ISO 14540 -Dimensions and requirements for screw-to-connect quick-action couplings for use at a pressure of 72 MPa

Screw-to-connect quick-action couplings conforming to this International Standard are designed o join or separate fluid conductors ensuring, at the same time, sufficient resistance and safety in applications characterized by very high working pressures up to 72 MPa.

ISO 14540 specifies dimensional and performance requirements for hydraulic screw-to-connect quick-action couplings designed to be used at a pressure of 72 MPa in static conditions as an interface between a hydraulic power unit and a tool.

Typical applications for these couplings are related to hydraulic jacks, rams, clamping devices, hand tools, and cylinders.

This International Standard covers two types of such couplings: the “P” type, which has a poppet valve, and the “S” type, which has a spherical valve.

 

Dimensional requirements

ISO 14540 High pressure Quick Coupling dimensional requirements
  • a The shape of the valve is optional; “P” type version (with poppet valve) is shown

  • b The shape of the valve is optional; “S” type version (with spherical valve) is shown

  • c Use dimension D4, unless the valve is spherical

  • d Maximum valve travel against stop.

  • e ealing diameter.

  • All dimensions and shape after L1 and D1 are left to the manufacturer

Body Size
mm		 Body Size
inch		 φD1 D2c φD3 φD4b L1 L2 L3 L4 L5 R1 R2
min min max max max max
6.3 1/4" 26.5 1-18 UNS 15.77
15.85		 1.9 18.95
19.15		 7.75
7.98		2.0 4 0.4 0.5
1.0		 0.6
10 3/8" 31.5 1-3/16-16 UN 18.96
19.04		 2.5 25.32
25.47		 9.30
9.52		 2.5 4 0.4 0.5
1.3		 0.6
a Size designation corresponds to the nominal hose size of the recommended hose; see ISO 4397.
b Use dimension D4 unless the valve is spherical
c In accordance with basic dimensions and formulae given in ISO 725 and ISO 5864, tolerance class 2A. See Annex A for the dimensions of the 1-18 UNS thread.

Performancer equirements

Couplings conforming to this International Standard shall meet or exceed the performance requirements specified in Table.

Performance parameter 6.3 (1/4") 10 (3/8")
Working pressure b 72 MPa (720 bar)
Minimum burst pressure (coupled) c 216 MPa (2160 bar)
Minimum burst pressure for the "P" type (uncoupled) c 216 MPa (2160 bar)
Minimum burst pressure for the "S" type (uncoupled) c 144 MPa (1440 bar)
Rated flowd d 12 l/min23 l/min
Maximum pressure drop at rated flow d 300 kPa (3 bar)450 kPa (4,5 bar)
Maximum fluid loss per disconnection e 0,5 ml1 ml
Maximum residual static pressure for connection e 10 MPa (100 bar)
a Size designation corresponds to the nominal hose size of the recommended hose; see ISO 4397
b The working pressure shall be verified in both the coupled and uncoupled conditions by pressure impulse testing for 10 000 cycles at the working pressure (low-cycle fatigue test) using the test pressure waveform specified in ISO 7241-2.
c The burst pressure shall be verified by testing in both the coupled and uncoupled conditions in accordance with ISO 7241-2
d The pressure drop at rated flow shall be verified by testing in accordance with ISO 7241-2.
e The fluid loss per disconnections hall be verified by testing in accordance with ISO 7241-2.
f Internal residual static pressure present in one coupling half.

Best practice

Manufacturers of couplings conforming to this International Standard shall give proper written information to the customer about safety, correct use, best practice, and maintenance in order to allow correct and safe use of the products.

Couplings conforming to this International Standard are subject o very high internal pressure. The final user shall always use the most suitable protection devices when using the product and shall keep out of the product’s range of action.

Couplings conforming to this International Standard are not designed to be connected and disconnected under working pressure. However, the Table provides information about the maximum residual static pressure, which is present in one half only, that is allowable for connection.

Couplings of the “S” type, which have a spherical valve, are not preferred for applications that require that the coupling be pressurized in the disconnected condition.

Basic dimensions of the 1-18 UNS inch screw thread

Dimensions for 1-18 UNS, class 2A, inch screw threads (external)

Thread Allowance Major diameter Pitch diameter Minor diameter
max. min. max. min. max.
1-18 UNS in 0,0014 0,9986 0,9899 0,9625 0,9578 0,9325
mm 0,037 25,364 25,144 24,447 24,329 23,686

Dimensions for 1-18 UNS, class 2B, inch screw threads (internal)

Thread Minor diameter Pitch diameter Major diameter
max min max min min
1-18 UNS in 0,953 0,940 0,9701 0,9639 1,0000
mm 24,206 23,876 24,640 24,484 25,400