Vacuum Table

The vacuum surface is the size of an Imperial sheet of paper plus one inch added to each dimension (31 inches x 23 inches). It is made of sintered polyethylene which has a slight resistance to the passage of air, enough to distribute the level of vacuum evenly over the whole surface. The material is washable. The sintered polyethylene is carried on a PVC insert which is drilled and grooved, again, to ensure an even vacuum over the whole surface. Both are carried in a polypropylene tray.


Two vacuum pumps are provided. There is a low pressure regenerative blower made by FPZ of Italy; this creates a maximum vacuum of 275 millibars. It shifts a maximum of 400 litres per minute, it is of light construction but highly effective. The second is the Gast 1023 oilless rotary vane pump which is high vacuum and shifts a maximum of 200 litres per minute. The FPZ pump gives the initial seal and vacuum. If more vacuum is needed the Gast is turned on automatically. They help each other up to a vacuum level of, say, 220 millibars and then the Gast takes over and can lift the vacuum to 800 or 850 millibars. Once the vacuum is over 220 millibars the FPZ pump is automatically turned off by a vacuum switch. Each pump is fitted with a non-return valve to ensure that one pump does not draw air through the other.


A vacuum pad, 2 inches x 4 inches is provided. It can be placed under a large object or can be inserted into a book.


A vacuum gauge is provided to indicate the level of vacuum between 0 and 1 atmosphere.


A ball valve is provided for coarse control of airflow and a needle valve is provided to give fine control of airflow.


A flowmeter indicates the volume of air passing through the vacuum surface.


There are two free-liquid traps provided, each with a capacity of 150ml and each containing a floating ball which isolates the vacuum pump when the trap is full to prevent damage.


A filter is provided which removes solvents from the airflow so that the unit can be used anywhere in the studio without polluting the atmosphere.


A lightbox is built in beneath the vacuum table. The components of the base of the tray that carries the vacuum surface are of clear, translucent material. This allows light to pass through these elements and the sintered polyethylene. There are six lamps made by General Electric of America. They are high frequency fluorescent tubes each of which provides 55W of light for 12W input with a colour temperature of 4000 degrees Kelvin. Two small fans keep the compartment cool.


The trolley is made of 1 inch x 1 inch hollow steel box section with 4 castors. This carries the vacuum tray on top and the pumps, filter, etc., below. The pumps are in an enclosed space which is surrounded with accoustic foam, making noise levels easily tolerated. All surfaces are painted with powder coating, heat set paint.