Purge Adapter
High-Pressure up to 700 Bar
The Nitto Kohki Purge Adapter PAD-2 is an accessory for high-pressure lines up to 700 bar that allows the residual pressure in a pressurised line to be safely vented before the main coupling (e.g. HSU Cupla or other high-pressure series) is disconnected. The PAD-2 is steel with an NBR seal. This pressure-relief step is a safety requirement in high-pressure applications, since couplings disconnected under residual pressure can release fluid or gas in an uncontrolled manner.
| Part number | Body material | Seal | Function |
|---|---|---|---|
| PAD-2 | Steel | NBR | Residual pressure relief, high pressure up to 700 bar |
Typical applications: Preparing pressure-free disconnection of Nitto Kohki high-pressure couplings (HSU, 700R, 450B and related series) on hydraulic test rigs, machine tools with high-pressure coolant systems, waterjet cutting installations, and all high-pressure systems where residual pressure relief before coupling changeover is a safety or process requirement.
Technical data from the manufacturer catalogue
| Series | PURGE ADAPTER |
|---|---|
| Body material | Steel (nickel plated) |
| Seal material | NBR (Nitrile rubber) |
| Max working pressure | 35.0 MPa {357 kgf/cm2} |
| Working temperature | NBR (Nitrile rubber): -5 to +80 deg C |
| Applicable fluids | Hydraulic oil |
| Vacuum service | Not suitable for vacuum application. |
| Size range | 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 |
| Catalogue page | C01en-b, 168 |
Operating principle
- Can be attached to hydraulic lines to purge residual pressure effectively.
- Residual pressure is purged just by pushing the residual pressure purge button; the pressure leaves through the drain outlet port.
- Can be operated with a screwdriver if the button is stiff. Insert an ordinary flat head screwdriver into the groove in the Valve Holder and press the button by leverage.
- PAD-2 comes with the tube fitting included; for the PAD-FM types tube fittings are not included.
- Residual Pressure Purge Speed Comparison on page 170 shows PAD-2 and PAD-FM purging faster than the previous model (test conditions: fluid hydraulic oil, fluid viscosity 32x10-6 m2/s, pressure 35 MPa, cubic capacity of piping approx. 5 L; pressure axis 0 to 40 MPa over 0 to 5 s).
All models of the series
PAD-2 - T1 male thread R 1/4, drain outlet port for 8 mm OD tube (tube fitting included)
| Model | Coupling part | Application | Total (g) | øH (WAF) | øL1 | øP1 | øP2 | øT1 | øøD | øøT2 |
|---|---|---|---|---|---|---|---|---|---|---|
| PAD-2 | purge adapter | R 1/4 | 235 | Hex.36 | (62) | (48) | 14 | R 1/4 | 39.5 | 8 |
PAD-FM - For thread connection, T1 male thread R and T2 female thread Rc, drain outlet port Rc 1/8
| Model | Coupling part | Application | Total (g) | øB | øH (WAF) | øL1 | øL2 | øL3 | øP1 | øP2 | øT1 | øT2 | øøD |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PAD-3FM | purge adapter | R 3/8 x Rc 3/8 | 320 | (11) | 29 | 72.5 | (39) | 21.5 | (51) | (33.5) | R 3/8 | Rc 3/8 | 10 |
| PAD-4FM | purge adapter | R 1/2 x Rc 1/2 | 307 | (11) | 29 | 72.5 | (39) | 21.5 | (51) | (33.5) | R 1/2 | Rc 1/2 | 12.5 |
| PAD-6FM | purge adapter | R 3/4 x Rc 3/4 | 665 | (15.5) | Hex.46 | 86 | 21.5 | - | (63.5) | (38) | R 3/4 | Rc 3/4 | 16.5 |
| PAD-8FM | purge adapter | R 1 x Rc 1 | 620 | (15.5) | Hex.46 | 86 | 21.5 | - | (63.5) | (38) | R 1 | Rc 1 | 21.5 |
FM - Both ends Rc 3/8 female thread
| Model | Coupling part | Application | Total (g) | L | øD | øH1(WAF) | øH2(WAF) | øT1 | øT2 |
|---|---|---|---|---|---|---|---|---|---|
| FM-03-B | flow meter | Piping for mold cooling water | 190 | (89) | (33) | Hex.23 | Hex.26 | Rc 3/8 | Rc 3/8 |
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 |
|---|---|---|---|---|
| 210 CUPLA | 206 bar | 1/4 inch to 1 inch | Two-way shut-off | Hydraulic oil |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 450B CUPLA | 441 bar | 3/8 inch | Two-way shut-off | Hydraulic oil |
| 700R CUPLA | 686 bar | Thread 3/8 inch, 1/2 inch | Two-way shut-off | Hydraulic oil |
PURGE ADAPTER is not an alternative to the coupling itself: the sibling series HSP CUPLA, 210 CUPLA, 280 CUPLA and 350 CUPLA are two-way shut-off couplings, while this adapter sits in the line and releases the trapped pressure through its drain outlet port before one of them is disconnected. Its working pressure of 35.0 MPa {357 kgf/cm2} covers lines built with HSP CUPLA, 210 CUPLA, S210 CUPLA, 280 CUPLA and 350 CUPLA, whose working pressures run from 14.0 to 34.5 MPa. On lines built with 450B CUPLA at 44.1 MPa {450 kgf/cm2} or 700R CUPLA at 68.6 MPa {700 kgf/cm2} the line pressure is above its rating and it does not apply.
Body and seal materials
| Body material |
|---|
| Steel (nickel plated) |
| Seal material | Mark | Working temperature | Remarks |
|---|---|---|---|
| NBR (Nitrile rubber) | - | -5 to +80 deg C | - |
Further catalogue data
| Note | Value |
|---|---|
| Working pressure (all units) | 35.0 MPa, 357 kgf/cm2, 350 bar, 5080 PSI |
| Application (thread) - PAD-2 | R 1/4 |
| Application (thread) - PAD-3FM | R 3/8 x Rc 3/8 |
| Application (thread) - PAD-4FM | R 1/2 x Rc 1/2 |
| Application (thread) - PAD-6FM | R 3/4 x Rc 3/4 |
| Application (thread) - PAD-8FM | R 1 x Rc 1 |
| Drain outlet port - PAD-2 | For 8 mm OD tube |
| Drain outlet port - PAD-3FM to PAD-8FM | Rc 1/8 (Max. Tightening Torque: 5 Nm) |
| Maximum tightening torque - R 1/4 | 28 Nm {286 kgf cm} |
| Maximum tightening torque - R 3/8 x Rc 3/8 | 40 Nm {408 kgf cm} |
| Maximum tightening torque - R 1/2 x Rc 1/2 | 80 Nm {816 kgf cm} |
| Maximum tightening torque - R 3/4 x Rc 3/4 | 150 Nm {1530 kgf cm} |
| Maximum tightening torque - R 1 x Rc 1 | 250 Nm {2550 kgf cm} |
| Minimum cross-sectional area - PAD-2 | - |
| Minimum cross-sectional area - PAD-3FM | 78.5 mm2 (ø10) |
| Minimum cross-sectional area - PAD-4FM | 122 mm2 (ø12.5) |
| Minimum cross-sectional area - PAD-6FM | 213 mm2 (ø16.5) |
| Minimum cross-sectional area - PAD-8FM | 363 mm2 (ø21.5) |
| Seal material remark | NBR is the standard material. |
Safety and application notes
- Not suitable for vacuum application.
- Maximum tightening torque of the Rc 1/8 drain outlet port is 5 Nm.
- Note (FLOW METER on page 169): plastic part (scale tube) cannot be replaced.
All technical data on this page is taken from the Nitto Kohki general catalogue Quick Connect Couplings C01en-b, page 168. The complete catalogue is available for download on this page.
