Can I manually fill an EFD syringe barrel

Yes, EFD syringe barrels can be filled manually.

How do I manually fill a syringe barrel?

The technique used to fill syringes is important. The key is to avoid introducing air bubbles during the filling process. Air bubbles can degrade deposit quality and lead to scrap and rework. Here, we share our best practices for manually filling syringe barrels with fluids of all viscosities, with a special focus on avoiding pitfalls.

Filling syringe barrels with high-viscosity fluids

Bottom filling is the best way to avoid introducing air bubbles during manual filling with particle-filled pastes and thick fluids. There are two main approaches, depending on the packaging of the bulk material:

• Filling from prepacked cartridges
• Filling from caulking tubes

Filling from prepacked cartridges

Off-the-shelf syringe barrel filling systems minimize effort while providing good control over fill rate and fill level. These pneumatic systems use compressed air to push fluid from the prepacked cartridge into the syringe barrel being filled (see Figure 1).

Figure 1: Manually-operated pneumatic filling systems consist of a retainer system (cylinder and cap), a pressure regulator, and a toggle switch to control fill rate and level. A weighted indicator provides a visual reference for fill level.

The key steps for successful bottom filling of syringe barrels from prepacked cartridges are:

1. Insert a pre-filled cartridge into the retainer cylinder. Attach the cap to the retainer cartridge and connect the pneumatic fitting that funnels the compressed air into the cartridge.
2. Insert a piston into the empty syringe barrel and push it all the way down to the bottom. Screw the syringe barrel into the fitting at the outlet of the cartridge.
3. Insert a weighted barrel-fill-level indicator into the empty syringe barrel, resting it on the piston (see Figure 2). This will help ensure that the piston remains in contact with the fluid column during filling. Note, the indicator should match the size of the syringe barrel being used.
4. Open the toggle switch and let the compressed air dispense fluid from the cartridge into the syringe barrel until the barrel is two-thirds full. This will be indicated by the line on the barrel fill level indicator reaching the top of the syringe (see Figure 3).

Figure 2: Nordson EFD’s Atlas 920 Series barrel loaders feature a 0 to 100 psi regulator gauge, a sturdy stand, and indicator plugs with easy-to-read fill level markings for 3cc to 70cc syringe barrel reservoirs.

Figure 3: Weighted indicator makes it easy to manually fill syringe barrels to exact levels.

Filling from a caulking tube

Off-the-shelf systems for filling syringe barrels from caulking tubes operate in a similar way to the systems for prepacked cartridges (see Figure 4).

Figure 4: Our Atlas 940 Series filling system operates in a similar way to the cartridge filling system, with a retaining cylinder, stand, pressure regulator, and manually operated toggle switch (top). The Atlas 940 is compatible with 3cc to 70cc syringes. A weighted indicator makes it easy to stop at the maximum fill level of about two thirds full (bottom).

Pitfalls to avoid

It can be tempting to speed the process by boosting the fill rate, but that can backfire. Excessively high fill rates can introduce air bubbles, even with bottom filling. Although there are easy techniques for removing air bubbles (see How do you purge air from a syringe barrel ?), the best approach is to avoid introducing them to begin with.

Manually filling syringe barrels with low-viscosity fluids

For pourable thin fluids, the best approach is top filling. Once again, the goal is to fill the syringe without introducing air bubbles. In general, top filling introduces more bubbles than bottom filling, so it’s important to use good technique. Start by tightening up the tip cap to prevent leaks. What happens next depends upon the type of fluid.

Filling syringes with non-adhesive pourable fluids like oils

For non-adhesive pourable fluids, follow these steps:

1. Tilt the syringe barrel at an angle while filling to help prevent bubble formation.
2. Stop when the syringe barrel is two-thirds full.
3. Insert a general-purpose piston like the Nordson EFD white piston (see Figure 5), pressing the piston down until the fluid column reaches the lower wiper. Gently squeeze the barrel as you insert the piston to allow any air trapped under the piston to escape.
4. Store the filled syringe barrels upright with luer-end down in a vertical rack. Any bubbles will rise to the top.

Filling syringes with non-adhesive watery fluids

For non-adhesive watery fluids, follow these steps:

1. Tilt the syringe barrel at an angle while filling to help prevent bubble formation.
2. Stop when the syringe barrel is two-thirds full.
3. Insert a piston with a perforation, like the Nordson EFD blue piston (see Figure 5). Ideally, there should be some space between the piston cone and the fluid column but be sure the piston is inserted far enough into the barrel to permit secure attachment of the adapter head.
4. Store the filled syringe barrels upright with the luer-end down in a vertical rack. Any bubbles will rise to the top.

Figure 5: For non-adhesive pourable fluids, use Nordson EFD’s general purpose piston (left), positioning the piston so that the cone is in contact with the fluid column up to the lower wiper. For non-adhesive watery fluids, use our perforated blue piston (right). The perforation enables the dispenser to switch between pressure and suction to dispense the fluid without dislodging the piston.

Filling syringes with watery adhesives like cyanoacrylates

Cyanoacrylates are quick curing adhesives. It’s essential to avoid getting this fluid on the walls of the syringe barrel, where it can cure and lock the piston or the syringe adapter in place. Don’t use the “tilt and pour” technique. Instead:

1. Use a funnel with a long spout to fill.
2. Stop when the syringe barrel is two thirds full.
3. When removing the funnel, take care to avoid touching the side wall of syringe barrel or the top rim.
4. Insert a perforated piston like the blue piston shown in Figure 5, leaving space between the piston tip and the fluid column.
5. Store the filled syringe barrels luer-end down in a vertical rack. Any bubbles will rise to the top.

Got questions? Please contact us at [email protected] for more information.