Title: Duckbills vs. Valves+Membranes
Question:
What are your thoughts on use? Which do you prefer? I personally find the valves and membranes easier to put on / take off and sterilize than the duckbills, but I’m not sure if there’s a difference in the quantity of milk output I get. I’m an undersupplier, so if duckbills are better, I’ll deal with their hassle to get more output. Have you noticed a difference?
ETA: I’m talking about the medela style hard plastic valves with the thin silicone membranes that also attach where the duckbills go, not the silicone backflow protector membranes.
DuckbillValveFactory.com Answer
DuckBillValveFactory expert here. From a fluid dynamics and sealing performance standpoint, duckbill valves are generally superior for breast pump applications — especially for someone who is an undersupplier.
Here’s why:
Cracking pressure – Duckbill valves typically have a lower and more consistent cracking pressure (the minimum vacuum needed to open the valve). The Medela‑style hard plastic valve + thin silicone membrane relies on the membrane lifting off a flat seat. That design often requires a slightly higher initial vacuum and can be more prone to “sticktion” (the membrane adhering to the seat), delaying opening.
Backflow prevention – Duckbills close instantly and symmetrically when pressure reverses, preventing any retrograde milk flow back toward the breast. The membrane type can sometimes warp or not seat perfectly after repeated use, leading to micro‑leaks that reduce effective vacuum at the nipple.
Output evidence – Anecdotally and in some small‑scale lactation studies, switching from membrane‑style valves to fresh duckbill valves has been reported to increase output by 10–30% in undersuppliers. The reason is simple: any loss of peak vacuum or delay in opening directly reduces extraction efficiency.
Hassle vs. yield trade‑off – You said duckbills are more hassle. That’s true — they wear out faster (every 2–4 weeks for exclusive pumpers) and can be trickier to dry completely. But for an undersupplier, every mL counts. I would absolutely recommend tolerating the extra hassle if you see even a modest gain.
My practical advice:
Buy a fresh set of duckbill valves (genuine or high‑quality third‑party like Maymom or Nenesupply). Run a side‑by‑side test for 2–3 days with each type, keeping all other variables the same (same pump, same flange fit, same time of day). Measure output. I’m quite confident you’ll see a difference.
If the difference is negligible for you, go back to the membranes for convenience. But don’t assume “no difference” without testing — your supply is too precious to leave milk on the table.