Watson-Marlow Fluid Technology Group

- Model Qdos - Chemical Metering Pumps



Accurate, versatile chemical metering pumps. Delivering flow rates that remain constant right up to 7 bar Qdos peristaltic chemical metering pumps give users a unique advantage over diaphragm metering pumps.

  • Cut chemical cost through higher accuracy metering
  • Simple drop-in installation eliminates ancillary equipment
  • Reduced maintenance with single, no-tools, component replacement
  • Flow rates from 0.1 to 2000 ml/min at up to 7 bar
  • Cost of ownership is less than that of a diaphragm pump

A diaphragm metering pump often requires a range of high maintenance ancillary items to function.

The Qdos pump eliminates ancillary equipment while ensuring accurate, linear and repeatable metering across all process conditions.

  • No backpressure valves
  • No pulsation dampener
  • No degassing valves
  • No foot valves and strainers
  • No float switches

ReNu peristaltic pumphead technology is at the core of the Qdos pump. This ensures the delivery of accurate and repeatable flow for fluids of wide ranging viscosities.

Process uptime is maximised by facilitating quick, safe and easy pumphead removal and replacement, with no need for tools, no specialist training and no maintenance technicians.

The contained pumphead design with integral leak detection reduces wastage and eliminates operator exposure to chemicals.

High suction lift and viscous handling eliminates the need for flooded suction and specialist piping systems.

Chemical metering with no gas locking
Victoria Water Treatment Works use Qdos chemical metering pumps to meter fluoride, chlorine and polyphosphate in the water filtration, clarification and distribution process. The pumps are employed to eliminate the gas locking problems previously experienced with pulsation diaphragm pumps. A Qdos 20 model with a tube material specifically formulated for high pressure sodium hypochlorite applications, has joined the chemical metering process. Running at between 70 and 100psi and controlled by a 4-20mA input signal, the Qdos pumps at the Victoria water treatment plant have significantly reduced maintenance downtime.

Precise delivery of electroplating chemicals
BIA Kunstoff - und Galvanotechnik is involved in electroplating plastic components with metallic surfaces for the automative industry. The Qdos pumps employed by BIA must precisely dose the chemical additives to the electroplating machines with minimal pulsation, to avoid them being 'shattered'. In addition to low pulsation, virtually no pump downtime and no additional accessories such as check valves, makes Qdos pumps the best choice for electroplatic duties.

Rare mineral recovery process
In vital floatation duties at British Fluorspar, twelve Qdos pumps meter reagents from mixer tanks to header tanks.
Acid grade fluorspar (fluorite) is a relatively rare industrial mineral and its extraction involves precise metering of reagents such as methyl isobutyl carbinol, sodium isopropyl xanthate, caustic soda pearl and other chemicals. Overdosing of these chemicals is a costly business which must be avoided.

Maintenance downtime cut from 1.5 hours to just five minutes
An important stage of wastewater purification at Selters (Westerwald) Germany, is the elimination of phosphates with the addition of precipitants, including ferric chloride. Ferric chloride is both chemically aggressive and abrasive and attacked the diaphragms of the pumps previously used at the sites' metering station. Technicians were replacing pump diaphragms every 3 to 4 months, and each one took at least one hour to change, plus clean up time for leaked chemical. Qdos pumps were installed in the precipitant metering station and immediately reduced maintenance time to five minutes.

Ensuring the supply of safe drinking water
High concentrations of iron and manganese in the Canadian Barrie region, mean that a sequestering agent is required for potable water. The City of Barrie Water Operations Branch uses sodium silicate (Na2SiO3) to bind the Fe/Mn and prevent it from oxidising. The effect is aesthetic to avoid staining sanitary ware. Diaphragm metering pumps had been chosen to meter between 4-6 parts sodium silicate, until sticking ball valves and clogging caused serious maintenance issues at the unmanned site. Investing in Qdos pumps was easy for the Water Operations Department to justify on the costs of downtime and spare parts alone.

High precision chemical metering on the go
Qdos pumps are available with either mains power or 12-24V DC. If your chemical metering application involves a mobile skid or a remote location without mains power, then 12-24V Qdos meets your requirements. The 12-24V DC power option further increases the range of applications for Qdos pumping.

Reduced maintenance with single, no-tools, component replacement

  • Revolutionary ReNu pumphead technology is at the core of the Qdos pump. This ensures the delivery of accurate and repeatable flow for fluids of wide ranging viscosities.
  • ReNu pumphead provides accurate, linear and repeatable low pulse flow under varying process conditions.
  • Safe, no tools maintenance. The ReNu pumphead has an integral leak detector which eliminates operator exposure to chemicals.
  • Qdos pumps can be ordered with the ReNu pumphead mounted on the left or right of the pump.

All models are IP66 rated for use in washdown environments.

The keypad, display and input/output connections are readily accessible for easy operation and maintenance.

An intuitive menu offers advanced control features including:

  • Fluid level monitoring
  • Fluid recovery
  • Line priming
  • Flow calibration

Universal +   

  • Configurable 4–20mA input
  • 4-20mA output
  • Configurable alarm outputs
  • Manual, analogue (4-20mA) or contact (pulse) mode functionality
  • Optional configurable output relays
  • Optional 110VAC inputs


  • Universal pump offers the same functionality as the Universal+ but with a fixed range 4-20mA input and no 4-20mA output.


  • Manual control of the pump
  • Colour graphical display
  • Ability to control the pump by switching the supply voltage


  • 4-20mA input
  • 4-20 mA output
  • Alarm output
  • Run status output


  • Manual and PROFIBUS control
  • Intelligent device capable of diagnostic feedback
  • PROFIBUS DP V0 – real time communication for secure and flexible processes
  • Bus speed 9.6 up to 1,500 kb/s

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