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Compressor for a 1/2 inch air impact wrench

Updated: 22 October 2026

The gun clicks, the socket barely twitches, and the compressor you bought for a nailer still shows pressure on the gauge. Pressure in the tank is not air arriving at a 1/2 inch impact wrench. This page on a compressor for a 1/2 inch air impact wrench asks whether free air around 90 psi, the hose and the tank will feed the gun. It does not pick a winner among the nine listings. Those rows, with GBP prices from amazon.co.uk in October 2026, stay on the [air impact driver comparison](/hub/tools/air-impact-driver). Peter F. is the DIY & tools editor. There was no compressor test against these guns. A qualifying purchase can earn a commission at no extra cost to you. If the listing states no consumption, assume short bursts and a real chance of a rattle rather than a freed nut.

The gun clicks, the socket barely twitches, and the compressor you bought for a nailer still shows pressure on the gauge. Pressure in the tank is not air arriving at a 1/2 inch impact wrench.

Our top picks

BESWELL BESWELL BW-112BN

Best overall

BESWELL BESWELL BW-112BN
8.1/10about £39.99
View offer
Hilka Hilka 85151617 set

Alternative

Hilka Hilka 85151617 set
7.8/10about £41.99
View offer
Blue Spot Tools Blue Spot 07945

Best value

Blue Spot Tools Blue Spot 07945
6.8/10about £26.97
View offer
On this page
  1. 1.CFM at 90 psi, not tank size alone
  2. 2.The one listing that states consumption
  3. 3.Hose bore and length
  4. 4.When the listing wants more than 90 psi

CFM at 90 psi, not tank size alone

Algar Air’s UK guide puts a typical 1/2 inch impact wrench at about 4–6 cubic feet per minute at 70–90 psi, and marks that as a guide, not a duty for a named tool. Other catalogues show why the band is not a law. One Draper 1/2 inch model is published at 16 CFM average, and a Clarke model at 6.5 CFM average with a higher maximum. Neither tool is in this comparison. You cannot paste 4–6 CFM onto a Hilka or a BESWELL that left the line blank. Metro Sales suggests, for home wheel work, at least 3 hp and 50 litres, with a 10 mm hose on a 1/2 inch gun. The tank is a buffer. The pump’s free air at the pressure the gun uses is what keeps the needle up. A 50 litre tank on a weak pump still fades. A smaller tank on a pump that can deliver the air will run in bursts and recover. The buying guide is where you choose the gun. Read CFM at pressure before you read the newton-metre title.

The one listing that states consumption

Blue Spot 07945 is the only listing in this set with a consumption figure: 4.5 CFM, also printed as 113 litres per minute, at 90 psi, with a 1/4 inch BSP inlet, at about £26.97. That sits inside Algar’s 4–6 CFM guide, so a compressor whose free air at about 90 psi meets that figure is the honest match for this one gun. It does not make the Blue Spot the most powerful tool here. The sample is 3.7 from 15 reviews, and one UK review says the inlet was smaller than the buyer’s other 1/4 inch fittings. Stated air is a buying fact, not a road test. The other eight listings do not state CFM. The Hilka set recommends 90 psi and stops there. The bare Hilka states neither pressure nor consumption, and UK reviews include guns with almost no torque, which is what a starved airline feels like. ORAZIO, Proster and both Ingersoll Rand pages leave consumption blank as well. Ask for the figure before you size a compressor around a blank line, and keep the returns window until you have tried the gun. Oil will not create cubic feet the pump does not have.
BESWELL BESWELL BW-112BN

Testsieger

BESWELL BESWELL BW-112BN
8.1/10about £39.99
View offer

Hose bore and length

Thorite’s guide warns that a 1/2 inch wrench on 20 metres of 1/4 inch hose can be left with under 40 percent of its power. The loss is friction, not a fault in the gun. Metro’s dealer rule is a 10 mm hose, about 3/8 inch, for a 1/2 inch wrench, and 8 mm only for lighter tools. Clarke’s CAT141 manual also specifies a 3/8 inch hose for that wrench. A short 10 mm run from a regulated outlet is the layout those guides describe. A coil of skinny hose across the garage is the layout that rattles. A 10 mm hose finished with a 6 mm nipple is a 6 mm hose. That is the ORAZIO review: a manual asking for a 10 mm feed, and a supplied fitting with a 6 mm passage. The Blue Spot inlet complaint is the same family of problem. Use a filter and regulator, and air-tool oil rather than engine oil. If the nut still will not move on a short, wide hose, the limit has moved to the gun or the fastener.

When the listing wants more than 90 psi

The BESWELL BW-112BN prints both 90–120 psi and 120–190 psi. The BW-112K bullets say 120–190 psi. Neither page states CFM. 190 psi is about 13 bar, well above the 90 psi, about 6.2 bar, that Clarke says not to exceed at the tool while that Clarke gun is running. Those are different documents. You do not correct a weak gun by removing the regulator, and you do not treat 190 psi as safe just because a bullet mentions it. The Health and Safety Executive’s compressed-air guidance is about injury from air entering the body. Higher pressure is a hazard, not a free torque upgrade. A French review of the BW-112K describes a 100 litre, 3 hp compressor, a direct tank outlet and a 13 mm hose removing large driveshaft nuts. That is one reviewer’s setup, not a specification, and it does not prove a 50 litre tank will deliver the title’s torque claim. The title and bullets do not even agree which unit 2,230 belongs to. A 24 litre tank is below Metro’s 50 litre suggestion, so expect a short burst and a drop unless you already know the pump’s free air at 90 psi covers the gun. When the plumbing is right and the anvil still only rattles, send the tool back.

Common questions

What CFM does a 1/2 inch air impact wrench need?
Algar’s guide says about 4–6 CFM at 70–90 psi for a typical 1/2 inch wrench, and labels it as a guide. Other models are published higher, so use your gun’s own figure when it exists. In this comparison only Blue Spot 07945 states one: 4.5 CFM at 90 psi. Do not paste 4–6 CFM onto the eight listings that left consumption blank.
Is a 50 litre tank enough?
Metro suggests at least 50 litres and 3 hp as a starting point for home wheel work. The tank only stores air. Enough means the pump’s free air at about 90 psi can keep up, or you pause while it recovers. Fifty litres does not make a headline torque true. Read the pump’s output, not only the tank badge.
What hose bore should I use?
Use about 10 mm, or 3/8 inch, for a 1/2 inch wrench, and keep the run short. Metro gives 8 mm only to lighter guns. Thorite says 20 metres of 1/4 inch hose can leave under 40 percent of the power. Match the nipple bore to the hose, or the wide hose is wasted at the fitting.
Which listing states its air consumption?
Only Blue Spot 07945: 4.5 CFM (113 L/min) at 90 psi, with a 1/4 inch BSP inlet. The Hilka set states 90 psi and no CFM. Both BESWELL guns state pressure ranges and no CFM. If you need the number before you buy a compressor, that Blue Spot row is the only one that prints it.
Is 8 bar better if 90 psi feels weak?
8 bar is about 116 psi. One UK review of the Hilka set still had no power at 8 bar, so extra pressure did not create the missing torque. Clarke says not to exceed 90 psi at the tool while that model is running. Fix the hose and the fitting before you treat the regulator as a power knob.
What if it still rattles on a large compressor?
The tank was not the limit. Check for water, a low regulator setting, a long 1/4 inch hose, and a nipple narrower than the hose, which is what the Blue Spot and ORAZIO fitting reviews describe. If a short 10 mm hose, oil in the inlet and pressure at the tool still leave a free socket barely turning, return the gun.

Related pages

How to use an air impact wrench

Air impact wrench wheel nuts

Air impact driver

Best air impact wrench UK: a home garage shortlist

Air impact wrench buying guide: anvil, air and kit

Sources

Public UK sources from the research digest, used for this page in October 2026. Prices, stars, review counts and specification lines are from the nine amazon.co.uk listings. Noise and vibration duties apply at work. They are not a certificate for a domestic gun, and no listing here was laboratory-tested.

  1. Control of Noise at Work Regulations 2005, regulation 4 (retrieved October 2026)
  2. HSE INDG362, Noise at work (retrieved October 2026)
  3. HSE, Hand-arm vibration regulations (retrieved October 2026)
  4. HSE HSG39, Compressed air safety (retrieved October 2026)
  5. ISO 11148-6:2012, Hand-held non-electric power tools, impact wrenches (retrieved October 2026)
  6. Homebuilding, Impact driver vs impact wrench (retrieved October 2026)
  7. Algar Air, Air tool consumption guide (retrieved October 2026)
  8. Ingersoll Rand safety information, via Cromwell (retrieved October 2026)