ERT™ Power Section Specification
825ERTcr7840
8.25" 7:8 Lobes 4.0 Stages
Rotor Specifications
Overall Length 196.50 in
Avg. Diameter 4.609 in
Contour Length 189.00 in
Eccentricity 0.288 in
Major Diameter 5.186 in
Head Diameter 4.850 in
Head Length 7.50 in
Weight 950 lb
Thread Form 3 1/2" API IF
Stator Specifications
Overall Length 212.25 in
Tube OD 8.25 in
Contour Length 187.30 in
Tube ID 5.405 in
Rubber Cut-back
Side 1: 13.00 in
Side 2: 13.00 in
Weight 1346 lb
Material Alloy Steel
Performance Specifications
Flow Range 300-900 GPM
Rev per Unit Volume 0.16 Rev/Gal
Speed Range 47-142 RPM
No Load Pressure Loss 242 psi
  POB XTH
Max Rec Press 1,110 psi 1,190 psi
Torque @ Max Press 18,650 ft-lbs 19,860 ft-lbs
Stall Pressure 2,010 psi 2,170 psi
Stall Torque 33,940 ft-lbs 36,520 ft-lbs
Stator Minors and Fit (in) at 70°F
  XTH POB
Group Minor Fit Minor Fit
B 4.596 0.013 4.554 0.055
0 4.603 0.006 4.604 0.005
2 4.612 -0.003 4.608 0.001
 
Reline Lengths (in) Max 212 Min 206
Alt. Stator OD (in)   -   -
Alt. Rotor Diameter (in) - - - -

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

Torque
Differential Pressure (psi) 0 1,000 Torque (ft-lb) 0
Fit Increase
Change in Temperature (°F) 0 100 200 300 Fit Increase (in) 0
Speed
Differential Pressure (psi) 0 1,000 Speed (RPM) 0
Mechanical Power
Differential Pressure (psi) 0 1,000 Mechanical Power (hp) 0
Torque
Differential Pressure (psi) 0 500 1,000 1,500 Torque (ft-lb) 0 10,000 20,000 30,000
Fit Increase
Change in Temperature (°F) 0 50 100 150 200 250 300 Fit Increase (in) 0 0.02 0.04 0.06
Speed
300 GPM 600 GPM 900 GPM Differential Pressure (psi) 0 500 1,000 1,500 Speed (RPM) 0 50 100 150
Mechanical Power
300 GPM 600 GPM 900 GPM Differential Pressure (psi) 0 500 1,000 1,500 Mechanical Power (hp) 0 200 400 600
©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.