IMPROVEMENTS IN COMPRESSION PUMPS FOR CONDENSABLE GASES
Year: 1884

page_text: I, SAMUEL PUPLETT of Westmoors, Knowle, in the county of Warwick Engineer do
hereby declare the nature of my invention for IMPROVEMENTS IN COMPRESSION
PUMPS FOR CONDENSABLE GASES and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement:-
The improvements relate to pumps used in compressing the condensable gases
In condensing these gases more especially those of high tension ammonia for
example there has always been great difficulty in retaining the gas in the machine
particularly in preventing its escape by or through the packing of the piston rod
this difficulty has been augmented by the rapid wear of every known kind of
fibrous packing making frequent adjustments necessary and even with the most
skillful adjustment possible with the packing heretofore in use escape of gas could
not be prevented without excessive friction owing to the rapid motion of the piston
rod through unyielding packing and through rigid metallic parts-Another but
less serious loss of gas occurs from the necessity of having frequently to remove the
covers of the valve chests to loosen the valves which from a variety of causes will
get fast.
Removing the valve covers involves the loss of all the gas in the pump and the
'annoyance and disagreeable effects of its escape and also the troublesome matter of
admitting air into the machine, where as is frequently the case the valve chest is
encased in a water tank the water must be partially or wholly withdrawn from
the tank before the valve covers can be removed.
The object of this invention
to remove or minimise these difficulties and this is
effected in the manner hereinafter described reference being made to the drawings
annexed.
In the accompanying drawings which form part of this specification Fig. 1
sheet 1 is a longitudinal sectional elevation on line A-B. of a double acting
compression pump constructed according to these improvements.
Fig. 2 is plan of same partly in section.
Fig. 3 is end elevation of piston rod end.
Fig. 4 is plan of the case and one set of the packing blocks (case in section). ;
Fig 5 shows outline of inlet and outlet passages to and from each set of valves.
a the cylinder. b the piston. c the piston rod. d selfadjusting piston rod
bushing collar.. e, e, chambers for metallic packings, f,f packing blocks-
f ball joints. f follower. g, g cases, containing the packing blocks, h, liquid

page_text: sealing chamber encircling the rod-i leather packing around the rod-; & j¹ inlet
and outlet valves-k, valve case- & inlet and outlet passages for the gas-
m, valve springs-n, arrangement for loosening the valves without removing the
valve covers.
o valve chest. 01 extension of sides and ends of valve chest to form water
tank-p valve covers outside of water tank..
The rationale of these improvements is as follows-It will be seen by the
drawings that the piston rod does not pass through any rigid parts the adjustable
bushing, the metallic packings, the ball joints, and the leather packing are all
arranged to adjust themselves to any faults of alignment of piston and rod with
the cylinder By this means every part in contact with the rod may be most
accurately fitted without causing any excessive friction.
The bore of the cylinder hond for the piston rod is of suitable diameter to receive
the bushing and to leave a space for a lateral motion of the selfadjusting bushing
in each direction-The inner face of the head of this bushing within the cylinder is
ground to fit a seating on the cylinder head around the piston rod-The pressure
in the cylinder acts against the outer surface of the bushing head and thus
maintains a tight joint whilst admitting of a free lateral movement of the bushing.
Upon the inner end of this bushing there is secured a collar d' which prevents
the bushing from being drawn'into the cylinder by the action of the piston rod.
The eight metallic blocks in the cases g, g, together forming the packing are so
constructed as to always be in close contact with the rod notwithstanding any
slight wear that may occur.
In lieu of the ball joint f¹ there (may be substituted a ring with two flat sides
cach having ground faces and a corresponding flat seating in the packing box.
The sealing chamber is kept filled with a liquid that is a good lubricant thus
ensuring an uniform and continuous lubrication; a connection is made from this
chamber to the inlet passage in valve chest thereby causing at every return stroke
of the pump the withdrawal of any gas that may have passed by the first or inner
packing and thus maintaining in the sealing chamber at all times when the machine
is at work the same pressure of the ingoing gas. -
The leather and outside packing preferably metallic have only to prevent the
escape of the liquid lubricant against this greatly reduced pressure.
The arrangement for loosening the valves without removing the covers consists
of a rod threaded at one end the other end having a ring or some suitable
arrangement for a handle a packing box in the valve cover a projecting nipple
threaded externally and a cap threaded internally to screw over the nipple-When
required to loosen the valve the cap is removed the threaded end of the rod screwed
into the valve which then may be worked backwards and forwards by the rod;
the packing preventing any troublesome escape of gas. When the valve is loosened
the rod is unscrewed and drawn back beyond the working motion of the valve and
the cap replaced; all this can be done without even stopping the pump and without
any considerable loss of gas and no admission of air.
The ends and sides of the valve chest are extended so as to form a water tank
but contrary to the usual practice the valve covers as will be seen are outside of
this tank and consequently they may be removed at any time or the valves be
loosened without withdrawing any water from the tank and without sacrifice of
any convenience in case the cylinder and chests are cooled by other means than the
use of water.
It will be obvious that various changes may be made in the details: of
construction without departing from the nature of this invention which consists
éssentially
First in interposing between cylinder end and sealing chamber a suitable
packing practically indestructible and only requiring adjustment at long intervals
and so arranged that the piston rod has not to pass through any rigid parts thereby
"effectually preventing the escape of gas and reducing the friction of moving parts
to a minimum.

page_text: Second In preventing the loss of gas from the pump and the admission of air
into the pump by the arrangement whereby the necessity of removing the covers
of the valve chest is very much less frequent than with machines heretofore
constructed.
Third In the method of constructing the tank inclosing the pump in such a
manner as to preclude all liability of water getting into the pump and also in
making the various parts more readily accessible.
I am aware that metallic packing in various forms for piston and valve rods is
not new and that a liquid seal to prevent the escape of gas by or through the
piston rod packing has been previously used and these are not claimed as part of
this invention.
I do not restrict myself to the particular kind of packing. described and
illustrated in this specification but any arrangement of metallic packing that is
efficient and not rigid and that does not require frequent adjustment may be used
without deviating from the essential features of this invention.
Neither do I confine myself to any particular kind of packing for the outer gland
which is readily accessible the requirement being a packing that will prevent the
escape of the sealing liquid at the reduced pressure without forming a rigid part
through which the piston rod must move.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
First In compression pumps for the condensable gases the interposing between
the cylinder end and a sealing chamber encircling the piston rod metallic packing
so arranged that it will adjust itself to faults in the piston rod or in the alignment
of piston and rod with the cylinder and yet remain in close and accurate contact
with the rod substantially as described and for the purposes specified.
Second-In compression pumps for the condensable gases the combination of
inetallic packing with a selfadjusting bushing arranged substantially as described
and shewn.
Third In compression pumps for the condensable gases the combination of a
selfadjusting bushing metallic packing and a sealing chamber encircling the rod
having a passage or connection to the inlet of suction pipe of the pump substantially
as and for the purposes hereinbefore described.
Fourth In compression pumps for the condensable gases the combination of
selfadjusting bushing metallic packing sealing chamber and outer packing all
arranged to admit of a free lateral movement in either direction and so yielding to
any deviation of the rod from its true course from whatever cause substantially as
herein before described.
Fifth In compression pumps for the condensable gases the arrangement for
loosening the valves without removing the valve covers substantially as described
and shewn.
Sixth In compression pumps for the condensable gases the method of forming
the water tank whereby the covers of the valve chest are outside the water tank
substantially as and for the purposes described and shewn.
Seventh In compression pumps for the condensable gases the general arrange-
ment of the various parts comprising the pump combined in the manner and for
the purposes described in the specification and as shewn in the drawings annexed.
Dated this 20th day of October 1884.
SAMUEL PUPLETT.