Valve limiter

Solution A valve limiter was installed on the vent control valve to limit opening. 

It is now an industrial standard to use positive identification of the valve position on all important safety valves — limit switches that are tripped when the valve is open or shut. In addition, all valve vent lines are now covered with bug screens to prevent blockage. 

Valves. Limited laboratory testing shows that emulsions can be let down across a pressure differential of 1000 ij/ (6895 kPa), typical of commer-... 

Valve limiting gas conductance at full valve travel ... 

Linear valve, so valve opening, y = x, valve travel. Valve limiting gas conductance at valve travel, x, Cg =... 

A safety valve limits the oil pressure to 50 atm, so that with a 9 1 amplification ratio the maximum solvent pressure is about 450 atm. The intensifiers have a double check valve assembly, the balls and seals of which are made of Kfil-F and ruby, respectively. The piston seal is made of graphite-impregnated PTFE. The solvent chambers have a capacity of 2.5 ml. Thus, with four intensifiers, the maximal flow-rate of 10 ml/min is obtained at the maximal frequency of 1 cycle/min. 

Restricting heat input to the reboiler This can be achieved by adding a restriction orifice or a short length of narrow-bore pipe in the heat input line to the reboiler, or a valve limiter to the heat input control valve. Alternatively, a pressure controller can be installed in the heat input line (in addition to the normal heat input controller). Restricting heat input is most effective when heat input failure sets column relief requirement. Two cases have been reported (60,414) where adding such a restriction orifice drastically reduced column relief requirements. Precautions are required to assure that the restriction orifice is not removed or resized in the future without resizing the relief device. Further discussion is in Sec. 9.4. 

Some troublesome experiences with liquid carryover fi om these condensers have been reported (381). The author had an experience with liquid carryover from a vent condenser mounted on top of a Cg splitter reflux drum (similar to Fig. 15.14c). Carryover occurred whenever the vent control valve opened excessively, and was recognized by "watering or icing up of the line downstream of the valve (due to liquid flashing). The author is familiar with other similar experiences. Installing a valve limiter was sufficient to prevent carryover in the above case. 

The non-linear limits imposed on the control systems, e.g. constraints on excitation current, valve limits on fuel valves. 

To ensure a consistent inspiratory flow rate during cough challenge studies, the author employs a compressed-air-driven nebulizer (model 646 De Vilbiss Health Care, Somerset, PA, USA) controlled by a dosimeter (KoKo DigiDoser nSpire Health, Louisville, CO, USA) that is modified by the addition of an inspiratory flow regulator valve (RIFR nSpire Health). The valve limits inspiratory flow rate to... 

The restricting orifice and the liquid knockout pot both guard against entrainment of liquid chlorine, which might create a serious hazard in the process. The orifice, sometimes replaced by a flow control valve, limits the flow to no more than the vaporizing capacity and so helps to avoid entrainment. Other possible measures include a high-level shutdown on the vaporizer and gas temperature control or low-temperature shutdown. The knockout pot is the second line of defense. 

Higher pressure in secondary circuit than in primary circuit - Isolation valves limits accident consequences ... 

Overcooling Transients All secondary penetrations to RPV protected by valves Limited flow rate for pumped injection Large primary inventory Small secondary inventory ... 

The System 80+ Standard Design addresses the integrity of the RCS under low temperature and pressure conditions by focusing on the issues that impact RCS and reactor vessel integrity (i.e., relief valves, limiting conditions for operation, reactor vessel materials, and vessel manufacturing techniques). 

Establish if the effect of failure of the valve limit switches needs to be included in the fault tree logic. 

The node with more components is the fifth, however the node with more deviations was the fourth. This reflected the high number and higher complexity of the valves between the storage tanks. Those are subject to human operation and possible errors in addition there are no safety equipment or any alarm to prevent unsafe operation. The installation of manual valves limit switches as a recommendation can eliminate most of those deviations. 

Pressure limiter valves limit the pressure in a specific circuit for a specific consumer. They close an open connection directly when the applied pressure exceeds a pre-set value. This is shown in the middle figure in Figure 5.9. 

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