What a Pneumatic Grease Gun Is
A pneumatic grease gun is a handheld lubrication tool that uses compressed air to drive a piston, pressurizing grease through a hose and coupler into a fitting. The ratio runs 60:1 to 70:1, turning 90-120 PSI at the inlet into 6,000-7,500 PSI (414-517 bar) at the coupler. For drum or keg supply, the air-operated pump system fits better. To compare gun types, see the air greaser overview.
Technical Specifications
| Parameter | Value |
|---|---|
| Output pressure | 6,000-7,500 PSI (414-517 bar) |
| Pressure ratio | 60:1 to 70:1 |
| Air input | 90-120 PSI (6.2-8.3 bar), regulated |
| Air consumption | 3-5 CFM at 90 PSI |
| Air inlet thread | 1/4″ NPT |
| Reservoir | 14 oz (400 cc) standard cartridge; bulk fill on select models |
| Single-shot delivery | 0.5-1.5 g per trigger pull |
| Continuous delivery | 4-8 oz/min (120-240 cc/min) |
| Hose | 30-48 in long, 1/8 in inside diameter |
| Grease grades | NLGI 0, 1 and 2 on all models; NLGI 3 on high-ratio variants |
| Weight | 2.5-4.5 lbs (1.1-2.0 kg) |
| Overall length | 12-16 in (305-406 mm) |
| Seal temperature rating | -29°C to +82°C |
Single-Shot vs Continuous Flow
A single-shot gun meters 0.5-1.5 g per pull, so the operator counts pulls and knows exactly how much went into the bearing. That suits small bearings and sealed cavities where overfilling pushes a seal out.
A continuous-flow gun delivers 4-8 oz/min (120-240 cc/min) while the trigger is held, filling large cavities fast. The trade is control: the operator judges fill by watching grease appear at the relief point.
Air Supply Requirements
| Item | Requirement |
|---|---|
| Air pressure at inlet | 90-120 PSI (6.2-8.3 bar), regulated |
| Air consumption | 3-5 CFM at 90 PSI |
| Compressor | 20-gallon tank or larger, 5+ CFM output |
| Air treatment | FRL (filter-regulator-lubricator) upstream |
| Inlet lubrication | 2-3 drops of air tool oil into the inlet per service |
| Air inlet thread | 1/4″ NPT |
Water in the line causes erratic operation: it washes grease off the piston seals, makes the piston stick, and the gun runs slow, then stalls. Regulate at the FRL, not the compressor, so the setting matches what the gun receives.
Loading: Cartridge, Bulk, and Suction
A 14 oz (400 cc) cartridge drops in, the plunger seats, and the change takes under a minute with no tools. Bulk fill suits one grease used in volume, refilling from a drum without buying cartridges.
Suction loading pulls grease from an open container through the follower using a priming stroke. Wipe the barrel threads and follower before reassembly, because grit that enters at loading finds the piston seals.
Grease Grades the Gun Handles
NLGI 0, 1, and 2 greases run on all models. Remember the scale: 000 is softest, higher numbers are stiffer. Stiffer grease needs more pressure to move, so NLGI 3 needs higher inlet pressure or a high-ratio variant.
Hose and Coupler Pairing
The standard hose is 30-48 in long with a 1/8 in inside diameter. The hose rating must cover the maximum gun output; the steel braided high pressure hose is the matching part.
A hydraulic coupler grips the fitting by spring force, and at 6,000-7,500 PSI the back pressure can exceed that grip. The fix is a locking design: the professional locking grease coupler addresses this, the DIN 71412 grease nipples page covers the fitting side, and the bent flex pipe gun reaches angled access points.
What Is Supplied
Each gun is supplied as the assembled handheld unit with barrel, follower and plunger, the trigger and air inlet assembly with a 1/4″ NPT port, and the standard hose with coupler fitted.
Frequently Asked Questions
Should I choose single-shot metering or continuous flow?
Choose single-shot for measured doses at small or sealed bearings, where counting pulls tells you what went in. Choose continuous flow for large cavities and fast route work.
What compressor do I need to run this gun?
Plan for a 20-gallon tank or larger with 5+ CFM output, delivering 3-5 CFM at 90 PSI. Regulate to 90-120 PSI at an FRL near the point of use.
Can the gun handle NLGI 3 grease?
Yes, but not on a standard configuration. NLGI 3 is the stiffest common grade, so it needs higher inlet pressure or a high-ratio variant.
How do I choose between cartridge, bulk and suction loading?
Use 14 oz (400 cc) cartridges if the gun sees several greases and you want a clean, fast change. Use bulk fill for one grease in volume.
What happens when the gun stalls?
Flow falls toward zero and pressure climbs toward the top of the 6,000-7,500 PSI band. Release the trigger, check the fitting and line, then resume.
Why does my coupler keep blowing off the fitting?
Back pressure at the coupler has exceeded the spring grip of the jaws. A locking coupler holds against that back pressure.
Which hose should I pair with this gun?
Use a hose rated above the maximum gun output, with the standard 30-48 in length and 1/8 in inside diameter. The steel braided high pressure hose fits.
What daily care does the gun need?
Drain the air line and compressor tank to keep water out of the piston, and add 2-3 drops of air tool oil per service. Clean, dry air keeps operation steady.
Can I use this gun to dispense oil instead of grease?
No. The piston, seals and follower are built for grease viscosity, and oil will pass the seals and deliver nothing useful at the coupler.
How do I confirm the right gun and parts for my route?
IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, matches the gun, hose and coupler to your fittings and grease grades. Send fitting types, grease grade and air supply details to inquiry@isohitech.com, or use the quote request form and the contact page for a configuration review.
