New S-flow Kinematic Viscometer

Houillon viscosity reinvented with an optional autosampler
“The newest generation of S-flow systems offers the ultimate in fast, accurate viscosity testing and now also features an optional autosampler for fully unattended operation.”
Small sample volume
High throughput
Low solvent consumption
Highly accurate
Maximum throughput and ease of use with very low sample and solvent consumption

The latest generation of new S-flow builds on the strong foundation of its predecessors to offer the ultimate in automatic viscosity testing of Newtonian samples such as petroleum products. The system offers all the tried and tested advantages of a Houillon-type tube design such as short process times, small sample volume and low solvent consumption, but now also includes an optional autosampler to allow for fully unattended operation. All controlled from a central software interface that takes care of result storage, autosampler control, calculations and much more. It complies fully with ASTM D7279 and as such, gives full correlation to ASTM D445. It is the ideal system for used oil analysis labs that need to test a wide range of lubricant viscosities.

The new S-flow range consists of 2 main models: S-flow IV, a single bath viscometer with 4 tubes configurantion and there is a second model, S-flow IVwhich has 2 baths with 2 tubes in each within the same footprint as the single bath viscometer, providing dual temperature measurement in an extremely compact package. Other options include dual solvent cleaning and integrated duplo testing which obtains 2 flowtime determinations with only 1 sample injection. 

All measurement parameters, such as warmup times and cleaning parameters can be set through the 12” touchscreen or through the complementary software. The diagnostic system alerts the operator to possible issues such as empty solvent supply tanks, full waste bottles, insufficient vacuum, etc. The optional autosampler is fully modular and can be installed aftermarket, meaning you can purchase the analyser first and then upgrade to auto-sampling when the need arises.

S-flow IV
S-flow IV+
Number of baths 1 2
Viscometers per bath 4 2
S-flow IV series
Standard methods Compliant with ASTM D7279, D2270
Correlation with ASTM D445
Built-in VI calculation Yes
Measuring range 0.3 - 3,000 mm2/s @40°C
Temperature range * 20 – 120°C *
Temperature stability Better than ±0.02°C
Timer resolution 0.001 s
Sample volume 0.3 – 1.0 ml
Solvent consumption 2 – 3 ml per cycle
Samples per hour ** Up to 80 samples per hour **
Viscometer type Houillon
Sensor type Optical, self-calibrating
Time measurement Automatic
Solvent injection Automatic
Advanced PC software option Yes
Dual solvent option Yes
Duplo measurement option Yes
External cooling system option Yes
Air compressor Yes
Silicone oil option Yes
Integrated cleaning pump Yes
Warmup prior to measuring Yes
PC Control Multiple instruments controlled with 1 PC
Touchscreen 12” capacitive
Optional autosampler Yes
Dimensions 43 x 58 x 66 cm / 17 x 23 x 26 in (w x d x h)
Weight 55 kg, 122 lbs
Data export USB storage device
Power requirement

1 kW; 115/240V - 50/60Hz 

* For temperatures around ambient, an external chiller is required
** Measurements per hour; depends on viscosity, tube, temperature and solvents 

Optional accessories & upgrades

Following items are optional accessories and upgrades to the instrument.

Dual solvent cleaning

A suitable solvent used for cleaning should have the following two main characteristics:

  •  It should be able to dissolve the sample that was tested, i.e. clean the tube completely
  •  It should evaporate quickly enough at the bath temperature so that the tube is fully dry after cleaning

If the solvent used does have the ability to dissolve the sample, but does not evaporate quickly enough, a second solvent can be used to rinse out the first solvent, as well as dry the tube. Usually, low boiling solvents are used for this purpose, such as Acetone or MEK. 

Cooling circulator

For measurements close to ambient (± 8°C), an additional cooling circulator is required to create sufficient offset for the temperature control unit. Each bath is fitted with a cooling spiral, to which an external cooling circulator can be easily connected. Complete with tubing and fittings. 


Single                    Duplo


Duplo measurement tubes

The optional duplo measurement configuration adds another array of optical detections to the instrument, bringing the total number of detection points to three per tube instead of two.  Together with adapted S-flow IV tubes, which are fitted with two measuring trajectories, this enables the S-flow series to perform duplo measurements with a single sample injection, increasing productivity, saving even more on solvent consumption and run time.


Omnitek S-flow IV series operate on clean and dry 5 bar @ 5 l/min of compressed air. A suitable compressor can be supply from Omnitek if no compressed air is available. 

Positive - displacement pipette

Air-displacement pipette is supplied with new S-flow series as a standard. It is recommended to use positive displacement pipette especially at higher viscosities (300 mm2/s and above) to avoid operator errors and for more accurate and repeatable injections.  


Omnitek S-flow IV series utilizes advanced and easy to use multi-lingual software, it can be operated directly from the touchscreen, and both calibration and viscosity measurements can be performed without PC or software. However, to have more control, dedicated optional software is available, which can be used to control multiple systems.


A PC system can be sourced locally or through Omnitek. Omnitek supplies the latest model entry level laptop or, if required, desktop. When sourcing locally, make sure the operating system is Windows 7 or later and that the PC/Laptop has 1 free USB port per instrument. 


Any kind of printer can be used if instrument is connected to a PC via software. A printer can be sourced locally or through Omnitek. Omnitek supplies the latest model entry level laser printer.

Autosampler operation

Omnitek offers autosampler operation for S-flow IV series. It is ideal for customers that run large numbers of samples and want to automate their sampling process. As each laboratory will have its own requirements, automation is a highly customized product which requires elaborate preparation. The autosampler stands out for being a modular high speed autosampler, it can be installed after market, services up to 2 S-flow instruments (8 tubes), processes 25-40 samples per hour and it is customizable to allow different sample cups and racks.

Please contact us for specific solutions to your sampling needs. 


The customer should have a DCT shaft diameter < 3mm. The recommended thermometers that can be supplied are the modern digital contact thermometers (DCT), used at multiple temperatures

  •  Applicable for fuels, base oils, formulated oils, and petroleum products as well as water-based fluids.
  •  Compliant with requirements for ASTM D7279, ASTM 2270 and correlation to ASTM D445.
  •  High throughput: up to 80 samples per hour per bath under ideal operation conditions.
  •  Very easy to use and maintain.
  •  Small sample volume: 0.3-1.0 ml.
  •  Low solvent consumption: 2-3 ml per sample.
  •  Extremely accurate temperature control and flow-time measurement independent of fluid type.
  •  Automatic flow time measurement with ultraprecise meniscus detection.
  •  Fully automatic cleaning and drying.
  •  Fast & easy tube replacement (tubes are not connected to optical sensors).
  •  No need to drain bath during tube replacement.
  •  Single or dual solvent injection (optional).
  •  Integrated VI calculations (only for S-flow IV+).
  •  Stand-alone unit. No PC required. Software operation is available as an option. 
  •  Chemically resistant to allow for all common solvents.
  •  Duplo measurement capability.
  •  Integrated back flushing.
  •  Optional autosampler

This product is compliant with the following test methods:

  •  ASTM D7279 
  •  ASTM D2270

This product is correlating with the following test method:

  •  ASTM D445
Petroleum Based Samples
Other Sample Types


Lubricating Oils

Printer ink

Terminals (Fuel Distribution)


Lubricant Manufacturers Base Stocks  

Additive Manufacturers

Industrial Oils


Condition Monitoring Labs

Transmission Oils


Third Party Testing Labs

Hydraulic Fluids


Research & Development Labs

Used Oils


Quality Control Labs

Waste Oils


Military Labs

Crude Oils


Power Plants

Fuel Oils









Bio Fuels



Marine Fuels


Chemical Plants



Iron & Steel








For other fluids / solutions please send your inquire