ERT™ Power Section Specification (Metric)
825ERT91039
209.6 mm 9:10 Lobes 3.9 Stages
Rotor Specifications
Overall Length 6362.7 mm
Avg. Diameter 125.26 mm
Contour Length 6121.4 mm
Eccentricity 6.14 mm
Major Diameter 137.54 mm
Head Diameter 123.19 mm
Head Length 241.3 mm
Weight 741 kg
Thread Form 3.688 XDV
Stator Specifications
Overall Length 6604.0 mm
Tube OD 209.55 mm
Contour Length 6070.6 mm
Tube ID 140.28 mm
Rubber Cut-back
Side 1: 266.7 mm
Side 2: 266.7 mm
Weight 816 kg
Material Alloy Steel
Performance Specifications
Flow Range 2271-3407 LPM
Rev per Unit Volume 0.03 Rev/L
Speed Range 66-99 RPM
No Load Pressure Loss 1924 kPa
  POB XTH
Max Rec Press 7,950 kPa 8,520 kPa
Torque @ Max Press 35,720 N-m 38,270 N-m
Stall Pressure 14,550 kPa 15,590 kPa
Stall Torque 65,360 N-m 70,030 N-m
Stator Minors and Fit (mm) at 21°C
  XTH POB
Group Minor Fit Minor Fit
C 125.53 -0.27 125.53 -0.27
2 125.27 -0.01
 
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 Torque (Nm) 0
Fit Increase
Change in Temperature (°C) 0 50 100 150 Fit Increase (mm) 0
Speed
Differential Pressure (kPa) 0 5,000 10,000 Speed (RPM) 0
Mechanical Power
Differential Pressure (kPa) 0 10,000 Mechanical Power (Kw) 0
Torque
Differential Pressure (kPa) 0 5,000 10,000 Torque (Nm) 0 10,000 20,000 30,000 40,000 50,000
Fit Increase
Change in Temperature (°C) 0 20 40 60 80 100 120 140 160 180 Fit Increase (mm) 0 0.5 1
Speed
2271 LPM 2839 LPM 3407 LPM Differential Pressure (kPa) 0 2,000 4,000 6,000 8,000 10,000 12,000 Speed (RPM) 0 50 100
Mechanical Power
2271 LPM 2839 LPM 3407 LPM Differential Pressure (kPa) 0 5,000 10,000 15,000 Mechanical Power (Kw) 0 100 200 300
©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.