Process Instruments were approached in 2008 by a customer who was having to change their pH sensor every week at massive cost due to the fouling of the sensor. In response Pi developed the Autoflush.

Autoflush System
The idea for the autoflush is simple and effective. After a user defined time period, the sample drains away and the sensor and sensor housing is flushed with clean water. This water flushes the whole of the inside of the sensor housing taking away any build-up of solids to the drain. The repeated flushing of the housing and sensor helps prevent the build-up of solids and so prolongs the life of the sensor and reduces maintenance. For waxy or fatty build-ups warm water can be used to flush the sensors. As standard heavy duty pinch valves ensure reduced maintenance over a long life.

The autoflush can be used with Pi’s pH, ORP, free chlorine, total chlorine, ozone or chlorine dioxide sensors (or a combination of sensors) and consists of a large flow cell that automatically empties on a user selectable time basis. The signal from the sensor is held and the whole flow cell including the sensor(s) is flushed with clean water. For the original customer this meant a new pH sensor after 18 months rather than sooner, resulting in a significant improvement in process control and a very significant saving in pH sensors. Since then many customers have taken advantage of the autoflush and it is installed around the world in paper mills, food factories and other plant where keeping the sensors clean enhances their performance.

  • Flushing prevents build-up of solids
  • Reduced maintenance
  • Suitable for pH/ORP/Cl2/O3/ClO2
  • User selectable flush duration
  • User selectable flush frequency
  • ‘Flush now’ facility
  • Simple, infrequent maintenance

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Document Type Size
Autoflush Brochure 384kB

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Many different sites ranging across the whole water industry have a daily struggle to keep instrumentation functioning correctly due to fouling. However did you know that…

… self cleaning and self flushing systems are now available from Process Instruments for most types of sensors?
… these fouling removal systems can extend the life of sensors and drastically reduce maintenance regimes?
… Pi’s self cleaning/flushing systems are affordable, simple and trouble free by design?

What is the problem?

Sensor Fouling

Sensor FoulingWhatever the process being monitored is, there is often something in the sample water capable of fouling a sensor, and therefore causing erroneous results. The obvious solution to this problem is to clean the sensor, but how regular should inspection and cleaning programs be for each piece of instrumentation? Too regular and the inspection and cleaning regime is time consuming and unnecessarily costly. Not often enough and the instrumentation will give false results and probably fail prematurely.

What is the solution?

Process Instruments’ Autoclean and Autoflush Systems

Simple, reliable and easy to maintain, Process Instruments’ Autoclean/Autoflush systems are an alternative to mechanical cleaning mechanisms which can clog and break. By regularly spraying the sensor/probe with clean water or air, the sensor remains clean and free from fouling for extended periods of time. The sensor cleaning cycle is activated by Pi’s controller for a user selectable length of time and frequency so that no matter how dirty the application, the probe remains clean. With no moving parts in the sensor body or in the cleaning attachment there is nothing to replace or check other than a simple valve positioned in an easy to reach location.

Pi’s Autoclean and Autoflush systems can give trouble free and fouling free functioning of sensors for weeks, if not months, at a time.

A solution for each application

Autoclean Cap


This option can be added to our pH, ORP, Turbidity, Suspended Solids and Dissolved Oxygen (DO) sensors. Consisting of an end cap to direct the flow of clean water (or air for a DO sensor) across the face of the sensor blasting any dirt away. The cleaning is controlled by a single valve positioned in an easily accessible location.


If using air to clean a DO sensor the system can also automatically verify that the sensor is still responding correctly, removing any need to remove the sensor from the sample for months at a time.
Autoflush System


For sensors that require flow cell mounting like Chlorine, Ozone and Chlorine Dioxide, an Autoflush system has inbuilt valves which automatically start/stop the sample flow and control the flow of clean water past the probe. The user can set the flushing interval and duration to keep the flow cell and sensor clear from fouling. For particularly dirty or stubborn contaminants, warm water can be used as the flush water to aid cleaning.

With the above options, whatever the application or parameter being measured, Process Instruments will be able to provide a monitoring system that will not only be accurate, precise and long lasting but that will also remain free from fouling and save the operator both time and money.

Contact us on...

Julius Guth
Head of Central Offices

"Get in touch with me. I'm here to help you"

Tel: +44 (0)7497 861662

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