ERT™ Power Section Specification (Metric)
500ERTcr7838
127 mm 7:8 Lobes 3.8 Stages
Rotor Specifications
Overall Length 4521.2 mm
Avg. Diameter 66.23 mm
Contour Length 4368.8 mm
Eccentricity 4.17 mm
Major Diameter 74.57 mm
Head Diameter 69.85 mm
Head Length 152.4 mm
Weight 106 kg
Thread Form 2 3/8" HEF
Stator Specifications
Overall Length 4749.8 mm
Tube OD 127.00 mm
Contour Length 4343.4 mm
Tube ID 80.67 mm
Rubber Cut-back
Side 1: 203.2 mm
Side 2: 203.2 mm
Weight 197 kg
Material Alloy Steel
Performance Specifications
Flow Range 568-1230 LPM
Rev per Unit Volume 0.13 Rev/L
Speed Range 76-166 RPM
No Load Pressure Loss 1613 kPa
  POB XTH
Max Rec Press 7,240 kPa 7,760 kPa
Torque @ Max Press 7,350 N-m 7,870 N-m
Stall Pressure 13,260 kPa 14,200 kPa
Stall Torque 13,450 N-m 14,410 N-m
Stator Minors and Fit (mm) at 21°C
  XTH POB
Group Minor Fit Minor Fit
T 66.37 -0.14 66.37 -0.14
0 66.62 -0.39 66.62 -0.39
4 67.01 -0.77 67.01 -0.77
 
Reline Lengths (mm) Max 4750 Min 4597
Alt. Stator OD (mm)   127.0   -
Alt. Rotor Diameter (mm) - 66.548 - 65.862

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 5,000 10,000
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
568 LPM 899 LPM 1230 LPM Differential Pressure (kPa) 0 2,000 4,000 6,000 8,000 10,000 12,000 Speed (RPM) 0 50 100 150 200
Mechanical Power
568 LPM 899 LPM 1230 LPM Differential Pressure (kPa) 0 5,000 10,000 15,000 Mechanical Power (Kw) 0 50 100 150
©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.