Every day we eat and drink processed food and drink from bottles, bags, and boxes. Have you ever wondered how these items stay clean enough to keep you from getting sick when you consume them? The answer is hygienic maintenance, and the technique is clean-in-place (CIP).
This article will shed some light on how cleaning is done in the industrial systems that require top-of-the-line hygienic maintenance, such as those used to process dairy products, grains, drugs, or even cosmetics.
Until the 1950s, plants had closed systems that they had to disassemble and clean manually. For small processes, this works okay, but for large factories, it would require days of downtime. To reduce this inefficiency, process engineers began developing methods to clean equipment in place: Clean-in-Place (CIP) systems.
Clean-in-place allows cleaning in one part of the plant while other areas continue to run. It also allows cleaning without major disassembly and assembly, reducing labor and time as well as improving production and safety in the plant.
Clean-in-Place system design goals
A clean-in-place system must remove product buildup, germs, and other detritus from equipment, vessels, and pipes in a process. The system consists of pipes and reservoirs for cleaning solutions, spray heads, controllers, and more, depending on what the process needs.
The cleaning agents in a CIP system – acids, alkaline solutions, and water – must maintain specific conditions, such as temperature and pressure. Operators must calibrate set points throughout the system to keep the process free of dirt, organic contaminants, and microorganisms.
To properly clean processing equipment, a plant must monitor and maintain the following parameters in its instrumentation.
Many clean-in-place systems use cold water at 20˚C, to flush pipes and tanks. However, you need warmer water to rid a process of substances like salt. Also, heated cleaning solutions can work more efficiently.
But keep in mind, heat doesn’t fix everything! Sometimes it causes a reaction with residues that makes them harder to remove. So you’ll need to regulate your heat carefully. For example, for removing bacterial residue, a cleaning solution is always heated over 75˚C.
Thermocouples and resistance temperature detectors (RTDs) can measure temperature in various CIP systems, and thermowells can protect sensors from direct contact with process fluids. To learn more about these devices, you can read our article on them.
Pressure can also improve cleaning efficiency, by sending the solutions faster or by adding a physical element to the chemical cleaning. So you can monitor the performance of tools such as spray heads with pressure transmitters to let you know how many solutions you have going to the target and how fast.
If your CIP system doesn’t use a lot of pressure, you can use flow meters rather than pressure devices. Turbulent flow in the pipes creates an abrasive force to clean the process equipment. And the right pump and flow meter can take care of this element for you.
As per the clean-in-place system requirement, the flow-meter should not be affected by chemicals used for cleaning and the turbulent flow. The flow meter has to stay accurate despite changes in the flow. A magnetic flow meter is the best choice for this! You can read our Picomag product review.
CIP system can go from small pipes to large and long pipe runs. Inline instruments, pipes and valves are required to be cleaned at a smaller flow rate to achieve completely filled lines. Magnetic flow meters offer a good turndown for a wide range of flow rates. Our articles on flow could take up a library on their own, but you may want to check out a few anyway.
Measuring conductivity can tell you whether your CIP system has properly performed its tasks. Conductivity meters can determine interfaces between the ionic cleaning solutions and the relatively non-conductive purified water.
Depending on your pipe size, the conductivity meter can be inserted into a pipe greater than 2 inches or clamped in the process flanges with pipe size less than 2 inches. Make sure you completely immerse your conductivity meter in the process fluid, because a partly immersed meter will produce noise and create bad readings.
So you’ll typically mount the meter on an upward-flowing pipe. We’ve talked about conductivity here at Visaya as well.
Hygienic requirements for Clean-In-Place
Your plant instruments, equipment, vessels, and pipes shall capable of withstanding clean-in-place system requirements. CIP system requirements are as follows
- A plant must comply with all document criteria for Hygienic requirement such as EHEDG certificate, 3A certificate, Material Surface Finish
- The material of construction must be non-porous, smooth, corrosion-resistant and suitable to the required chemicals. Stainless steel is the most commonly used material.
- All instruments to withstand Process conditions, Temperature up to 150˚C and sometimes Pressure up to 20 bar.
- All instruments to have proper Ingress Protection. Mainly, we consider as IP67, IP68, and IP69K as per the CIP system requirement.
Sterilization-in-place is a fully automated next step after CIP. SIP removes microorganisms that may have survived CIP. SIP also follows EHEDG and 3A guidelines.
CIP systems vastly improve the efficiency of automated plants. They clean faster, more reliable, and more safely than manual methods. They also reduce waste, save energy, and minimize downtime.
If you’d like to read more about the special requirements of clean-in-place systems, and wanted to know more about the products in the industry, you can get in touch with our engineers!