Marylebone H/O 1936-               part 3

MECHANICAL SERVICES

The Mechanical Engineering Services of the Building include heating, domestic hot and cold water' service's, drinking water services, gas supplies, compressed air and steam distribution, air conditioning and extract ventilation.

The central oil-fired boiler plant comprises two "Economic" double return tube type steam boilers, and two "Oilex" type steel water heating boilers. The "Economic" boilers generate steam for Works processes, air conditioning and for the hot water service calorifier. Steam and condense return mains are carried at high level in the Basement, and connect to a' pair of risers which distribute steam to Works Departments on the Sixth Floor of the Building. The whole of the condense return mains are in copper with screwed joints, these mains return all condensate into a high level hot well in the Boiler House, from which it is fed to the boilers through duplicate electrically driven single-throw double-acting horizontal boiler feed pumps. The operation of the boiler feed pumps is automatically controlled by a boiler feed regulator equipment.

The two hot water boilers are for heating purposes and maintain a hot water heating system with accelerated circulation designed on the Two-Pipe Up-Feed principle. The accelerators are in duplicate, and are of the electrically driven centrifugal type; suction and delivery connection's from these pumps are connected into the' main flow line of the system.

Radiators in most Office portions, Showrooms and special rooms are of the cast iron radiant panel type, fitted with special aluminium beading around the edges, to cover the joint of the panel with the plaster or panelling.

Throughout the Works Departments on the upper Floors, radiators of the Hospital type are installed.

The Offices, Showrooms, Demonstration Rooms, and Convention Hall and the whole of the Basement are' served by the air conditioning plant which is situated in the Basement. The plant consists of viscous air filter, pre-heater, air washer, secondary heater and air supply fan. The capacity of the plant is 16,500 cubic feet of air per minute, with thermostatically controlled final air temperature. The extract fan is installed in the Air Conditioning Chamber adjacent to the supply plant, and has a capacity of 12,500 cubic feet of air per minute. Low fan speeds and freedom from noise and vibration are features of the supply and extract systems.

The Basement is served by conditioned air and extract ducts of sheet metal at high level, discharging and extracting air at low speeds through gratings fixed directly on the ductwork. The Ground to Third Floors' are supplied with conditioned air through ma' in rising ducts, with branches into a complete system of distributing ductwork running at high level on the various Floors and ,concealed in false ceilings. The distributing ducts are generally run in the corridors, with short branches to high level gratings in the Offices.

The whole of the extraction from the Ground to Third Floors of the Building is by vertical ducts concealed behind firrings on the external walls. Gratings at low level in the Offices are connected to the vertical dropping ducts by short branches concealed by firrings or in the vertical firrings carrying the main ducts.

Every grating on both conditioned air and extract systems is fitted with a regulating damper of the adjustable louvre type.

The hot water supply is from a steam-heated horizontal calorifier in the Boiler House, from which a two-pipe system of distribution serves Lavatories and Works Departments. The circulation of the system is accelerated by centrifugal pumps fixed below the calorifier, the pumps being in duplicate and each capable of handling the full load of the system. The steam supply to the calorifier is thermostatically controlled by the temperature of the water in the flow main.

The cold water service system is supplied from storage cisterns situated on the roof on the drop principle through a main drop pipe, to the Basement, where it is distributed through sub-main and branch risers. The system supplies basins, sinks, water waste preventers and the Works Departments. For drinking purposes a branch main from the incoming supply serves "drinking water risers" which connect to drinking fountains on all Floors.

Gas is used in the Building for various Works purposes, Kitchen service, and for ignition in connection with the oil burning equipment of the four boilers. The supply is metered in the Basement, and the general distribution is by means of rising pipes.

A small rotary air compressor is installed in the Boiler House, with a large capacity container. This equipment supplies compressed air for agitation of Plating Shop tanks, and for paraffin and cellulose spraying. As in other systems, the distribution is again by means of rising mains, connected by short branch pipes to the Departments concerned. Each Department is served through its own pressure reducing equipment, so that any required adjustment of pressures is available.

On all distributing mains, valves and emptying cocks are provided so that any pair of risers or single riser can be isolated for extension or repair with a minimum of interference with the routine of the Building Staff.

Steam and condensate mains, heating, hot water, cold water and drinking water mains are lagged throughout with the exception of short branch pipes. The whole of the lagging is in glass silk with smooth cement and painted finish in exposed positions; in pipe ducts and on concealed pipes the finish is painted canvas.

In the Boiler House an instrument panel is provided for the use of the Maintenance Engineer Temperatures of heating and hot water service flow and return mains are indicated and recorded; boiler steam pressure is recorded and recorders are provided for flue gas temperature and C02 content of flue gases. A smoke detector is installed in the main flue to give a visible and audible warning when smoke is being produced. In addition to the indicating and recording instruments a system of signals is provided to give visible indication of the operation of equipment fixed in positions remote from the Boiler House. Other signals give visible and audible indication of undesirable conditions such as excessive heating or hot water flow temperatures, high or low level in the water storage tanks, etc.

Oil fuel for the boiler firing equipment is stored in two tanks in a chamber below the Garage and adjacent to the Boiler House. The filling pipes for these tanks terminate in the Garage, and a special alarm system is fitted to give warning when the tanks are filled to capacity.

In a small chamber adjacent to the Boiler House an incinerator of the steel plate firebrick lined type is installed. A sheet metal chute transports rubbish from the Garage level to the incinerator Chamber, where it is fed to the burning hearth by hand. A special water dust trap is provided on the gas outlet side of the incinerator to prevent particles of burnt rubbish passing up the flue to atmosphere.

For the Plating and Polishing Departments on the Sixth Floor special extract ventilation systems are installed. From a separate fan on the roof, ductwork is run to special hoods over the Plating Room Tanks. The ventilation of the Polishing Department takes the form of a dust extraction plant, with high level ductwork connecting from the polishing hoods, to a central equipment on the roof.

The Plating Department has been the subject of special treatment as regards tanks, steam and compressed air distribution; tanks for plating solutions and acids being rubber lined and arranged with standing wastes.

The Kitchen on the Fifth Floor is designed to serve a small canteen, and to provide tea for employees; its equipment comprises gas heated tea and water boiler, dish washing machine, with washing sinks and crockery cupboard.

The whole of the Engineering Equipment of the Building has been designed and installed to give the highest efficiency with lowest running costs and minimum maintenance. The Boiler House equipment and air conditioning plant is controlled automatically as far as this is possible, but all plant can be operated manually when required.

Marylebone H/O part 4