification, and the compression itself has to be set. What survives alkaline service, and how hard to press, is not easy to find published anywhere. A gasket does more than stop leaks: it sets how hard the membrane is pressed. Get the thickness wrong and electrolyte leaks, or the membrane is over-compressed and hydrogen crosses to the oxygen side. We settled each of these on our own stacks, running them under those conditions. Those figures go out with the parts, and we specify and supply the compression bolts and nuts as well.
Inside the stack the material question comes down to one thing: will it hold up while it sits in hot, strong alkali. What each part has to do is set out in the table below. The alternative materials column is for electrolyte and potential windows nickel does not survive, or for different structural requirements. We start from the requirement behind the change.
A stack is not bolted together so much as pressed together, so how hard it is pressed is the figure that matters. Too little clamping raises contact resistance and lets it leak; too much crushes the porous transport layer and the membrane. The window is narrow, which is why the sequence is fixed. On HXS-2, a hydraulic press takes it to a 5 tonne gauge reading; the bolts then go up in two torque steps, 5 N·m and 7 N·m; and finally the compressed length is measured on four sides to check it has not gone in crooked. That is why reassembly needs aluminium blocks and callipers as well as the press. These figures are for the stack. Do not carry them over to a single cell or a large-area cell: the structure and the gasket arrangement differ, and the compression is set separately.
The tie bolts around the end plates are the compression bolts holding the stack together. Undo them and the stack opens. That is not the same job as taking the stack out of a system. Disconnecting pipework and wiring to lift the stack out is not opening it; disassembly begins the moment the compression bolts come off. The warranty turns on that distinction. Removing the stack and sending it to us is the normal return route; undoing the compression bolts is treated differently. How it is treated is set out below, under what happens to the warranty if you open the stack.
The options and the models we handle
Three routes, ordered by how far they take you from standard. We build these parts ourselves, so give us the conditions and we make them to suit.
A nickel-based plate with SUS316L end plates. Our published performance data was measured on this combination, so this is the only route where you can read it off as it stands.
Quote this option→The change leaves the geometry alone, so it is open on all three stacks. What we can build instead is listed in the alternative materials column below.
Quote this option→The flow-field geometry of HXS-2 and HXS-30 is fixed. HXS-0 is where you can design your own, and because it changes the structure we settle it with you from the drawings and operating conditions.
Talk to us about a structural change→Gaskets are tied to the stack rather than chosen: film gaskets on HXS-0, and on HXS-2 and HXS-30 a set of five EPDM types, six pieces per cell. The O-ring is one shape within that set.
Not alternatives to each other — these go in together, and we supply them individually or as a set. The alternative materials column lists what we can build instead. Note that changing material means the published performance data no longer applies as it stands; we state the validated scope with the quotation.
| Model | Material | Alternative materials | Stacks | Quote this |
|---|---|---|---|---|
Bipolar plate | Nickel-based metallic plate | Pure Ni · titanium · platinum-coated titanium | HXS-0 · HXS-2 · HXS-30 | Get a quote→ |
Film gasket | PTFE, FEP and other fluoropolymers | Can be changed | HXS-0 | Get a quote→ |
EPDM gasket set (five types, six pieces per cell) | EPDM | Cannot be changed | HXS-2 · HXS-30 | Get a quote→ |
End plate | SUS316L | Titanium · SUS304 · steel | HXS-0 · HXS-2 · HXS-30 | Get a quote→ |
What to settle before a quotation
Only what has come up more than once in real enquiries.
It depends on the product. HXS-2 and HXS-30 plates are made with dedicated tooling, so geometry stays and only material changes. For a custom flow field, HXS-0 is the route.
Not unchanged. We state the validated scope with the quotation. We start from the requirement behind the change: electrolyte, temperature and potential window.
Yes, but it is compression assembled, so reassembly needs a hydraulic press, and we supply a reassembly guide with it. Tell us before you open it if you do not have a press and we will work out an approach with you. Gaskets fail most often: the O-ring rides out of its seat and the MEA gasket shrinks inwards.
Any defect confirmed before you open it stays covered. Performance and leak-tightness after you have opened it are not warranted, because reassembly quality governs the result. If you need conditions to apply after reassembly, we agree them case by case. This applies to the bare stack. On the HXB-V1 system and the HXD-V1 dryer, opening the enclosure at all counts as a modification and falls outside the warranty.
No. Disassembly begins the moment the compression bolts come off. MEA service runs the same route: send us the stack and we open it, replace only the MEA and reuse the hardware.
Fill in only what you know. We ask about the rest.
Warranty — We verify conformity to specification and workmanship at handover. Spare parts on their own do not carry a term warranty, and performance under your assembly and operating conditions is outside its scope The 12-month term warranty attaches to the HXB-V1 system. It does not apply to spare parts bought on their own