Size (Dash Numbers)
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.
To determine the replacement hose size, read the layline printing
on the side of the original hose. If the original hose layline
is painted over or worn off, the original hose must be cut and
inside diameter measured for size.
NOTE: Before cutting an original hose assembly, measure
the overall assembly length. This measurement will be required
to build the replacement assembly.
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 (see following table). This industry standard number denotes
hose I.D. in sixteenths of an inch. (The exception to this is
the SAE100R5 hoses C5C, C5D, C5E, C5M,C14 and AC134a, where
dash sizes denotes hose I.D. equal to equivalent tube O.D.)
Except C5 Series, C14 and AC134a
Series, C14 and AC134a
Hose O.D. can be a critical factor when hose routing clamps are
used or hoses are routed through bulkheads. Check individual hose
specification tables for O.D.'s. To
When selecting a replacement assembly, two areas of temperature
must be considered. These are fluid temperature and ambient
temperature. The hose selected must be capable of withstanding
the minimum and maximum temperature seen by the system. Care
must be taken when routing near hot manifolds and in extreme
cases a heat shield may be advisable. To
Determine where or how the replacement hose or assembly is to
be used. Most often only a duplicate of the original hose will
have to be made. To fulfill the requirements of the application,
additional questions may need to be answered such as:
- Where will hose be used?
- Fluid and/or Ambient Temperature?
- Hose Construction?
- Equipment Type?
- Fluid Compatibility?
- Thread End Connection Type?
- Working and Surge Pressures?
- Environmental Conditions?
- Permanent or Field Attachable Couplings?
- Suction Application?
- Routing Requirements?
- Thread Type?
- Government and Industry Standards being met?
- Unusual Mechanical Loads?
- Minimum Bend Radius?
- Non-Conductive Hose Required?
- Excessive Abrasion? To
to be Conveyed
Some applications require specialized oils or chemicals to be
conveyed through the system. Hose selection must assure compatibility
of the hose tube, cover, couplings and "O" rings with
the fluid used. Additional caution must be exercised in hose
selection for gaseous applications such as refrigerants and
LPG. NOTE: All block type couplings contain nitrile "O"
rings which must be compatible with the fluids being used. To
Most important in the hose selection process is knowing system
pressure, including pressure spikes. Published working pressures
must be equal to or greater than the system pressure. Pressure
spikes greater than the published working pressures of the hose.
Identify end connections using Gates coupling templates and
measuring tools. Once thread ends have been identified, consult
the appropriate section of the catalog for specific part number
selection. To Top
(Vacuum and Velocity)
If the same I.D. of the original hose is used, assume the system
is properly sized to efficiently transport fluid. If the system
is new or altered, determine the hose I.D. needed to transport
required fluid volume flow by using the Nomographic Chart.