Bailey Safety Valves

The effects of exceeding safe pressure levels in an unprotected pressure vessel or system, can have catastrophic effects on both plant and personnel. Safety relief valves should be used to protect any pressurised system from the effects of exceeding its design pressure limit.
A safety relief valve is designed to automatically discharge gas, vapour or liquid from any pressure containing system, preventing a predetermined safe pressure being exceeded, and protecting plant and personnel.

 

Safety Valve
A valve which automatically discharges gases and vapours so as to prevent a predetermined safe pressure being exceeded. It is characterised by a rapid full opening action and is used for steam, gases or vapour service.


Relief Valve
A valve which automatically discharges fluid, usually liquid, when a predetermined upstream pressure is exceeded. The term is commonly used for pressure relieving valves in which the lift is proportional to the increase in pressure above the set pressure.

 

Safety Relief Valve

A valve which will automatically discharge gases, vapours or liquids, to prevent a predetermined safe pressure being exceeded. It is characterised by a rapid opening action.

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707 Safety Relief Valve

 

The Bailey 707 Safety Relief Valve encompasses a top guided design, combining an unobstructed seat bore with high lift capability. This bronze bodied valve can be supplied with a resilient or metal trim with a choice of screwed and flanged connections.


The Bailey 707 is certified to BS EN 4126 Part 1 (BS6759 pt 1:2:3) and is suitable for duty on air/gas, steam/hot water (above 100ºC) and process liquid.

 

Test levers are available for inline safety checking, alternatively a sealed dome can be supplied for service conditions requiring a pressure tight seal on the discharge side, eg. liquid service with enclosed discharge.

716 Safety Relief Valve

 

The 716 Safety Relief Valve combines a top guided, unobstructed seat bore with full lift capability to provide maximum discharge capability.

 

Positive reseating is achieved with freely pivoting EPDM discs for gas, hot water and other liquid duties up to 150°C. Optional Aflas soft seats increase the range to 200°C. Precision lapped stainless steel trim gives positive re-seating for steam duty at higher temperatures. Fitted with a test lever for inline safety checking, or alternatively with a sealed dome for service conditions requiring a pressure tight seal on the discharge side, eg. liquid service.

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716H Safety Relief Valve

 

The figure 716H safety relief valve is a high pressure version of the popular 716 valve.

 

Pressures up to 102 Barg (orifice dependent) can now be accommodated in two high grade materials, Carbon Steel A216-WCB and Stainless Steel A351-CF8M.
 

The 716H is certified to the ASME VIII code for the full range of flowing media.

 

716T Pressure & Temperature Safety Relief Valve

 

The 716T is the ultimate solution to hot water system protection, it protects unvented hot water systems, against both excess pressure and excess temperature. Increasing pressure is sensed by the spring, which automatically opens the relief valve at the pre-set pressure and the integral probe independently monitors increases in temperature, safely opening the relief valve between 90°C and 95°C.
 

The 716T has capacities well in excess of EN1490:2000 code requirements, and has been
independently tested by the Building Research Establishment, in accordance with EN1490:2000 which is to supersede BS6283 pt3.

 

The temperature probes are designed to have a smooth surface free from crevices, to reduce mineral build-up, and are white powder coated to minimise galvanic action within the heater.

 

The 716T has a bronze body, Dzr brass internals and silicone seat in accordance with potable water code requirements. A soft seat provides leak tight operation. The spring and spring chamber are protected from the hot water by the EPDM diaphragm, reducing corrosion and increasing life in service.

 

The manual test lever can be easily operated from any position around the valve.

 

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746-safety-relief-valve
746 Safety Relief Valve

 

The 746 Safety Relief Valve incorporates a freely pivoting disc, which ensures correct alignment with the nozzle. The combination of top guiding,unobstructed seat bore and full lift capability ensures the highest possible discharge rate thus maximum plant protection.

 

Due to the large flows available the inlet pipework must be sized to give a maximum inlet pressure drop of 3%.

 

The 746 safety relief valve is available in both conventional and balanced bellows types, and features a special disc style for liquid application, which enhances valve performance.

 

The ‘conventional’ arrangement is suitable for applications where the built up pressure will not exceed 5%. The conventional valve can also be used in systems where the superimposed backpressure is at a constant level (up to 80%).

 

The ‘balanced bellows’ arrangement is for applications where several safety relief valves discharge into a common discharge manifold, or in any circumstances where a variable back pressure can occur, up to a maximum of 40%.

 

756 Safety Relief Valve

 

The 756 Safety Valve combines a top piston guided valve and an unobstructed seat bore with a full lift capability, giving maximum discharge capacity. The design incorporates an adjustable blowdown ring and meets all the requirements of BS6759 Part 1.

 

A freely pivoting disc and precision lapped stainless steel trim gives positive re-seating for steam duty. As standard the 756 is fitted with a test lever for inline testing. Ideally suited to applications on steam boilers and pipelines where blowdown tolerances are critical.

 

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Bailey-766-safety-relief-valve
766 Safety Relief Valve

 

The 766 Safety Valve is a double spring high lift valve with high discharge capacity. The top guided piston design incorporates an adjustable blowdown ring and meets all the requirements of BS6759 Part 1.

 

A freely pivoting disc and precision lapped stainless steel trim gives positive re-seating for steam duty. Fitted as standard with test lever for inline testing.Ideally suited to applications on steam boilers and pipelines where blowdown tolerances are critical.

 

776 Cryogenic Safety Valve

 

The 776 Safety Relief Valve is designed for cryogenic duty down to -196°C. The valve combines a full lift design and top guided construction with an unobstructed seat bore to provide maximum discharge capacity. Positive sealing is achieved through a freely pivoted disc with Kel F (PCTFE) soft seat technology.

 

The valve is designed to conform with ISO4126, AD Merkblatt A2, ASME VIII and BS6759 Parts 2 & 3.

 

Production assembly and tests are carried out in accordance with both BOC and Air Products specifications.

 

BOC specification: 1819660 and 399856.

 

Air Products specification: 4WPI-EW80010, and 4WPI-SW70003.

 

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Bailey-480-485-490-safety-relief-valve
480 / 485 / 490 Safety Valve

 

This spring operated liquid relief valve has a cartridge type assembly which can be withdrawn from the body without disturbing the spring setting and hence relieving pressure. This allows the seating surfaces to be cleaned without the need to reset the valve. The 480 is a bronze relief valve, the 485 is also bronze with a renewable stainless steel seat and disc, while the 490 is all stainless steel.

 

Typically for use on positive displacement pumps, for relief or bypass duties. The spring cartridge assembly can be supplied separately for use as an integral pump bypass relief valve.

 

The spindle is normally fitted with an ‘O’ ring to protect the spring particularly on corrosive duties.

 

616 D Safety Valve

 

The type 616D is a spring operated high capacity safety valve for low-pressure air applications. It is designed to deliver precise relieving and re-seating pressures while the protected open discharge gives downward flow. The non-stick seating surfaces give positive shut-off and freedom from sticking, whilst the mixture of aluminium and gunmetal make it light but
very robust. Typically used on blowers or bulk transfer road/rail transport vehicles.

 

It is specially designed to give overpressure protection of positive displacement air blowers and associated tanks or pressure vessels.

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© 2019 by GTSB Team

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