Close-coupled pumps brochure

Close-coupled pumps brochure

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Watson-Marlow 521VI/RELC, 521I/RELC, 521F/RELC, 521FX/RELC: 0-2bar IP55 pumps fitted with LoadSure low-pressure element pumpheads

521 close coupled pumps offer IP55 ingress protection for light industrial environments. They offer rugged, industrial pumping, with all the pumphead features of cased drives, but at the lowest whole-life cost.

521VI Varmeca close coupled drives bring 10:1 speed control, constant torque output and total reliability to the industrial environment. The drive offers 230V and 400V three-phase power options, plus 110V and 230V single-phase. Control is by a large speed knob and forward/reverse switching.

521F Fixed speed drives are three-phase powered

521FX Duplex fixed speed drives have twin pumpheads allowing two channel pumping.

521I Inverter-controlled, variable speed drives include a stand-alone Siemens inverter to control pump speed.


  521F 521V 521P
Industry approved motors with 2 standard gearing speeds
Supplied with free standing variable frequency drive (VFD)  
Speed start/stop forward/reverse keypad control with remote control features    
Speed control ratio   10:1 5:1
VFD input power 230/3/60, 460/3/60, 115/1/60 in either NEMA 1 or NEMA 4X    
Standard integral gearmotor 3 phase 230/460V 60Hz TEFC  
Optional 115/1/60    
Optional gearbox and NEMA C motor  
Optional explosion proof (XP) motor  
Four vane pneumatic motor with speed limiting    
Optional FDA approved white epoxy paint
Optional baseplate mounting


Close coupled drives offer rugged, industrial, quality pumping, with all the pumphead features of cased drives, but at the lowest possible whole-life ownership cost.

Datasheet download

521 Close coupled pumps

Manual download

521F/RELC, 521I/RELC, 521VI/RELC, 521FX/RELC

521 REL Closed Coupled


LoadSure® Element tubing flow rates, ml/min (gph)
Tube Material Speed 3.2mm 6.4mm 9.6mm

Pumpsil, Sta-Pure PFL, Neoprene
6-57rpm 10-105(0.2-1.7) 40-400(0.6-6.3) 90-905(1.4-14)
  23-227rpm 40-400(0.6-6.3) 155-1560(2.5-24.7) 360-3590(5.7-57)

Marprene TL, Bioprene TL
6-57rpm 10-95(0.2-1.5) 40-380(0.6-6.0) 85-865(1.3-14)
  23-227rpm 40-380(0.6-6.0) 155-1560(2.5-24.7) 345-3430(5.5-54)

Tubing and hoses for your industry

  • Contact us

    To order this product please contact UK Sales Support:

    Phone: +44 (0) 1326 370362

    You can also send us an email or find your nearest distributor.