Quality control

To ensure we consistently supply a top quality product involves a great deal of process management. It begins with selecting raw materials, involves fabrication process control, stock control, packaging and despatch management. Each part of the process has to be closely monitored and this is where choosing a liner from GORDON LOW PRODUCTS makes a difference. We offer a lifetime guarantee that means something because we are supplying a premium product backed up by some of the biggest material manufacturers in this field. Quality does not come cheap, but we constantly monitor material prices to ensure we can offer highly competitive products, even against lower grade products.

Material Approval Specifications :

BS903 - Physical testing of rubber

WRc approval to BS6920:2000

EN13948 - Root penetration test

DIN 4062 - Root penetration test

BS6906/4 - Puncture strength

ASTM G53-84 - UV resistance

The life expectancy of a Butyl rubber liner is dependant not only on the level of exposure to the elements but also to any mechanical stress due to incorrect fitting or subsequent ground movement any time after installation. Whereas a relaxed liner below the water line could be expected to last for say 30 to 40 years, under severe mechanical stress (stretch) and exposed to ozone, sun and weathering, this could reduce to 15 to 20 years.

MATERIALS

Like any manufacturing process, raw material selection is vital to produce a quality product. We have sourced (and used for many years) what we believe to be the most effective Butyl Rubbers, EPDM Rubber and PVC lining materials available.

To understand what makes a good quality rubber liner, you must first know how it is made and how the raw materials themselves are produced. Basically a synthetic rubber compound is a mixture of one or more base rubber polymers, i.e Butyl (IIR - isobutylene isoprene - rubber) or Ethylene-Propylene-Diene-Monomer (EPDM), reinforcing carbon black, fillers, process chemicals, antioxidants and vulcanising agents to give the rubber the required strength, flexibility, exposure resistance and even colour. This compound is blended and then passed through steel rollers which create the thin film of sticky, uncured rubber. Vulcanising the rubber in an autoclave (baked under pressure) sets or 'cures' the rubber into the tough elastic material we know. The vulcanisation process means that the material differs from all thermoplastic products (i.e. PVC), in that its properties are not affected by varying temperatures. The product is chemically stable and always returns to its original dimensions after stretching. The cross-linked molecular structure gives EPDM and Butyl rubber their unique properties. Ageing or changes in characteristics are negligible despite decades of exposure to the atmosphere, sunlight, UV radiation, chemical fallout, water or major temperature fluctuations. EPDM and Butyl rubber contain no plasticisers or additives which can evaporate or be washed out over the years. The strength and elasticity of the membrane remain practically unchanged for decades, without shrinkage, brittleness, melting or cracking. The membrane is equally elastic, regardless of whether the temperature is -30°C or +120°C.

The handling process used to carry the uncured rubber has a big effect on the final appearance of the sheet. Prior to vulcanisation the rubber is very sticky and it has to be prevented from sticking to it's self before it is baked. Two common methods are used in the manufacture of our chosen rubber lining materials, it is either dusted with mineral talc (Firestone EPDM) or supported by a carrier sheet which creates a cloth-like texture impression on the sheet surface (Trelleborg-Värnamo BUTYL).

Different compounds of rubber are used for particular applications and price can vary greatly depending on the type, quality and quantity of polymers used. Obviously all of our liners are manufacturer guaranteed fish and plant friendly, but we can also produce liners in drinking water quality grades when required (WRc approved BS6920). Cheaper, readily available 'Roofing' grade materials can be highly toxic to fish so beware if choosing cheap alternatives. Always compare material test certificates before offering products for particular applications. With Gordon Low Liners you can rest assured that not only have we selected the best available materials, from recognised manufacturers, but we also regularly have samples tested with independant testing authorities to confirm the quality.

FABRICATION

Butyl rubber is the most expensive raw material we use for liners, our material is produced in Sweden by one of the leading material producers. We fabricate sheets in house from 1.7m wide strips using our own specialised technique. The resulting seam is an incredibly strong 25mm wide overlapping joint produced by heating, under pressure, an uncured jointing tape. This process is extremely reliable and quality ensured by a combination of our own design of welding press and stringent quality control procedures. This process enables us to fabricate Butyl sheets in the factory up to 28m x 40m.

STOCK CONTROL

Barcoded, batch numbered, product identification labels ensure traceability of materials throughout the manufacturing process.

PACKING AND DESPATCH

Utmost care is taken with packaging our lining products, all heavy items are palletised and shrink-wrapped to ensure maximum product protection during delivery. (We use carrier's so always inspect outer wrapping before signing for a delivery).