IMPROVEMENTS IN COMPOUND VACUUM PUMPS
Year: 1882

page_text: LETTERS PATENT to John Henry Johnson of 47 Lincolns Inn Fields -in
the County of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS
IN COMPOUND VACUUM PUMPS" Communicated to him from abroad by
Wilhelm Richter, Engineer, residing in Berlin, Kingdom of Prussia, Germany.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 28th September 1882.
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex;
Gentleman, "IMPROVEMENTS IN COMPOUND VACUUM PUMPS "a communication to
me from abroad by Wilhelm Richter, Engineer, residing in Berlin, Kingdom of
Prussia, Germany.
The compound vacuum pump of Windhausen and the like pump of Galland
consist of two cooperating pumps, of which the one producing the deep vacuum;
discharges the aspired air or vapour into a partially evacuated space, while the
other pump expels the air or vapour (the latter after being condensed) from the
said space into the surrounding air.
According to this invention, the second pump is replaced by an ejector of any
suitable design. In case of the evacuation of vapour, such ejector, when operating
by means of a jet of water, will by itself condense the vapour, so that neither a
condenser nor any special condensing water are then required.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Henry Johnson in the Great Seal Patent Office on the
17th March 1883.
"6
JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields, in the county of Middlesex,
Gentleman IMPROVEMENTS IN COMPOUND VACUUM PUMPS," a communication
to me from abroad by Wilhelm Richter, Engineer, residing in Berlin, Kingdom of
Prussia, Germany.
The compound vacuum pump of Windhausen (described in the specifications of
the British patents No. 1678 A.D. 1878, and No. 1801 A.D. 1880) and also the pump
of Galland serving for the same purpose, consist of two cooperating pumps, of
which the one producing the deep vacuum, discharges the aspired air or vapour
into a partly evacuated space, while the other pump, which is of less capacity than
the former, expels the air or vapour (the latter after being condensed) from the
said space into the surrounding air.
According to the present invention the second pump is replaced by an ejector of
any suitable design working by means of a jet of steam or water. The pump
entering into the combination with the ejector, then draws the air and, when
present, vapour from the vessel or space in which the vacuum is to be created or
maintained, and partly recompresses them, while the ejector draws off the air and
vapour in this state and discharges them from the apparatus. When vapours are
to be removed, and the ejector works by steam, it is advantageous to place a
condenser between the pump and the ejector, as in the original duplicate pump;
but when the ejector operates by means of a jet of water, will by itself condense
the vapour, so that then no special condenser is required.
:
The pump is provided with slide or beat-valves as usual, and these may be
arranged to operate automatically, or they are worked by mechanical means from
the outside, as, is for instance the case in the pump described in the specification of
the British patent No: 1801 A.D. 1880.
By the described arrangement the compound air-pumps are rendered more simple
as well in respect to their construction as to the means to be employed for their
operation.
Having thus described the nature and objet [sic] of this Invention, and the
manner in which it is to be carried out in practice, as communicated to me by my.
correspondent, I hereby claim as new and important features of the same:
1. The combination with an ordinary efficient air-pump provided with slide or
beat-valves, of an ejector of any suitable construction, in the manner and for the
purpose described.
2., The construction of a vacuum-pump in which are combined an ordinary
efficient air-pump provided with slide or beat-valves, and an ejector working by
means of a jet of water, but in which a condenser is not used, substantially as
specified and for the purpose of removing condensible vapours.
In Witness whereof, I, the said John Henry Johnson, have hereunto set
my hand and seal this Sixteenth day of March in the year of our Lord
One thousand eight hundred and eighty-three.