Open bonnet

If emission of the fluid into the atmosphere is acceptable, the spring housing may be vented to the atmosphere in an open bonnet design, as shown in Figure 5.11. This is usually advantageous when the SRV is used on high-temperature fluids or for boiler applications as otherwise,... 

They should preferably not be used on steam service, steam boiler drums or superheaters, where an open bonnet-type SRV is generally preferred because of the temperature of the spring, which is required to be cooled off in order for it to keep its characteristics and maintain stability in the set pressure. 

Open bonnet valves are used where the operating temperatures are high and the spring is required to be cooled off in order to retain its characteristics. 

Open bonnet valves are characterized by a rapid opening or pop action and small blowdown. 

Open bonnet valves are not recommended for liquid or toxic applications. 

Gate valves are used to minimize pressure drop in the open position and to stop the flow of fluid rather than to regulate it. The problem, when the valve is closed, of pressure buildup in the bonnet from cold liquids expanding or chemical action between fluid and bonnet should be solved oy a relief valve or by notching the upstream seat ring. 

Conventional Safety Relief Valve - A conventional safety relief valve is a closed-bonnet pressure relief valve that has the bonnet vented to the discharge side of the valve and is therefore unbalanced. The performance characteristics, i.e., opening pressure, closing pressure, lift and relieving capacity, are directly affected by changes of the back pressure on the valve. 

The valve consists of a valve inlet or nozzle mounted on the pressurized system, a disc held against the nozzle to prevent flow under normal system-operating conditions, a spring to hold the disc closed and a body/bonnet assembly to contain the operating elements. The spring load is adjustable to vary the pressure at which the valve opens. 

Das, U. Crousse, B. Kesavan, V. Bonnet-Del-pon, D. Begue, J.-P. Facile ring opening of oxiranes with aromatic amines in fluoro alcohols. /. Org. Chem. 2000, 65, 6749-6751. 

The bonnet opening of the disabled valve body below Tank No. 7 provided a steady stream of fuel to create a blow-torch like flame aimed beneath Tanks Nos. 5, 6, and 7, which threatened the equipment. Within a short length of time, safety relief valves on these tanks opened with a loud shrill sound to cope with the heat-induced rising pressure in the tanks. 

The poHceman didn t tiy to hide his displeasure. We went outside, squinting m the sudden brightness. The house was the end one of a row of small stone cottages. Our cars were parked mthe lane. I took the imp out ofny Land Rover and opened it on the bonnet. The sun glanced off the battered metal, making it hot to the touch. 

When washing is used for preparing the column for personnel entry, it is important to avoid trapping undesirable materials in valve bonnets, piping, and dead pockets. All valves should be opened, all dead pockets and valve bonnets should be flushed, and... 

Pages, X., C. Bonnet, and J. Laur, Synthesis of New Derivatives from High-Oleic Sim-flower Methyl Esters via Epoxidation and Oxirane Opening, Presented during the 1998 AOCS Annual Meeting, Chicago, IL. 

Engine bonnet Opening upwards and backwards, single arm hinge... 

The kinetics of the conformational transitions can therefore be fit with a simple exponential function (or in some cases better described by a stretched exponential [45]) and the observed kinetic rate constant can be determined (see Figure 2.15). Since the equilibrium constant (measured easily in a number of ensemble assays) gives the ratio of the opening and closing rates, then data can then be combined with the observed kinetic rate constant to give the opening and closing rate constants. This important technique introduced in a paper by Bonnet and co-workers [46] is reviewed more completely in Chapter 5. 

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