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CIP: The Industrial-Grade Dishwasher
by Chad Enck
There is an episode of the ’90s hit comedy show Home Improvement that I think of every time I pull out dirty dishes from the dishwasher at home. You know, after they’ve supposedly been cleaned…it’s the peanut butter spoons, the charred grit burnt onto the bottom of the pan, the baked on meatloaf, etc.…In this episode, Tim “The Toolman” Taylor observes his wife pre-rinsing the dishes prior to putting them into the dishwasher. This was an action The Toolman couldn’t wrap his head around. After all to Tim’s point—isn’t that the purpose of the dishwasher? What proceeded from there is Tim’s extreme attempt to “beef-up” the dishwasher with extra horsepower to handle those sticky situations. And while humorous, Tim’s goal to address this issue is a serious matter within the food and beverage industry. Just ask any dairy farmer, production supervisor, sanitation technician, process engineer, or quality manager what their solution to ensuring food safety is in their industry and they’ll point to the clean-in-place (CIP) system, an industrial-grade dishwasher sure to gain the approving nod, and primitive grunt “ooo, ooo, ooo…” from Tim The Toolman himself.
CIP systems are process systems tasked with the objective to clean the equipment used in the receiving, delivery, distribution, processing, and manufacturing of food and beverage products. The systems themselves are an arrangement of tanks, valves, pumps, heat exchangers, and associated instrumentation such as temperature/level/pressure/conductivity transmitters, flowmeters, chart recorders, and automated control systems. These components are traditionally assembled onto a prefabricated stainless steel skid, giving way to the commonly used term of CIP skid.
The primary advantage of CIP systems is they relieve the burden of having to tear down equipment to be cleaned. Instead of running ingredients through the process system, as would be done while in production, the line and/or equipment is connected to the CIP skid which runs the cleaning solution through the process. Therefore, they are used to clean virtually everything, including the pipes, valves, fillers, homogenizers, pasteurizers, tanker trucks, and all other associated equipment.
To gain a better understanding of these industrial-grade dishwashers, here are the answers to frequently asked CIP questions.
Q: Are CIP systems automated?
A: Yes, but they weren’t always this way. Early CIP systems consisted of a CIP skid with wash and rinse tanks like they do today. However, those early systems were independent islands of control that lacked automation and integration with the systems being cleaned. Once upon a time, device sequencing was made possible with rotary cam switches and other electro-mechanical devices. These mechanical sequencers limited control capabilities to the skid devices only. Field devices relied on isolated relay valve pulsing that could never be fully synchronized with the skid sequence—resulting in improper and inefficient cleaning.
For example, due to the disconnect between skid and field device sequencing, water-hammer would result. This occurs when the skid’s supply pump is running at full speed and the field routing valves close at the wrong time, causing liquid in the line to abruptly slam like a “hammer.” Water-hammering is detrimental to valve seals and pipe welds. Additionally, because of a lack of instrumentation and monitoring, often length of time for a run had to be extended just to ensure the circuit was cleaned.
Some chemical engineers and process engineers still see the skid and field as two separate entities. But that limits the advantages a fully automated system can provide.
Automated system advantages include:
- Integrated skid and field device sequencing, resulting in coordinated and optimized routing paths (the elimination of water-hammer);
- Use of valve position feedbacks to generate routing path faults to halt the CIP process;
- Accurate flow monitoring using flow meters instead of flow switches;
- Tracking total water usage;
- Ensuring proper supply and return temperatures are achieved;
- Conductivity monitoring to verify desired chemical strengths are satisfied;
- Level and pressure monitoring;
- Allergen-wash categorization; and
- Electronic records, reporting, alarm/fault logs, and time/date stamping.
Consider the quality assurance gained in comparing active trends to a previously captured “ideal” trend.
Q: What components comprise the CIP control system?
A: At the heart of the control system is the programmable automation controller (PAC) that runs the program(s) controlling the operation. The devices (i.e. valves, pumps, sensors, meters, etc.) on the CIP skid are wired to the PAC as analog or digital inputs/outputs (I/O) points. Tethered to the PAC is the operator interface, or human machine interface (HMI), which is used to monitor the CIP system, select the circuit to clean, and to start/stop/abort the process. Additional components include the chart recorder and the pin-sheet.
Chart recorders are used to monitor and record the system’s key performance indicators (KPI) as they pertain to temperature, level, pressure, conductivity, and flow. Pin-sheets are used to document the system’s circuits, phases, and device sequences. The Information Age has enveloped both the chart recorder and pin-sheet. Many systems now feature “chartless” electronic records and trending. Refer to Figure 1. These trends provide the same information as a chart but with the added advantages of being retrieved, viewed, and stored with the click of a mouse. Additionally, the use of electronic signatures permits supervisory “sign-off” of the overall effectiveness of the cleaning process. Industry regulations such as the Pasteurized Milk Ordinance recognize the benefits of electronic chart recorders. Additionally, pin-sheets are being improved upon functionally by their electronic counterparts. Electronic pin-sheets, through the use of spreadsheet software or the HMI, have been embraced as a valuable tool for supervisory level staff to create and modify the CIP process.
Q: What defines the CIP automated process?
A: In many ways, the CIP process can be likened to the batch process used to make a product. Batching is comprised of recipes, steps, ingredient additions, and timed holds/agitations sequences. Similarly, CIP processes are comprised of circuits, phases, steps, and sequences. Circuits can be categorized as to the function and/or equipment they are cleaning. Some common circuit types can be Line, Tank, Tank and Line, or a specific piece of equipment like Filler, for example. Circuits are comprised of cycles or phases. Common phases include Prerinse, Wash, Postrinse, and Sanitize. These are easily remembered by thinking how the dishwasher cycles (pre-rinse the plates to drain before washing, wash, rinse-off the detergent, then sanitize). Phases are made up of steps. Steps might include rinse to drain, pump down, caustic wash, acid wash, fresh water rinse, and air blow. The specific sequence executed involves the “pinning” of the devices through the use of the pin-sheet.
The pin-sheet is a spreadsheet that serves as the master schedule for the CIP process. The pin-sheet identifies the system name, the circuit name, and contains detailed sequence information per its phases: step description, number, time, targeted supply line temperature and flow rate, and return line conductivity. Furthermore, the pin-sheet contains a bit position within the sequence word(s) for every device residing on the CIP skid and within the field. This bit position represents the “device pin” for which the sheet gets its name.
Recall that a primary advantage of modern CIP systems is the integration of the CIP PAC with the production system PACs. The pin-sheet has the ability to reach across into the production controller to set and cycle process equipment as part of the CIP program.
Q: How is the data in the pin-sheet brought into the PAC?
A: The fields on the pin-sheet are translated into programming parameters that are downloaded into the PAC. The PAC executes the CIP program based on this data. The data takes on two forms: discrete (digital 1s and 0s) and analog values (percentages, flow rates, time, temperature, etc.).
Discrete signals passing from the pin-sheet to the PAC are used as run requests. Devices are assigned a bit position within the sequence word that corresponds to the column assignment for the device. If a device is required to run on a specific step, then its bit position will be assigned a logical “1.” The device is now considered “pinned” and when the logic sequencer executes that step, the bit position is referenced as a run condition for that pump or valve and it is commanded to turn on. If assigned a logical “0” then the condition is not true and the device is not requested to run.
Analog values passing from the pin-sheet to the PAC are used as set points. For example, on a hold for temperature step, the return water temperature set point specified in the pin-sheet is referenced and the actual temperature transmitter is monitored to satisfy that targeted value.
Q: What are some user interface features?
A: The HMI is the primary interface for operations personnel interacting with the CIP process. Figures 2 and 3 show two graphic display screens: The CIP Setup screen and the CIP Overview screen.
The Setup screen provides a means to configure and control the process. Here the operator selects the circuit, can further refine the type of wash, and control the process via start/stop/pause alarm reset and abort buttons. Pertinent status information and alarms are displayed for the user to show what is happening in the process. The cycle name, current step and description, remaining time and started/paused/stopped status are displayed. Additionally, all “hold for conditions” are populated.
The Overview screen is very similar to that found on many process control systems in that the environment is shown through the use of graphical symbols representing the real world devices on the CIP skid. Tanks and their levels, pumps and speed feedbacks, valves, and instrumentation KPIs are displayed and animated accordingly. Navigation buttons to the setup and past cycles screens provide the user with access to the CIP cycle currently running and access to logged data trends on previously cleaned circuits.
Q: How does data collection benefit the CIP system?
A: Simply stated, it closes the loop by using the data already available for purposes of verifying food safety and efficiency. Consider when the production line is being cleaned, it is worse than downtime. It is not just losing money—it is using money. Data collection allows the users to investigate the process and optimize their return on investment.
Most importantly is food safety. Trending the instrumentation KPIs on electronic chartless recorders allows technicians, engineers, and quality personnel to confidently review the CIP for compliance and diagnose areas of concern. Consider, for example, the quality assurance gained in comparing active trends to a previously captured “ideal” trend.
Monitoring the time taken to clean a circuit is merited because it affects the plant’s indirect costs in many ways. Cleaning too long increases labor requirements and challenges production/cleaning schedules. By adding simple time and date stamps, registered at the completion of a CIP run, will ensure the circuit won’t be cleaned prematurely and quality is not short changed.
Usage reports showing the amount of water and chemicals consumed in the process can be investigated so that circuits can be optimized to reduce costs. For instance, strategies can be launched to use the least amount of fresh water necessary, reclaim post-rinses for subsequent pre-rinses, and adjust chemical doses to their desired strengths for proper cleaning. These cost saving efforts also contribute to water treatment as well.
The CIP system has come a long way in recent years with advancements in automation, integration, and data collection. These tools have taken a once self-contained process and enhanced it to become the intelligent system it is today. Because of those combined efforts, CIP systems are handling the most challenging cleaning requirements that industry demands while benefitting from the highest level of performance, quality, and efficiency being offered.
Enck is the sales engineer and quality manager at GES Automation Technology, a certified member of the Control System Integrators Association (CSIA), www.controlsys.org, a global non-profit professional association that seeks to advance the industry of control system integration. He can be reached at ChadE@gestech.com.
LOOKING FOR MORE INFORMATION ON CIP TECHNOLOGY? Then check out this issue's online exclusive, "Recipe Managed CIP--Safe and Efficient," which explores the benefits of a recipe managed CIP system.