No u velles in terna tio nales specified, each contributing 60~,,, of the design cooling duty. Two STAL-Mini screw com"pressors, type RVR 55, incorporating stepless capacity control to 30~ of nominal capacity were used and air cooled condensers were installed on the roof. STAL-Levin, the company awarded the contract, have avoided the use of water for cooling in this plant and claim that this will make a considerable reduction in maintenance work and render the operating conditions for the plant much more stable, A programmable logic controller has been used for each system, and the PLC controls the compressor capacity regulating condenser performance by fan cycling and providing control of all sequences as well as of aircooler defrosting. Taking advantage of the low vibration levels of the STAL-Mini, an elevated plant room above the loading bay was incorporated to permit future extensions if additional low temperature storage should be required. To simplify the work of maintenance, and with the exception of the cooler expansion valves, all pipeline controls, valves and filters are located within the plant room. STAL-Levin Limited, River Pinn Works, Yiewsley High Street, West Drayton, Middlesex, UB7 7TA, UK.
Drift eliminators for cooling towers An inexpensive and reliable high efficiency eliminator has been produced which is available in l-pass and 2-pass modules that will virtually stop all drift from cooling towers. The new eliminator, produced by Visco, is now being used to replace existing designs which have a lower efficiency. When it was first suspected that Legionnaire's Disease could be spread in the drift from an infected cooling tower, Visco immediately instigated a research programme to find a method to eliminate virtually all drift loss. For years manufacturers
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have been attempting to find ways of reducing drift loss from cooling towers because of the problems it can cause, particularly in winter time when the precipitation can turn into ice on roads and pavements. But when it became apparent that the Leqionella pneumophilla bacteria could be spread in the drift, i.e. the fine droplets of water entrained in the outlet air from cooling towers, this presented a completely new aspect of the problem. The risk of contamination from the Legionella bacteria should be minimal if a cooling system is correctly and regularly maintained. However, from the latest reports, it would appear that it may be possible for some to survive, even after the water has been treated. But, if the new high efficiency eliminator can stop the bacteria from exiting into the air in the form of water droplets, the Visco system could be a line of secondary defence to combat the spread of the disease in the future. Visco Limited, Stafford Road, Croydon, UK.
New environmental test facility A new environmental test facility for refrigerator and freezer research and development has been designed by Hotpoint. The facility comprises three climatic test chambers with a central control room. The climatic chambers
Crompton Instrument panel meter at the new Hotpoint environmental test facility
are each capable of testing up to six 'fridges or freezers continuously and comprehensively for extended periods, for development and testing to the relevant British standards for safety and performance. Crompton Instruments" panel meters are used to monitor physical and electrical parameters of the appliances under test. Power consumption for each of the six test cells in each chamber is displayed on electronic LCD wattmeters from the new Crompton 26 series. Refrigeration system pressure is shown on digital panel meters with LED readouts. The variable mains voltage to each test chamber is measured on conventional analogue meters. The electronic LCD panel meters combine an analogue indicator and a digital readout in a simple integrated unit. Using long-scale, 240 ~ circularscale format, the liquid crystal display provides the control room operator with a 'moving pointer' analogue measurement system giving trend and rate of change information, while the integral digital display provides an accurate instantaneous reading. Conditioned signal inputs for the panel-mounted control and surveillance instrumentation in the central control room are supplied from modular transducers and transmitters from the Crompton Paladin range. Hawker Siddeley Group, 32 Duke Street, St. James's, London, SWIY 6DG, UK.
Energy saving unit from Johnson Controls To complement their MPI000 range of energy management systems, Johnson Controls have released an intelligent sequencing unit. The MPI000 Sequencer is a step/sequence controller. This, because it is microprocessor based, makes it suitable for an extensive range of industrial and commercial applications including boiler step/sequence control, refrigeration
Industrial n e w s
No u velles de I "industrie
MPI000 ~quencer unit
control, air compressor control and electric heater binary switching control. The same unit is used for all these applications. Miniature switches located inside the unit give configuration instructions to the processor. The Sequencer will accept 0-10 V, 2-10V or pulsed three point (increase/decrease/hold) signals, with a wide range of adjustments possible. It will control up to 12 stages, expandable to 24 using a second slave unit. Each output is via SPDT volt free contacts with front panel indication and auto-on-off override switch. The Johnson MP1000 Sequencer is competitively priced and comes in two standard versions for surface mounting or two part panel mounting. Special versions, however, will be considered on request. Johnson Control Systems Limited, PO Box 79, Stonehill Green, Westlea Down, Swindon, Wiltshire. UK.
Additions to Trox range The latest development from Trox is an addition to their range of VAV boxes called Varycontrol. Exhibited as a working demonstration at the London H & V Show last November, Varycontrol can achieve significant reductions in the working pressures within an air conditioning system, giving accurate control of air flow even with a 90' bend on the inlet spigot. Considerable savings on energy consumption are possible with
Varycontrol and noise levels are reduced by improved attenuation. Special features include: variable air volume for both supply and extract air; it is available in eight sizes, 151780dm 3 s - l ; volume turn-down range 10-1; working pressures from 5 Pa; averaging sensor developed for accurate control; pressure independant controls (pneumatic or electronic); secondary attenuators (re-heat coils are also available); ); and the models are available with or without shut-off. Another new product which was on display at the 1985 H & V Show is the Trox jet nozzle, designed for handling large air volumes and for long throw situations. Ideal for buildings with high ceilings such as airport terminal buildings, hotel reception areas, shopping arcades and departmental stores.
Moduline used for tower block refurbishment Over 1.6 km of Carrier Moduline has been used to totally refurbish a 1960s built 20 storey tower block in London, UK. The new system also uses three Carrier chillers and was selected by consultants, M & E Design Services as being simple to use, a well tried system and easy to maintain. All the equipment was supplied by Carrier Distribution Limited. City Tower, developed by Wates City of London Properties pie and Phoenix Assurance pie, has ground and mezzanine floors surmounted by a 20 storey tower and was refurbished specifically for multi-tenancy. When the refurbishment work commenced, AMA Limited, the mechanical and electrical contractors, only had access up to the 12th floor. The first phase therefore involved removal of the existing induction unit system and installation of two Carrier 30h reciprocating chillers in the basement. From the basement, chilled water
Varycontrol single duct terminal box
The jet nozzles can be used in heating or cooling and have fully adjustable discharge patterns. Four sizes are available. Trox Brothers Limited, Caxton Way, Thetford, Norfolk, UK.
risers feed perimeter four-pipe fan coil units on the ground and mezzanine floors and individual air handling units on floors I to 12. The moduline VAV system, of which there are 77 terminals per floor, connects with the AHU's. the distribution fan speeds of which are controlled by the master terminals to reduce energy consumption. Fresh air intakes are at twelfth floor level, and this floor was used as a buffer area to enable the
Two 30 h reciprocating chillers in the London tower block basement
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