Bailey Technical Catalogue - Safety Systems UK Ltd

766 Safety Relief ValveDESIGNThe 766 Safety Valve is a double spring high lift valvewith high discharge capacity. The top guided pistondesign incorporates an adjustable blowdown ring andmeets all the requirements of BS6759 Part 1.A freely pivoting disc and precision lapped stainlesssteel trim gives positive re-seating for steam duty.Fitted as standard with test lever for inline testing.Ideally suited to applications on steam boilers andpipelines where blowdown tolerances are critical.TECHNICAL SPECIFICATIONApprovalsBS6759 Pt 1PED certified Category IVMaterialsBody - Carbon St. gr WCB (-29 to 230°C)Trim - Stainless Steel (-29 to 230°C)Size RangeOrifice Min (Barg) Max (Barg)Size mm 2 Pressure PressureDN40 (1 1 ⁄2") 2280 0.35 24DN50 (2") 4054 0.35 24DN65 (2 1 ⁄2") 6334 0.35 24DN80 (3") 9121 0.35 24PerformanceOver BlowKdr pressure downSteam 0.4 10% 10%**or 0.3 Barg minMaximum Back PressureBarg CS 12 / CI 6Constant 0%Built-up 50%Variable 0%(Total % must not exceed Barg shown)ConnectionsFlanged In x Flanged OutConstructionTop Guided / High LiftCap OptionsOpen lever fitted as standardSizingRefer to Capacity Charts (page 60-67)FIGURE NUMBERING766TYPE1. ConventionalVALVE SIZE*†3. 40mm (2 1 ⁄2" x 3")4. 50mm (3" x 4")5. 65mm (4" x 5")6. 80mm (4" x 6")CONNECTIONS1. PN 16 RF x PN 16 RF2. PN 40 RF x PN 16 RF5. ANSI 150 RF x 150 RF6. ANSI 300 RF x 150 RFFEATURESG. GagM. Open LeverBODY MATERIAL2. Carbon Steel21*Flange sizes are larger than the valve size, refer to the dimension tableNotes:A. Any special requirements will be indicated by the letter X which will be agreedwith the sales office. For example, paint specification or spring material.B. Any combination of features can be called up eg. MG etc.C. Flange options are dependant on Valve Body materials, as detailed opposite.† Please see table on page 22 for inlet and outlet connection sizes.