ERT™ Power Section Specification (Metric)
850ERT8967
215.9 8:9 Lobes 6.7 Stages
Rotor Specifications
Overall Length 6362.7 mm
Avg. Diameter 126.21 mm
Contour Length 6121.4 mm
Eccentricity 7.28 mm
Major Diameter 140.77 mm
Head Diameter 123.19 mm
Head Length 241.3 mm
Weight 611 kg
Thread Form 3.688XDV
Stator Specifications
Overall Length 6604.0 mm
Tube OD 215.90 mm
Contour Length 6070.6 mm
Tube ID 140.82 mm
Rubber Cut-back
Side 1: 266.7 mm
Side 2: 266.7 mm
Weight 898 kg
Material Alloy Steel
Performance Specifications
Flow Range 1703-3596 LPM
Rev per Unit Volume 0.05 Rev/L
Speed Range 77-164 RPM
No Load Pressure Loss 1662 kPa
  POB XTH
Max Rec Press 13,220 kPa 14,160 kPa
Torque @ Max Press 38,740 N-m 41,500 N-m
Stall Pressure 24,190 kPa 25,920 kPa
Stall Torque 70,910 N-m 75,970 N-m
Stator Minors and Fit (mm) at 21°C
  XTH POB
Group Minor Fit Minor Fit
B 126.09 0.13 126.09 0.13
 
Reline Lengths (mm) Max 6604 Min 6452
Alt. Stator OD (mm)   -   -
Alt. Rotor Diameter (mm) - - - -

Max DP for reliable operation will vary based on
operational conditions. Refer to ERT Operational
Guidelines for guidance.

Torque
Differential Pressure (kPa) 0 10,000 20,000 Torque (Nm) 0
Fit Increase
Change in Temperature (°C) 0 50 100 150 Fit Increase (mm) 0
Speed
Differential Pressure (kPa) 0 10,000 20,000 Speed (RPM) 0
Mechanical Power
Differential Pressure (kPa) 0 10,000 20,000 Mechanical Power (Kw) 0
Torque
Differential Pressure (kPa) 0 5,000 10,000 15,000 20,000 Torque (Nm) 0 20,000 40,000 60,000
Fit Increase
Change in Temperature (°C) 0 20 40 60 80 100 120 140 160 180 Fit Increase (mm) 0 0.2 0.4 0.6 0.8 1
Speed
1703 LPM 2650 LPM 3596 LPM Differential Pressure (kPa) 0 5,000 10,000 15,000 20,000 Speed (RPM) 0 50 100 150 200
Mechanical Power
1703 LPM 2650 LPM 3596 LPM Differential Pressure (kPa) 0 5,000 10,000 15,000 20,000 Mechanical Power (Kw) 0 200 400 600 800
©2026 NOV. All rights reserved. Except as noted, all trademarks referenced in this document are trademarks of NOV. Performance curves describe theoretical performance with 175°F (79°C) water and are for reference only. Operational fit and drilling conditions will affect performance. Operation above maximum recommended limits will reduce life. Specification data are subject to change without notice.
PS App v.