For molds I use chamber reduced to 12 litres from total 45 litres. For making molds it is enought. For casting I use pressure. These test casts were from smaller 1 liter chamber casted with 8 bar pressure.
It is used for pressure casting on 1 liter chamber. It can make 8 bars in couple of seconds. Refrigerator compressor can make pressure about 15 bars and have flow 20-25 liters/min. This black valve on chamber is safety valve for 8 bars.