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Dry Chemical Powder (DCP) Extinguisher (Gas cartridge type) Explain by Lokesh Singh

Dry Chemical Powder Extinguisher (Gas cartridge type)




(A) Construction:- The extinguisher is cylindrical in shape, made of solid drawn Steel cylinder. It has a removable internal shell having gas pores and is protected with thin rubber rings and rubber washer at its neck. The extinguisher is fitted with a siphon tube connected to the body with a small length of high pressure flexible hose terminating into a squeeze grip type nozzle attached to its end. The nozzle is protected with a rubber cap against entry of moisture. The expellent is CO2 gas in a cartridge which is sealed. The CO2 gas cartridge is screwed to the operating had which is fixed with a piercing mechanism. Dry chemical powder is filled in the body in quantities as per capacity.


(B) Application:- All classes of Fire accept d class which require special composition of powders

Capacity:- portable 1kg, 2kg, 5kg, 10kg

Mobile:- 22.5/25kg, 50 kg, 75 kg, 150 kg, 200 kg, 250 kg, 300 kg, 500 kg.


(C) Operation:- 

  1. Remove the safety clip.
  2. withdraw rubber cap from the nozzle.
  3. Hold the squeeze (the lever of) nozzle valve in open position.
  4. Press the plunger and direct the Powder into to the flame with a fast sweeping motion.


(D) Performance:- At the press of the plunger, CO2 cartridge gets punctured. CO2 gas is released to pressurize the extinguisher up to 7 kg / CM2 pressure. The Powder in the outer body is pushed out through the nozzle.


(E) Recharging:-

  • Recharging should be done on a sunny day with least humidity in the air.
  • Clean the extinguisher body and other parts thoroughly.
  • Make the body as dry as possible before feeling after unscrewing the cap.
  • Fill the outer vessel with recharge powder as supplied by the the supplier in quantities according to the size of the extinguisher.
  • Place the Inner vassel with CO2 cartridge in the outer vessel.
  • Screw back the cap after applying a little grease on the threadings. The charge composition varies as follows:


(F) Testing:- 

  1. Gas cartridge should be weighed in once in three months. Replace if loss of CO2 exceeds 10%.
  2. The extinguisher should be opened and checked against plugging of nozzles, siphon tube, washers, vent holes etc. Periodically.
  3. Check all movable parts for their free movement periodically.
  4. Body should be hydraulically tested at 25 kg / cm2 once in every 4 years.


Charge composition:- 

(a) normal DCP extinguisher

Sodium bicarbonate – 97%

Magnesium stearate – 1%

Magnesium carbonate – 1.5%

Calcium phosphate – 1/2 %


(b) special powders (for 'D' class fires)

(1) Bitumen– 45%

Seage powder – 45%

Aluminium sulphate – 10%

(2) sodium chloride – 20%

Potassium chloride – 29%

Barium chloride – 51%


(G) Labelling:- Every extinguisher must be clearly labelled in a permanent manner to indicate.

  1. The name of the manufacturer
  2. Capacity
  3. Year of manufacture
  4. Method of operation
  5. The class of Fire.


Explain By Lokesh Singh



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