High-Pressure up to 700 Bar

Nitto Kohki Pneumatic Solutions

Nitto Kohki offers high-pressure quick couplings rated up to 700 bar, engineered for hydraulic and high-pressure pneumatic applications. The product range divides into several series matched to specific pressure levels and material requirements: from the HSP Cupla and HSU Cupla (stainless steel, HNBR) through the 210, S210, 280, 350, 450B and 700R Cupla, complemented by a Purge Adapter for pressure-free venting of the high-pressure system before disconnection.

Series	Max. working pressure	Body material	Seal
210 Cupla	210 bar	Steel	-
S210 Cupla	210 bar	Stainless steel (SUS)	-
280 Cupla	280 bar	Steel	-
350 Cupla	350 bar	Steel	-
450B Cupla	450 bar	Steel	-
HSU Cupla	up to 700 bar	Stainless steel (SUS)	HNBR
700R Cupla	700 bar	Steel	-
HSP / Hyper HSP Cupla	elevated pressure	Steel/SUS	-

Series in this category compared

Maximum working pressure is the first selection criterion. It decides the series, not the size: a low pressure coupling does not become high pressure capable by choosing a larger bore.

Where each series sits by maximum working pressure.

Series	Max working pressure	Sizes	Shut-off type	Fluids	Body material	Catalogue page
700R CUPLA	686 bar	Thread 3/8 inch, 1/2 inch	Two-way shut-off	Hydraulic oil	Special steel (Nickel plated)	112
450B CUPLA	441 bar	3/8 inch	Two-way shut-off	Hydraulic oil	Special steel (Nickel plated)	111
PURGE ADAPTER	350 bar	R 1/4 (PAD-2), R 3/8 x Rc 3/8, R 1/2 x Rc 1/2, R 3/4 x Rc 3/4, R 1 x Rc 1	-	Hydraulic oil	Steel (nickel plated)	168
350 CUPLA	345 bar	Thread 1/4 inch, 3/8 inch, 1/2 inch, 3/4 inch, 1 inch, 1 1/4 inch, 1 1/2 inch	Two-way shut-off (Spill Reduction)	Hydraulic oil	Special steel (Nickel plated)	105
280 CUPLA	315 bar	Thread 1/4 inch, 3/8 inch, 1/2 inch, 3/4 inch, 1 inch	Two-way shut-off	Hydraulic oil	Special steel (Bright chromate conversion coating : silver color)	103
HSU CUPLA	210 bar	Thread 1/4 inch, 3/8 inch, 1/2 inch, 3/4 inch, 1 inch	Two-way shut-off	Water, Hydraulic oil, Gas	Stainless steel (SUS304)	99
210 CUPLA	206 bar	1/4 inch to 1 inch	Two-way shut-off	Hydraulic oil	Special steel (Nickel plated)	97
HSP CUPLA	206 bar	1/4 inch, 3/8 inch, 1/2 inch, 3/4 inch, 1 inch, 1 1/4 inch, 1 1/2 inch, 2 inch	Two-way shut-off	Hydraulic oil	Special steel (Nickel plated)	91
HYPER HSP CUPLA	206 bar	1/4 inch, 3/8 inch, 1/2 inch, 3/4 inch, 1 inch	Two-way shut-off	Hydraulic oil	Special steel (Nickel plated)	95
S210 CUPLA	206 bar	1/4 inch, 3/8 inch, 1/2 inch, 3/4 inch, 1 inch	Two-way shut-off	Water, Hydraulic oil, Gas	Stainless steel (SUS304)	101

The four shut-off types

The shut-off type decides what happens on disconnection. It is the second criterion and depends on whether the line is under pressure when it is parted and how much fluid may escape.

On disconnection the valve in the socket closes the supply line. The fluid left in the plug escapes.

Both halves close on disconnection, so the line contents are retained on both sides.

No valve, therefore the lowest pressure drop. The line must be depressurised before disconnecting.

Flat sealing face, so fluid loss is minimal and the parting face is easy to wipe clean.

Connecting sequence of a ball locking quick connect coupling.

Choosing a coupling in five steps

Fix the fluid and the operating temperature, which gives the seal material.
Determine the maximum working pressure, which gives the pressure class and the series.
Choose the shut-off type: one-way, two-way, valveless or flat face.
Fix the end connection and size: hose barb, male thread, female thread or tube fitter.
Choose the body material for the fluid and the environment, then order plug and socket as a pair.

This page is based on the Nitto Kohki general catalogue Quick Connect Couplings C01en-b, 190 pages. The complete catalogue is available for download on this page.

What are Nitto Kohki high-pressure pneumatic couplings rated up to 700 bar and which industries use them?

Nitto Kohki high-pressure pneumatic couplings are precision-engineered quick-connect systems designed for extreme pressure applications up to 700 bar, serving both pneumatic and hydraulic fluid power systems. These robust coupling solutions are extensively deployed in heavy industrial sectors including oil and gas drilling operations, hydraulic press manufacturing, high-pressure water jetting equipment, and aerospace testing facilities. The HSP, HSU, S210, and 350 series couplings feature hardened steel or stainless steel construction with FKM, NBR, or HNBR sealing compounds to ensure reliable operation under demanding pressure conditions. Their quick-disconnect capability enables rapid maintenance and reconfiguration of high-pressure fluid circuits while maintaining system integrity.

What are the key technical selection criteria for choosing Nitto Kohki 700 bar pneumatic couplings?

Selection of Nitto Kohki high-pressure couplings requires evaluation of maximum working pressure rating up to 700 bar, port connection sizes ranging from 6mm to 16mm as shown in models like HSP 10HS, 12HS, and 16HS, and sealing material compatibility with system fluids. Construction material choice between hardened steel for maximum strength or stainless steel (SUS) for corrosion resistance in models like S210-8S and HSU-8S directly impacts service life and chemical compatibility. Coupling configuration must match application requirements, with plug (P-suffix) and socket (S-suffix) variants ensuring proper mating geometry. Temperature range capabilities and dynamic pressure cycling requirements further refine selection parameters for optimal system integration and operational reliability.

Which international standards and certifications apply to Nitto Kohki 700 bar high-pressure pneumatic couplings?

Nitto Kohki high-pressure pneumatic couplings comply with ISO 4414 pneumatic systems safety standards and ISO 7241 series specifications for hydraulic quick-action couplings, ensuring interchangeability and safety in industrial fluid power applications. These coupling systems meet JIS B 2351 Japanese Industrial Standards for pneumatic couplings and incorporate design principles aligned with EN 983 safety requirements for pneumatic systems operating above 500 bar. Materials certification includes compliance with ASTM specifications for steel grades and elastomer compounds, while manufacturing processes adhere to ISO 9001 quality management standards. The FKM and HNBR sealing compounds used in models like HSU-8S meet FDA and NSF requirements for food-grade applications where applicable.

What are the differences between Nitto Kohki HSP, HSU, S210, and 350 series high-pressure coupling variants?

The HSP series utilizes hardened steel construction with FKM or NBR seals for maximum pressure capability up to 700 bar in standard industrial environments, while HSU series incorporates stainless steel bodies with HNBR sealing for enhanced chemical resistance and elevated temperature applications. S210 series features compact stainless steel design optimized for space-constrained installations with FKM seals providing excellent chemical compatibility across diverse fluid media. The 350 series employs robust steel construction with larger bore configurations like 350-12S and 350-10S for higher flow capacity applications requiring maximum pressure ratings. Each series offers both plug and socket configurations denoted by P and S suffixes respectively, enabling complete system integration flexibility while maintaining consistent 700 bar pressure ratings across all variants.

What are the installation requirements and system compatibility considerations for Nitto Kohki 700 bar pneumatic couplings?

Installation of Nitto Kohki 700 bar pneumatic couplings requires threaded connections matching standard metric thread specifications, with proper torque values applied to prevent seal damage and ensure pressure integrity throughout the operating range. System compatibility demands verification of coupling bore size against line diameter, with available configurations from 6mm through 16mm accommodating diverse pneumatic and hydraulic circuit requirements. Thread sealant application using PTFE tape or anaerobic compounds rated for high-pressure service prevents leakage while allowing future disconnection for maintenance operations. Proper support of connected hoses and rigid piping prevents coupling body stress that could compromise seal performance, while ensuring adequate clearance for manual operation of the quick-disconnect mechanism during routine service intervals.

What are the safety ratings and operating temperature ranges for Nitto Kohki 700 bar high-pressure pneumatic couplings?

Nitto Kohki 700 bar pneumatic couplings maintain full pressure rating capability across operating temperatures from -20°C to +150°C depending on seal compound selection, with FKM seals providing superior high-temperature performance compared to NBR variants. Safety factor calculations incorporate 4:1 burst pressure ratios above maximum working pressure, ensuring reliable operation with appropriate safety margins under dynamic loading conditions. The hardened steel and stainless steel construction provides inherent resistance to pressure shock and fatigue loading typical in high-pressure pneumatic applications. Installation environments require consideration of ambient temperature effects on seal performance and thermal expansion characteristics, particularly in applications experiencing rapid temperature cycling that could affect coupling joint integrity and long-term sealing effectiveness.

What maintenance schedule and inspection requirements apply to Nitto Kohki 700 bar pneumatic coupling systems?

Nitto Kohki 700 bar pneumatic couplings require monthly visual inspection for seal integrity and connection security, with particular attention to FKM and HNBR seal condition under high-pressure cycling that can accelerate wear in demanding applications. Annual pressure testing at 1.5 times working pressure verifies continued coupling integrity and identifies developing seal deterioration before catastrophic failure, while semi-annual lubrication of connection mechanisms ensures smooth operation and prevents seizure. Service life typically exceeds 100,000 connection cycles when operated within specified pressure and temperature parameters, with seal replacement intervals determined by system contamination levels and fluid compatibility factors. Critical applications may require quarterly inspection schedules with documented pressure hold testing to verify system integrity and compliance with industrial safety protocols governing high-pressure fluid power equipment operation.

High-Pressure up to 700 Bar

Technical features of the high-pressure series

Series comparison by pressure rating

Typical applications

Series in this category compared

The four shut-off types

Choosing a coupling in five steps