Gas Cylinder Safety Consciousness Session (Question on acetylene cylinder)
Regulator
The regulator is the next most important safety device to be fitted to a gas cylinder before operation/use. It allows for the high pressure of the cylinder contents to be brought down to a usable working pressure.
Regulators come as a single stage for short term applications and two stages for long term applications. Regulators are also constructed from different materials, mainly brass or stainless steel.
The application will define the required regulator. If you are unsure of which kind of regulator to use, consult your gas supplier.
Regulators are designed to be fitted directly to the cylinder valve. No other fittings, connections or lubricants shall be used to connect a regulator to a gas cylinder valve.
Regulators for flammable gasses are left hand threaded and have a notch cut out of faces on the securing nut to distinguish them from non-flammable gas regulators.
Most cylinders have one or more safety relief devices. These devices can prevent rupture of the cylinder if internal pressure builds up to levels exceeding design limits. Pressure can become dangerously high if a cylinder is exposed to fire or heat, including high storage temperatures.
There are three types of safety-relief devices. Each relieves excessive gas pressures in a different way:
Safety- or Pressure-Relief Valves: These valves are usually a part of the cylinder. They are normally held closed by a spring. The force holding the valve closed is set according to the type of gas in the cylinder. The valve opens if the cylinder pressure exceeds the set safety limit. Gas is released until the cylinder pressure drops back to the safety limit. The valve then closes and retains the remaining gas in the cylinder.
Rupture Discs (also known as frangible or bursting discs): These discs are usually made from metal. They burst or rupture at a certain pressure, releasing the gas in the cylinder. The bursting pressure is designed so that the disc ruptures before the cylinder test pressure is reached. These devices cannot be reclosed, so the entire contents of the cylinder are released.
Fusible Plugs (also called fuse or melt plugs): Temperature, not pressure, activates fusible plugs. These safety devices are used where heat could initiate an explosive chemical reaction. A pressure-relief valve or rupture disc acts too slowly and too late to prevent rupture of the cylinder if an explosive reaction has already begun. The fusible plug releases the gas before the hazardous reaction can begin. Fusible plugs are made of metals that melt at low temperatures. For example, acetylene cylinders have a fusible plug which melts at about 100°C (212°F). This temperature is safely below the temperature at which hazardous polymerization may occur.
Not all compressed gas cylinders have safety devices. Some gasses are so toxic that their release through a safety device would be hazardous. Cylinders for these gasses are built to withstand higher pressures than normal cylinders. When these "toxic gas" cylinders are involved in a fire, the area must be evacuated.
IS Standards CHAPTER V
DISSOLVED ACETYLENE GAS CYLINDERS
37. Additional requirements for dissolved acetylene gas cylinders— Dissolved acetylene gas cylinder shall comply with following additional provisions, namely: -
(i) The porous substance shall fill as completely as possible the cylinder into which the acetylene is compressed.
(ii) The porosity of the substance shall not exceed 92 percent and in no case shall be less than 75 percent.
(iii) Any solvent used shall not be capable of chemical reaction with the acetylene gas or with the porous substance or with the metal of the cylinder.
(iv) If acetone is used as a solvent it shall comply with the requirements of IS:170, the quantity of acetone including the gas in solution shall be such that the cylinder meets the requirements of additional tests specified in IS:7312.
(v) The valves of the cylinders shall not contain more than 70 percent copper in their composition.
(vi) The pressure in the cylinder shall not exceed 16 kgf/cm2 at a temperature of 15 °C.
(vii) Every cylinder shall before being filled with porous mass be tested by hydrostatic pressure to a pressure of not less than 60 kgf/cm2. This pressure may be reduced to 53 kgf/cm2 if the cylinder is fitted with fusible plug. No cylinder which shows a permanent stretch in excess of 7½ per cent of the total stretch suffered during hydrostatic stretch test shall be allowed.
(viii) The safety relief devices if fitted, shall operate at a pressure of 53 kgf/cm2 or at a temperature of 100 °C + 40 °C/–2 °C.
(ix) Every cylinder shall have permanently and conspicuously marked upon it or upon a brass plate soldered to it the name of the manufacturer and the words “Acetylene properly compressed into porous substance” and shall bear the following markings, namely: -
(a) Serial number and identification of manufacturer;
(b) Number of the standard;
(c) Test pressure;
(d) The date of hydrostatic stretch test with code mark of the place where the test was carried out;
(e) Date of filling of porous mass;
(f) Water capacity’;
(g) A symbol to indicate the nature of heat treatment;
(h) Identification of porous mass and porosity percentage;
(i) Tare weight (inclusive of valve);
(j) Inspector’s official mark;
(k) Maximum gas capacity.
“dissolved acetylene cylinder” means a cylinder having a valve and with or without safety devices, containing a porous mass, a solvent for the storage of dissolved acetylene and at least sufficient acetylene to saturate the solvent at atmospheric pressure and at a temperature of +15°C; Explanation. -Acetone or any other solvent used shall not be capable of chemical reaction with the acetylene gas or with the porous mass or with the metal of the cylinder or valve;
- “dissolved gas” means a gas which under pressure is dissolved in a fluid solvent appropriate to the particular gas as for example, acetylene in acetone or ammonia in water;
- “tare weight” in relation to - (1) acetylene cylinder means the weight of the cylinder together with any fittings, permanently attached and includes the weight of valve any safety device, porous mass, requisite quantity of solvent for dissolving acetylene, and the weight of acetylene gas saturating the solvent at atmospheric pressure and temperature of 15°C;
- Particulars of MATERIAL SAFETY DATA SHEET to be referred before handling any compressed gas cylinder.
Note: All Consciousness Sessions are customized to suite site, client and level of candidates, these customizations are required to specifically address knowledge sessions, make the right connect to the people attending.
Properly researched training / Consciousness session can give correct and effective information with an enhanced knowledge sharing session.
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On completion of this training programme you will:
- Understand the importance of safety and safety awareness.
- Understand accident and causes of accident.
- Understand various types of workplace hazards.
- Understand various control measures that can be used to minimize the risk.
- Understand how you can contribute to enhance your workplace safety.
