The following article was published in Process &
Posted on 09/13/04
Editor: John Houston
Eurotherm Control Solution
Chosen for Purified Water System at Moorfields Hospital
A new 'state-of-the-art' Pharmacy Manufacturing Unit (PMU) at Moorfields
Eye Hospital NHS Trust, London, features sophisticated Water for
Injection (WFI)and Clean Steam generation systems for cleaning and
The system, designed and engineered by specialist consultants Honeyman
Group, uses a Eurotherm T800 (Visual Supervisor) based control solution
for all supervisory control functions. The system meets the demanding
requirements of FDA 21CFR Part 11 with respect to electronic records.
The products of the system are used for a variety of manufacturing,
cleaning and sterilizing purposes. WFI is used for production, a
number of equipment washing machines and cleaning in place (CIP)
tasks, while Clean Steam is used for high temperature autoclaves
and steam in place (SIP) purposes.
The complex system consists of three packaged plants, operating
independently within an overall supervisory control architecture.
In the first plant, raw water is purified by passing it through
reverse osmosis filters and de-ionisation processes to produce Purified
Water. This is stored as feed water for two additional processes,
clean steam generation and distillation for WFI, and distributed
throughout the building to points of use. The entire process is
predominantly automated and thus requires minimal operator intervention.
The three individual packaged plants are self contained modules
with integral on-skid local control systems, hand shaking locally
and communicating with the central control panel through hard wired
connections. A number of independent local control panels are also
provided for control of dispensing at WFI & Clean Steam points-of-use.
The central control panel is also hard wired into the Building Management
System (BMS) for soliciting an operator response to alarm conditions.
The Eurotherm T800 at the central control panel provides the operator
with a graphical process interface, and is used to execute across-network
control operations. Also known as Visual Supervisor, the T800 is
a powerful multifunction controller with integrated touch screen
display and data logging facilities. It provides all the features
required to control and monitor complex processes like this one.
It is operated here in conjunction with five eight-way Eurotherm
2500 I/O controllers.
The five panel-mounted 2500 controllers are used primarily for data
acquisition purposes, and interconnect with the T800 Visual Supervisor
via an open 'Profibus DP' network. 2500 configuration is achieved
using proprietary Eurotherm 'iTools' software. Three of the 2500s
are mounted with the central control panel, the remaining two operating
remotely at local control panels. Some of the I/O controllers execute
discrete logic functions, while Eurotherm 'LinTools' software is
used to open and close vessel filling valves via the T800. All valves
throughout the process also have hard-wired interlock arrangements,
giving a failsafe function on conductivity alarms.
Standard features of the T800 controller include a clear touch screen
display for screen navigation and execution of operator commands,
batch management to ISA-S88 with batch log, recipe & setpoint programmer,
accurate continuous and sequential control, support for Modbus and
Profibus, as well as time synchronisation. In this particular application,
the controller provides process mimics, bar-graph displays, historic
trends, alarm and event logs, keeping the operator fully informed
of system status.
A key issue in specifying the T800 solution for this WFI /CS system
was Honeyman's clear requirement for creating detailed tamper-proof
records of key parameters within the essentially analogue processes.
At the same time, the processes required continuous control to fine
Process data is logged continuously by the T800 Visual Supervisor.
This uses flash memory for short-term data-storage, with an integral
3.5" 1.44MB diskette for long-term storage. Data is recorded in
a proprietary tamper proof binary format, while preview software
allows restricted read-only access to the data stored on diskette
via any standard PC.
In this system, each diskette can contain at least 10 days worth
of data. Process values and trending data are logged once every
minute, with events and alarms being logged as they happen. Diskette
status is checked daily by the operator. An operator alarm, activated
through the Building Management System, is raised if the diskette
reaches 95% capacity.
In terms of access control, the T800 provides four levels of password
protected access to authorised personnel only. A time lock facility
ensures that access is cancelled and locked after 15 minutes of
operator inactivity. The entire system was designed and commissioned
by Honeyman Group Ltd. This specialist consultancy provided initial
consultancy to MEH, design, supervisory implementation, writing
of protocols, validation and final commissioning. System software
was designed, tested and commissioned in accordance with the GAMP3
Guide For Validation of Automated Systems in Pharmaceutical Manufacture.
Roger Newton, Honeyman Project Manager for the MEH System, believes
that the T800 based control solution was the best possible. He commented: "Visual Supervisor offers a number of powerful hardware capabilities,
supported by a proven suite of configuration and operation software
tools designed for both analogue and digital parameters. We have
therefore been able get exceptional functionality into compact,
cost-effective package. This amounts almost to DCS performance without
the high cost." "That, together with the high level of support provided
by Eurotherm's technical people, made this an obvious choice. And
the solution not only meets the current needs of the system but
has the flexibility to meet future needs as well."