Rotor pair for a compression block of a screw machine

A rotor pair for a compressor block of a screw machine, wherein the rotor pair comprises:

• a secondary rotor that rotates about a first axis and a main rotor that rotates about a second axis, wherein a number of teeth of the main rotor is 3 and a number of teeth of the secondary rotor is 4, wherein a relative profile depth of the secondary rotor
• PT
• rel
• =
• rk
• 1
• -
• rf
• 1
• rk
• 1
• is between 0.50 and 0.65, wherein rk1 is an addendum circle radius drawn around the outer circumference of the secondary rotor and rf1 is a dedendum circle radius starting at the profile base of the secondary rotor, wherein a ratio of an axis distance a of the first axis from the second axis and the addendum circle radius rk1
• a
• rk
• 1
• is between 1.636 and 1.8, wherein the main rotor is configured with a wrap-around angle ΦHR for which it holds that 240°≤ΦHR≤360°, and wherein for a rotor length ratio LHR/a:
• 1.4≤LHR/a≤3.4,
• wherein the rotor length ratio is formed from a ratio of the rotor length LHR of the main rotor and the axis distance a, and the rotor length LHR of the main rotor is formed by a distance of a suction-side main-rotor rotor end face to an opposite pressure-side main-rotor rotor end face.