What Is the Dash on a Hydraulic Fitting?

••• K-Paul/iStock/GettyImages

In hydraulic systems, the dash number, dash size or simply dash is an industry standard measuring system for hoses and fittings. If you are replacing hoses or fittings, you should choose the correct dash size to avoid damage from heat or turbulence.


The size of a hydraulic hose is described by its internal diameter, expressed as a dash number. The internal diameter of a hose measuring 1/4 of an inch can be divided into four segments, each measuring 1/16 of an inch, so the hose has a dash number of 4.


Dash is used, along with other configuration codes, to provide meaningful shorthand descriptions of hydraulic parts. The dash is a single number that precedes the coupling description of a hydraulic part and denotes the fitting size in sixteenths of an inch.


If a hydraulic adapter part is described as 6 MP – 4 FPX 90, the numbers 6 and 4 are dash numbers; this part has a 6/16 (3/8) of an inch male connector on one end and a 4/16 (1/4) female swivel connector on the other, at right angles (90 degrees) to each other.

Related Articles

Ace Your Middle School Science Fair with These Science...
How to Calculate KVA to MVA
How to Measure Electric Motor Torque
What Is a Hydraulic Power Pack?
How to Convert HP to BTU/hr
How to Convert KPS to PSI
What are Gehl 4625 Skid Steer Specifications?
How to Calculate Hydraulic Press Force in Tons
How to Calculate Test Accuracy Ratios
How to Calculate CFM Output
How to Convert MPa to N/mm^2
How to Convert KBTU to BTU
Tecumseh Carburetor Identification
What Is a Solenoid?
How to Install a Flow Control Valve
How to Calculate Mechanical Advantage Screws
How Hydraulic Pilot Valves Work
How to Make a Robotic Arm
How to Convert mm Hg to in Hg
The Dimensions of a NEMA 56C
How to Calculate the Efficiency of an Electrical Generator