We check the cylinder markings to identify its construction, working pressure, valve connection and periodic test date. If a cylinder has a fixed service life, we also check its marked end-of-life date. These details determine whether the cylinder can be accepted and which filling connection and pressure must be used. A cylinder with unreadable identification, an expired test date or an exceeded service-life limit cannot be filled and returned to use.

Before the cylinder is connected, we examine its body, valve and outlet. Composite cylinders also require an inspection of the fibre overwrap that provides part of their structural strength. Our technicians look for corrosion, cuts, abrasion, impact damage, heat exposure, contamination, leakage and damaged valve components. Any defect that could affect the cylinder’s integrity or prevent a secure filling connection is investigated before any decision is made about whether the cylinder can be filled, serviced or requires further testing.

The cylinder is connected to filling equipment that matches its valve outlet and pressure rating. It is then charged with compressed breathing air in accordance with the working pressure and filling requirements specified for the cylinder, commonly 200 or 300 bar for breathing-apparatus cylinders. Compressing air creates heat, which temporarily raises both the temperature and pressure inside the cylinder. The filling rate must therefore be controlled to prevent excessive heating and over-pressurisation.

As your cylinder cools after filling, its internal pressure falls. A pressure reading taken immediately after a fast or hot fill may therefore make the cylinder appear more fully charged than it will be once it has returned towards normal temperature. We check the final settled pressure so that the recorded figure provides a more accurate indication of the charge available when the cylinder is placed into storage or issued for use. The cylinder is then recorded as successfully filled or redirected for further work.

Turnaround depends on the batch size, cylinder type and whether any units require additional testing, investigation or valve work. We recommend planning refilling requirements in advance so that suitable collection, processing and return arrangements can be agreed around your operational cover.

Yes. The breathing-air supply used for refilling is tested periodically to confirm it meets BS EN 12021 quality requirements.

Yes. Multiple cylinders can usually be processed as one batch, provided they are compatible with the filling system and pass the required pre-fill checks. Grouping them together can simplify collection, records and turnaround.

Yes. Every cylinder should receive a pre-fill inspection to confirm it is correctly identified, within its periodic test date and free from visible damage, corrosion or valve defects. Cylinder owners also have a legal responsibility to ensure their cylinders undergo periodic pressure testing at the required intervals, in line with the Pressure Systems Safety Regulations 2000 and the relevant standard for the cylinder type (BS EN 1968 for steel cylinders, BS EN 12245 for composite cylinders).