How to prime the pen and clear air bubbles
Priming brings the piston rod up to the cartridge stopper after a cartridge goes in: turn the dose knob to 50 or 60 and press the button until the rod meets the stopper, and repeat that a few times if you need to. Do not force it; stop pressing once the rod sits gently against the stopper. Until the rod touches the stopper the pen pushes no liquid, which is why a freshly loaded pen can seem to deliver nothing on the first press. Prime after every cartridge change.
Once the pen is primed, clear the air before the first dose: sanitize the rubber stopper with an alcohol pad, screw on a new pen tip, dial 1 and press the button slowly until a bead of liquid appears. Every needle starts full of air, so repeat that bead check with each new pen tip. Resetting the piston is the opposite move, pushing the rod back into the pen by hand before a new cartridge goes in; the cartridge loading guide covers it.
How to prime the pen and clear the air
- Prime the pen: turn the dose knob to 50 or 60 and press the button until the piston rod meets the cartridge stopper. You may need to repeat this a few times. Do NOT force it: stop pressing once the piston sits gently against the stopper.
- Sanitize rubber stopper with alcohol pad, screw on new pen tip, dial pen to 1 and press button slowly until a bead of liquid appears. Pen is now ready to dispense.
What the bead tells you
A bead of liquid at the needle tip means the path from cartridge to tip is full of liquid and the mechanism is pushing. If nothing appears on the first press, dial 1 again and press again. If nothing appears after a few tries, the usual reasons are a loose cartridge holder, a needle that is not screwed all the way on, or a pen that has not been primed yet, so the piston rod is not at the cartridge stopper. Fix those before trying a new needle.
Air inside the cartridge
Air that was left in the cartridge when it was filled shows up as a bubble near the stopper. Hold the pen with the needle pointing up, tap the holder so the bubble rises to the needle end, then dial 1 and press as above until the bead appears and no bubble is left at the top. Repeat if a bubble remains. Large bubbles are best cleared at filling time with a vent needle, which is what the fill guide covers.
On the Auto Pen
The Auto Pen clears its air the same way with a small difference in feel: dial 1 or 2 units, hold the needle up, tap the holder, then press and hold the button until the dial returns to zero and you hear the click. The manufacturer says to repeat up to four more times and then try a new needle if no drop appears, and to do this every time you change a cartridge or a needle.
Why a drop appears after use
A small drop at the tip after the button has been pressed is normal with any pen needle. Liquid in the needle channel keeps moving for a moment after the mechanism stops. Keeping the button pressed for 10 seconds after the window reaches 0, removing the pen tip and only then releasing the button keeps that drop to a minimum. It is not a sign of a leak. Leaks are covered in the troubleshooting guide.
Watch the pen setup video on the how-to videos page.
Products in this guide
Related guides
For research use only. Not for human or animal therapeutic, clinical, or diagnostic use. Not FDA-approved.
