Safety Information for Hydraulic Swivels
This safety bulletin is to warn against improper selection, installation, use, etc. of Hydraulics, Inc. swivel joint products in fluid power system.
A copy of this safety information should be provided to all persons that are responsible for selecting, applying and using these swivel joints. Do not attempt to select or use these products without clearly understanding this guide and the definitions and instructions provided by this specific Hydraulics, Inc. publication.
It is possible for a swivel or its attached fluid conductors to fail without warning for a number of reasons. Design all systems and equipment for fail-safe operation such that failure of swivel, fluid conductor or other component will not endanger persons or damage property.
Due to the differences in operating conditions of fluid power systems, Hydraulics, Inc. and it’s distributors do not represent or warrant that any fluid conducting swivel is adequate for any particular fluid power system use. Therefore, it is the swivel users sole responsibility for reading and following this safety bulletin and other Hydraulics, Inc. catalogs and any other documents pertaining to swivel use. Also, through it’s own analysis and testing, the user must determine if the swivel meets the use requirements and does not present a health or safety hazard.
Selection of Hydraulics, Inc. Swivels
The basic in-line and ninety degree type swivels provide the basis to catalog a total of four types of swivel configurations. When planning a fluid system conductor arrangement, it is suggested all types and kind of swivels be considered. Each size if offered with the range of SAE and ISO fluid ports and other port options.
Advantages in use & General Guidelines
Simplified plumbing arrangements – Swivels connect directly to hose ends and can eliminate adapters. Less hose needed and more space saved – Swivels provide rotation on planes relative to system piping and/or fixed components wherein reduction of fluid conductors may be achieved. Longer hose life – Life is extended by swivel eliminating the effects of torque and bending stress on hose. Saves money – Simplified plumbing // Longer hose life // Less down time // Increased reliability.
Selection Guidelines (Swivel and Port Working Pressure)
Hydraulics, Inc. swivel joints are designed for low speed rotation common to many fluid powered systems. Swivel life relates to conditions of fluid pressure, temperature and rotation. A swivels recommended working pressure is based on results from controlled laboratory test conditions. Stated working pressure ratings do not take into consideration fluid system conditions such as bearing deflection, high amplitude hydraulic and mechanical shocks or high cyclic rates. Functional life for a swivel in an application should be determined by laboratory and prototype testing. Avoid bearing stress by selecting swivels compatible with the desired plane of rotation. Also consider, when swivels, port adapters, and associated fluid conductors are in final assembly, the working pressure range for the assembly does not exceed the lowest pressure rated component in the assembly.
Temperature Range of Equipment and Fluid
Fluid and ambient temperatures determine swivel seal type needed. Should fluid temperature exceed the standard (Buna-N) seal temperature rating of (-30° to 250° F // -34° to 121° C), seal deterioration will likely result in fluid leakage. Transient temperatures also have potential for damaging seals, especially at system shut down. High temperatures can also damage protective plating and precipitate swivel housing corrosion.
Composition of the swivel carbon steel body, Buna-N seals and Teflon™ seal back-up rings must be compatible to the fluid systems environment. Other materials may be required.
Bearing Rotation Life
To gain acceptable swivel bearing rotation life requires a swivel configuration of a type that permits fluid conductors attached at swivel port to be routed to attach it’s opposing port in a manner that prevents swivel bearing stress. The goal is an installation providing unrestricted freedom of swivel bearing rotation.
As fluid system pressure increases, so does swivel rotation torque drag. Rarely is torque a problem for attached flex hose in that fluid pressure increase also increases hose rigidity. Refer to cataloged torque values.
Pressure drop of differential pressure is the loss of pressure between any two points in a fluid system. Measured as a loss in pounds per square inch, it is the resistance to fluid flow through a component based on a given volume. Swivel designs take flow into account. Refer to cataloged torque values.
Swivels of carbon steel receive an exterior coating of zinc plating with a yellow chromate RoHS compliant finish. Both fluid media and system operating environment should be considered if corrosion is a factor.
Welding & Brazing
Heating plated swivel joints and port adaptors above 250° F (121° C) as in welding, brazing etc., may result in seal and plating damage resulting in fluid loss and/or corrosion.