ERT™ Power Section Specification (Metric)
825ERTcr7840
209.6 mm 7:8 Lobes 4.0 Stages
Rotor Specifications
Overall Length 4991.1 mm
Avg. Diameter 117.07 mm
Contour Length 4800.6 mm
Eccentricity 7.33 mm
Major Diameter 131.72 mm
Head Diameter 123.19 mm
Head Length 190.5 mm
Weight 431 kg
Thread Form 3 1/2" API IF
Stator Specifications
Overall Length 5391.1 mm
Tube OD 209.55 mm
Contour Length 4757.4 mm
Tube ID 137.29 mm
Rubber Cut-back
Side 1: 330.2 mm
Side 2: 330.2 mm
Weight 611 kg
Material Alloy Steel
Performance Specifications
Flow Range 1136-3407 LPM
Rev per Unit Volume 0.04 Rev/L
Speed Range 47-142 RPM
No Load Pressure Loss 1669 kPa
  POB XTH
Max Rec Press 7,630 kPa 8,200 kPa
Torque @ Max Press 25,280 N-m 26,930 N-m
Stall Pressure 13,880 kPa 14,930 kPa
Stall Torque 46,020 N-m 49,520 N-m
Stator Minors and Fit (mm) at 21°C
  XTH POB
Group Minor Fit Minor Fit
B 116.74 0.33 115.67 1.40
0 116.92 0.15 116.94 0.13
2 117.14 -0.08 117.04 0.03
 
Reline Lengths (mm) Max 5391 Min 5239
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 5,000 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
Fit Increase
Change in Temperature (°C) 0 20 40 60 80 100 120 140 160 180 Fit Increase (mm) 0 0.5 1
Speed
1136 LPM 2271 LPM 3407 LPM Differential Pressure (kPa) 0 2,000 4,000 6,000 8,000 10,000 12,000 Speed (RPM) 0 50 100 150
Mechanical Power
1136 LPM 2271 LPM 3407 LPM Differential Pressure (kPa) 0 5,000 10,000 15,000 Mechanical Power (Kw) 0 100 200 300 400 500
©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.