- Email: [email protected]
New design of X-ring is introduced
NEWS
Are all nitrile O-rings the same?
New design of X-ring is introduced
Zatkoff Seals and Packings has commissioned an investigation to compare a widely used, USmanufactured O-ring compound with four compounds imported from Asia. This work has shown that the US-manufactured material exhibited lower compression set in standard tests. The work, which was carried out by an independent laboratory, compared O-rings manufactured from Parker N674-70 with samples from four Asian suppliers, claimed to be the best of a number surveyed for the study. Five cross-sections of seal were used in the tests. They were O-ring sizes 015, 120, 214, 320 and 425. These have cross-sections of 1.78, 2.62, 3.53, 5.33 and 6.99 mm, respectively. Compression set tests were carried out on the O-rings to ASTM procedure D395 Method B. This involves compressing the seals by 25% and heating for either 22 h or 70 h. After exposure for the test period the fixtures are removed from the oven, the seals released and allowed to cool. The set dimensions are then measured. The test temperature selected was 100°C.
German-based Simrit has introduced ISC X-rings, a specially developed four-lip seal profile, as a replacement for O-rings in lowspeed dynamic and oscillating motion applications. The limitations of O-rings for dynamic applications are well known, with the possibility for twisting and instability; they are often selected for economy and convenience. This new X-ring design is intended to overcome these problems. It has a double sealing function: first, the special seal profile allows for a considerable reduction in initial compression; and secondly, this low initial compression reduces friction in dynamic applications so that the ring will not twist in the groove. Also, the X-shaped contour fits easily into square grooves. The decisive advantage claimed for the ISC X-ring is that the greater supporting area minimizes the risk of tilting and distortion. The cord cross-section also creates a lubricant reservoir between the sealing lips. This helps reduce friction, and therefore considerably extends service life. X-rings are suitable for axial, rotary and oscillating movements of shafts, spindles, pistons, rods and plungers up to an operating pressure of 50 bar and at speeds of up to 2.0 m/s. Pressure of up to 300 bar can be sealed using a combination of X-rings and backup rings. The seals have been shown to be reliable in safety-critical applications such as the oscillating piston strokes in ABS pump systems.
The results show that the American compound had suffered less compression set in these tests than the other materials, and were more consistent across the size range. Contact: Zatkoff Seals and Packings, 23230 Industrial Park Drive, Farmington Hills, MI 48335-2850, USA. Tel: +1 248 478 2400, Fax: +1 248 478 3392, Email: [email protected]
Editor’s comment: The number of replicates tested and the results scatter were not reported. This is of particular interest, as some of the differences are well within the typical scatter of compression set tests. Plenty of work has shown that a 70 h test is not a sound basis for selecting a material for extended use, especially as the standard compression set procedure does not reflect the hot and cold material recovery properties, both of which are important for seal applications. I have carefully avoided the claim in the report that the US compound tested is the ‘best available’ industrial material. A number of manufacturers in the US, Europe and Asia may wish to see a more extensive range of compounds tested more thoroughly before such a claim is made.
The results of the 70 h compression set tests on five O-ring crosssections.
Editorial office: Elsevier Advanced Technology, PO Box 150, Kidlington, Oxford OX5 1AS, UK. Tel: +44 (0)1865 843239, Fax: +44 (0)1865 843971 Editor: Bob Flitney, Tel: +44 (0)1799 501659, Email: [email protected] In-House Editor: Steve Barrett, Email: [email protected] Production Coordinator: Tracey Scarlett Editorial advisory board: William V Adams (USA) • Yves Birembaut (F) • Cyril X Latty (F) • Amrat Parmar (UK) • John Plumridge (UK) • Richard F Salant (USA) • Wolfgang Schöpplein (D) • Neil M Wallace (UK) Permissions may be sought directly from Elsevier Rights & Permissions Department, PO Box 800, Oxford OX5 1DX, UK; Tel: +44 (0)1865 843830, Fax: +44 (0)1865 853333, Email: [email protected]. You may also contact Rights & Permissions directly through Elsevier’s home page (http://www.elsevier.com), selecting first ‘Customer Support’, then ‘General Information’, then ‘Permissions Query Form’. In the USA, users may clear permissions and make payments through the Copyright Clearance Center, Inc, 222 Rosewood Drive, Danvers, MA 01923, USA; Tel: +1 978 7508400, Fax: +1 978 7504744, and in the UK through the Copyright Licensing Agency Rapid Clearance Service (CLARCS), 90 Tottenham Court Road, London W1P 0LP, UK; Tel: +44 (0)207 436 5931; Fax: +44 (0)207 631 5500. Other countries may have a local reprographic rights agency for payments.
2
A selection of the new Freudenberg Simrit ISC X-rings, intended as O-ring replacements for dynamic applications.
They are also suitable for static sealing tasks on flanges, caps, fittings and pipeline tubes, where they can easily seal at pressures of up to 100 bar, and up to 400 bar with a backup ring. The standard materials for these seals are the same as those used for O-rings: NBR, FPM, EPDM and MVQ. By adding surface coatings, they can be modified to suit the application with respect to factors such as assembly. Contact: Freudenberg Simrit, D-69465 Weinheim, Germany. Tel: +49 1805 746748, Fax: +49 1803 746748, Web: www.simrit.de
Editor’s comment: This is the latest addition to a long line of O-ring substitutes. It will be interesting to see if they become available in sufficient quantities and at a price that will encourage their application.
Derivative Works Subscribers may reproduce tables of contents or prepare lists of articles including abstracts for internal circulation within their institutions. Permission of the publisher is required for resale or distribution outside the institution. Permission of the publisher is required for all other derivative works, including compilations and translations. Electronic Storage or Usage Permission of the publisher is required to store or use electronically any material contained in this journal, including any article or part of an article. Contact the publisher at the address indicated. Except as outlined above, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without prior written permission of the publisher. Address permissions requests to: Elsevier Rights & Permissions Department, at the mail, fax and email addresses noted above. Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made. Although all advertising material is expected to conform to ethical (medical) standards, inclusion in this publication does not constitute a guarantee or endorsement of the quality or value of such product or of the claims made of it by its manufacturer. 02129 Printed by Mayfield Press (Oxford) Ltd
Sealing Technology February 2004
Are all nitrile O-rings the same?
New design of X-ring is introduced
Zatkoff Seals and Packings has commissioned an investigation to compare a widely used, USmanufactured O-ring compound with four compounds imported from Asia. This work has shown that the US-manufactured material exhibited lower compression set in standard tests. The work, which was carried out by an independent laboratory, compared O-rings manufactured from Parker N674-70 with samples from four Asian suppliers, claimed to be the best of a number surveyed for the study. Five cross-sections of seal were used in the tests. They were O-ring sizes 015, 120, 214, 320 and 425. These have cross-sections of 1.78, 2.62, 3.53, 5.33 and 6.99 mm, respectively. Compression set tests were carried out on the O-rings to ASTM procedure D395 Method B. This involves compressing the seals by 25% and heating for either 22 h or 70 h. After exposure for the test period the fixtures are removed from the oven, the seals released and allowed to cool. The set dimensions are then measured. The test temperature selected was 100°C.
German-based Simrit has introduced ISC X-rings, a specially developed four-lip seal profile, as a replacement for O-rings in lowspeed dynamic and oscillating motion applications. The limitations of O-rings for dynamic applications are well known, with the possibility for twisting and instability; they are often selected for economy and convenience. This new X-ring design is intended to overcome these problems. It has a double sealing function: first, the special seal profile allows for a considerable reduction in initial compression; and secondly, this low initial compression reduces friction in dynamic applications so that the ring will not twist in the groove. Also, the X-shaped contour fits easily into square grooves. The decisive advantage claimed for the ISC X-ring is that the greater supporting area minimizes the risk of tilting and distortion. The cord cross-section also creates a lubricant reservoir between the sealing lips. This helps reduce friction, and therefore considerably extends service life. X-rings are suitable for axial, rotary and oscillating movements of shafts, spindles, pistons, rods and plungers up to an operating pressure of 50 bar and at speeds of up to 2.0 m/s. Pressure of up to 300 bar can be sealed using a combination of X-rings and backup rings. The seals have been shown to be reliable in safety-critical applications such as the oscillating piston strokes in ABS pump systems.
The results show that the American compound had suffered less compression set in these tests than the other materials, and were more consistent across the size range. Contact: Zatkoff Seals and Packings, 23230 Industrial Park Drive, Farmington Hills, MI 48335-2850, USA. Tel: +1 248 478 2400, Fax: +1 248 478 3392, Email: [email protected]
Editor’s comment: The number of replicates tested and the results scatter were not reported. This is of particular interest, as some of the differences are well within the typical scatter of compression set tests. Plenty of work has shown that a 70 h test is not a sound basis for selecting a material for extended use, especially as the standard compression set procedure does not reflect the hot and cold material recovery properties, both of which are important for seal applications. I have carefully avoided the claim in the report that the US compound tested is the ‘best available’ industrial material. A number of manufacturers in the US, Europe and Asia may wish to see a more extensive range of compounds tested more thoroughly before such a claim is made.
The results of the 70 h compression set tests on five O-ring crosssections.
Editorial office: Elsevier Advanced Technology, PO Box 150, Kidlington, Oxford OX5 1AS, UK. Tel: +44 (0)1865 843239, Fax: +44 (0)1865 843971 Editor: Bob Flitney, Tel: +44 (0)1799 501659, Email: [email protected] In-House Editor: Steve Barrett, Email: [email protected] Production Coordinator: Tracey Scarlett Editorial advisory board: William V Adams (USA) • Yves Birembaut (F) • Cyril X Latty (F) • Amrat Parmar (UK) • John Plumridge (UK) • Richard F Salant (USA) • Wolfgang Schöpplein (D) • Neil M Wallace (UK) Permissions may be sought directly from Elsevier Rights & Permissions Department, PO Box 800, Oxford OX5 1DX, UK; Tel: +44 (0)1865 843830, Fax: +44 (0)1865 853333, Email: [email protected]. You may also contact Rights & Permissions directly through Elsevier’s home page (http://www.elsevier.com), selecting first ‘Customer Support’, then ‘General Information’, then ‘Permissions Query Form’. In the USA, users may clear permissions and make payments through the Copyright Clearance Center, Inc, 222 Rosewood Drive, Danvers, MA 01923, USA; Tel: +1 978 7508400, Fax: +1 978 7504744, and in the UK through the Copyright Licensing Agency Rapid Clearance Service (CLARCS), 90 Tottenham Court Road, London W1P 0LP, UK; Tel: +44 (0)207 436 5931; Fax: +44 (0)207 631 5500. Other countries may have a local reprographic rights agency for payments.
2
A selection of the new Freudenberg Simrit ISC X-rings, intended as O-ring replacements for dynamic applications.
They are also suitable for static sealing tasks on flanges, caps, fittings and pipeline tubes, where they can easily seal at pressures of up to 100 bar, and up to 400 bar with a backup ring. The standard materials for these seals are the same as those used for O-rings: NBR, FPM, EPDM and MVQ. By adding surface coatings, they can be modified to suit the application with respect to factors such as assembly. Contact: Freudenberg Simrit, D-69465 Weinheim, Germany. Tel: +49 1805 746748, Fax: +49 1803 746748, Web: www.simrit.de
Editor’s comment: This is the latest addition to a long line of O-ring substitutes. It will be interesting to see if they become available in sufficient quantities and at a price that will encourage their application.
Derivative Works Subscribers may reproduce tables of contents or prepare lists of articles including abstracts for internal circulation within their institutions. Permission of the publisher is required for resale or distribution outside the institution. Permission of the publisher is required for all other derivative works, including compilations and translations. Electronic Storage or Usage Permission of the publisher is required to store or use electronically any material contained in this journal, including any article or part of an article. Contact the publisher at the address indicated. Except as outlined above, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without prior written permission of the publisher. Address permissions requests to: Elsevier Rights & Permissions Department, at the mail, fax and email addresses noted above. Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made. Although all advertising material is expected to conform to ethical (medical) standards, inclusion in this publication does not constitute a guarantee or endorsement of the quality or value of such product or of the claims made of it by its manufacturer. 02129 Printed by Mayfield Press (Oxford) Ltd
Sealing Technology February 2004