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Sensors help provide a clean bill of health

Hospital and healthcare buildings comprise of various environments that need to be considered carefully when installing sensor equipment. Alan Braybrook explains what specifiers and contractors should think about when installing sensor equipment
Hospitals and healthcare estates bring unique challenges when it comes to installing a building management system. There are a number of different areas and services which need to be catered for including; treatment areas, clinical laboratories, accident & emergency areas, sterile theatres as well as catering and housekeeping facilities. The sensor needs of each area are complex and each one requires unique treatment.

To aid specifiers of building management systems (BMS), the Department for Health has developed the Health Technical Memorandum (HTM) 03-01. This document offers guidance and advice for installing a BMS/HVAC system in this specialised environment. The document outlines the basic controls needed within BMS, there are: functions that start, set-back, and stop the plant; control volumetric air flow; system or room pressure controls; temperature control and indication; humidity control and indication; monitoring the plant's operating state and indication of plant failure; low air flow and filter state. HTM 03-01 also states that the controls installed must be simple to use, robust and reliable.

The location of controls is extremely important in hospital and healthcare buildings. Whether they are placed within the rooms, plants or ducts, the sensors must be easy to find, easy to read and provide accurate readings. To ensure the sensors are easy to use, they should be marked with either 'raise' or 'lower' or a +/- mark so the operator can easily and quickly change the settings. An analogue or digital indication of the temperature is also needed on a local panel or at a staff base.

A key part of providing the right comfort level within hospitals is accurately and reliably measuring the temperature and humidity. It terms of humidity, the levels can be between 35% and 70% depending on the area. The temperature can vary between individual areas within the hospital, for example a cooler temperature may be required in operating theatres but a higher temperature will be needed in wards to increase patient comfort. According to HTM 03-01, the temperature set-points can generally be between 16 and 25 deg C. The industry standard for temperature is sensors which tolerate +/- .3 degrees C over the entire range (-10 to +70) but it is also important for devices to remain accurate within the manufacturer's specification (+/- .3 degrees) for the life of the device.

Communal areas in the hospital will require optimal ventilation which can be achieved by monitoring air quality and CO2 levels. With the diverse mix of people and procedures the air quality could be pretty poor so by measuring this and ventilating where required, the hospital will be a much more pleasant place to be. High CO2 levels can cause drowsiness and feeling of giddiness which could be detrimental to patients who are already poorly, therefore it is important to measure this and ventilate accordingly. Modern devices, such as our GS-CO2-AQ-RHT, can measure important variables within the overall space conditions including air quality, CO2 for occupancy alongside traditional temperature and humidity measurements.

Areas such as operating theatres require regular wash downs to ensure sterilisation. Any sensors fitted in these areas must be able to withstand this procedure so must have protection of IP65 or above. Typically, products such as the TT-331 outside air temperature sensor or the RH-631 wall mount relative humidity and temperature sensor would be used.

Energy savings can be made by using lighting controllers and light level sensors in rooms such as toilets and consulting rooms to ensure that lights are switched off when the rooms are not in use. Products such as the LL-C-M lighting controller and LL-E-V and LL-C-V light level sensors can be used to achieve this. Occupancy detectors can also be used to control other parameters such as heating when rooms are not in use.

An example of how an efficient building management system can help a new hospital is the Mater Dei Hospital in Malta. The hospital is one of the largest building automation projects to take place in Malta in recent times and features an extensive range of building control peripherals and field device products from Sontay.

Mater Dei Hospital is a state of the art acute teaching hospital located in Tal Qroqq Malta, providing a full range of general services as well as specialist care. Controls specialist Engineering for Science and Industry (Malta) (ESI) has integrated over 1,500 Sontay products into this vast project.

Eyes and ears of the system
They provide the eyes and ears for the Siemens building management system and ensure that building services systems and equipment operate at optimum efficiency and performance. These include air differential pressure switches, temperature sensors, liquid pressure sensors and switches, liquid level switches and sensors and air quality sensors.

ESI has selected Sontay TT temperature sensors for a wide range of different applications at the hospital. These include sensors which measure air temperature in the air-conditioning ductwork running through the hospital, immersion sensors detailing the water temperature at various points in the building's pipework system and space sensors which provide air temperature readings in operating theatres, patient wards, treatment rooms and other spaces.

The project also features nearly 650 of Sontay's PA-604 Air Differential Pressure Switches. These are used to provide an important indicator of fan status and 'filter dirty' conditions within the building's air-conditioning and ventilation plant.

'Sontay was chosen for the project because of its technical support, the reliability of its products, the company's speed of delivery and value for money' said Simon Abela, Project Manager at Engineering for Science and Industry (Malta) Ltd. 'I have worked with Sontay on other projects so know how well the company and its products perform. This project was a larger scale than anything we have undertaken with Sontay before but still we were confident they were the right choice and the products work exceptionally well.'

At Mater Dei, ESI provided the engineering, design, supply, installation, software development, testing and commissioning of the BMS based on a Siemens S7 PLC system with a Siemens WinCC SCADA system to control and monitor the new hospital. The BMS controls and monitors all HVAC plant, corridor lighting, lifts and escalators, medical gases, generator sets, pumps, boilers, calorifiers, heat exchangers and other equipment. It also controls a number of life safety systems such as fire smoke dampers, smoke fans and provides a critical link between all HVAC plant and the Fire alarm. Engineering for Science and Industry (Malta) [ESI] is an ISO 9001-2000 certified Maltese owned and registered company which is a specialist contractor in the field of industrial and building automation.

The author is sales and marketing director at Sontay
14 May 2013

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