37. Additional requirements for dissolved acetylene cylinders.
- The 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 ninety two percent and in no case shall be less than seventy five 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 seventy 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 7-1/2 percent of the total stretch suffered during hydrostatic stretch test shall be allowed.(viii)The safety relief device if fitted shall operate at a pressure of 53 kgf/cm2 or at a temperature of 100° C + 4° 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.Explanation. - Acetylene cylinders are designed for a specified charge of acetylene, the quantity of the gas is determined in relation to the nominal quantity of the solvent. Complying with the appropriate ratio of gas and quantity of the solvent is one of the conditions for the safe operation of the cylinder. Excess solvent may result to a hydraulically full cylinder that, when subjected to temperature increase, can develop extremely high internal pressures. Shortage of the solvent will result in the cylinder becoming less resistant against decomposition due to flashback. Solvent replenishing of the acetylene cylinders is therefore essential and this operation shall therefore be carried out with due care before refilling of the cylinders with acetylene gas.
