Flocculators - JLT Series

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Flocculators with multiple stirrers to allow standard conditions to be met during analysis, a basic requirement in order to obtain reliable and repeatable results.


Standardized Control

  • Digitally selectable speed from 10 to 300 rpm
  • Microporcessor controlled operating time for unattended operation
  • Identical speed and time for all positions for comparable results
  • Reliable and repeatable results from VELP stirring quality
  • Precise speed from an electronically controlled DC gear motor


Practical Operation

  • Choice of 4- or 6-place models
    JLT4, 4-position jar tester
    JLT6, 6-position jar tester
  • High visibility LED displays for speed and time
  • Illuminated back panel to simplify sample observation
  • Stirring rods adjustable in height without tools


Robust Design

  • Strong resistance to chemical and mechanical corrosion




Construction material Epoxy painted metal structure
Models JLT4: 4 positions
JLT6: 6 positions
Back panel disconnectable illuminated
Stainless steel stirring rods Adjustable in height by a selfblocking chuck
DC gear motor  
Monoselector same speed for each rod
Power JLT4: 11 W
JLT6: 19 W
Weight JLT4: 13 kg
JLT6: 17 kg
Dimensions (WxHxD) JLT4: 645 x347 x 260 mm
JLT6: 935 x 347 x 260 mm



Electronic speed control from 10 to 300 rpm
Electronic speed control 20 - 40 - 50 - 100 - 200 rpm
Speed setting interval 1 rpm
Microprocessor controlled timer 0÷999 min or 0 ÷99 hours (or continuous)




Intuitive Parameters Setting, Digital Display

JLT Series, with 4- or 6- position Floc Tester, offers continuously variable stirring speed (if required), up to 300 rpm and settable through the relative digital display located on the front panel.

In addition, the user can program the operating time for unattended operation, through a second digital display. When time expires, stirring will be stopped automatically.

In addition, the user can program the operating time for unattended operation. When time expires, stirring will be stopped automatically.

An illuminated back panel simplifies the observation of the samples, whilst height adjustment option for the stirring blades during operation increases its capabilities.



Jar testing is a pilot-scale test of the treatment chemicals used in a particular water plant. In few words, it simulates the coagulation/flocculation process in a water treatment plant, helping the operator in the determination of the right amount of treatment chemicals, and, thus, in improving the plant’s performance.

Jar testing entails adjusting the amount of chemicals and their sequence in which they are added. The sample requires to be stirred so that the formation, development, and settlement of floc can be watched just as it would be in the fullscale treatment plant.

The operator then performs a series of tests to compare the effects of different amounts of flocculation agents at different pH values to determine the right size floc.


Few operations are required for a correct test:

  • For each water sample, usually raw water, a number of beakers (jars) are filled with the same amounts of water sample
  • Each beaker is treated with different doses of chemical; other parameters may be altered besides dosage, including chemical types, mixing rate, aeration level/time, filtration type, etc.
  • Then, by comparing the final water quality in each beaker, the effect of the different treatment parameters can be determined and the best formula can be reproduced on large scale