High Flow Cupla

Quick couplings

The Nitto Kohki High Flow Cupla is a quick coupling with an enlarged flow cross-section, designed for applications where conventional couplings would cause unacceptable flow restriction. The 18-item range covers nominal sizes 2, 3 and 4 as plug (P) and socket (S), in three material/seal combinations: brass with FKM, stainless steel (SUS) with FKM, and stainless steel (SUS) with EPDM. This selection covers a wide range of media, from general hydraulics to water and steam applications (EPDM).

⚡ Enlarged flow cross-section - reduced flow resistance for pressure-drop-sensitive applications

⚙ Brass with FKM - HFL-2/3/4 S and P, for hydraulic and chemical media

✓ Stainless steel with FKM - SUS versions HFL-2/3/4 S and P, for aggressive and corrosive media

↕ Stainless steel with EPDM - SUS versions HFL-2/3/4 S and P, for water, steam and aqueous media

✦ Nominal sizes 2, 3, 4 - plug (P) and socket (S) per size in all three seal variants

Body material	Seal	Nominal sizes	Plug	Socket
Brass	FKM	2, 3, 4	HFL-2P, HFL-3P, HFL-4P	HFL-2S, HFL-3S, HFL-4S
Stainless steel (SUS)	FKM	2, 3, 4	HFL-2P (SUS), HFL-3P (SUS), HFL-4P (SUS)	HFL-2S (SUS), HFL-3S (SUS), HFL-4S (SUS)
Stainless steel (SUS)	EPDM	2, 3, 4	HFL-2P (SUS/EPDM), HFL-3P, HFL-4P	HFL-2S (SUS/EPDM), HFL-3S, HFL-4S

Typical applications: Hydraulic circuits with high flow rates and low tolerable pressure drop, coolant return lines in machine tools, hot-water and steam lines (EPDM variant, SUS), chemical process plant with corrosive media (SUS/FKM), laboratory circulators and thermostat baths, and all applications where coupling geometry would otherwise limit system flow.

Technical data from the manufacturer catalogue

Series	HI FLOW CUPLA / HI FLOW CUPLA BI Type
Body material	Stainless steel, Brass
Seal material	Ethylene-propylene rubber (EPDM), Fluoro rubber (FKM)
Max working pressure	1.0 MPa {10 kgf/cm2}
Working temperature	Ethylene-propylene rubber (EPDM): -40 to +150 deg C \| Fluoro rubber (FKM): -20 to +180 deg C
Valve structure	Two-way shut-off
Applicable fluids	Water, Temperature control refrigerant
Vacuum service	1.3x10-1 Pa {1x10-3 mmHg}. Socket only: -, Plug only: -, When connected: Operational.
Size range	1/4 inch, 3/8 inch, 1/2 inch
Catalogue page	C01en-b, 159

Operating principle

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

Connecting sequence of a ball locking quick connect coupling.

Both socket and plug have built-in automatic shut-off valves.
High flow rate type to increase cooling effect.
Quick connection and disconnection of cooling pipes.
Compact and space-saving design. Compared with the coupled length of SP CUPLA type A, that of HI FLOW CUPLA is reduced by 22%.
Installation and maintenance can be done within a short time.
BI Type: easy connection with stainless steel pipe.
BI Type: connection to plastic hose is possible with optional hose connection kit.
BI Type: connection to various tubes is also possible via the use of appropriate optional inserts.

All models of the series

HFL-P - Female thread

Model	Coupling part	Application	Brass (g)	Stainless steel (g)	L	H	øD	C	T
HFL-2P	Plug	R 1/4	31	28	30	Hex.17	18.5	16.5	Rc 1/4
HFL-3P	Plug	R 3/8	47	43	31	Hex.21	23	18	Rc 3/8
HFL-4P	Plug	R 1/2	91	82	37.5	Hex.29	32	22.5	Rc 1/2

HFL-S - Female thread

Model	Coupling part	Application	Brass (g)	Stainless steel (g)	L	H	øD	T
HFL-2S	Socket	R 1/4	110	99	(47)	19	26	Rc 1/4
HFL-3S	Socket	R 3/8	165	150	(49)	24	32	Rc 3/8
HFL-4S	Socket	R 1/2	231	211	60	29	35	Rc 1/2

HFL-P-BI - For pipe connection (bite type tube fitting)

Model	Coupling part	Application	Stainless steel (g)	L	H	øD	A	C	T	øB
HFL-2P-BI 1/4	Plug	6.35 mm (1/4 inch) pipe	66	(51.9)	Hex.20.64 (13/16 inch)	23	(15.4)	16.5	Hex.14.29 (9/16 inch)	(6.35)
HFL-2P-BI 3/8	Plug	9.53 mm (3/8 inch) pipe	74	(53.4)	Hex.20.64 (13/16 inch)	23	(17)	16.5	Hex.17.46 (11/16 inch)	(9.53)
HFL-3P-BI 3/8	Plug	9.53 mm (3/8 inch) pipe	109	(54.8)	Hex.26.99 (1 1/16 inch)	29.5	(17)	18	Hex.17.46 (11/16 inch)	(9.53)
HFL-3P-BI 1/2	Plug	12.7 mm (1/2 inch) pipe	134	(59)	Hex.26.99 (1 1/16 inch)	29.5	(23)	18	Hex.22.23 (7/8 inch)	(12.7)
HFL-4P-BI 1/2	Plug	12.7 mm (1/2 inch) pipe	160	(68.7)	Hex.28.58 (1 1/8 inch)	32	(23)	22.5	Hex.22.23 (7/8 inch)	(12.7)

HFL-S-BI - For pipe connection (bite type tube fitting)

Model	Coupling part	Application	Stainless steel (g)	L	H	øD	A	T	øB
HFL-2S-BI 1/4	Socket	6.35 mm (1/4 inch) pipe	97	(54.9)	Hex.20.64 (13/16 inch)	26	(15.4)	Hex.14.29 (9/16 inch)	(6.35)
HFL-2S-BI 3/8	Socket	9.53 mm (3/8 inch) pipe	105	(56.5)	Hex.20.64 (13/16 inch)	26	(17)	Hex.17.46 (11/16 inch)	(9.53)
HFL-3S-BI 3/8	Socket	9.53 mm (3/8 inch) pipe	165	(60.3)	Hex.26.99 (1 1/16 inch)	32	(17)	Hex.17.46 (11/16 inch)	(9.53)
HFL-3S-BI 1/2	Socket	12.7 mm (1/2 inch) pipe	189	(64.6)	Hex.26.99 (1 1/16 inch)	32	(23)	Hex.22.23 (7/8 inch)	(12.7)
HFL-4S-BI 1/2	Socket	12.7 mm (1/2 inch) pipe	233	(73.2)	Hex.28.58 (1 1/8 inch)	35	(23)	Hex.22.23 (7/8 inch)	(12.7)

Dimensions in millimetres. Values in brackets apply in the connected condition.

Legend: L = overall length; H = width across flats or outside dimension; D = socket outside diameter; A = hose barb length; C = sleeve dimension; T = thread or barb size; B = bore

Series comparison

Series	Max working pressure	Size range	Valve structure	Applicable fluids
HI FLOW CUPLA / HI FLOW CUPLA BI Type	10 bar	1/4 inch, 3/8 inch, 1/2 inch	Two-way shut-off	Water, Temperature control refrigerant
COMPACT ZEROSPILL CUPLA	10 bar	Thread 1/8 inch, 1/4 inch	Two-way shut-off (Spill Reduction)	Air, Water
CUPLA HOSE with FULL BLOW CUPLA	10 bar	Hose size ø5 mm×ø8 mm, ø6.5 mm×ø10 mm, ø8.5 mm×ø12.5 mm	One-way shut-off	Air
FLOW MONITOR	10 bar	Rc 3/8 and Rc 1/2	-	Water
ANTI-VIBRATION PLUG HOSE	15 bar	R 1/4 (SHA-3-2R), R 3/8 (SHA-3-3R)	One-way shut-off	Air
HI CUPLA BL	15 bar	1/4 inch, 3/8 inch, 1/2 inch (thread and hose barb); SN type for urethane hose: for 6.5 x 10 mm, 8 x 12 mm and 8.5 x 12.5 mm hose	One-way shut-off	Air, Water
FLATFACE CUPLA F35	350 bar	Thread 1/4 inch, 3/8 inch, 1/2 inch, 3/4 inch, 1 inch	Two-way shut-off (Spill Reduction)	Hydraulic oil
FLATFACE CUPLA FF	350 bar	3/8 inch, 1/2 inch, 3/4 inch, 1 inch (thread)	Two-way shut-off (Spill Reduction)	Hydraulic oil

Pick HI FLOW CUPLA when the cooling or temperature control line has to be closed on both sides, since every peer series in this group except COMPACT ZEROSPILL CUPLA is one-way shut-off. Against COMPACT ZEROSPILL CUPLA, which is also rated 1.0 MPa {10 kgf/cm2} and two-way shut-off, HI FLOW CUPLA is the high flow rate version with a coupled length 22% shorter than SP CUPLA type A. Where the line runs at 1.5 MPa {15 kgf/cm2}, HI CUPLA BL, LOCK CUPLA 200 or the other one-way shut-off series carry the higher pressure.

Body and seal materials

Body material
Stainless steel
Brass

Seal material	Mark	Working temperature	Remarks
Ethylene-propylene rubber (EPDM)	-	-40 to +150 deg C	-
Fluoro rubber (FKM)	-	-20 to +180 deg C	-

Further catalogue data

Note	Value
Flow direction	Fluid flow can be bi-directional when socket and plug are connected.
Minimum cross-sectional area (mm2)	HFL-2P / HFL-2S: 32, HFL-3P / HFL-3S: 53, HFL-4P / HFL-4S: 91
Maximum tightening torque, stainless steel, Nm {kgf cm}	HFL-2P / HFL-2S: 14 {143}, HFL-3P / HFL-3S: 22 {224}, HFL-4P / HFL-4S: 60 {612}
Maximum tightening torque, brass, Nm {kgf cm}	HFL-2P / HFL-2S: 9 {92}, HFL-3P / HFL-3S: 12 {122}, HFL-4P / HFL-4S: 30 {306}
BI Type body material	Stainless steel
BI Type applicable pipe size	1/4 inch, 3/8 inch, 1/2 inch. See the stainless steel pipe, hose and tube size list for hose and tube size.
BI Type stainless steel pipe dia.	HFL-2SP-BI 1/4: 1/4 (6.35 mm), HFL-2SP-BI 3/8: 3/8 (9.53 mm), HFL-3SP-BI 3/8: 3/8 (9.53 mm), HFL-3SP-BI 1/2: 1/2 (12.7 mm), HFL-4SP-BI 1/2: 1/2 (12.7 mm)
BI Type hose connection nut (optional)	HFL-3SP-BI 1/2 and HFL-4SP-BI 1/2: E1-6x11 for hose 6 x 11 mm (ID x OD), E1-8x13.5 for hose 8 x 13.5 mm (ID x OD). Not offered for HFL-2SP-BI 1/4, HFL-2SP-BI 3/8, HFL-3SP-BI 3/8.
BI Type tube connection insert (optional), pipe 1/4 inch	DTI 4-2: tube 3.18 x 6.35 mm, E 2.3, L 11.9, A 6.35, D 3.18; DTI 4-2.5: tube 3.97 x 6.35 mm, E 2.7, L 11.9, A 6.35, D 3.97; DTI 4-2.72: tube 4.32 x 6.35 mm, E 2.7, L 11.9, A 6.35, D 4.32; DTI 4-3: tube 4.76 x 6.35 mm, E 3.5, L 11.9, A 6.35, D 4.76
BI Type tube connection insert (optional), pipe 3/8 inch	DTI 6-3: tube 4.76 x 9.53 mm, E 3.0, L 14.3, A 9.53, D 4.76; DTI 6-4: tube 6.35 x 9.53 mm, E 4.8, L 14.3, A 9.53, D 6.35
BI Type tube connection insert (optional), pipe 1/2 inch	DTI 8-4: tube 6.35 x 12.7 mm, E 4.8, L 19.1, A 12.7, D 6.35; DTI 8-6: tube 9.53 x 12.7 mm, E 7.9, L 19.1, A 12.7, D 9.53
Flow rate	Flow rate - pressure loss characteristics graphs are printed on pages 160 and 161. Test conditions: fluid water, temperature 23 deg C +/-5 deg C. Page 160 curves: HFL-2S x HFL-2P, HFL-3S x HFL-3P, HFL-4S x HFL-4P. Page 161 curves (connected to stainless steel pipe): HFL-2S-BI 1/4 x HFL-2P-BI 1/4, HFL-2S-BI 3/8 x HFL-2P-BI 3/8, HFL-3S-BI 3/8 x HFL-3P-BI 3/8, HFL-3S-BI 1/2 x HFL-3P-BI 1/2, HFL-4S-BI 1/2 x HFL-4P-BI 1/2.

Interchangeability and size groups

Socket and plug of different sizes cannot be connected. The same statement is printed for HI FLOW CUPLA and for HI FLOW CUPLA BI Type.

Safety and application notes

Before use, please be sure to read the Safety Guide described at the end of this book and the Instruction Sheet that comes with the products.

All technical data on this page is taken from the Nitto Kohki general catalogue Quick Connect Couplings C01en-b, page 159. The complete catalogue is available for download on this page.

What are Nitto Kohki High Flow Cupla quick couplings and what industrial applications do they serve?

Nitto Kohki High Flow Cupla quick couplings are precision-engineered pneumatic connectors designed to maximize airflow efficiency in industrial compressed air systems. These couplings feature an enlarged internal bore diameter that significantly reduces pressure drop compared to standard couplings, making them essential for high-flow applications requiring rapid air delivery. Primary applications include automated manufacturing lines, pneumatic tool operations, spray painting systems, and material handling equipment where consistent high-pressure air supply is critical. Industries utilizing these couplings span automotive manufacturing, aerospace assembly, food processing, and chemical processing where reliable pneumatic connections are mandatory for operational efficiency.

What are the key technical selection criteria for High Flow Cupla couplings with specific material and seal options?

Selection of High Flow Cupla couplings depends on three critical material specifications available in the HFL series. Body material options include corrosion-resistant SUS (stainless steel 316) for chemical environments or BRASS for standard industrial applications with lower corrosive exposure. Seal material selection between FKM (fluorocarbon) and EPDM (ethylene propylene diene monomer) determines chemical compatibility, with FKM providing superior resistance to oils, fuels, and high temperatures up to 200°C, while EPDM offers excellent performance with water, steam, and polar solvents. Available port configurations include sizes HFL-2, HFL-3, and HFL-4 with both socket (S) and plug (P) variants to accommodate different system architectures and flow requirements.

Which international standards and certifications apply to Nitto Kohki High Flow Cupla quick couplings?

Nitto Kohki High Flow Cupla couplings comply with ISO 4414 pneumatic system safety requirements and ISO 7241-1 quick-acting coupling specifications for industrial fluid power applications. The stainless steel variants meet DIN EN 10088-2 corrosion resistance standards for austenitic stainless steels, ensuring long-term performance in demanding environments. Pressure testing follows ISO 1402 hydraulic fluid power component standards, while the coupling design adheres to ISO 5675 pneumatic quick-connect fitting dimensional requirements. Manufacturing quality systems maintain ISO 9001 certification, guaranteeing consistent production standards and traceability throughout the supply chain for critical industrial applications.

What are the main differences between HFL socket and plug variants in different sizes and materials?

The High Flow Cupla series differentiates between socket (S) and plug (P) configurations across three primary sizes designated as HFL-2, HFL-3, and HFL-4, with larger numbers indicating increased bore diameter for higher flow capacity. Socket variants (HFL-2S, HFL-3S, HFL-4S) feature the female receiving mechanism with integrated shut-off valve, while plug variants (HFL-2P, HFL-3P, HFL-4P) provide the male insertion component with corresponding valve system. Material combinations vary between SUS stainless steel construction for corrosive environments and BRASS bodies for standard applications, with each available in FKM or EPDM seal configurations. The modular design ensures complete interchangeability within size categories while maintaining optimal sealing performance and flow characteristics across all material combinations.

What installation requirements and system compatibility considerations apply to High Flow Cupla connections?

High Flow Cupla installations require NPT or BSP threaded connections depending on regional standards, with proper thread sealant application essential for leak-free operation at working pressures. System compatibility demands matching of socket and plug variants within the same size designation (HFL-2, HFL-3, or HFL-4) to ensure proper engagement and sealing performance. Installation torque specifications must follow manufacturer guidelines, typically 15-25 Nm for brass variants and 20-30 Nm for stainless steel versions to prevent thread damage or seal deformation. The coupling design accommodates both vertical and horizontal mounting orientations, with adequate clearance space required for manual engagement and disengagement operations during maintenance procedures.

What safety ratings, pressure ranges, and operating temperature limits apply to High Flow Cupla couplings?

Nitto Kohki High Flow Cupla couplings operate safely within working pressure ranges of 0-16 bar (0-232 psi) for standard pneumatic applications, with proof pressure testing conducted at 24 bar (348 psi) to ensure structural integrity. Operating temperature ranges vary by seal material, with FKM seals performing from -20°C to +200°C (-4°F to +392°F) and EPDM seals rated for -40°C to +150°C (-40°F to +302°F) continuous operation. Safety factor calculations incorporate a 4:1 burst pressure ratio, ensuring reliable performance under dynamic loading conditions typical in automated manufacturing environments. The coupling design includes fail-safe shut-off mechanisms that automatically seal both sides upon disconnection, preventing pressure loss and maintaining system safety during maintenance operations.

What maintenance schedules and service life expectations apply to High Flow Cupla quick couplings?

High Flow Cupla couplings require quarterly visual inspections for wear patterns, seal integrity, and proper engagement function, with particular attention to seal surfaces and threading conditions. Service life typically exceeds 100,000 connection cycles under normal operating conditions, with stainless steel variants providing extended durability in corrosive environments compared to brass alternatives. Annual maintenance procedures include complete disassembly for internal cleaning, seal replacement if wear indicators show degradation, and verification of spring tension in the shut-off mechanism. Predictive maintenance monitoring should track connection force requirements and leak rates, as increased effort or air loss indicates approaching end-of-service intervals requiring seal replacement or complete coupling renewal to maintain system reliability.