Applications
As safety and environmental issues have become of greater concern to mankind, the need for assured valve shut off providing absolute and verifiable isolation are regularly becoming the standard specification for critical applications.Typical areas of application include on- and off-shore petrochemical production, gas and water injection, gas and oil transmission lines, airport fuelling facilities and other areas where flammable and toxic emissions are unacceptable.

• New design provides a high double seal with bleed facility between
• Any seapage through the first seal drains through hole between seals
• Drain tap to check for leakage

Design
Previous common practice has been to use two valves, such as plug or ball valve designs, in series with a bleed facility located between them in order to establish the sealing between them in order to establish the sealing integrity of the upstream valve. This configuration is far from optimum as more space is required, with considerable extra weight quite apart from the additional maintenance requirements of having two valves and the extra associated costs.The Solent & Pratt Double Block and Bleed design utilises our well established, patented triple offset segment valve (TOSV). Two seals are incorporated on the disc segment thus providing sequential sealing. The downstream seat is not spring loaded, as is the practice for trunnion mounted pipeline valves, which are also very heavy and expensive. Sealing integrity is therefore maintained should the upstream seat fail. When the valve is closed a channel between the two seats connects with a purge or bleed port in the valve body which is connected to an external outlet where an isolation valve or relief value may be fitted for manual or automatic bleed. This compact Double Block and Bleed Design negates the need for using two valves in series.

Key Features

Inherently Firesafe Pprimary metal/metal sealing certified to API 607 4th Edition Zero leakage shut off Available in both directions Replaceable body seat & laminated disc seal Triple offset Design (non-rubbing) Anti-blowout stem standard. API 609 cat B NACE Requirements Materials of construction available to NACE requirements Weld Ends Wafer, lugged, double flanged and butt weld ends available ANSI 150, 300, 600, 900, & 1500 with fully rated trims ISO QA Quality Assurance System approved to ISO 9001 Global IP Patented in UK with worldwide patents pending Sizes Size range 6" to 36", ANSI 150, 300, 600, 900 & 1500 Large sizes available on request Technical Description SOLENT & PRATT, TOSV series valves are of dedicated Triple Offset geometry design. This particular feature eliminates the disc-to-seat rubbing condition, normally associated with 'HPBV' butterfly valves, which induces wear of varying degrees, even in metal seated versions. The standard valve construction has been developed and modified to create the Double Block and Bleed Valve. In the Double flanged body version it utilises the same face to face length casting , enabling a standard TOSV to be replaced by a TOSV - DBB with out alteration to the pipework. The advantages of using this innovative Butterfly Valve design rather than the use of a conventional ball valve is weight and space saving in addition to obvious economies in terms of cost. To create this design feature, it was necessary to provide a gallery into which any fluid which passed the seals would drain. This gallery, of annular form, was created by using two seals with an interposed spacing ring, allowing for fluid leak-off to pass via the interconnecting body port to a manual valve or other auto relief device. This facility allows checks to be carried out on the seat / seal integrity. The trims are all fully rated in pressure ranges from 150# to 1500#, making it an ideal PROCESS VALVE which is inherently FIRESAFE, having no soft components in it's construction. To summarise, this is an ideal replacement valve for Ball, Plug or Gate types, since it offers: Seat tightness - Zero leakage Non - jamming seat design Control & Isolation use Weight savings Easily maintained ** ** Both Seat and Seal are field replaceable

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