Catalyzes the hydrolysis of inorganic pyrophosphate (PPi) forming two phosphate ions (By similarity) (PubMed:26546423). The hydrolysis of PPi by inorganic pyrophosphatase releases a considerable amount of energy that can drive unfavorable biochemical transformations to completion (Probable). Is not active on nucleoside triphosphates (ATP, TTP, GTP, or CTP) or nucleoside diphosphate (ADP) (PubMed:26546423). diphosphate + H2O = H(+) + 2 phosphate Inhibited by sodium fluoride (NaF) in vitro, similarly to other class A type inorganic pyrophosphatases. Displays non-Michaelis-Menten kinetics for PPi hydrolysis. Hill coefficients indicate cooperative binding to PPi and Mg(2+). Optimum pH is 8-9. Optimum temperature is 42 degrees Celsius. Is moderately thermostable, with a half-life of thermal inactivation of 2 hours at 65 degrees Celsius, and retains 82% activity after incubation for 2 hours at 42 degrees Celsius. Homohexamer (By similarity) (PubMed:26546423). Also forms homotrimers, but the trimeric form is 23% less active than the hexamer. In fact, likely forms a dimer of trimers (PubMed:26546423). Inorganic pyrophosphatases are used in a wide variety of biotechnology applications based on the ability of these enzymes to drive reactions forward and generate an easily assayed product. Since HvPPA displays robust activity under high-salt conditions and in organic solvents, it could be a valuable tool for use in bioindustry. A unique feature of H.volcanii PPA (HvPPA) is its high tolerance to organic solvents, with little if any enzyme inactivation after 2 hours of incubation in buffers supplemented with 50% (vol/vol) dimethyl sulfoxide (DMSO), dimethylformamide (DMF), ethanol, or methanol. The catalytic activity of HvPPA is also found to be robust when assayed in organic solvents. Moreover, HvPPA is fully active over a wide range of salt concentrations. Belongs to the PPase family.