The sequence from the stack in place to your first hydrogen, in nine steps.
The HXS-30 is a 46-cell, 30 kW stack. You build the rectifier, electrolyte circulation, cooling, gas handling, instrumentation and interlocks around it. The connection specification is in the datasheet, and if you send us your system conditions we will agree the interface with you.
- PrerequisiteAn external BoP and a DC supply
- Rated input80 V · 360 A
- Recommended condition0.1 M KOH · 50 °C
- PPEEye protection · alkali-resistant gloves
First timeWork through the nine steps in order. This is a bare stack, so the BoP has to exist first. Step 1 lists what you need.
Done this beforeRe-check the ports and the loop, then jump to the first run. The operating range and the shutdown sequence are in the operation and shutdown chapter.
On this page1. What you need in place
1. What you need in place
1 × DC power supplyThe rated operating point is 80 V at 360 A. Stack voltage rises during operation, so we recommend a supply able to deliver up to about 92 V. It needs a constant-current mode.
Electrolyte circulation and temperature controlA tank, a circulation pump, a heat exchanger and cooling, all in KOH-compatible materials. Design the cooling to carry away the heat a 30 kW-class stack produces.
Gas-liquid separation and purificationGas-liquid separation after the hydrogen outlet, and drying or purification equipment for the purity you need.
Pressure and safety systemsUp to 10 barg on the hydrogen side, with the anode at atmospheric pressure. Provide pressure protection, detection, interlocks and an emergency stop to suit.
Electrolyte and DI waterFor the first fill, 0.1 M KOH in DI water; for make-up during operation, DI water.
Photos show the type of item only.
2. Identify the ports
Find the labels on the stack and confirm the four connections below. Naming can vary by revision, so follow the labels on the unit you received.
| Connection | What passes through | Fitting |
|---|---|---|
| Electrolyte inlet | Electrolyte in | 1-inch double ferrule |
| Oxygen and electrolyte outlet | Oxygen and electrolyte out, together | 1-inch double ferrule |
| Hydrogen outlet | Hydrogen out | 3/4-inch double ferrule |
| DC terminals | DC power in | M10 |
3. Connect the electrolyte loop
A typical arrangement leaves the tank and comes back to it.
- Tank → pump → heat exchanger → electrolyte inlet → oxygen and electrolyte outlet → tank
- Connect the tank outlet to the circulation pump inlet.
- Place the pump below the tank liquid level. With the suction side always flooded, it does not draw in air.
- Do not use the pump to pressurise the anode loop. The anode side runs at atmospheric pressure.
- Connect the pump outlet through the heat exchanger to the stack's electrolyte inlet.
- Return the oxygen and electrolyte outlet to the tank.
- The return has to flow smoothly. A line that climbs and falls traps gas and interrupts the return.
- Do not neck the return line down below the port size (1 inch).
4. Connect the hydrogen line
- Connect a 3/4-inch line to the hydrogen outlet.
- Route the hydrogen outlet to a safe, well-ventilated discharge point, or to approved downstream equipment.
- Downstream you need gas-liquid separation: moisture leaves with the hydrogen.
5. Fill the electrolyte
Before filling, check the loop connections and the tightness of the fittings again.
- Make up 0.1 M KOH in DI water.
- KOH of 95% purity or better, and water to ASTM D1193 Type II (1.0 µS/cm or below at 25 °C) recommended. The maximum is 30 µS/cm.
- Fill the tank to a level that suits your circulation loop.
- Run the circulation to purge air from the loop and the stack, then top the tank back up.
6. Set flow and temperature
- Start circulation and confirm the flow is stable.
- Control the electrolyte temperature to 50 °C.
7. Connect the DC supply
- Connect supply + to stack + and supply − to stack −.
- Size the cables and lugs for 360 A continuous.
- Tighten the M10 terminals securely.
- Confirm the tightening torque with us on delivery. Over-torque damages the terminal; under-torque overheats the joint.
- Verify the polarity again before switching on.
8. Start the first run
- Confirm circulation is running and flow and temperature are stable before applying current.
- Set the DC supply to constant current.
- Ramp the current in steps up to the rated 360 A.
- At each step, confirm flow, temperature control and voltage response are normal before moving to the next.
- Heat rises with current. Check that the cooling keeps up.
9. First-run checks
Once at rated current and after a short hold, confirm three things.
- No electrolyte leaking at the stack ports, the fittings or the cell edges, by eye.
- The electrolyte flow and temperature are stable.
- Stack voltage rises sensibly with current. The first-run measurement in the datasheet is about 76 V for the stack at 362 A (1.660 V per cell).
What to record
Once the first run is stable, write that day's values down once. It becomes the starting point when you read the voltage trend later.
| Item | What to write down |
|---|---|
| Identification | Model and serial number, from the label |
| Operating point | Stack current and voltage, electrolyte flow and inlet and outlet temperatures, at the operating point you have chosen |
| Cell voltages | If you can measure them, the individual cell voltages and the spread between the highest and the lowest |
| If instrumented | Hydrogen flow and pressure, hydrogen purity, hydrogen in oxygen |
| Electrolyte and water | Make-up date and concentration, feed-water quality |
What this chapter is based on
- HXS-30 datasheetPDF · 502 KB
- HXS-30 exterior STEP modelOn request
Ask the engineer who built it
If your case is not covered here, send us the operating condition and what you observed. The engineer who designed the system answers directly.