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Compressor for a caulking gun

Updated: 23 October 2026

You already own a compressor, or you are about to rely on one, and you want to know if it can feed an air caulking gun. The answer depends which gun. Clarke states a nominal 1 cfm for the CAT82B. Chicago Pneumatic states 8 l/s for the CP9885 at load. Sealey’s AK41.V3 manual states 3.5 cfm with a 3 bar cap. We set this page from those manuals, from HSE’s note on pressure systems, and from the listings on our [air caulking gun comparison](/hub/fillers-adhesives-and-sprays/air-caulking-gun). Shelf figures are from 19 October 2026. If you buy through our links, we may earn a commission at no extra cost to you.

You already own a compressor, or you are about to rely on one, and you want to know if it can feed an air caulking gun. The answer depends which gun. Clarke states a nominal 1 cfm for the CAT82B.

Our top picks

banapoy banapoy 600 ml pneumatic caulking gun

Best overall

banapoy banapoy 600 ml pneumatic caulking gun
4.9/10about £65.44
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Chicago Pneumatic Chicago Pneumatic CP9885

Best value

Chicago Pneumatic Chicago Pneumatic CP9885
7.2/10about £40.71
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Clarke Clarke air driven caulking gun

Rank 3

Clarke Clarke air driven caulking gun
8.6/10about £26.99
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On this page
  1. 1.Flow and pressure are different limits
  2. 2.What the manuals actually ask for
  3. 3.Set the gun, not the tank
  4. 4.Hose, water, and a workplace receiver

Flow and pressure are different limits

Pressure, in bar or psi, is how hard the air pushes. Flow, in cfm or litres a second, is how much air the gun wants while it is dispensing. A tank can show 8 bar and still fail a thirsty gun, because the compressor cannot replace the air as fast as the tool uses it. A UK Clarke reviewer said a small 15–25 litre oil-free compressor was not enough, even though the listing states 1 cfm. If your compressor’s stated output is below the gun’s stated use, assume it will lag on a long bead.

What the manuals actually ask for

Clarke’s amazon bullets for the CAT82B say 1 cfm and 4.8–10.3 bar. The manual is the figure to set: about 70 psi while running, and do not exceed 90 psi. It also wants a 1/4 BSP inlet and a hose of at least 8 mm inside diameter. Seventy psi is about 4.8 bar, the bottom of that marketing range, not the 10.3 bar top. Sealey’s AK41.V3 is a different gun: maximum 3 bar and about 3.5 cfm. None of those numbers paste onto the Clarke. Chicago Pneumatic’s CP9885 page states 8 l/s at load, 6.3 bar maximum, and a minimum hose of 10 mm. The amazon.co.uk row states no cfm. A brad-nailer compressor will not impersonate that flow. Which gun is a sensible buy is on the best air caulking gun page.
banapoy banapoy 600 ml pneumatic caulking gun

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banapoy banapoy 600 ml pneumatic caulking gun
4.9/10about £65.44
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Set the gun, not the tank

An 8 bar receiver is normal. It is not the set point for the gun. If you connect a Clarke and leave the regulator wide open, you can put tank pressure onto a tool whose manual stops at 90 psi. The cartridge ovalises, air slips past the plunger, and you get a hiss or a blast. The bead steps for that fault are on how to use an air caulking gun. Compressors condense. If you never drain the receiver, water travels down the hose onto the washer that should seal the cartridge. Clarke’s manual tells you to drain water. A gun that suddenly hisses after months of quiet work is often a wet line or a tired washer.

Hose, water, and a workplace receiver

Hose bore is part of flow. Clarke asks for at least 8 mm inside diameter. CP asks for at least 10 mm on the CP9885. A long, thin hose starves a gun that looked fine on a short whip. Do not leave a quick-coupling stacked on the Clarke. At work, compressed air above 0.5 bar is a relevant fluid under the Pressure Systems Safety Regulations 2000. Schedule 1 drops some written-scheme duties for certain vessels under 250 bar litres. Other duties remain. Householders should still drain the tank and stay inside the gun manual.

Common questions

Will my small compressor run a caulking gun?
It might run a Clarke-class gun that states about 1 cfm, and it will not run a CP9885 at the maker’s 8 l/s. Even the 1 cfm claim has a UK review against it: a 15–25 litre oil-free compressor was not enough for that person. Compare your compressor’s stated output with the gun’s stated use at the pressure the manual allows. If the gun prints no cfm, you do not have an answer yet.
What is the difference between 1 cfm and 8 l/s?
They are both flow, and they are far apart. Clarke states a nominal 1 cfm. Chicago Pneumatic states 8 l/s for the CP9885 at load, which converts to about 16.8 cfm. We did not measure that. Sealey’s manual sits around 3.5 cfm and SIP around 6 cfm, each with a 3 bar cap. Quoting one of those numbers for a different gun is how people buy the wrong compressor.
What pressure do I set?
The running figure in that gun’s manual, using a regulator, not the tank’s maximum. Clarke: not above 70 psi while running, and do not exceed 90 psi, even though the amazon line says up to 10.3 bar. Sealey AK41.V3: 3 bar maximum. CP9885 maker page: 6.3 bar maximum dynamic pressure. If your gun is none of these, use its own sheet.
What hose size do I need?
Clarke’s CAT82B manual asks for a minimum inside diameter of 8 mm and a 1/4 BSP inlet, without a quick-coupling on the tool. CP’s page for the CP9885 asks for at least 10 mm. A longer hose needs to stay at that bore. Sealey flags runs over about 8 m. A skinny hose on a long reel is a flow restriction even when the compressor badge looks adequate.
Does a 24 litre receiver need a written scheme?
Multiply the plate. A 24 litre vessel at 8 bar is 192 bar litres, which is under the 250 bar-litre line in Schedule 1 of the Pressure Systems Safety Regulations 2000. That schedule drops some written-scheme duties for certain vessels. It does not remove every duty, and it applies at work, where air above 0.5 bar is in scope. A 50 litre receiver at 8 bar is 400 bar litres, which is over that line.

Related pages

Air caulking gun buying guide

Air caulking gun

Best air caulking gun: cartridge, sausage, or skip

How to use an air caulking gun: set pressure first

Pneumatic vs manual caulking gun for thick adhesive

Sources

Public UK sources used for this comparison. amazon.co.uk prices, stars and review counts were taken from the listings on 19 October 2026.

  1. HSE HSG39, compressed air safety (retrieved 19 October 2026)
  2. Pressure Systems Safety Regulations 2000 (retrieved 19 October 2026)
  3. Control of Noise at Work Regulations 2005, regulation 4 (retrieved 19 October 2026)
  4. HSE, isocyanates in construction (retrieved 19 October 2026)
  5. Clarke CAT82B product page (retrieved 19 October 2026)
  6. Clarke CAT82B manual (retrieved 19 October 2026)
  7. Chicago Pneumatic CP9885 (retrieved 19 October 2026)
  8. COX AirFlow 3 310 ml (retrieved 19 October 2026)