A flow figure, a receiver capacity, a noise rating or the cost of running a compressor for a year all come from somewhere specific, and that source is named alongside the figure so it can be checked directly.

Manufacturer figures

A flow, pressure or noise figure quoted for a compressor, dryer or receiver comes from the maker's own published datasheet, with the date that datasheet was read. That applies to any maker figure used on this site, whether or not a product listing exists for it yet. Free air delivery (FAD), the volume a compressor actually delivers at atmospheric pressure and temperature at a stated working pressure, and displacement, the volume swept by the piston or screw element before losses, are given separately, each with the pressure it was measured at, because a figure that gives only displacement can make a compressor look more capable than it is at working pressure. The gap between the two, and why it matters when reading a listing, is worked through with real numbers in Displacement and Free Air Delivery.

Running costs

Electricity costs use the non-domestic price published each quarter by the Department for Energy Security and Net Zero (DESNZ), and any figure built from it states the quarter the price covers and whether VAT is included, so a cost worked out from an earlier quarter's price is never carried forward without saying so. The arithmetic behind a running-cost figure, and behind the cost of a leak, is set out in full in Running Costs and The Cost of Leaks, in Pounds, so it can be checked against a reader's own hours and pressure.

Directory entries, once the directories open

The compressor and air-treatment brand directory, the distributor and service firm directory, and the pressure systems inspection body directory are planned. Once they open, each entry will carry the date its company record, trade membership or accreditation was last read from the relevant register, with a link to that register, so a claim about BCAS (British Compressed Air Society) membership, SAFed (Safety Assessment Federation) membership or UKAS accreditation can be checked against the register itself.

One method across guides, calculators and listings

The sizing guides and the interactive calculators already work in the same units and follow the same worked method, so a free air delivery figure produced by a calculator can be set directly against the reasoning in a guide. Product listings will use the same units and method once they open, so a free air delivery figure from a sizing calculation and a free air delivery figure on a listing will be figures a reader can set against each other directly.

What a date does not mean

A date shown against a figure says when it was read from its source, not that the source itself is current or that the figure has been re-checked since. A calculator works out its result from the numbers entered and the method set out beside it, and it can return a wrong answer if either is wrong, so a result worth acting on is worth checking against your own arithmetic before it goes into a purchase or a compliance decision.

Marked links to retailers

Product listings are planned for this site, and no product listing page exists yet. No link anywhere on the site today carries an affiliate mark. Once the listings open, a link that goes straight to a retailer's own product page will carry a mark showing that a purchase made through it will pay a commission from the retailer, and that commission will come out of the retailer's own margin. The mark will sit next to the link itself.

Quote enquiries to distributors

Once the enquiry form opens, sending your sizing figures through Get Compressor Quotes will pass them to the distributors named on the form, and only with your consent to do so.

A flow figure, a receiver capacity, a noise rating or the cost of running a compressor for a year all come from somewhere specific, and that source is named alongside the figure so it can be checked directly.

Manufacturer figures

A flow, pressure or noise figure quoted for a compressor, dryer or receiver comes from the maker's own published datasheet, with the date that datasheet was read. That applies to any maker figure used on this site, whether or not a product listing exists for it yet. Free air delivery (FAD), the volume a compressor actually delivers at atmospheric pressure and temperature at a stated working pressure, and displacement, the volume swept by the piston or screw element before losses, are given separately, each with the pressure it was measured at, because a figure that gives only displacement can make a compressor look more capable than it is at working pressure. The gap between the two, and why it matters when reading a listing, is worked through with real numbers in Displacement and Free Air Delivery.

Running costs

Electricity costs use the non-domestic price published each quarter by the Department for Energy Security and Net Zero (DESNZ), and any figure built from it states the quarter the price covers and whether VAT is included, so a cost worked out from an earlier quarter's price is never carried forward without saying so. The arithmetic behind a running-cost figure, and behind the cost of a leak, is set out in full in Running Costs and The Cost of Leaks, in Pounds, so it can be checked against a reader's own hours and pressure.

Directory entries, once the directories open

The compressor and air-treatment brand directory, the distributor and service firm directory, and the pressure systems inspection body directory are planned. Once they open, each entry will carry the date its company record, trade membership or accreditation was last read from the relevant register, with a link to that register, so a claim about BCAS (British Compressed Air Society) membership, SAFed (Safety Assessment Federation) membership or UKAS accreditation can be checked against the register itself.

One method across guides, calculators and listings

The sizing guides and the interactive calculators already work in the same units and follow the same worked method, so a free air delivery figure produced by a calculator can be set directly against the reasoning in a guide. Product listings will use the same units and method once they open, so a free air delivery figure from a sizing calculation and a free air delivery figure on a listing will be figures a reader can set against each other directly.

What a date does not mean

A date shown against a figure says when it was read from its source, not that the source itself is current or that the figure has been re-checked since. A calculator works out its result from the numbers entered and the method set out beside it, and it can return a wrong answer if either is wrong, so a result worth acting on is worth checking against your own arithmetic before it goes into a purchase or a compliance decision.

A figure can go stale, a calculator can be misread, a regulation can get renumbered after a page was written. Any of that can happen here, and the way to flag it is to write in rather than work around it.

What's useful to send

• The page or tool where you spotted it
• What you entered, if it was one of the calculators
• What you expected against what you got
• The source you're checking it against, if you have one to hand

Send that to aircompressors, or use the contact page. The same address takes a general question too, though a specific sizing or written-scheme question is often answered faster by the calculators and guides linked around this site than by waiting on a reply.