Skip to main content

Unical, Uniclean and cCare: Automated Cleaning Without the Confusion

Sensors foul. On a wastewater plant or in metal processing they foul fast enough that manual cleaning becomes the limiting factor on how many measuring points a team can look after. Knick has three control units for automating that job, and the names get used interchangeably when they should not be. Here is what each one is.

The problem being solved

A fouled sensor does not stop working. It carries on reporting, slowly and plausibly wrong, until somebody notices the reading has drifted away from the laboratory result. That is worse than an outright failure, because a failure announces itself and a drift does not. In the meantime, decisions are being made on the number.

Manual cleaning fixes it and does not scale. Every measuring point added is another visit on the round, and when the round gets long the cleaning interval stretches to fit the available hours rather than the fouling rate. Automating the cleaning means the sensor is cleaned when it should be, whether or not anybody had time that week, and the reading stays trustworthy between calibrations.

The three control units

Uniclean 700 is the modular, entry-level option, and it installs quickly and inexpensively. The important distinction is this: it does not require the special controlling program in the Protos transmitter. A cleaning cycle can be triggered by a simple switching signal, so the system does not oblige you to have a particular transmitter at that measuring point. On a site with mixed instrumentation, or where the transmitter was chosen years ago by somebody else, that is often the deciding factor.

Uniclean 900 and Unical 9000 are the fuller systems. They clean the sensor automatically, with water or a cleaning solution, at user-defined intervals and without interrupting the process, and they extend into calibration rather than cleaning alone. Uniclean 900 is available with a hygienic surface, and in an Ex version with a corrosion-proof coating, which tells you plainly where these are expected to be installed.

So what exactly is cCare?

This is where the naming causes trouble, and it causes it regularly. cCare is the fully automated sensor maintenance system, and these control units are what it runs on. Uniclean 700, Uniclean 900 and Unical 9000 are the control end of it.

So "cCare or Unical" is not the question. The question is which control unit suits your duty, your fitting and your existing transmitter. If cCare is to be driven from the control room rather than locally, that is a separate question about the transmitter and its fieldbus module, which we have covered elsewhere.

Fittings and utilities: decide them together

The Uniclean 700 control systems suit both static and retractable fittings, and because the system is modular, any retractable fitting can be used. Optimum functionality is achieved with Ceramat and SensoGate, Knick's own sensor lock-gates, and one SensoGate variant is specified for Uniclean and Unical explicitly. Drives are pneumatic.

The practical lesson is to specify the fitting and the cleaning system as one decision. Choosing the fitting first and bolting cleaning on afterwards is how sites end up with an arrangement that works, but never quite as designed, and where every subsequent change is constrained by a decision nobody remembers making.

Utilities deserve the same attention. Automated cleaning needs a supply of clean water or cleaning solution at the measuring point, a drain for what comes off, and reliable instrument air for the drive. None of that is difficult, but all of it is easier to arrange during installation than to retrofit up a gantry.

Where automated cleaning earns its money, and where it does not

The clearest cases are the dirty ones. Wastewater treatment and metal processing are the two Knick names, and both share the same profile: heavy soiling, high sensor wear, and manual cleaning that is frequent, unpleasant and easy to defer.

The return is not only labour, and it is worth setting out properly:

  • Longer sensor life, because a sensor that is cleaned regularly is not being attacked by whatever has caked onto it.
  • Readings you can act on, which is the point of the measuring point existing.
  • Fewer control decisions made on a fouled measurement, which in some processes is a quality or a safety matter rather than an instrumentation one.
  • Predictable maintenance, rather than an escalating round that quietly falls behind.

It is only fair to say where it does not pay. A clean process with a stable sensor and a long calibration interval does not need it. A single, modest measuring point at ground level, five minutes from the workshop, is usually cheaper to clean by hand than to automate. The economics turn on fouling rate, access, and how many measuring points share the problem.

What a cleaning cycle actually involves

It is worth being concrete, because "automated cleaning" sounds vaguer than it is. On a retractable arrangement the cycle runs roughly like this: the sensor is withdrawn from the process into the chamber, the seal closes, the chamber is rinsed, cleaning medium is applied for a set period, the chamber is rinsed again, and the sensor returns to the process. On a system that extends to calibration, buffer or standard solution is introduced at that point and the transmitter takes the readings before the sensor goes back.

The process itself never stops, which is the whole point. Nothing is opened, nobody stands at the measuring point, and the sequence runs at an interval you set rather than one the rota allows.

Retrofit or new installation

Both are normal, and they are different jobs. On a new installation the fitting, the cleaning system, the media supply and the drain are designed together and the cost is mostly the equipment.

On a retrofit, the equipment is often the smaller part of the job. The questions that decide it are whether there is a water or cleaning-solution supply within reach, whether there is a drain, whether instrument air is available and dry, whether there is sufficient clearance for sensor retraction and maintenance, and whether the existing installation can accommodate the required controls and piping. Where these conditions already exist, retrofitting an automated cleaning or cleaning-and-calibration system is usually straightforward. Where they are not, the honest answer is sometimes that this particular measuring point is better relocated than automated.

The entry-level route exists precisely for this situation: because Uniclean 700 does not depend on a particular transmitter program and can be triggered by a switching signal, it can often be added to a measuring point that was never designed with automation in mind.

At DP-Flow we supply the full range along with the fittings and sensors they work with. If you can tell us what the medium does to your sensors and how often somebody is out there cleaning them, we can tell you whether automating it is worth doing in your operating context.