We are still coming across dry powder extinguishers inside buildings despite the fact that they have not been recommended by the BSI for many years. They are multipurpose extinguishers but if you were to discharge them to deal with a small fire under most normal circumstances you would most likely regret it.
They create a great deal mess, are not friendly to anyone in the area of the discharge and can obstruct both your vision and affect your breathing.
They should only be provided if there is a specific reason for them that has been identified in the risk assessment.
Carbon Dioxide and Foam or Water will be the most suitable in the majority of situations.
The new Water Mist extinguishers are also very efficient and clean.Where possible ask for extinguishers that have passed the electrical conductivity discharge or dielectric test.
This will make them far safer if operated near to live electrical sources.
Do not just accept what the extinguisher provider gives you, ask the question!