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Parker Hannifin Corporation
Cylinder Division
Des Plaines, Illinois www.parker.com /cylinder
Hydraulic and Electrohydraulic Actuators
HAS Series Analog Drives Manual
Catalog HY08-4005-M3
124
Cylinder Safety Guide
Before selecting or using Parker Hannifin Corporation (the Company) cylinders
or related accessories, it is important that you read, understand and follow the
following safety information. Training is advised before selecting and using the
Company’s products.
1.0 General Instructions
1.1 Scope
– This safety guide provides instructions for selecting and using
(including assembling, installing, and maintaining) cylinder products. This
safety guide is a supplement to and is to be used with the specific Company
publications for the specific cylinder products that are being considered for
use.
1.2 Fail Safe – Cylinder products can and do fail without warning for many
reasons. All systems and equipment should be designed in a fail-safe mode
so that if the failure of a cylinder product occurs people and property won’t
be endangered.
1.3 Distribution – Provide a free copy of this safety guide to each person
responsible for selecting or using cylinder products. Do not select or use
the Company’s cylinders without thoroughly reading and understanding
this safety guide as well as the specific Company publications for the prod-
ucts considered or selected.
1.4 User Responsibility – Due to very wide variety of cylinder applica-
tions and cylinder operating conditions, the Company does not warrant that
any particular cylinder is suitable for any specific application. This safety
guide does not analyze all technical parameters that must be considered
in selecting a product. The hydraulic and pneumatic cylinders outlined in
this catalog are designed to the Company’s design guidelines and do not
necessarily meet the design guideline of other agencies such as American
Bureau of Shipping, ASME Pressure Vessel Code etc. The user, through its
own
analysis and testing, is solely responsible for:
• Making the final selection of the cylinders and related accessories.
• Determining if the cylinders are required to meet specific design require-
ments as required by the Agency(s) or industry standards covering the
design of the user’s equipment.
• Assuring that the user’s requirements are met, OSHA requirements are
met, and safety guidelines from the applicable agencies such as but not
limited to ANSI are followed and that the use presents no health or safety
hazards.
• Providing all appropriate health and safety warnings on the equipment on
which the cylinders are used.
1.5 Additional Questions – Call the appropriate Company technical
service department if you have any questions or require any additional in-
formation. See the Company publication for the product being considered
or used, or call 1-847-298-2400, or go to www.parker.com, for telephone
numbers of the appropriate technical service department.
2.0 Cylinder and Accessories Selection
2.1 Seals
– Part of the process of selecting a cylinder is the selection of
seal compounds. Before making this selection, consult the “seal informa-
tion page(s)” of the publication for the series of cylinders of interest.
The application of cylinders may allow fluids such as cutting fluids, wash
down fluids etc. to come in contact with the external area of the cylinder.
These fluids may attack the piston rod wiper and or the primary seal and
must be taken into account when selecting and specifying seal com-
pounds.
Dynamic seals will wear. The rate of wear will depend on many operating
factors. Wear can be rapid if a cylinder is mis-aligned or if the cylinder has
been improperly serviced. The user must take seal wear into consideration
in the application of cylinders.
2.2 Piston Rods
– Possible consequences of piston rod failure or
separation of the piston rod from the piston include, but are not limited to
are:
• Piston rod and or attached load thrown off at high speed.
• High velocity fluid discharge.
• Piston rod extending when pressure is applied in the piston
retract mode.
Piston rods or machine members attached to the piston rod may move
suddenly and without warning as a consequence of other conditions
occurring to the machine such as, but not limited to:
• Unexpected detachment of the machine member from the piston rod.
• Failure of the pressurized fluid delivery system (hoses, fittings, valves,
pumps, compressors) which maintain cylinder position.
• Catastrophic cylinder seal failure leading to sudden loss of pressurized
fluid.
• Failure of the machine control system.
Follow the recommendations of the “Piston Rod Selection Chart and Data”
in the publication for the series of cylinders of interest. The suggested pis-
ton rod diameter in these charts must be followed in order to avoid piston
rod buckling.
Piston rods are not normally designed to absorb bending moments or loads
which are perpendicular to the axis of piston rod motion. These additional
loads can cause the piston rod to fail. If these types of additional loads are
expected to be imposed on the piston rod, their magnitude should be made
known to our engineering department.
The cylinder user should always make sure that the piston rod is securely
attached to the machine member.
On occasion cylinders are ordered with double rods (a piston rod extended
from both ends of the cylinder). In some cases a stop is threaded on to one
of the piston rods and used as an external stroke adjuster. On occasions
spacers are attached to the machine member connected to the piston
rod and also used as a stroke adjuster. In both cases the stops will create
a pinch point and the user should consider appropriate use of guards. If
these
external stops are not perpendicular to the mating contact surface, or if
debris is trapped between the contact surfaces, a bending moment will be
placed on the piston rod, which can lead to piston rod failure. An external
stop will also negate the effect of cushioning and will subject the piston rod
to impact loading. Those two (2) conditions can cause piston rod failure.
Internal stroke adjusters are available with and without cushions. The use of
external stroke adjusters should be reviewed with our engineering depart-
ment.
The piston rod to piston and the stud to piston rod threaded connections
are secured with an anaerobic adhesive. The strength of the adhesive
decreases with increasing temperature. Cylinders which can be exposed to
temperatures above +250°F (+121°C) are to be ordered with a non studded
piston rod and a pinned piston to rod joint.
2.3 Cushions
– Cushions should be considered for cylinder applications
when the piston velocity is expected to be over 4 inches/second.
Cylinder cushions are normally designed to absorb the energy of a linear
applied load. A rotating mass has considerably more energy than the same
mass moving in a linear mode. Cushioning for a rotating mass application
should be reviewed by our engineering department.
2.4 Cylinder Mountings – Some cylinder mounting configurations may
have certain limitations such as but not limited to minimum stroke for side or
foot mounting cylinders or pressure de-ratings for certain mounts. Carefully
review the catalog for these types of restrictions.
Always mount cylinders using the largest possible high tensile alloy steel
socket head cap screws that can fit in the cylinder mounting holes and
torque them to the manufacturer’s recommendations for their size.
2.5 Port Fittings – Hydraulic cylinders applied with meter out or decelera-
tion circuits are subject to intensified pressure at piston rod end.
The rod end pressure is approximately equal to:
operating pressure x effective cap end area
effective rod end piston area
Contact your connector supplier for the pressure rating of individual
connectors.
3.0 Cylinder and Accessories Installation and Mounting
3.1 Installation
3.1.1
– Cleanliness is an important consideration, and cylinders are
shipped with the ports plugged to protect them from contaminants
entering the ports. These plugs should not be removed until the piping
is to be installed. Before making the connection to the cylinder ports,
piping should be thoroughly cleaned to remove all chips or burrs which
might have resulted from threading or flaring operations.
Safety Guide for Selecting and Using Hydraulic, Pneumatic Cylinders and Their Accessories
WARNING: FAILURE OF THE CYLINDER, ITS PARTS, ITS MOUNTING, ITS CONNECTIONS TO OTHER
OBJECTS, OR ITS CONTROLS CAN RESULT IN:
• Unanticipated or uncontrolled movement of the cylinder or objects connected to it.
• Falling of the cylinder or objects held up by it.
• Fluid escaping from the cylinder, potentially at high velocity.
THESE EVENTS COULD CAUSE DEATH OR PERSONAL INJURY BY, FOR EXAMPLE, PERSONS FALLING FROM
HIGH LOCATIONS, BEING CRUSHED OR STRUCK BY HEAVY OR FAST MOVING OBJECTS, BEING PUSHED INTO
DANGEROUS EQUIPMENT OR SITUATIONS, OR SLIPPING ON ESCAPED FLUID.