If you have an air ratchet or you’re looking to purchase one for projects at home or in your workshop, you may be wondering what size air compressor do I need for air ratchet?
This page will serve as a guide into what size air compressor you need for your air ratchet wrench by presenting all the key considerations and relevant information to help you find a solution!
Table of Contents
Key Considerations – Choosing an Air Compressor for Air Ratchets
There are a few very key considerations you must look at when finding an air compressor suitable for an air ratchet. These are:
- Use cycle – continuous vs intermittent use
- CFM requirements & CFM rating of the air ratchet
- Pressure requirements of the air ratchet
- Duty Cycle of the air compressor
- CFM delivery capability of the air compressor
- Air compressor tank size (compressed air storage capacity)
- Distance you’ll be using the air ratchet from the compressor (hose length)
Are You Using the Air Ratchet Continuously or Intermittently?
One of the first things you must consider is whether you will require to use the air ratchet wrench continuously or intermittently. If you only require intermittent use of your air ratchet then a small compressor may suffice but if you require continuous use then the compressor has to have the discharge capacity that the air ratchet demands.
A typical use cycle on an air ratchet wrench in a non-assembly line environment is likely to be far less than 50% of the time drawing its full CFM rating, and therefore it can comfortably be run intermittently.
What CFM Rating Air Ratchet Have You Bought or Are You Considering Buying?
Air ratchets come with CFM ratings, often expressed as SCFM ratings (as it’s a standardized unit). This can also be expressed as “Air Consumption”. I will now present to you an example of each different air ratchet and their respective CFM ratings. To learn more about CFM visit our SCFM vs CFM for Air Tools & Air Compressors GUIDE To Compressor Ratings!
To aid with the comparison in this article, I have described the following tools as “small”, “medium”, and “large” based on their average air consumption ratings.
Example of a Small Air Ratchet Wrench
Here’s an example of a small/mini air ratchet, the Neiko Pro 30119B 1/4″ mini air ratchet which is rated at an average consumption of 2.6 CFM.
- CFM: 2.6
- Torque: 30 ft/lbs
- Inlet Size: 1/4″
Example of a Medium Air Ratchet Wrench
Here is an example of a medium sized air ratchet that has an average consumption of 3 CFM, the Ingersoll Rand 109XPA 3/8″ air ratchet wrench.
- CFM: 3
- Torque: 70 ft/lbs
- Inlet Size: 3/8″
Example of a Large Air Ratchet Wrench
Here’s an example of a DeWalt air ratchet that requires an average air consumption of 3.6 CFM.
- CFM: 3.6
- Torque: 65 ft/lbs
- Inlet Size: 3/8″
What Pressure Rating Air Ratchet Have You Bought or Are You Considering Buying?
All air tools, air ratchet wrenches being no exception, have a recommended operating pressure. The different tools listed above each have their own pressure specified by their manufacturers in their respective manuals:
- The Neiko Pro ratchet has an operating pressure in the range of 70 PSI to 90 PSI.
- The Ingersoll Rand air ratchet states that it requires an operating pressure no greater than 90 PSI
- The DeWalt air ratchet states that the maximum operating pressure is 90 PSI
Note: it is important to not exceed the maximum operating pressure or operate on pressure lower than the minimum, otherwise you will risk hindering your air ratchet projects.
Air Compressor Duty Cycle
The typical duty cycle of an air compressor is normally 50% as can be seen in this Craftsman 919 manual for example. The manual states that the compressor’s maximum pumping time per hour is 30 minutes.
If you want to know more about air compressor duty cycles, how they’re expressed and calculated, you should read our article on air compressor duty cycles here!
Here’s another example of a product manual that describes the duty cycle of a compressor in these terms:
“INTERMITTENT DUTY FORMULA
Pump-up time should not ordinarily exceed thirty (30) minutes or be less than ten (10) minutes. Shutdown periods between cycles of operation should be at least equal to the pump-up time. Note: When the compressor is regulated by constant speed control, the shutdown period is the time the compressor is operating unloaded.“
This basically describes a 50% Duty Cycle. Some compressors may have a 100% duty cycle and be rated for continuous flow, allowing you to work non-stop!
CFM Delivery Capability of the Air Compressor
What size air compressor for ratchet will typically come down to the CFM rating of the compressor. CFM ratings of air compressors tend to be based on the output of the air compressor pump.
However, to understand what ability the air compressor has to deliver CFM continuously you need to multiply the CFM rating by the Duty Cycle percentage.
So an Air Compressor CFM rating of 10 CFM with a 50% Duty Cycle would have the ability to deliver:
10 CFM * 50% = 5 CFM
Example of a Pancake Air Compressor Suitable for Air Ratchets
This very popular Pancake air compressor is capable of delivering 2.6 CFM with a duty-cycled specified in the manual to be 50%, 5 minutes on, and 5 minutes on. Therefore, for a continuous draw of air, this compressor would actually deliver 1.3 CFM (2.6 * 50%).
This compressor would just about be able to provide air to the small Neiko Pro air ratchet intermittently (at 50% of the time). If the medium Ingersoll Rand air ratchet and large DeWalt air ratchet were only used intermittently, say 25% of the cycle, their required CFM’s would become 0.75 CFM (3 * 25%) and 0.9 CFM (3.6 * 25%) respectively, and so, the compressor would be able to provide this amount of airflow.
Example of a Portable Air Compressor Suitable for Air Ratchets
Here’s an example of a portable air compressor that delivers 2.4 CFM – and the product manual describes what would be determined as a 50% duty cycle. Therefore the compressor would actually deliver 1.2 CFM (2.4 CFM * 50%) if you require continuous airflow.
This compressor wouldn’t really be suitable for any of the air ratchets unless they’re used intermittently, say only 25% of the time (15 minutes per hour cycle). Their required CFM’s would become 0.65 CFM (2.6 * 25%), 0.75 CFM (3 * 25%), and 0.9 CFM (3.6 * 25%) respectively.
Example of a Wheelbarrow Air Compressor Suitable for a Air Ratchets
Here’s an example of a wheelbarrow air compressor that is rated 5.30 CFM. Although the product manual does not describe the duty cycle, a customer Q&A response has declared that the compressor has a 70/30 (70%) duty cycle, which would be determined as needing 18 minutes of rest during each hour cycle.
Therefore, this wheelbarrow air compressor is actually capable of delivering 3.71 CFM (5.3 * 70%). Making it capable of powering all the air ratchet examples provided in this article continuously.
It’s possible, however, that you will obtain, or have, an air ratchet that requires a CFM greater than the 3.71 of this compressor. I picked out examples I found on Amazon, but of course, there are hundreds if not thousands of various versions of air ratchets, all with varying CFM requirements. In this case, this compressor may be slightly undersized for your requirement and so you would require a larger compressor.
Example of a Twin Pontoon Air Compressor Suitable for Air Ratchets
Here’s an example of a twin pontoon Air compressor, the Ingersoll-Rand 8 Gallon twin compressor capable of delivering 11.5 CFM with a 100% continuous duty cycle.
This compressor is capable of powering all the air ratchet wrenches presented in this article continuously. It could even power all of them simultaneously (2.6 + 3 + 3.6 = 9.2 CFM).
If this compressor were to have a 50% duty cycle, and therefore would provide 5.75 CFM (11.5 * 50%) it would still be able to power each air ratchet continuously, and even a few of them together simultaneously. You get the idea now!
Air Compressor Tank Size (Compressed Air Storage Capacity)
The tank size will determine how much air is available to be drawn at any time. This is also a key enabler in keeping a compressor within its duty cycle. If you have a small tank, the air ratchet will quickly pull the pressure down below the level needed to activate the compressor. While a larger capacity tank will allow the compressor to run less frequently.
Therefore a 10 CFM compressor with a 50% Duty Cycle can be used to run an air ratchet wrench that’s rated at 10 CFM – if used intermittently with a sufficiently large air tank.
To keep a compressor running for at least 10 minutes with an air ratchet consuming 10 Cubic Feet of air per minute for 50% of the time, the storage capacity would be:
10 CFM * 10 minutes * 50% = 50 Cubic Feet of air (at atmospheric pressure – 15PSI)
As atmospheric pressure is 15 PSI and the output pressure is 90 PSI and pressure and volume are inversely proportional 15 PSI / 90 PSI = 6
Therefore, you need 1/6th the volume of air at 90 PSI
50 Cubic Feet * 1/6th = 8.33 Cubic Feet
8.33 Cubic Feet = 236 Liters
Note: This simplified example is to provide you with a basic idea of the tank capacity that is needed.
Distance You’ll be Using the Air Ratchet From the Compressor (Hose Length)
Long hoses will result in pressure drop, which is certainly undesirable. I could not find any recommendations in any of the air ratchet manuals, but it can generally be recommended that you should not exceed a hose length that is just long enough to serve the working area.
Any hose length greater than 25 feet will result in a pressure drop that will need to be compensated for by the compressor to ensure that the air ratchet is receiving the right operating pressure.
For further information on air hoses visit our Air Compressor Hose & Tube Guide here!
FAQs (Frequently Asked Questions)
The size air compressor you need for your air ratchet should have a CFM greater than 5 to provide sufficient airflow, along with the air receiver tank being around 8-gallons or more.
The size of air compressor you need for a 3/8 inch ratchet depends on the CFM rating of the tool, which you can find out in the owner’s manual. You will then need an air compressor with a greater CFM rating than the ratchet wrench, along with a sufficiently sized tank, probably 8-10 gallons.
Additional CFM reading:
- SCFM Vs ACFM Vs ICFM – What’s The Difference? Converting & Calculating
- Best Ways to Increase CFM On Air Compressors
- Connecting Two Air Compressors Together
- How to Calculate CFM of Air Compressors
- CFM Pipe Size Chart
- SCFM vs CFM for Air Tools & Air Compressors Guide to Compressor Ratings
- What Is CFM and What Does CFM Mean on An Air Compressor?
- Air Compressor Size For Spraying Stucco & Plaster
- Does a die grinder require low or high CFM?
- Speedaire 4B247 swapped with 2Z499 and its effect on CFM?
- 20 CFM Air Compressor – Buying, Hiring, What Can They Run?
- Air Compressors That Produce 500 CFM And Above
- CFM SCFM PSI Compressor Flow Issues
- Ingersoll Rand Type 30 model 242 HP and CFM?
- CFM rating of Black Max compressor
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If you have any questions regarding what size air compressor you need for an air ratchet wrench, please leave a comment below, with a photo if applicable, so that someone can help you!