An air of quality

Jet Environmental Techniques has installed a bespoke air induction system for Pharmacia that meets EU regulatory GMP EMS requirements for its new distribution centre

Heating, ventilation and cooling solutions specialist Jet Environmental Techniques (JET) has installed a bespoke air induction system to meet the regulatory requirements of the new distribution centre built for US drugs firm Pharmacia in Milton Keynes, UK.

The new 6,141m² facility must rate as one of the most extensively monitored in the UK. To monitor the environmental conditions in which pharmaceutical products are stored - and ensure compliance with EU Directive 91/356/EEC as laid out in Rules and Guidance for Pharmaceutical Manufacturers and Distributors (2002) - a separate GMP (validated) environmental monitoring system (EMS) was installed utilising 90 temperature monitoring points at various locations within the warehouse.

This EMS monitors conditions continuously within the space, logging data every 15 minutes and outputting a daily download to a data historian, which stores the data from each of the temperature monitoring points. The EMS system is also capable of providing both high and low alarms and has the ability to calculate the mean kinetic temperature of the space.

new dimensions

The distribution centre measures 99m (length) by 62m (width) and has a mean height of 12.7m. It consists of a densely racked area for product storage and an open goods receiving and despatch area. The building and application criteria call for a HVAC system which can supply conditioned air to all areas of the warehouse, since any shortfalls in distribution would be immediately highlighted by the EMS.

Employing its Balanced Jet technology, JET engineered a self-balancing air induction system, using advanced computational fluid dynamics (CFD) and software modelling techniques, to meet the specific and exacting HVAC requirements of the new Pharmacia distribution centre.

With regulations dictating that the internal temperature had to be controlled within a 15-25°C range in order to handle an external ambient ranging from -5°C to +30°C, an air induction system which provides both heated and cooled air was specified.

fully modulating

The distribution system was supplied by a single JET air handling unit (AHU) with an indirect gas fired heat exchanger using a fully modulating burner for winter heating plus a four-stage (DX) cooling coil operating with the green refrigerant 407C. The AHU was also supplied with a mixing box to provide free cooling when external conditions dictate. A frequency inverter was fitted to the supply fan to reduce the supply air volume and the electrical consumption, and therefore the running costs, during low load conditions.

As far as the supply system was concerned, the combination of dense racking and extensive monitoring meant JET's air induction-based solution was designed to achieve a high degree of controlled air movement and ensure even temperature distribution throughout the space.

JET specialises in low maintenance HVAC solutions which can be co-ordinated around a range of ancillary services. In the case of the new Pharmacia distribution centre, JET's ductwork and nozzle outlets had to be co-ordinated with the racking layout and positioned around an ESFR (Early Suppression Fast Response) sprinkler system.

Meanwhile, without dampers in the ductwork or at the outlets, maintenance is limited to the AHU installed within a purpose-built first floor plant room adjacent to the main warehouse. There is therefore no need for expensive access equipment or disruption to the operational space for routine maintenance, giving significant cost savings for the life of the system and enabling the facility to operate at peak performance.

The AHU is also linked to the site's BMS system, which will provide both control and monitoring of the air induction system, while attenuators provided on the plant give an internal noise level of NR 45.

Tom Rush is senior design engineer of Hilton Building Services, which acted as the mechanical services contractor on the Pharmacia distribution centre, and contracted JET to provide the HVAC system for the project which was completed in January 2003. He said: 'We are very happy with the HVAC installation and were particularly impressed with JET's ability to fast track the process as well as the overall quality and performance of JET's air induction system.'

temperature control

On commissioning of the environmental monitoring system the variance in temperature between the 90 temperature sensing points was measured at less than 1°C. Based on readings taken from varying positions and heights within the warehouse these results demonstrate that JET's air induction system is extremely efficient in distributing air and maintaining the temperature required by this type of application.