Polysilicon is the main raw material used to manufacture silicon wafers, either for semiconductor or solar cell production. Through the reaction of metallurgic grade silicon (derived from high purity sand) with hydrogen, chloride trichlorosilane is formed. Several process steps follow to obtain pure SiHCl3. The subsequent reaction of SiHCl3 with hydrogen in a chemical reactor will deposit very pure polysilicon onto a monosilicon seed rod. The NEA reciprocating compressors` function is to recover the vent gas to the pressure level of the subsequent purification step.