Editorial: The Critical Hygiene Aspect - Cleaning in Place (CIP)

CIP, or Cleaning in Place, is a critical hygiene aspect of any food, beverage or pharma plant to ensure the health and safety of the consumer. Poor hygiene can be disastrous for any organisation, and so this editorial discusses the concept of cleanability by the process known as CIP. The plant is left intact and cleaning fluids are forced through the system to flush out the old product, scour and clean the pipework, valves, filling heads, vessels and process systems and finally rinse and apply a terminal sterilant to clean/sterilise the system.

To be able to CIP a process system, we have to assume that the system has been designed to be cleaned by CIP and doesn't have elements which are not reached by the CIP fluids because of poor design, leaving dead zones and crevasses, such as threaded joints, where CIP fluids cannot penetrate. Prior to effective CIP systems, hygienic process plants would be stripped down and manually cleaned and soaked, so old systems needed much less design due diligence for traditional cleaning. Before implementing CIP on an old plant or commissioning a new plant, it's essential to audit the plant, identify any areas of concern, and ideally rectify them to be suitable for CIP.

The Brewology CIP systems are assembled from standard modules within a limited range of capacities, from 250L to 2000L. They have flow rates to suit most process plants with either 1.5 inch (Din 40) or 2 inch (Din 50) maximum pipework sizes.

There are many options available when selecting a CIP set, from a very simple solution single tank and pump with manual controls, to a fully automated "lights out cleans" in a Brewology CIP system. There are various tank options such as a single unheated tank, to multiple tank systems - some heated, chemically monitored and dosed. The heating options can also vary, from simple direct electric heating via an immersion heater, steam coils and direct gas immersion tube heaters.

The Single Tank Manual CIP Set (mobile or static)

This is our very simple lowest cost CIP set, which is a variation on our Hot Water Tanks / Hot Water Generators. This is a 250L, highly-insulated rectangular tank on feet or castors (mobile) with electric heating and a variable speed pump.

As a single tank, single phase 240v CIP set, it has the aforementioned variable speed pump, alongside level controls, manual fill valve, a 6 kW electrical immersion heater, temperature controls, and needs a 1 phase 415v 32A DP&N electrical supply via a blue industrial 3 pin plug. Heat up time - from 10 to 70°c in 180 minutes,

Similarly, on our single tank three phase 415v CIP set, it has a variable speed pump, level controls, manual fill valve, an 18 kW electrical immersion heater, temperature controls, and needs a 3 phase 415v 32A TP&N electrical supply via a red industrial 5 pin plug. Heat up time - from 10 to 70°c in 60 minutes.

This CIP set can be used to heat hot water for flushing and general cleaning, or you can heat up detergent to circulate around a vessel of filler. You can then keep, reuse and reheat the hot detergent for another simple CIP.

The variable speed, reliable and powerful 3 phase pump can deliver 8m3/hr at up to 3.5 bar gauge pressure to clean a 1.5 inch system, from either a single phase 240v or three phase 415v supply. It's the heating capacity which is limited by the single-phase.

Twin Tank Manual CIP Set (mobile or static)

This is our basic starter CIP set. It can be supplied as a simple manually operated twin tank CIP set with a recovery/pre-rinse and a hot detergent tank. This can then have a clean final rinse and blended terminal sterilant such as PAA. This assumes that you have a reasonable cold water supply which can be connected to the CIP set (via a hose). This must be WRAS Compliant and have enough pressure and constant flow into which the PAA can be blended in.

If you have a non-compliant plant cold water supply with poor pressure and flow, it's often preferable to resolve this issue at source with a WRAS compliant cold-water break tank and constant pressure pump set.

The twin tank manual mobile CIP set is a stripped-down automated CIP, thus you can have the option to add-on the automation at a future date when you can afford the additional cost. The mobile CIP set is limited to 250L tanks to provide a practical solution to move around on wheels/castors.

As a mobile manual system, the CIP process involves locally circulating cleaning and sterilisation fluids. This needs the full attention of a trained operator to deliver a good clean and sterilisation. Mobile CIP systems often require additional manual cleans and inspections, and there is always a much higher risk to the operator when handling hot detergents and chemical sterilant.

Brewology Automated CIP Sets

A Twin Tank 250L fully automated CIP Set with a 10-inch screen and electric heating

These are full automated CIP systems which rely on the operator to set up and confirm the cleaning route before the automated CIP process takes over. On a CIP set clean, the aim is to cast out the cleaning fluids via the casting pump for a closed route clean. The fluid should return after a reasonable time or after a specific recipe set volume has been cast out. On a Brewology automated CIP clean, cold water can be used to test the route before any chemicals are cast around the system. On open route cleans when vessels are to be cleaned which breaks the route, a special scavenge pump will be required to return the cleaning fluids, which run to the bottom of the vessel. On an automated Brewology CIP set, the special scavenge pump is normally controlled by the CIP set controller.

Product Contamination

It's essential that any cleaning system which uses potentially dangerous fluids always remains isolated from the products produced on the plant. The Brewology CIP systems are commonly used on smaller craft production plants where hoses, swing bends, flow plates etc., are used to connect up the CIP set to the product process plant, and so the software is designed to prompt the operator to connect up the CIP Set route correctly and confirm that he/she has connected up the clean route.

A Brewology automated CIP set can be used to clean a small plant with permanently connected routes but it then becomes essential to employ very special automated routing (Block and Bleed valves) to ensure that cleaning fluids can never mix with a product via a single leaking valve. This open to atmosphere chamber prevents a build up of contaminating cleaning chemicals at pressure which forces its way into the product lines.

Brewology process engineers are always happy to advise should you be unsure of any possible product contamination routes on your plant.

Stacked Cleans

On an automated Brewology CIP Set, you also have the option to add additional "stacked cleans". Again, it's essential that any possible product contamination route is isolated before using and setting up stacked cleans.

A stacked clean system provides the operator with the option to set up several cleaning routes at one time and then leave the automated CIP set to step through each stacked clean route. With three stacked cleans set up, the operator can walk away and leave the automated CIP set to step through each stack clean, thus it will clean stack A clean route, then stack B and stack C to complete its stacked up cleans. Each stack clean is a full CIP set process clean, starting by topping up, heating up and dosing the CIP set tanks to the recipe setting and then running through each operation i.e. pre-rinse, detergent wash, system flush and finally terminal sterilisation again to match its recipe settings.

The Standard CIP Process

On most of the Brewology CIP Sets sold in the UK, the CIP process is from twin tanks and provides pre-wash using recovered liquor, collected after the detergent wash has finished and is flushed out with clean water. Once the detergent tank is full, the flush liquor is returned to fill up the recovery/pre-wash tank. This liquor will contain some detergent residue and so it's useful to pre-wash the plant. When the pre-wash fluid arrives back at the CIP set, it's then normally discarded to drain, leaving the pre-wash/recovery tank empty to receive the next flushings after the next detergent wash.

The detergent wash can be hot or cold to a clean recipe for each plant/item clean route. The temperature and detergent strength will be made up during each CIP pre-start routine for each clean to match the recipe. Most hot detergent cleans are made using the volume of hot detergent held in the detergent tank at its strength and temperature achieved during its pre-start make up period. Once the fluid is cast out from the CIP set, it's not normally re-heated or dosed until the next pre-start make up routine as the heating capacity may not be sufficient to recover the temperature and the heating coils may also be exposed during the detergent clean.

However, we do have an option to top up, reheat and detergent dose on our Det Set/CIP Set systems which have an inbuilt Hot Water Generator that can enable the detergent tank to be topped up with hot water, dosed with detergent and often have larger detergent tank heaters. The Det Set/CIP Set is a special Brewology process system used for cleaning brewery kegs as a continuous process.

For normal CIP systems, it's preferable to size the tanks so that there is always enough detergent to fill the clean route and still leave some fluid to be pumped out and around the clean route. Thus, the working volume of the Recovery/Detergent tanks should ideally always be larger than the process system they serve. If you need help and advice on selecting the CIP set tank sizes, ask for the Brewology CIP Set sizing paper or ask a Brewology process engineer for help.

We do have options and customers who require or prefer a second detergent tank, often with an acid-based detergent to use as a second clean after a hot caustic-based primary clean. This option for a second detergent tank can be hot or cold (no heating), and should be separated by a very short interface clean water flush. The other option is to periodically change over the primary detergent product. This can be done simply via an extra set of recipes for caustic or acid detergent cleans.

The addition of Flow Meter Control

Modern reliable mag flow meters offer a viable option to control the casting flow rate/casting pressure generated by the casting pump. On all Brewology CIP Sets, we use a digitally controlled variable speed pump via a frequency inverter drive. This enables the casting pump to be run at either a fixed set sped, run to a pressure set point, or, with a flow meter, you can operate the casting pump to deliver a set flow rate of the cleaning liquids. On automated CIP Sets, pressure or flow control is normally used.

Pressure Casting Pump Control

This is the traditional method of control for automated CIP Sets. Its drawback is that the pressure transducer is normally just after the casting pump and does not consider the pressure drops around the CIP distribution pipework. Thus, for identical tanks and cleaning devices, you may require separate recipes to account for variations in pipe length runs.

Flow Meter Casting Pump Control

This option offers many more advantages and drastically simplifies commissioning and early stage CIP recipe setups. The ideal flow rate for each machine or cleaning device is normally specified, thus you simply set the recipe to the flow rate required and the system casts out the specified flow. The flow meter is also able to measure the volume of each clean route and, again, this parameter can be used to replace crude timing for checking a route's validity and filling the system full of terminal sterilant. The flow meter option also makes it much easier to ratio balance, and blend in PAA (Terminal Sterliant) as the metered cold water is pumped and cast around the system even if the incoming water pressure varies.