Hydraulic quick coupler (quick coupling)

01

Match interchange standard, size and flow

ISO 16028 specifies flush-face type quick-action couplings for hydraulic fluid power at pressures from 20 MPa (200 bar) to 31.5 MPa (315 bar); the 1999 edition has been replaced by ISO 16028:2023. Couplings made to the same interchange standard and size from different makers are meant to connect with each other. [1]

Poppet-type couplings follow ISO 7241, whose second edition was published on 10 July 2023 and replaced the 2014 edition. It specifies the interface dimensions and basic performance requirements for two series: the ISO abstract associates Series A with Europe and with agricultural and forestry machinery worldwide, adding requirements for Series A in the agricultural applications of ISO 5675, and associates Series B with North America and the chemical industry. [3]

Editorial note: ISO 7241 Series A and Series B halves are two different interfaces, and neither is a flat-face ISO 16028 coupling, so the series must be named in the order alongside the size. [3] [1]

Faster's FFH flat-face series, ISO 16028 interchangeable, is rated at a working pressure of 35 MPa in sizes from 3.2 mm (1/8 in) to 25 mm (1 in), with rated flow of 12, 25, 50, 110, 125, 160 and 230 l/min for the 1/8, 1/4, 3/8, 1/2, 5/8, 3/4 and 1 in sizes; it publishes pressure-drop curves for each size. [2]

Editorial calculation: a hydraulic breaker needing 90 l/min would fit the 1/2 in size (110 l/min rated) but not the 3/8 in (50 l/min); running near rated flow raises pressure drop and heat, so check the curve at your actual flow. [2]

Give the supplier the interchange standard (ISO 16028 flat-face, ISO 7241 Series A or Series B, or other), size, thread type and size on each half, flow and working pressure, peak pressure, fluid and temperature range, seal material, plating, dust caps, connect-under-pressure needs and quantities, and the coupling already fitted to the machine.

02

Check burst pressure, spillage, connection force and operating limits

Faster lists burst pressures of 140–170 MPa for male halves, 140 MPa for female halves and 140–180 MPa for the connected pair, spillage per disconnection from 0.001 ml (1/8 in) to 0.03 ml (1 in), and connection forces from 105 N to 280 N. The couplings are steel with zinc-nickel plating, NBR, PUR or Viton seals, a working temperature range of −25 to +100 °C (−20 to +200 °C with Viton), push-to-connect and sleeve-retraction release, and connection under pressure is not allowed. [2]

Editorial calculation: for the 1/2 in size, 140 MPa burst over 35 MPa working pressure gives a 4:1 ratio. Flat-face valving keeps spillage to 0.03 ml or less per disconnect in this series and leaves a face that can be wiped clean before connecting, limiting dirt entering the circuit. [2]

Editorial note: if attachments must be changed with residual pressure in the lines, specify couplings rated for connection under pressure or pressure-relief features, because the series reviewed is not.

03

Who lists flush-face and ISO 7241 A/B poppet couplers

Listings include ISO A and ISO B poppet couplers, flush-face hydraulic quick couplers and push-and-pull couplings among hydraulic fittings.

04

Check pulsating, peak and residual-pressure ratings separately

Danfoss's 2023 whitepaper on its Hansen Flat Face (FF) series separates ratings that a single working-pressure figure hides: up to 400 bar for static, non-pulsating use across 6 sizes, but 350 bar where pressure pulsates; 1,400 bar static pressure before fracture; and no plastic deformation or loss of sealing up to 600 bar for short-term pressure rises. The series is qualified for one million impulse cycles with a safety factor of 1.33 on pulsating pressure. [4]

The standard FF coupling is designed to connect under residual pressure up to 50 bar without seal damage, and a separate plug with a patented valve bleeds off residual pressure above 350 bar internally. Danfoss rates flow as the rate through the coupling at a pressure drop of 1 bar, and guarantees at least 720 hours against red rust in salt spray to EN ISO 9227 (ASTM B117) for its plating. [4]

Editorial calculation: 1,400 bar fracture pressure is 3.5 times the 400 bar static rating and 4 times the 350 bar pulsating rating, so ask each supplier which rating a quoted burst ratio is taken from, the pressure drop at which flow is rated, and whether connection under residual pressure is allowed. [4]

05

Male and female halves, flat valves, seals, plating and dust caps

The Faster FFH data sheet supplies the valve, seal and plating rows; dust caps are an ordering item with no source value behind them.

06

What the Faster FFH sheet fixes, and the thread and weight it leaves open

Nine of the eleven rows carry values from the Faster FFH data sheet; it gives no thread type or weight, so both must come from the supplier.

07

Send the standard, size and circuit data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Standard: [ISO 16028; ISO 7241; existing coupling]
Size: [nominal size; threads]
Circuit: [flow; working and peak pressure]
Fluid: [type; temperature]
Use: [connect under pressure; spillage limit]
Supply: [seals; plating; caps; quantity]

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