# Geometrical Models

## The right geometry for every application – it’s possible with the NETZSCH modular design!

The NEMO^{®} Pump belongs to the family of rotary positive-displacement pumps. The two conveying elements are comprised of the fixed stator and the rotor which turns within it.

4 different helical rotor and stator geometries, along with an extensive selection of sealing and material of construction options allow our specialists to select the NEMO^{®} pump that is tailor made for your application.

The design is modular since the outer dimensions of the pumps are identical, as are the connections on the suction side and the discharge side, for all four geometries. With the exception of the rotor and the stator, all other components are also identical. This means that, if it is ever necessary to adapt a NEMO PUMP^{®} to new flow rates or pressures after installation, this can be done by simply exchanging the rotor and stator to better suit the new conditions.

## S/L Geometry

The helical eccentric screw/rotor has a circular cross section, a very long pitch and large thread depth. It oscillates in the fixed stator, which has an internal thread with the same profile as the rotor, but with 180° interval twin starts and twice the pitch.

As a result of this 1/2 ratio lobe geometry, cavities are formed between the rotor and the stator when the two are put together. When the rotor turns within the stator, the progressing cavities between the two transport the medium in a smooth and continuous manner from the suction to the discharge side of the stator.

The flow rate is determined by the pitch of the rotor/stator, the diameter and the eccentricity, as well as by the pumping rotation speed. The pressure capability depends on the number of stages, with the differential pressure being up to 6 bar per stage.

The 2-stage NEMO^{®} Pump in S-Geometry can reach differential pressures of up to 12 bar at a flow rate of 100%. A single-stage NEMO^{®} Pump in L-Geometry has the same outer dimensions as the 2-stage pump in S-Geometry, the same diameter and eccentricity, but twice the pitch of the rotor/stator. This pump therefore produces a flow rate of 200% over the S-Geometry at a differential pressure of up to 6 bar.

## D/P Geometry

The helical eccentric screw/rotor has an elliptical cross section, a long pitch and large thread depth. It turns in a circular eccentric motion within the fixed stator, which has an internal thread with the same profile as the rotor, but with 120° interval triple starts and 1.5 times the pitch. As a result of this 2/3 ratio lobe geometry, cavities are formed between the rotor and the stator when the two are put together. When the rotor turns within the stator, the progressing cavities between the two transport the medium in a smooth and continuous manner from the suction to the discharge side of the stator. The cavities in D/P-Geometries are about 75% of the size of those in S/L-Geometries, but they are passed through twice per revolution instead of only once, resulting in a flow rate 50% higher. The flow rate is determined by the pitch of the rotor/stator, the elliptical diameter and the eccentricity, as well as by the pumping rotation speed. The pressure capability depends on the number of stages, with the differential pressure being up to 6 bar per stage. The 2-stage NEMO^{®} Pump in D-Geometry can reach differential pressures of up to 12 bar at a flow rate of 150% over that of the S-Geometry. A single-stage NEMO^{®} Pump in P-Geometry has the same outer dimensions as a 2-stage pump in D-Geometry, the same ellipse and eccentricity, but twice the pitch of the rotor/stator. This pump therefore produces a flow rate of 300% over that of the S-Geometry at a differential pressure of up to 6 bar.