Understanding Dash Sizing: A Guide to Properly Sizing Hydraulic Hoses
When it comes to hydraulic hose fittings, it’s important to get the correct size to prevent issues such as leaks or flow restrictions and to ensure optimal performance while protecting your equipment. In the hydraulics world, the dash size, sometimes referred to as dash number or dash, is an industry standard measuring system for hoses and fittings. The dash sizing system is one of most common misunderstandings when ordering hydraulic fittings.
Hydraulic Hose Diameter and Length
Familiarizing yourself with the length and depth, the inner and outer diameter, of the hose and how they impact sizing is the first step in ensuring your find the right fit.
The inner diameter (ID) refers to the space inside the hose encircled by it's layers. These layers typically include the inner tube, a thinner layer that prevents liquids from sticking to the tube. Followed by the reinforcement layer that provides strength and shape to the tube and outer cover which adds additional protection and stability while protecting the hose from weather or rugged use.
The outer diameter (OD) refers to the full width of the hose, including the inner layer, reinforcment layers, and outer cover.
The lenght of the hose is also worth considering as the longer the hose, the greate the pressure loss within the hose.
What is Dash Sizing?
Simply put, a dash size refers to the inside diameter of a hose, tube, or fitting in 1/16” increments.
For example, if the size of a hydraulic fitting is -8AN, sometimes written as -08, the fitting is 8/16ths of an inch. Simplified down, the size of the hole is 1/2”. With the inside diameter being 1/2”, the threads of the fitting need to be larger to ensure a snug, but not too tight, fit. Following the chart below, the external threads of an -8AN fitting is 3/4”-16 UNF (Unified Fine Pitch). These dimensions often get mixed up resulting in the wrong fitting size being ordered.
The AN Thread Sizes chart to the right will help clarify the dash sizing system.
How to Find the Correct Fitting?
For the best results, both the dimensions of the inside diameter of the fitting hole and the thread pitch of the outside of the fitting should be measured. Follow these simple steps to correctly measure these dimensions.
1. Using a caliper, measure the inside diameter of the hole going through the fitting.
2. Using a thread pitch gauge, find the thread pitch of the outside of the fitting.
3. Relay these two measurements to your FORCE America Inside Salesperson for expert assistance.
Conclusion
Dash sizing refers to the inside diameter of hydraulic hoses, tubes, or fittings, measured in 1/16-inch increments. Proper sizing ensures efficient system performance, avoiding issues like leaks or pressure loss. The dash number indicates the size, such as -08 representing 8/16" (or 1/2"). To ensure accurate fitting selection, it's important to measure both the inside diameter and thread pitch. Using tools like calipers and thread pitch gauges can help ensure a precise fit.
Still having trouble? Contact one of our knowledgable salesperson at your local FORCE America Service Center or call 1-888-993-6723.