• 4520B UNx Fluid End Upgrade UNx-Cutaway

3720B UNx Fluid End Upgrade - #9 Plungers

Part No: 54790

Increase productivity and reduce operating cost with a UNx® Fluid End Upgrade. Flow up to 17.8 gpm (67 l/min) at 17,500 psi (1200 bar). Designed to fit Butterworth L-375, Gardner-Denver TF-375, and others.

The Jetstream UNx Fluid End Upgrade is ideal for replacing a damaged, costly, or unreliable fluid end. It is also a cost-effective solution to increase the available operating pressure or range of pressure for those who have already converted to the UNx. The upgrade delivers all of the benefits of the UNx Fluid End design.

  • Five plunger (quintuplex) design
  • Superior performance
  • Greater flexibility in the field
  • Reduced downtime and maintenance
  • Clamp-style plungers
  • Bolt-on installation requires only minutes
  • Once upgraded to the UNx design, the unit can be supplemented with additional fluid ends to expand its range of operating pressures


Model Name 3720B
Maximum Power (hp) 200
Maximum Operating Pressure (psi) 17500
Maximum Flow (gpm) 17.8
Maximum Power (kW) 149
Maximum Operating Pressure (bar) 1200
Maximum Flow (l/min) 67
Plunger Size #9
Plunger Diameter (in) 0.9
Plunger Diameter (mm) 22.86
Number of Plungers 3
Plunger Stroke (in) 3.75
Plunger Stroke (mm) 95
Discharge Port Connection Jetstream 20K Port Female
Accessory Port Connections Jetstream 20K Port Female
Number of Accessory Ports 3
Suction Port Connection 2"NPT Female
Maximum Pump Speed (RPM) 575
Flow at 200 RPM (gpm) 6.2
Flow at 300 RPM (gpm) 9.3
Flow at 400 RPM (gpm) 12.4
Flow at 500 RPM (gpm) 15.5
Flow at 575 RPM (gpm) 17.8
Flow per Revolution (gal/rev) 0.031
Flow at 200 RPM (l/min) 23
Flow at 300 RPM (l/min) 35
Flow at 400 RPM (l/min) 47
Flow at 500 RPM (l/min) 59
Flow at 575 RPM (l/min) 67
Flow per Revolution (l/rev) 0.117

UNx Conversion Video

This video highlights the ease of maintenance and pressure convertibility of Jetstream UNx Pump. (3:59)

20K Bypass Valve - Pump Mount

A bypass valve diverts a portion of pump flow to a low- pressure outlet and is used to prevent bogging of diesel engines when using flows at the low end of the pump’s capability or to adjust pressure on electric motor driven systems.  20,000 psi (1400 bar).  Pump-mounted.

20K Handle-Adjustable Regulator

Maintains constant system pressure when operating one or more shut-in devices. Knob-adjustable. Field-replaceable valve cartridge. For operation at 15,000 - 20,000 psi (1000 - 1400 bar). Pump-mounted.

UNx Spare Parts Packages

Packages include all major fluid end replacement packaged together for easy transport and storage.

20K Pressure Gauge (psi) - Jetstream 20K Port Male Inlet

0 - 35,000 psi scale. 1,000 psi graduations. Working pressure up to 20,000 psi. Jetstream 20K Port Male connection.

20K Rupture Disc Holder - 20K Port Male

Prevents over-pressurization of waterblasting systems using inexpensive and easily replaceable discs manufactured to burst at predetermined pressures. For operating pressures up to 20,000 psi (1400 bar). 20K Port Male connection.

20K Relief Valve - 20K Port - 18,000-24,000 psi (1240-1655 bar)

Factory set to open at customer specified pressures to prevent system overpressurization. For operating pressures from 15,000 - 20,000 psi (1000 - 1400 bar). 20K Port Male connection.

3700B UNx Fluid End Upgrades

Increase productivity and reduce operating cost with a UNx® Fluid End Upgrade. Operating pressure up to 40,000 psi (2750 bar). Designed to fit Butterworth L-375, Gardner-Denver TF-375, and others.