Chinese Gas Market

Rubber for the Chinese gas market.

We have recently been contacted by several companies in regards to supplying diaphragms for regulators for the Chinese market.

In Europe for the gas diaphragm market there are European standards such as EN549.

EN549 has a test for pentane resistance.

We use pentane because it’s chemically similar to gasses that we will all know.

For example look at these common gases.

Name                    Number of Carbons                        Formula               Boiling point Celcius

Methane             One Carbon                                        CH4                        -161

Ethane                  Two Carbons                                    C2H6                      -88.5

Propane               Three Carbons                                  C3H8                      -42

Butane                 Four carbons                                     C4H10                   0.5

Pentane follows this pattern and has a five carbon structure with a formula of  C5H12.  Its boiling point i.e. when it becomes a gas is around 32 Celsius.

So having liquid gas is useful for testingWe can now submerge our product in something that simulates years in gas.

Typically for the EN549 specification we look at mass swelling in the liquid.

For the Chinese standards for gas diaphragms we are looking at changes in Volume.

However the principles are the same.  We want something that is very gas resistant. We want low temperature materials as China can have extremely cold winters. We want long temp age performance.

Our reaction to the potential growth of the ever-increasing Chinese Regulator and Membrane market is by undergoing a stringent qualification regime. That now incorporates the Chinese standards.  Research and development is continuing to target this new exciting market with lower temperature variants being developed.  Both our unique DFT rubber materials as well as homogenous diaphragms have been developed.

All new Chinese standards such as ICS91.140 which replicate EN334:2005 will continue to be monitored and evaluated to enable Metflex to offer the highest level of products and support possible.

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Aerospace Seals

Aerospace seals

Metflex have been manufacturing diaphragms for the gas industry for over 60 years. We are widely known for innovate materials for the gas, offshore and vibration damping  industries.

In addition to this extensive range Metflex are now offering seals for the aerospace industry.  The current list of materials include.

DTD 5612A  – Ministry of Defence – Aerospace Material Specification for a Fluorocarbon rubber with very low compression set.  Various NBR materials including  BS 2751, BA 70 ,APR 352, APR 341

Quality and traceability back to the batch and works order has been paramount.  Each batch of material is supplied with full test data to the standard, with traceability throughout.

Materials can be stored on site in our large purpose built walk in fridge. Ensuring that compound remains in top condition prior to moulding.

Each tool has been carefully setup with full measurement to drawings. Metflex use the latest in non-contact measurement techniques and full statistical process control.

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Metflex Successful Transition to ISO9001:2015

Metflex is pleased to announce that it has been awarded the ISO9001:2015 quality assurance accreditation. Our new certificate issued by BSI is proudly displayed in our reception.

Metflex recently made the strategic decision to upgrade its certified ISO9001:2008 Quality system to the latest :2015 standard. This was successfully achieved in March this year. Within the QMS (Quality Management System) scope: “The manufacture of Precision Rubber Components, including customised tools and material development services”, The Metflex quality team provided guidance in relation to requirements of certification.

As Metflex manufacture components for Subsea and Offshore Energy, as well as Gas diaphragms for the growing Smart Meter sector of the gas industry, Risk management and data driven decision making is key to our current daily decision making process. We are pleased the new Quality system adopts these philosophies, as well as improved focus through management commitment and leadership.

Metflex were audited by BSI who are accredited through UKAS. By achieving transition early, demonstrates Metflex’s commitment to Quality and continuous improvement.

We are delighted how the 2015 accreditation ensures and guides us to apply risk based thinking. Metflex has used statistical process control for many of our operations for many years. It’s a clear example of how it’s possible to gain the maximum amount of knowledge from sampling. Our company has been dedicated to producing rubber components to the tightest of specifications for many years.

So using statistics and key performance indicators allows us to concentrate on quality. However risk based thinking has channeled Metflex  into maximizing resources right across the company.  The standard has a high focus on how organizations meet the expectations and needs of all interested parties.

It has been a useful journey and Metflex have worked hard to use and be inspired by the many good practices that we see in other standards such as the Aerospace AS9100  or the Automotive standard TS16949

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Gas Meter Diaphragm Performance

Metflex Gas meter diaphragm performance

Gas Meter diaphragm performance is of paramount importance to our customers.

The rubber membrane enables the Gas Meter to register correctly, giving highly accurate readings. It has to perform this function consistently throughout the lifespan of the Gas Meter and has become even more critical with the advent of Smart Metering.

The membrane works by ‘rolling’ back and forth on a sectional radius or ‘convolution’ and hence the Thickness of the rubber component is fundamentally critical to its function.

Metflex Gas Meter diaphragms are manufactured to be very thin (typically between 0.3-0.5mm) and must be controlled to precision level tolerances.

To do this Metflex deploy Statistical Process Control to monitor the consistency of component thickness. This gives us the ability to make data driven decisions regarding the process and ultimately provide assurance that the customer receives their product that will consistently perform to their requirements ‘straight out of the box’.

Manufacturing diaphragms at these thicknesses can also present other issues.

Durability of components at this thickness can be reduced. To address this problem, our highly skilled and experienced technical and material engineering staff developed DFT (Dispersed Fibre Technology). This innovative advancement, strengthens the diaphragm at a material structural level, and assures its continued performance throughout the full lifespan of the Gas Meter and beyond.

Thin rubber components of this nature can also be prone to ‘pinholes’. These are very small holes in the component which can let Gas through and cause the diaphragm to perform incorrectly.

To combat this Metflex tightly control the process from raw material to finished product to ensure no contaminate is present within the rubber, and utilise a stringent inspection regime, involving a dedicated ‘darkroom’ where any holes, small or large, very quickly become apparent.

All our product range is manufactured under the requirements of the Metflex Management System. Certified to the very latest ISO Quality Management standards (ISO9001:2015), demonstrating our ongoing commitment to providing first class leadership and helping our customers to effectively manage their risk…

… at the forefront of rubber component technology.

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Research Highlights Biogas Threat to Gas Regulators

Failure to adequately remove sulphur from biogas poses a threat to commercial and industrial gas regulators, reports world leading gas meter and regulator diaphragm maker, Metflex. Research carried out by Metflex, in collaboration with independent test laboratories, has shown that levels of hydrogen sulphide as little as 1% can significantly reduce the regulator’s rubber diaphragm service life.

Biogas production buildings and windmillRubber diaphragms are widely used in gas meters and commercial and industrial gas regulators. Traditionally made from either NBR (nitrile butadiene rubber) or ECO (Epichlorohydrin Rubber), the diaphragms are used to ensure continuous flow and regulate gas flow respectively. A regulator diaphragm exposed to natural gas can expect to flex through over several million cycles over 5 years operational life.

Biogas generated through either anaerobic digestion or fermentation of biodegradable materials, comprises typically 55-65% methane, 35-45% carbon dioxide, 0.5-1.0% hydrogen sulphide and traces of water vapor. Long-term exposure to sulphur can cause the diaphragm to harden, leading to cracking and premature failure. Flex testing has shown a reduction of up to 70% in diaphragm service life due to sulphur.

“Rubber diaphragms for gas meters and regulators are designed for natural gas where levels of sulphur are negligible,” says Chris Greenwood, sales director, Metflex Ltd.

“With biogas, the energy industry is faced with either investing in more sophisticated gas scrubbing equipment or switching to a rubber with greater resistance to sulphur.”

HNBR – biogas resistant

Metflex research has identified a peroxide-cured, hydrogenated NBR (HNBR) as the most cost-effective alternative to NBR. Hydrogenation eliminates the NBR’s structural ‘double bond’ attacked by sulphur.

“HNBR has the same mechanical properties as NBR but with greater chemical resistance. Tests of HNBR diaphragms exposed to biogas have shown a flex life more in line with that expected with natural gas,” Chris Greenwood notes.

Metflex is the clear technology leader in the manufacture of rubber diaphragms for consumer, commercial and industrial gas meters and regulators. The company’s Dispersed Fibre Technology (DFT) enables production of ultra-thin, precision moulded diaphragms that have set the standard for performance and longevity within the global gas meter industry.

For more information on Metflex call +44 (0)1254 884171, visit the web site or email

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Difficult Moulding – Tight Tolerances

Metflex has applied SPC to achieve high moulding precision in rubber manufacturing.

Rubber by its very nature can be difficult to mould to very tight tolerances. Leaving aside environmental conditions, the shape of the pre-moulded blank, the viscosity of the rubber, the condition of the tool and press, moulding tool configuration, and even a change of press operator, can all have a bearing on the tolerances of the finished moulded product.

Understanding how these factors affect the dimensional accuracy of precision moulded parts has prompted Metflex Ltd to introduce statistical process control (SPC) monitoring techniques to consistently achieve unprecedented levels of moulding precision.

Moulding Tolerances

Two years ago, Metflex observed an unexplainable variation in the dimensional accuracy of its gas meter diaphragm mouldings – the thickness of the diaphragm had increased. Domestic gas meters operate by the action of a diaphragm constantly flexing, alternately filling and expelling gas, to produce a constant gas flow. The thickness of the diaphragm is thus critical to the meter’s performance and diaphragm service life, typically 20 -30 years.

Although still within permitted tolerances, the inability to explain the variation in thickness highlighted the fact that traditional process control and inspection techniques were unable to provide the fine grain analysis needed.
The decision to introduce Statistical Process Control was based on the premise that ‘There can be no action without analysis, and no analysis without measurement’.

Statistical Process Control

Statistical Process Control (SPC) allows Metflex to collate data from a variety of production and metrology sources to monitor the moulding thickness. It uses statistical methods to monitor and control a process, with the aim of achieving optimum process conditions. Its main advantage over ‘inspection’ is that it allows early detection of a problem, thus making it easier to identify the cause.

Metflex has implemented WinSPC statistical process control software. It produces Control Charts that graphically represent the variability in a process over time, making it easier to spot inconsistencies and unnatural fluctuations.

Control charts typically display the limits that statistical variability can explain as normal. If the process is performing within these limits, it is said to be in control; if not, it is out of control. The area between each control limit and the centerline is divided into thirds. The third closest to the centerline is referred to as Zone A, the next third is Zone B, and the third closest to the control limits is Zone C. Note that there are two of each of the Zones, one upper and one lower.

Where 3-sigma is used for the control limits, Zone A is called the “1-sigma zone”, Zone B is “2-sigma zone”, and Zone C is “3-sigma zone”.

The 3-sigma rule states that nearly all values lie within three standard deviations of the mean in a normal distribution. As a result 68.3% of results (1-sigma / Zone A) are within one standard deviation, 95.5% of results (2-sigma / Zone B) are within two standard deviations, and nearly all values are within 99.7% of the standard deviation (3-sigma / Zone C).

Achieving Consistent Dimensional Accuracy

Working with its customer, Metflex established the critical dimensional parameters for the gas meter’s diaphragm and seals. The diaphragm is measured at 16 points, the seal at 8 points. At the thinnest point, the rubber moulded part is less than 2mm thick. Moulded parts are collected over an 8-hour production cycle. Four mouldings are measured per hour. The data collection is semi-automated such that thickness measurements are automatically entered into the SPC software.

The SPC control chart shows how moulding thickness varies over time. The centre line is the ideal. Within Zone A (Green) the parts are being moulded to a high degree of dimensional accuracy (nominal spec). Moving into Zone B (Yellow) indicates the parts are within tolerance, but the process needs to be tweaked to move the tolerance back into the green zone. If the results go into the Zone C (Red) – production is stopped and action taken to investigate the problem. Sharp movements/variation in thickness pinpoint where the process has changed.

Insights into the Moulding Process

Statistical process control has allowed Metflex to gain insights into the rubber moulding process that are simply beyond the reach of traditional process / inspection techniques.

Control chart A shows how the slightest change in the processing conditions can be quickly detected using SPC.

L to R – Initially there is a large variation in the thickness of the moulded part within the 1-sigma (Green) zone, eventually falling into the 2-sigma (Yellow) zone. By adjusting the moulding pressure – a known variable that can affect part thickness –

Statistical Process Control Chart A

Control Chart A

the thickness is brought closer to the centre line. Increasing the moulding pressure to 2,100psi retrieved the situation. Reducing it to 1,700psi proved to the optimum moulding pressure for this particular press, enabling a more consistent moulding.

Production Plant Efficiency

Moulding presses are used to manufacture a variety of parts. Over time the press will need maintaining as part of a preventative maintenance schedule. For the rubber moulder wishing to maximise manufacturing productivity, this may not be the best guide to press maintenance. The introduction of SPC has enabled Metflex to take an informed approach to press maintenance. Control Chart B shows the effect of press refurbishment on the thickness of the moulded part.

L to R -. Here the press initially performed well, but gradually moved into the 2-sigma zone (Yellow),

Statistical Process Control Chart B

Control Chart B

providing early warning of moulding problems. With all other processing conditions optimised, it soon became clear that the problem lay with the condition of the press. By refurbishing the press, the thickness of the moulded part was reduced from the top end of the tolerance limit to a point closer to the centre line (nominal spec).

Pushing the limits of rubber moulding

As the two Control Charts show, the application of SPC techniques has allowed Metflex to fine tune the moulding parameters to achieve greater consistency in the dimensional accuracy of its gas meter diaphragm and other rubber mouldings.
The company is now taking this a stage further to begin manufacturing even thinner rubber parts at tolerance levels far in excess of accepted industry norms such as BS 3734 : Part 1 : 1997 for rubber part manufacture. Application of SPC techniques will ensure Metflex is able to consistently meet the higher tolerance requirements needed for these ultra-thin parts.

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MetflexSubsea Update

Metflex Subsea

2014 is proving to be hugely successful for Metflex within the Subsea sector, one of our key targeted strategic growth areas.

MetflexSubsea supply large multi-national companies with products both for use in the North Sea as well as into export markets.

Continuous development and material innovation are key in ensuring we stay in a strong position in this very demanding market.

All of our products are manufactured to exacting standards and as increased product life and performance are becoming part of the expectations of our customers, our in house design team work tirelessly to look beyond today’s requirements.

Metflex welcome the opportunity to discuss your existing requirements or development projects which require rubber based products.

Do not hesitate to call Mike Wynburg, director of business development on 01254 884 171 alternatively email

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Factory Purchase Shows Metflex’ Commitment to Great Harwood

Metflex are pleased to announce the purchase of its Alan Ramsbottom Way site this week.

The purchase highlights Metflex’ commitment to the local area of Great Harwood and John Holland, Managing Director, speaks about the decision;

“When we moved to the site in 2010 we initially leased the premises and ensured that we had the opportunity to buy at some point in the future.

Metflex staff have shown much dedication to this organisation, with 11 employees reaching either 25 or 35 years of service this year. This, alongside our level of confidence in the economic climate has aided our decision to make this purchase to safeguard the future of Metflex in Great Harwood.”

2014 is proving to be the most prosperous of our 95 years, with an expected £10m sales target in sight, exceeding last year’s outstanding performance of £8.5m. Metflex’ recent success lies with strong sales into the global gas meter and subsea markets. We look forward to embracing this milestone and developing in all markets in the near future.

Machine producing rubber coated fabric

Coated Fabric Production

Birds eye internal view of factory

Internal View of Factory

Outside view of Metflex Reception

Metflex Reception

The Mayor of Hyndburn Cllr Malcolm Prichard Opening the Building in 2010

The Mayor of Hyndburn Cllr Malcolm Prichard Opening the Building in 2010










Workman mixing rubber

Rubber Mixing









Metflex welcome all enquiries, contact us today to discuss your needs on 01254 884171, or email





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Metflex Expands Offshore and Subsea Manufacturing Capability

v ingham 017Precision rubber moulding specialist, Metflex Ltd has invested over £35,000 in a new 400Te press for the production of large mouldings at its Great Harwood manufacturing facility in Lancashire, UK. The investment follows a significant increase in offshore and subsea business, and the development of the MetflexSubsea NRX range of high performance rubber grades for the oil and gas sector.

Metflex manufactures API 17 compliant, large rubber blocks, piggyback pipeline blocks, and rubber springs for use in riser and umbilical connection systems. For subsea applications where greater stiffness is needed, the company is able to supply mouldings containing single and multiple metal inserts.

The new press will allow production of rubber mouldings up to 2,000mm in length, 450mm wide and a depth of 300mm, significantly expanding the scope for Metflex to supply new NRX rubber engineered products offshore.

“Natural rubber has many advantages over other materials subsea, specifically very high tensile strength, resilience and the ability to absorb dynamic stresses, and withstand abrasion,” says Steve Parry, director of development, Metflex Ltd. “Our experience of precision moulding allows us to optimise the innate strengths of rubber to offer bespoke engineering solutions to the challenges of deploying systems subsea.”

MetflexSubsea is the family branding for all Metflex products and services for the subsea sector.

Subsea Image Depicting use of Metflex Rubber in Industry

Metflex Purchase 2000mm Press

Metflex is an established supplier to the offshore industry, and has over 70 years’ experience in rubber moulding. It manufactures precision rubber moulded components, rubber seals and gaskets, and diaphragms to a worldwide customer base.

Metflex offers a complete design service, and innovative production methods including rubber to metal bonding, and ultra-thin (0.2mm), 3D fibre reinforced mouldings based on the company’s proprietary DFT (dispersed fibre technology), using a combination of injection, compression, transfer and flashless fabrication techniques.

For more information on Metflex and MetflexSubsea call +44 (0)1254 884171, email and visit the web site

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Positive Meetings for Metflex Sales Executives at Utility Week

Utility Week Slide 2Arno Schlabertz, European Sales Manager (2nd from left) and Chris Greenwood, Director of Sales (far right) had a very successful visit to the RAI Exhibition Centre in Amsterdam last week.



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