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Air compressor for a grease gun

Updated: 21.10.2026

Tank litres on the badge do not tell you whether a compressor will run a grease gun. An air compressor for a grease gun has to hold the pressure on the gun’s plate and move enough free air while you pull the trigger. A pistol and a keg are not the same demand, and the KATSU listings do not print a cfm figure. The guns are on the [air grease gun comparison](/hub/compressors/air-grease-gun). Products Compared used maker pages, retailer guides and HSE notes. We did not run a lab test. A qualifying purchase through an amazon.co.uk link can earn us a commission at no extra cost to you.

Tank litres on the badge do not tell you whether a compressor will run a grease gun. An air compressor for a grease gun has to hold the pressure on the gun’s plate and move enough free air while you pull the trigger.

Our top picks

Draper Draper 70836 air grease gun (400 cc)

Best overall

Draper Draper 70836 air grease gun (400 cc)
7.4/10about £30.99
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KATSU KATSU 40 litre pneumatic grease pump

Alternative

KATSU KATSU 40 litre pneumatic grease pump
6.4/10about £119.99
View offer
KATSU KATSU 12 litre pneumatic grease pump

Rank 3

KATSU KATSU 12 litre pneumatic grease pump
6.2/10about £87.99
View offer
On this page
  1. 1.Pressure first, then air volume
  2. 2.Why the published CFM figures disagree
  3. 3.A pistol on a small workshop compressor
  4. 4.A keg pump is a different demand
  5. 5.The receiver, not the grease hose

Pressure first, then air volume

The gauge on a full receiver shows stored pressure, around 8 bar (about 115 psi) on a small UK workshop compressor. That is not airflow, and it is not the pressure the gun wants. Handheld guns in these UK notes sit between about 30 and 150 psi, with 90 psi (6 bar) a common feed. Draper’s page for the 70836 prints 30–120 psi, which is not on the amazon.co.uk capture, so the plate or that maker page is the source. Free air delivery is what the pump can keep supplying. Displacement is the optimistic number. Sealey’s guide says compare free air delivery, not displacement.

Why the published CFM figures disagree

There is no single cfm for an air grease gun. Groz’s ZAGG is about 1 cfm from 40–120 psi. A Spaldings hand gun is about 3 cfm from 60–120 psi. Tooled-Up and MyToolShed allow 4–6 cfm at about 90 psi, with a 50 litre tank for intermittent use or 100 litres for long spells. SGS puts a typical grease gun at 4 SCFM. Those lines can all be true of different tools. The 4–6 cfm figure is a category guide, not the Draper plate and not the KATSU listings. A 1 cfm plate does not need a 6 cfm compressor. A 4 SCFM plate still needs that airflow at 90 psi.
Draper Draper 70836 air grease gun (400 cc)

Testsieger

Draper Draper 70836 air grease gun (400 cc)
7.4/10about £30.99
View offer

A pistol on a small workshop compressor

SGS says multiply the tool’s air demand by 1.2 for the free air delivery to look for, and multiply the SCFM figure by 6 for a rough minimum tank in litres. Sealey adds about a 50 percent margin on cfm. Both say the tool guide wins. Draper asks for a 3/8 inch hose on the 70836. Sealey’s SA401 wants at least a 1/4 inch bore. Drain the receiver daily, then couple up and bleed. That order is on the how to use page.

A keg pump is a different demand

The KATSU 12, 20 and 40 litre pumps state 450 bar and a 3.7 m hose. They do not state inlet psi, cfm or a pressure ratio on amazon.co.uk, so you cannot size a compressor from that capture. Aim Tools lists 90 psi and 50:1 for the 12 litre 481125 and the 20 litre 481133 only. Do not copy that onto the 40 litre listing, and do not borrow about 6 cfm from the Sealey AK453X. That pump is not in this set. Who should buy the pistol and who should buy the keg is on the best air grease gun page.

The receiver, not the grease hose

The Pressure Systems Safety Regulations 2000 apply above 0.5 bar. HSE is explicit that hydraulic oil is not the relevant fluid. The grease hose is not the vessel on a written scheme. The compressor receiver is. At home, drain the tank, leave the relief valve alone and set the regulator. At work, a competent person examines that receiver. None of this sizes the cfm. If the KATSU plate is missing, get the inlet figure from the maker. A full tank at 8 bar only proves you can store 8 bar.

Common questions

What size compressor do I need for a grease gun?
You need one whose free air delivery covers the gun’s plate, with a regulator that can sit in the gun’s pressure window. For a pistol whose plate says about 4 SCFM, SGS’s rule of thumb points at about 4.8 cfm of free air and a tank on the order of 24 litres. Retailers often say 50 litres for intermittent use. Both are rules of thumb. A plate that says 1 cfm is a smaller ask. The KATSU listings do not give you this number.
Is tank litres the same as CFM?
No. Litres are what the receiver stores. CFM, or litres per minute of free air, is what the pump can keep making. A large tank hides a small pump for a few seconds, then the pressure falls and the gun waits. Buy on free air delivery at the working pressure, then treat tank size as reserve for the pauses in the job.
Is 8 bar enough?
Eight bar is about 116 psi, which sits inside many pistol windows that top out around 120 psi, including the Draper 70836 maker window of 30–120 psi. It is enough only if you can regulate down to the recommended feed, often about 90 psi, and if the pump still delivers the cfm at that pressure. The top of the gauge is not the setting you leave the regulator on.
What if the hose is long?
A long, narrow hose drops pressure before the gun. Sealey notes that runs over about 8 metres may need a higher pressure at the compressor, and the SA401 wants at least a 1/4 inch bore. Draper specifies 3/8 inch for the 70836. Fit the bore the maker names, and put the extra length in a hose of that bore rather than in a connector that necks down.
Does a keg pump need more air than a pistol?
Often yes, and the KATSU amazon pages do not prove it, because inlet air and cfm are missing. Use the figure for the model you are buying. Some large pumps are published at about 6 cfm, and some pistols at 1 or 3 cfm. Do not copy one model’s inlet onto another keg.

Related pages

Air grease gun buying guide

Air grease gun

Best air grease gun for a UK home workshop or a keg

How to use an air grease gun: load, bleed and stop

Air grease gun vs manual: when the airline is worth it

Sources

Public UK sources and maker pages from the research digest, checked for this page on 20 October 2026. Listing prices, stars and review counts are amazon.co.uk figures from the comparison files.

  1. HSE: hydraulic injection injury (retrieved 20 October 2026)
  2. HSE: track tensioning and high-pressure injection (retrieved 20 October 2026)
  3. HSE: PUWER overview (retrieved 20 October 2026)
  4. HSE: Pressure Systems Safety Regulations (PSSR) (retrieved 20 October 2026)
  5. Draper Tools: air grease gun 70836, 400 cc (retrieved 20 October 2026)
  6. Kennedy PGC400 instructions (Cromwell) (retrieved 20 October 2026)
  7. Sealey SA40.V2 instructions (retrieved 20 October 2026)
  8. SGS Engineering: air compressor buyer's guide (retrieved 20 October 2026)