Last updated: October 28, 2026
Short answer: most syringe dispenser problems are not dispenser failures. They come from the components or the setup. Dripping usually means the vacuum setting or the piston is wrong for a thin fluid. Inconsistent shots usually mean air is trapped under the piston. Clogs usually mean the tip is wrong for the fluid. When nothing comes out at all, it is almost always air supply, the hose clip or a blocked tip. Use the table below to find your symptom, then read the matching section.
Quick Diagnosis Table
| Symptom | Most likely cause | First fix |
|---|---|---|
| Nothing comes out | No air to the dispenser, safety clip closed, clogged tip | Work through the two-level checklist below |
| Drips after the shot (thin fluid) | Vacuum too low, wrong piston, tip too narrow | Raise vacuum gently, use a blue LV Barrier piston, try a crimped or PTFE tip |
| Oozing or drooling after the shot (thick fluid) | Air trapped under the piston (piston bounce) | Purge air, check piston insertion, change piston type |
| Shot size varies | Air bubbles, piston bounce, too much pressure through too small a tip | Purge air, switch to a tapered tip, lower pressure |
| Fluid creeping up the outside of the tip | Wicking (capillary action) | PTFE-coated or chamfered tip |
| Fluid getting past the piston | Wrong piston, pressure and tip out of balance | Match piston to fluid, use a tapered tip for thick fluids |
| Fluid pulled back into the hose or dispenser | Suck-back from too much vacuum | Reduce vacuum, add a filter trap adapter |
| Cyanoacrylate curing in the tip or barrel | Wrong tip, moisture in the air supply | PTFE-lined tip, coalescing filter regulator |
Nothing Comes Out of the Tip
Nordson EFD’s service desk recommends two levels of checks before anyone assumes the equipment has failed.
Level 1, setup: is the dispenser plugged in and powered on, is the foot pedal connected, and is the air hose connected to a compressed air source?
Level 2, quick diagnostics:
- Remove the adapter head from the barrel and cycle the dispenser. If no air comes out, the problem is upstream in the shop air.
- Check the safety clip on the adapter hose. If it is closed, nothing will dispense.
- Swap in a new tip. Clogs are common with thick pastes and cyanoacrylates when the tip style doesn’t suit the fluid.
- Check the vacuum (suck-back) setting so fluid hasn’t been pulled into the dispenser.
Still stuck? Call us at 562-698-0901 and we will walk through it with you.
Dripping After the Shot
Thin fluids flow under gravity, so they react to the smallest pressure change. Three fixes, in order:
- Adjust vacuum. Dispensers apply a slight vacuum after each shot to hold thin fluid in the barrel. Raise it gently until the drip stops. Too much vacuum pulls fluid back toward the dispenser.
- Use a barrier piston. The blue LV Barrier piston has the tightest fit and a small vent hole. It sits about an inch above the fluid and stays in place while the dispenser cycles between pressure and vacuum. Do not use an orange flat-wall piston with watery fluids.
- Change the tip. A crimped cannula slows the flow. Per Nordson EFD, a cannula slightly larger than the minimum can actually reduce dripping, because a very narrow bore holds fluid by capillary action.
For very thin fluids, a low-pressure dispenser (0–15 psi) such as the Ultimus II or Performus X15 gives you finer control. See our dispenser comparison.
Oozing and Inconsistent Shots: Piston Bounce
Piston bounce happens when air collects between the piston and the fluid. Air compresses, so pressure on the piston no longer equals pressure on the fluid, and the piston springs back up after each shot. The result is oozing and shot-to-shot variation. Nordson EFD lists four causes:
- Wrong piston. The white SmoothFlow piston fits about 90% of applications. For thick, stringy RTVs, use the orange Flatwall piston. For very thick or particle-filled materials at high pressure or high cycle rates, use the Clear Flex piston. See how to choose a syringe piston or shop pistons.
- Air left in during insertion. Squeeze the barrel where the piston sits and push the piston down until it touches the fluid. If that doesn’t release the air, slide a soft shim, such as fishing line, alongside the piston while inserting it. Don’t use a wire, which can damage the wipers.
- Bubbles in the fluid. See the next section.
- Too much pressure or speed. Forcing a thick paste through a narrow tip with high pressure pushes air past even a tight piston. Switch to a SmoothFlow tapered tip. Nordson EFD reports pressure dropping from about 80 psi on a general purpose tip to about 30 psi on a tapered tip for thick fluids.
Air Bubbles in the Syringe
Bubbles get in during filling, from shipping (pressure and vibration), from thawing frozen fluids too fast, and from air bypassing the piston during high-speed dispensing of thick pastes. To get them out:
- Pourable fluids: turn the barrel tip-up, tap the side so bubbles rise, remove the tip cap and gently push the piston up to purge them.
- Thick fluids and pastes: tapping won’t work. Run the barrel in a centrifuge to collect bubbles at the tip end, then purge.
- Storage: store filled barrels vertically, tip down, so air migrates to the piston. Before use, squeeze the barrel at the piston to release it.
- Frozen fluids: follow the fluid manufacturer’s thaw instructions. Heating too fast creates voids between the fluid and the barrel wall.
Prevention is easier than cure. Fill to about two-thirds of the barrel, bottom-fill thick fluids, and don’t rush the fill rate. Our syringe barrel guide covers filling.
Fluid Getting Past the Piston
Three usual causes: the piston type doesn’t suit the fluid; pressure, tip size and cycle time are out of balance (for example, very high pressure forcing a thick fluid through a very small tip); or the tip itself is wrong, since general purpose tips compress thick fluids at the hub. One exception: the orange Flatwall piston is designed with a small gap, so some residue on the barrel wall is normal and expected with RTVs.
Wicking: Fluid Climbing the Tip
Thin fluids such as solvents can creep up the outside of a metal cannula by capillary action, which throws off deposit accuracy. A PTFE-coated tip breaks the capillary effect, and a chamfered tip reduces the surface area at the end. Browse chamfered tips or the dispensing tip gauge chart.
Suck-Back: Fluid in the Hose or Dispenser
If vacuum is set too high, thin fluid can be pulled into the air tubing or the dispenser itself, which can damage the controller. Reduce vacuum, use a piston, and fit an adapter assembly with a filter trap (also available for 10cc, 5cc and 3cc barrels).
Cyanoacrylate Clogging and Curing
Cyanoacrylates (instant adhesives) cure fast, and moisture speeds that up. Use a PTFE-lined tip for thin CAs and a tapered polyethylene tip for gel CAs. Keep the barrier piston clear of the fluid so it doesn’t bond to the barrel wall. A filter regulator with a coalescer on the air line keeps moisture from curing the CA inside the barrel. More detail is in dispensing by fluid type.
Don’t Reuse Barrels or Tips
Nordson EFD designs syringe barrels and tips for single use. Cleaning leaves residue, can change the barrel surface, and risks blocked tips. Reuse costs far more in scrap, rework and downtime than it saves.
Get Help on Your Bench
J.A. CRAWFORD CO. supports Nordson EFD users across Southern California, Arizona and Baja Mexico. Tell us the fluid, the symptom and your current barrel, piston and tip, and we can usually point to the fix. We can also come out and look at the process. Email technicalservices@jacrawfordco.com or order replacement components online.
Frequently Asked Questions
Why is my syringe dispenser dripping after each shot?
With thin fluids, the usual causes are too little vacuum, the wrong piston, or a tip that is too narrow. Raise vacuum gently, switch to a blue LV Barrier piston, and try a crimped or PTFE tip. A 0–15 psi dispenser also gives finer control of thin fluids.
What is piston bounce?
Piston bounce is air trapped between the syringe piston and the fluid. Because air compresses, the piston rebounds after each shot, causing oozing and inconsistent deposits. Causes include the wrong piston, air left in during insertion, bubbles in the fluid, and excessive pressure or speed.
Why is nothing coming out of my dispense tip?
Check power, the foot pedal and the air supply first. Then remove the adapter head and cycle the dispenser to confirm air flow, make sure the adapter hose safety clip is open, replace the tip in case it is clogged, and check the vacuum setting.
How do I get air bubbles out of a syringe barrel?
For pourable fluids, point the tip up, tap the barrel, remove the tip cap and push the piston up. For thick pastes, use a centrifuge. Store filled barrels tip-down, and squeeze the barrel at the piston before use to release trapped air.
Can I reuse syringe barrels and dispensing tips?
No. Nordson EFD designs them for single use. Residue and surface changes from cleaning make results unpredictable, and reuse can block tips.