UCL Fire Technical Note - TN033
Fire Safety
Technical Guide
USER GUIDE TO THE M28 DRY POWDER FIRE
EXTINGUISHER
M28 Dry Powder (Class D) with Low Velocity Discharge Applicator
New Colour Code
(BS EN 3)
Extinguisher Supported on
small Hand trolley
Special Low Velocity Dispensing Applicator
Fitted
Use M28 Dry Powder on ‘Class D' specialist metal fires - particularly those
involving Alkali metals such as Sodium, Potassium, Magnesium and
Aluminium when in the form of swarf or powder. (Note: M28 is not suitable
for use on Lithium fires - see Lithium L2 powder extinguishers at TN037.
M28 DRY POWDER:
1. M28 is a dry powder fire extinguisher based on Sodium Chloride, treated with flow
and moisture repellent additives. M28 extinguishes metal fires by fusing the powder to
form a crust, which then excludes oxygen from the surface of the molten metal. The
addition of a specific agent prevents the powder from sinking into the surface of the
molten metal.
2. Generally, the quantity of M28 Dry Powder required will be approximately 3 - 5 Kgs
of powder, per kilo of metal involved depending on whether it is a shallow or deep
pool fire and on the nature of the metal involved.
3. To prevent splashing of the molten metal these extinguishers are fitted with a slow
low velocity applicator cup 2m in length, this provides a degree of safety to the
person operating the extinguisher.
GENERAL INSTRUCTIONS FOR USE:

Read instruction plate before use to ensure that you have selected the correct
extinguisher for the fire you intend to fight.

Pull out safety pin firmly (this will be held in by an anti-tamper seal). Note: there is
a short time delay with this type of extinguisher due to the low velocity applicator
design.

Apply the powder via low velocity applicator by slow circular movements over
the burning metal, keeping out of the smoke products.

Ensure that the trolley is located close to the work area and ‘operators’ are
trained in the use of the extinguisher.
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Date Last Amended: Jun 15
1.
Issued by the - Fire Safety Manager, UCL Estates, Gower Street, London, WC1E 6BT - This guide is to be regarded as a general statement of UCL local
requirements, information or guidance only & supplements relevant British Standards or Manufacturers Instructions etc.