STAMPED Series — Part 1
Proper hose selection is critical to realize a safe hydraulic system. The first step in having a safe hydraulic system is selecting the proper components that meet the needs of each individual system. Compromises in hose selection may create situations of danger, as well as affect the performance and durability of the system. The choice may work for the short run, but may not be a good long-term decision. This guide uses the STAMPED process. STAMPED is an acronym and stands for the 7 major information areas required to provide a quality hose assembly. In this post, we will focus on the S for Size.
Size: I.D. (Inside Diameter)
The hydraulics industry has adopted a measuring system called Dash Numbers to indicate hose and coupling size. The number which precedes the hose or coupling description is the dash size. This industry standard number denotes hose I.D. in sixteenths of an inch. (The exception to this is the SAE100R5, SAE100R14 hoses as well as SAEJ51 and SAEJ2064 refrigerant hoses, where dash sizes denote hose I.D. equal to equivalent tube O.D.)
Hose O.D. (Outside Diameter) can be a critical factor when hose routing clamps are used or hoses are routed through bulkheads. Check manufacturers’ individual hose specification tables for O.D.’s.
The inside diameter of the hose must be adequate to keep pressure loss to a minimum and avoid damage to the hose due to heat generation or excessive turbulence. Note: for existing assemblies, to determine the replacement hose I.D., read the lay line printing on the side of the original hose. If the original hose lay line is painted over or worn off, the original hose must be cut and inside diameter measured for size.
Flow Rate / Fluid Velocity
The flow rate of the system in conjunction with the inside diameter of the hose will dictate the fluid velocity through the hose. Please consult your hose supplier for specific recommended velocity ranges. Please note that suction line recommendations are different than pressure lines.
The correct inside diameter should be determined for the hose required for the application. If the flow rate of the system allows two options for a suitable inside diameter, it is recommended that the larger be selected if pressure allows. High fluid velocities can contribute excessive noise and heat to hydraulic systems and can reduce efficiency.
The above is an excerpt from NAHAD’s Hose Safety Institute HANDBOOK, which provides performance standards for hose assembly specification, design, handling and management.
For a general overview on STAMPED, check out this post: What does STAMPED stand for?
Hose Safety Institute