This is the simplest form of green sand molding, particularly suitable for solid patterns. The entire mold is made in foundry floor or in bed of sand above floor level for inconvenience in working and pouring. No molding box is necessary and the upper surface of the mold is open to air. The sand in the foundry floor is made loose and perfectly leveled to obtain uniform thickness of the casting. As there is no head of metal the sand may be rammed lightly, just hard enough to support the weight of metal only. After proper leveling, the pattern is pressed in the sand bed for making mold. The pouring basin is built up at one end of the mold, and the overflow channel is cut at the sides of the cavity at the exact height from the bottom face of the mold to give the desired thickness
Advantages Of Air Refrigeration : 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to ton of refrigeration ratio is less as compared to other systems. Disadvantages Of Air Refrigeration : 1. The quantity of Refrigerant used per ton of refrigeration is high as compared to other systems. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content.
Comments
Post a Comment