A dry riser is not equipment the building uses. It is an empty pipe running up through the structure with an inlet at ground level and landing valves on each floor, so the fire service can pump water in at the bottom and take it out on the floor they need. Installing one is therefore a job judged by whether it works for them, not by whether anything in the building can be seen to work.
What the installation consists of
An inlet breeching in an accessible cabinet at ground level, the riser itself running up the building, a landing valve on each floor it serves, an air release valve at the top, and drainage so the pipe empties after use. Position matters as much as pipework: the inlet has to be reachable from where an appliance can stand, and the landing valves have to be where firefighters will look for them.
Where the requirement comes from
The requirement for a riser comes through building regulations guidance and the fire strategy for the building rather than from the Fire Safety Order directly, and it follows from height and from the distance firefighters would otherwise have to run hose. The Order's part in it is article 38, which requires facilities provided for the use of firefighters to be maintained in effective working order.
Dry riser servicing: the test at installation and the ones afterwards
A new installation is pressure tested wet before it is accepted, because the only way to know an empty pipe will hold water is to fill it. After that it is tested periodically on a cycle, with a visual inspection more often. A riser that has never been wet tested since installation is an unknown, and the point at which it is discovered is the worst possible one.
What the handover has to produce
The commissioning and pressure test records, drawings showing the route and every landing valve, the inlet location, the cabinet keys and signage, and the maintenance schedule with the first due date. Risers are buried in risers and forgotten, so the handover pack is what lets the next duty holder maintain something they cannot see.
Questions people ask about dry riser installation
Who uses a dry riser?
The fire service. Water is pumped into the inlet at ground level and taken from a landing valve on the floor being fought, which saves running hose up the stairs.
What is the difference between a dry and a wet riser?
A dry riser is empty until the fire service charges it. A wet riser is permanently charged and pressurised, which is used where height makes a dry system impractical.
How often should a dry riser be tested?
A visual inspection at short intervals and a full wet pressure test on a longer cycle, with the results recorded. Article 38 requires facilities for firefighters to be maintained in effective working order.
What is the difference between wet and dry risers?
A dry riser is an empty pipe the fire service charges from a pumping appliance at the inlet. A wet riser is kept permanently full and pressurised by the building, which is what taller buildings need because a pump at the kerb cannot reach the top floors.
What does a dry riser system have to include?
The inlet where the appliance connects, the pipework, the landing valves on each floor they serve, and the outlet cabinets. The handover has to produce the pressure test result and the drawings, because the people who use it have never seen the building before.
What is a dry riser cabinet for?
It houses the inlet at ground level, or the landing valve on each floor, and keeps them secure and weatherproof. It has to be findable, unobstructed and openable by the attending crew, which is why access to it is inspected along with the pipework.