The law does not name a qualification for the person who services an extinguisher. It requires that maintenance is carried out by a competent person, and it leaves the duty holder to decide who that is. That places a selection decision on people who mostly have no way of assessing the technical work, which is why third party certification schemes exist and why the trade has a long history of poor practice at its edges.
How competence is normally evidenced
By certification of the firm under a recognised scheme, which audits their procedures, their engineers' training and their record keeping, and by the engineer carrying identification and working to the relevant British Standard. A duty holder who has checked the scheme registration and kept a copy has done what can reasonably be expected of them.
The free extinguisher pattern
A caller offers a free extinguisher, a free survey, or a free safety check, and the visit results in a signed agreement for several years of servicing at a rate well above the market, often with automatic renewal. Nothing about it is unlawful, and the cost is the contract rather than the equipment. Any offer of free fire equipment should be read as a contract proposal.
Over provision as a sales strategy
A second pattern is a survey that recommends far more units than the risk assessment supports, since the servicing revenue follows the count. The defence is the fire risk assessment: it names the fuels and the areas, and the provision should be traceable to it rather than to a supplier's survey sheet.
What to ask before signing
The scheme the firm is certificated under and its registration number. The term of the agreement and how it renews. Whether extended services and pressure tests are included or charged separately, since those are the large costs. Whether condemned units are replaced at a quoted rate or at a rate set later.
Questions people ask about fire extinguisher engineer
Is a free fire extinguisher offer legitimate?
Sometimes, as a genuine introductory offer from an established firm. Frequently it is the front end of a long servicing agreement, so the question to ask is what is being signed rather than what is being given.
Does the engineer need to be certificated personally?
The law asks for competence, not a specific certificate. Scheme certification of the employer is the usual way that competence is evidenced, and it covers the training of the engineers it employs.
Can a building service its own extinguishers?
It can if it genuinely holds the competence, the equipment and the spares. Very few buildings do, and the record has to demonstrate it to the same standard a contractor would.