El Paso herald. (El Paso, Tex.) 1901-1931, 1914-09-08
PACKING IS NOT
4 SIMPLE THING
It Has to Be Treated to Pre-
vent It Solidifying
Under Pressure.
An analysis Of the packing question
" H S pemarest. MANAGER hacking

An analysis Of the packing question
by H S Demarest manager packing
department, Greene, Tweed & Co.
Unfortunately the subject of rod
packings for steam and air pressures
has become unnecessarily enshrOuded
in mystery, due to the fact that brands
have been multiplied without number,
many of which are made Of the same
materials and process Of manufacture.
This together with the fact that most
of the manufacturers make the most
extravagant claims for their brands,
renders the selection of a brand Of
packing for a definite service more or
less difficult
Let US, therefore, briefly analyze the
subject of packings, and II possible
strip il Of the mystery that seems TO
surround it. We must first consider the
condition Of service under which the
hacking is TO work, and the power of
endurance of which such packing IS
made. In considering the elementary
subject of material all packlngs metal
lie backing not being here cOnsidered)
must necessarily fall into two classes:
those manufactured Of materials OF
vegetable fibre and those Of mineral
substance.
The vegetable fibres generally used
in the manufacture Of packings are
jute, flax, hemp cotton duck and rub
Der all of which begin to deterlOrate
by charring at certain easily deter
mined temperature, which is FAR below
that incident to present steam pres
sures. particularly those standard on
the railroad systems in this country
today.
When only low pressure steam was
carried, pacl1ings made Of vegetable
fibres gave satisfaction but as pres
sures increased and superheated steam
was added, they fail to possess lasting
qualities in proportion TO the increase
Of pressure It is therefore apparent al
a glance that packings made OF Yege-
table Ibres are absolutely useless I'M
der the abnormal temperature Of super
heated steam and compressed air
Rubber which is very popular IN the
manufacture Of packings is utterly use
less under present pressures because
them and for that reason does not
possess the residence. the only reason
for its use. The constant increasing
price Of crude rubber drives the manu-
facturer TO substitutes. which are even
more worthless than pure rubber under
present conditions In fact, rubber
varies with age and uniform quality Of
manufacture is difficult and lubricant
which is most necessary quickly de-
StrOyS rubber. all operate against II as
a suitable material out of which TO
manufacture packing for the present
steam pressures.
Eliminating then all vegetable fibres
as packing materials we must turn to
asbestos, a mineral substance. with its
well known heat resisting qualities. In
its natural state il unfortunately pos
sesses a quality that if not neutralized
operates very strongly against il for
packing purpose. The Objectionable
feature of asbestos is the tendency of
the fibreized particles to soIidify back
into the rock from which it was fibre
lied when compressed in the stuffing
box
This objection can be overcome by
injecting between the fibres of asbestos
some foreign substance that viii not
only prevent solidifying but also serve
as a lubricant. The effect Of lubricant
on asbestos is the opposite from that
on rubber fer where II destroys rubber