FOOD SAFETY

PLANT MANAGEMENT

Tackling CIP
Automation
with S88
S88 can aid in automating a clean-in-place system. CHRISTIE DEITZ,
YOGESH RATHI,
EMERSON LIFE SCIENCES
INDUSTRY CENTER

C
lean-in-place (CIP) is a method of cleaning vessels and
lines without disassembling them. It involves delivering
solutions of chemical detergents and rinses at specified
flow rates and temperatures. Typically, a CIP skid
creates the cleaning solutions and routes them to a user skid that
requires cleaning.
CIP is commonly used in the food and beverage, pharmaceutical, and
cosmetics industries. Originating in the 1950s, early CIP systems
were manually operated. Today, most CIP operations are automated.
However, there are still some common challenges to automating a
CIP system and these are:

• Finding an efficient way to automate similar actions

Making an alkaline wash solution may be very similar to making an
acid wash solution, for example. Likewise, the routing of the alkaline
wash though the skid being cleaned usually differs minimally from
the routing of the acid wash through the skid — perhaps only in the
flow rates or cycle times.

• Managing resources
Commonly, a single CIP skid will, at different times, clean several user
skids. There is a need to supply solution to the different user skids
and return to it. If the supply and return paths are not dedicated,
there is a need to ensure that there is no conflict among the paths.

• Minimizing time required for CIP cycle

Some of the operations can be performed simultaneously. Chemical
wash solution can be prepared during rinsing, for example.

There are two most common physical layouts for CIP systems:

CIP has grown over the last 50 years to be very important in the • Fixed CIP systems connected to multiple user skids by transfer
food and beverage, pharmaceutical, and cosmetics industries. panels and/or distribution headers. (Fig. 1)
Automating CIP effectively is a key factor in the plant This is the most common approach. Cleaning solutions are routed
running smoothly.

26 Asia Food Journal November-December 2008

 Fig. 1: Each fixed CIP skid can clean one of several user skids by
transferring though a distribution header.

through distribution headers or transfer panels to the skids requiring

cleaning. The fixed skids with two vessels per CIP skid can handle
high volumes of cleaning solutions. However, managing the complex
distribution paths can be difficult.
Fig. 2: Each portable CIP skid can clean one of several
• Portable CIP system connected directly to a user skid (Fig. 2) user skids connected directly to the skid.
Portable CIP skids are small-capacity movable skids with a single
vessel that is utilized for all rinses. Used mainly in multi-product • Allow every CIP skid in the plant to operate similarly. The
facilities, this approach reduces the amount of CIP supply and return distribution path from a CIP skid to a user skid is not part of the
distribution piping required. A point-of-use (POU) connects the unit.
utilities and chemicals to the portable skid. Typically, the portable skid Fig. 5 shows the S88 physical boundaries for the portable CIP layout.
has a control panel mounted on it and has three or four connections When a user unit needs cleaning, it can acquire the portable CIP
to the user unit. skid, which is an independent equipment module. This next section
ANSI/ISA-88 (S88) provides standards and terminology for batch explains how this physical layout simplifies the procedural layout.
control. S88 features a physical model that provides a way to organize
the physical equipment. It also has a procedural model that defines CIP procedural model
the control required for the equipment to perform its tasks (Fig. 3). To a large extent, the physical model drives the procedural model.
The S88 model can provide a framework to address these challenges The following sequences are typically required for the CIP skid:
for either CIP layout. drain CIP skid, circulate pre-rinse, acid preparation, circulate acid
wash, circulate post acid wash, alkali preparation, circulate alkali
CIP Physical model wash, circulate post alkali wash, circulate final water-for-injection
The first step to automating a CIP system is to define the S88 physical (WFI) rinse, air blow, and drain CIP skid. The following sequences
model. For fixed CIP systems, the S88 unit boundaries are drawn are common for the user skid: set up, pre-rinse (circulate routes
such that the CIP skid and the user skid are units (Fig. 4). Each unit 1-x), acid wash (circulate routes 1-x), post acid wash (circulate
consists of equipment modules (such as temperature control and routes 1-x), alkali wash (circulate routes 1-x), post alkali wash
level control) that are not shown in the figure. (circulate routes 1-x), final WFI rinse (circulate routes 1-x), and
The distribution headers and/or transfer panels that connect the CIP air blow (through routes 1-x). The sequences that operate the
skid to one of several units can be made into equipment modules CIP skid equipment become phases on the CIP skid unit, and the
that are independent of either unit. While Fig. 4 provides a relatively sequences that operate on the user skid become phases on the
simple diagram, the paths shown can be very complex in the plant. user skid unit. Similar sequences can be modularized or made into
Having unique distribution path settings in equipment modules, reusable, flexible phases. The differences are handled with recipe
which is separate from the unit, would accomplish two things: parameters.
For example, acid and alkali preparation may be combined into
• Allow resource management of the distribution path. Each CIP a single phase called solution preparation (Fig.8). Pre-rinse and
event can acquire the distribution path equipment modules it final rinse circulation can be combined into a single phase called
requires, leaving the ones it does not require to be acquired by circulate rinse. Acid and alkali circulation can be combined into a
other events. single phase called circulate wash.

www.asiafoodjournal.com Asia Food Journal 27

 FOOD SAFETY

Clean-in-place (CIP) is a method of cleaning vessels and lines

without disassembling them.

ANSI/ISA-88 (S88) provides

standards and terminology for batch
control. S88 features a physical Fig. 3: A S88 physical and procedural model.

model that provides a way to

not require unique logic to handle the differences between cleaning
organize the physical equipment. the different user skids and can operate exactly the same regardless
of which user it is cleaning.
The S88 procedural model for the fixed CIP skid can also be optimized
Similarly, on the user skid, all of the sequences that circulate the by running phases in parallel to reduce CIP cycle time. For example,
different solutions through routes of the user skid can be combined while circulating the pre-rinse solution from one of the vessels on
into a single phase circulate route 1-X, using recipe parameters the CIP skid to the user, the other vessel on the CIP skid can prepare
to handle the differences. This modular approach helps to ensure the acid rinse solution (Fig.9).
consistency and also decreases software development and Likewise, if one of the two CIP vessels is draining, the other vessel
maintenance costs. can position the valves for re-circulation or for receiving water for
The phases on the two units would coordinate with each other when the next wash or rinse. By taking advantage of phases executing in
the CIP skid and the user vessel need to interact with each other. parallel, the CIP procedure can run more quickly and the user skid
The user vessel acquires and sets required equipment modules on has more time available for making product.
the distribution path. For the procedural model for the portable CIP system, each phase
This approach allows a generic CIP skid. The CIP skid phase does addresses the sequencing requirements for both the CIP skid and the

Fig. 4: A physical model for fixed CIP. Fig. 5: A physical model for portable CIP.

Using an S88 approach helps to effectively address the challenges of CIP

automation by driving modularity, which is the key to making batch logic work
efficiently and consistently.
28 Asia Food Journal November-December 2008
 Fig. 8: Acid and alkali preparation may be combined into a single phase called <one character spacing> solution preparation.

user skid. When it requires cleaning, the user skid unit acquires • Minimizing time required for CIP cycle
the portable CIP skid equipment module (EM). Since the user skid If the physical equipment supports it, as in the case of the fixed
unit acquires and drives the CIP skid EM directly, there is no CIP system, the procedural model can be defined so that different
coordination between phases on two different units. phases can run in parallel. This approach can minimize cleaning
Similar to the fixed CIP skid, phases can be modularized in time and allow the user skid more time for making product.
order to increase consistency and decrease the cost of software
development and maintenance. For example, the pre-rinse, acid
wash, post-acid rinse, alkali wash, post-alkali rinse, final rinse,
and air blow can be modularized into one phase with recipe
parameters to handle thedifferences. This modular approach helps
to ensure consistency and also decreases software development
and maintenance costs.

Conclusion
CIP has grown over the last 50 years to be very important in the
food and beverage, pharmaceutical, and cosmetics industries.
Automating CIP effectively is a key factor in the plant running
smoothly.
Using an S88 approach helps to effectively address the challenges
of CIP automation by driving modularity, which is the key to
making batch logic work efficiently and consistently.
The two most common equipment architectures are fixed CIP skids
that use distribution headers and portable CIP skids. Although
the S88 physical and procedural models are different for each,
applying the S88 modular approach helps tackle the challenges
for either architecture:

• Modularizing software
Using a modular approach makes automation more efficient and
more consistent. Drawing unit and equipment module boundaries
can make it possible to create classes of equipment modules and
units. It can also help to combine sequences into a smaller number
of more modular phases. This approach increases consistency and
decreases development and maintenance costs.

• Managing resources
Drawing unit and equipment module boundaries appropriately
makes it possible to better manage the resources in the plant. CIP
Fig. 9: Minimize CIP cycle time through parallel operations.
distribution headers can be defined and managed as independent
equipment modules in order to avoid resource conflicts. In the case
of the portable CIP skid, the entire CIP system can be managed as www.emersonprocess.com/LifeSciences
an independent equipment module. Tracking Number ER-00103-NOV08

www.asiafoodjournal.com Asia Food Journal 29