I. BSP Fitting (British Thread Hydraulic Fittings)
Thread standard: BSP is divided into BSPP (parallel threads, code G) and BSPT (conical threads, code R).
Sealing principle:
BSPP: The seal is achieved by using a combination of gaskets (metal gasket + rubber) or a 60° internal conical surface.
BSPT: It relies on the self-cone of the thread for interference sealing, and requires the use of sealant or tape.
Applicable scenarios:
European-originated hydraulic equipment
Industrial machinery, machine tool hydraulic systems
General purpose low and medium pressure lines
Selection Tip: The BSPP and NPT threads cannot be interchanged. The tooth profiles are different (55° vs 60°). Forceful insertion may result in oil leakage or damage to the ports.
II. JIC Fitting (37° Flared Fitting)
Thread standard: Utilizes UN/UNF straight threads (American Standard Unified Fine Thread).
Sealing principle: Achieve metal-to-metal line contact sealing through the 37° expanded conical surface, without the need for O-rings or sealing gaskets.
Applicable scenarios:
Construction machinery (excavators, loaders)
Agricultural machinery
High pressure and high vibration environment
Selection Tip: The JIC fitting has excellent vibration resistance performance and is suitable for equipment that undergoes frequent impacts. During installation, ensure that the flared surface is free from scratches, and follow the standard torque for the nuts.
III. ORFS Fitting (Flat O-ring Sealing Fittings)
Thread standard: Straight thread (UN/UNF or metric options are available, but UN/UNF is the most common).
Sealing principle: The end face of the fiitting is a flat surface, and an O-ring is embedded inside. After being pressed tightly against the opposite flat surface, a positive pressure seal is formed.
Applicable scenarios:
High-pressure hydraulic system (with a pressure of up to 42 MPa or more)
In situations where strict requirements are imposed on leakage (such as in environmental protection and for precision equipment)
Working conditions with significant temperature fluctuations
Selection Tip: ORFS is currently recognized as the most reliable type of leak-proof fitting. However, it is important to note the compatibility of the O-ring material with the hydraulic oil (for example, nitrile rubber for mineral oil, fluorine rubber for high temperatures or phosphate esters).
Iv. Metric Fittings (DIN standard 24° Cone Fitting)
Thread standard: Metric thread (M series), in accordance with DIN 2353, DIN 20066, etc.
Sealing principle: 24° conical surface metal seal. An enhanced sealing type with O-ring is also available as an option.
Applicable scenarios:
German and Eastern European original equipment
High pressure hydraulic line
Compression Tube Fitting System
Selection Tip: Metric fittings are commonly used in European OEM equipment and are not compatible with JIC/BSP. When selecting, it is necessary to confirm the thread size (such as M18×1.5) and the taper angle.
