The double-acting Parker Prädifa OA piston sealing set featuring a Slipper Seal® design consists of a PTFE piston sealing ring and an elastomer O-ring as a preloading element. The seal design is intended for pneumatic applications. The symmetrical cross-section of the sealing ring is designed for the uniform formation of the lubricant film during the stroke in both directions. The OA sealing set is particularly well suited for double-acting pistons.
Due to the material combination of the slide ring (PTFE) and O-ring (elastomer), this product is suitable for a wide range of applications, especially for aggressive media and/or high temperatures. For pneumatic applications, the piston sealing ring is preferably made from a carbon-filled PTFE compound in order to avoid chemical reactions with the aluminum components of the cylinder. Alternatively, several compounds can be selected, depending on the specific application’s profile.
- Due to application-optimized geometry and compounds suitable for use in oiled as well as in oil-free air (after initial lubrication on assembly).
- Good sealing performance in an extremely small assembly condition.
- It can also be used for single-acting applications.
- Good wear resistance.
- Minimal break-away and dynamic friction and no stick-slip tendency to ensure uniform motion even at low speeds.
- Good energy efficiency due to low friction.
- Very good emergency running properties in low-lube conditions.
- Assembly on the one-part piston is possible.
- High-temperature resistance assured by suitable O-ring compound selections.
- Adaptable to nearly all media thanks to the high chemical resistance of the sealing ring and large O-ring compound selection.
- Short axial assembly length.
- Installation in closed and undercut housings.
- Available in diameters from 4 to 4500 mm.
- Additional sizes of machined products available on short notice.
Range of application
Piston sealing set for pneumatic applications.
| Operating pressure | ≤ 16 bar |
| Operating temperature | -30 °C to +80 °C 1) |
| Sliding speed | ≤ 4 m/s |
| 1) With deviation from the standard temperature range, please contact our consultancy service for the adequate O-ring compound. | |
Compounds
Sealing ring: Polon® 033, modified PTFE + 25 % carbon. O-ring: N0674, NBR elastomer with approx. 70 Shore A.
Installation
The Parker Praedifa grooves must be carefully cleaned and deburred. The cylinder bore must have a lead-in chamfer. When fitting the piston sealing ring there is always a risk that the ring may tilt and be sheared off by normal lead-in chamfers (see chapter “General installation guidelines for piston seals, PTFE seals”, fig. 1). We, therefore, recommend that up to a cylinder diameter of 230 mm a lead-in chamfer according to fig. 2 or detail “A” is considered. In the case of smaller rings which are especially liable to bending, we recommend an open-groove design for diameters smaller than 30 mm.
This seal should only be used in combination with guiding elements (e.g. profile F2).
| Size | Ø D mm | Groove Ø d mm | L mm | Size | Ø D mm | Groove Ø d mm | L mm | |
| 70 | 7 | 3 | 2 | 750 | 75 | 62.50 | 5.60 | |
| 80 | 8 | 4 | 2 | 800 | 80 | 67.50 | 5.60 | |
| 90 | 9 | 5 | 2 | 850 | 85 | 72.50 | 5.60 | |
| 100 | 10 | 6 | 2 | 900 | 90 | 77.50 | 5.60 | |
| 110 | 11 | 7 | 2 | 920 | 92 | 79.50 | 5.60 | |
| 120 | 12 | 8 | 2 | 1000 | 100 | 87.50 | 5.60 | |
| 140 | 14 | 10 | 2 | 1050 | 105 | 92.50 | 5.60 | |
| 160 | 16 | 10 | 2.85 | 1100 | 110 | 97.50 | 5.60 | |
| 180 | 18 | 12 | 2.85 | 1150 | 115 | 102.50 | 5.60 | |
| 190 | 19 | 13 | 2.85 | 1200 | 120 | 107.50 | 5.60 | |
| 200 | 20 | 14 | 2.85 | 1250 | 125 | 112.50 | 5.60 | |
| 220 | 22 | 16 | 2.85 | 1300 | 130 | 115 | 7.55 | |
| 250 | 25 | 19 | 2.85 | 1400 | 140 | 125 | 7.55 | |
| 280 | 28 | 20.50 | 3.80 | 1500 | 150 | 135 | 7.55 | |
| 300 | 30 | 22.50 | 3.80 | 1600 | 160 | 145 | 7.55 | |
| 320 | 32 | 24.50 | 3.80 | 2000 | 200 | 182 | 7.55 | |
| 350 | 35 | 27.50 | 3.80 | 2200 | 220 | 202 | 7.55 | |
| 360 | 36 | 28.50 | 3.80 | |||||
| 380 | 38 | 30.50 | 3.80 | |||||
| 400 | 40 | 32.50 | 3.80 | |||||
| 420 | 42 | 34.50 | 3.80 | |||||
| 450 | 45 | 37.50 | 3.80 | |||||
| 480 | 48 | 40.50 | 3.80 | |||||
| 500 | 50 | 37.50 | 5.60 | |||||
| 550 | 55 | 42.50 | 5.60 | |||||
| 600 | 60 | 47.50 | 5.60 | |||||
| 630 | 63 | 50.50 | 5.60 | |||||
| 650 | 65 | 52.50 | 5.60 | |||||
| 700 | 70 | 57.50 | 5.60 | |||||
| 740 | 74 | 61.50 | 5.60 |
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