Hydraulic Packings & Sealing Products

Shallex ® — rod/ram & piston packing
Application considerations
Non-adjustable housings: we need
to be informed so that overall packing
depth can be controlled and adequate
compression is obtained. When ordering
from our standard charts, the appropriate
part number should be specified.
Non-adjustable housing depths should be
equivalent to the normal set depth C
(page 14) with the following limits
applying:
Packing ID
Inch housings (inch)
Limits
≤ 20 +0.01 / -0
>20 +0.015 / -0
Metric housings (mm)
≤ 500 +0.25 / -0
>500 +0.40 / -0
Piston heads: we recommend that
two Shallex ® packing sets be used on
double-acting pistons operating under
constant pressure. These should be fitted
in opposed mode, and independently
housed to avoid undesirable pressure
transference — see typical installation
below.
Endless rings are always preferred for
piston head assemblies, and this should
be noted when placing inquiries or orders.
Shallex ® double-acting piston arrangement
Design considerations
This information is for guidance only, as
other considerations may affect the final
decision. If in doubt, please contact our
Technical Department.
Tolerances: for optimum sealing, the
diameters shaft/cylinder and housing
should be as close to nominal as possible,
and adjacent fits kept to a minimum. ISO
tolerance scale H8/f8 or ANSI B4.1 RC5
are ideal for most services.
Surface finish: surfaces with movement
relative to the packing should have a finish
of 8-16µin (0.2-0.4µm) Ra or CLA.
On static surfaces a finish of 16-32µin
(0.4-0.8µm) Ra or CLA is acceptable.
Assembly
Shallex Packing is entirely self-sealing and
heavy gland compression is undesirable
as it can reduce packing life.
Adequate chamfer should be provided
at the entrance to all packing spaces to
avoid lip damage on assembly.
How supplied
Shallex Packing sets are available in
sections from 3/16in (5mm) upwards,
except for spring-loaded versions where
minimum section is 1/4in (6.5mm).
Split rings are supplied to any maximum
diameter, and endless rings up to 88 1/2in
(2250mm) OD. For non-standard sizes,
sets may be supplied in split form at our
discretion, unless endless packing rings
are specifically requested when ordering.
See page 14 for recommended packing
dimensions relating to shaft and cylinder
dimensions and pressure.
When ordering please state:
l Type of machine.
l Gland or piston head (for piston, state
if cover plate is bolted or screwed)
l Exact diameters of ram and stuffing
box.
l Length of gland lip.
l Adjustable or non-adjustable housing.
l Pressure medium.
l Pressure.
l Temperature.
l If application involves edible products.
l Whether ram is assisted on downstroke,
or falls by gravity.
l Whether endless or split rings required.
To order or get further details, please call your local contact 13 shown on back cover or listed at www.jameswalker.biz 13