Oil Resistant Fluorosilicone Hoses

Fluoro Silicone Hoses Explained

Normal automotive grade silicone material has many advantages compared to organic rubber, which we talk about in several other sections of our website. Normal silicone is however not suitable for contact with oil and some chemicals. Hoses built with normal silicone grades are permeable to oils and will perish faster as the oils of vapours passing through the hose will eventually works its way through the material and cause swelling of the hose. The integrity of the hose will quickly be compromised.  

When oil, oil mist, fuel and or, certain chemicals may be present in turbo-charger and other air or exhaust gas systems, it is necessary to use a fluorosilicone liner in a silicone hose. Normal silicone will not offer sufficient resistance to oil.

Fluorosilicone inner linners can also be used to protect against waterless coolants (OAT). Certain aggressive rust inhibitors sometimes used in coolant systems bi-products from EGR (Exhaust Gas Recirculating) systems and other chemicals also call for the use of Fluorosilicone.

Fluorosilicone offers good temperature stability from -55°C up to +230°C but will need to be used as an inner liner inside the hose together with an appropriate silicone compound and fabric reinforcements in multiple payers of additional reinforcement plies. Normally Viper Performance hoses have a minimum of 3 plies or reinforcements, increasing o four plies from 51mm Diameter hoses, then 5 plies or more on larger bores of 102mm  onwards, Fluorocarbon lined hoses offer slightly better high temperature stability however, are not as resistant to extreme low temperatures. 

Most of the universal hoses found on our website such as elbows, bellows, straight lengths etc..can be made to order with a Fluoro Silicone liner. Viper Performance can also produce custom or O.E hoses in this material. Please contact our technical sales for information.

Cost Implications:

Fluorosilicones are expensive as at 2014 prices a good quality pure fluorosilicone costs £80 per KG which is often over then times greater than the costs of normal automotive raw material silicone!

At Viper Performance Hoses we only use high quality undiluted fluoro silicone base materials and apply a 1mm inner liner which will be in contact with the oil. With a one 1mm inner liner Fluoro Silicone lined hoses cost double the price of normal silicone and is made to order only. It is not necessary and would be costly to make hoses completely out of Fluoro silicones to include the inner liner plus the reinforcement layers. Doing so is of  course possible by request, Viper Performance does produce this for certain clients or applications from time to time, however the cost of a hose completely made from Fluoro Silicone throughout costs four to six times the price of a normal silicone hose from Viper on average.

Money saving practices, what you need to know

When producing Fluoro Silicone Hoses (FVMQ), it is important to use only the highest quality materials.  Some manufacturers will dilute the lining material (known as a Fluoro Blend) to reduce cost, this is done by mixing normal grade silicone with Fluoro Silicone. We are aware that some other hose manufacturers will have a 80/20 mix of Fluoro Silicone and Normal Silicone, this is acceptable  for oil mist and vapour, however some will dilute the materials to 60/40. We have even seen some manufacturers outside the UK shaving costs by diluting Fluoro materials to only 20% Fluoro blended with 80% normal silicone rubber. This practice of course reduces the Fluoro cost a great deal, however the effect on the performance and life expectancy of a hose built this way will be very noticeable.  At this level of blending the cost of a Fluoro Lined hose may only be about 20% more than a normal hose. Viper Performance Hoses in Fluro Silicones use only 100% pure material, and a 1mm liner guaranteeing the best possible resistance to oils and chemicals.

Any dilution of the liner material, will reduce the performance and resistance of the hose to oils and other chemicals. Another way of saving money on fluoro is making a 100% pure material hose which is indeed non diluted, however some hose manufacturers may reduce the thickness of the inner liner to 0.5mm thick, in effect this halves the raw material costs. An inner liner of this thickness will not offer sufficient long term protection, and small tears and cracks can easily appear letting oil seep into the reinforced layers.  

Important: When specifying or requesting a quotation for FluoroSilicone lined hoses do ask your hose manufacturer or supplier their specification of Fluoro material and thickness.
Tip: if it is cheap there is reason



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