Valve functions

The commercial appHcation of this concept (68) is portrayed ia Figure 8, which shows the adsorbent as a stationary bed. A Hquid circulating pump is provided to pump Hquid from the bottom outiet to the top inlet of the adsorbent chamber. A fluid-directing device known as a rotary valve (69,70) is provided. The rotary valve functions on the same principle as a multiport stopcock in directing each of several streams to different lines. At the right-hand face of the valve, the four streams to and from the process are continuously fed and withdrawn. At the left-hand face of the valve, a number of lines are coimected that terminate in distributors within the adsorbent bed. 

Variation to the slide valve is the turn valve. The valve functions by turning rather than sliding but has the same effect as the slide valve. The plug is... 

Echocardiogram Used to assess LV size, valve function, pericardial effusion, wall motion abnormalities, and ejection fraction. 

The safety relief valve is used for liquid and gas service. Safety relief valves function as relief valves for liquids and as safety valves for gases. 

The unmanned compressor building was equipped with a combustible gas detection system. However, it failed to sound an alarm because of a faulty relay in the control room. Automatic fail-safe valves functioned properly, blocking-in the flow of ethylene, but not before 450-11,000 lb of gas had already escaped. 

Osada et al. [52] have also grafted PMAA to a porous substrate in order to achieve an environmentally sensitive membrane. This sensitivity was termed a chemical valve function because mechanochemical forces caused the pores to enlarge and contract. PMAA was grafted onto poly(vinyl alcohol) (PVA) films which had a mean pore radius of 4 pm. The water permeation of the membrane was strongly affected by the conformational state of the PMAA grafts. At low pH the chains were contracted and the water permeability was... 

All valves contain rubber components (gaskets, tank seals, seats, or sleeves) and at least one stainless steel part (spring). Both are vital to valve functionality. Some types of valves contain more plastic or stainless steel components than others. Drawings of individual subcomponents of the valve should be on hand for reference to the incoming components. Periodic checking of the rubber or other components may be needed to ensure that the supplier has not changed any compositions or processing procedures. 

As explicitly mentioned in ASME, never install an SRV horizontally, both for the above reason - debris collection - and also for valve function. Although this seems obvious, the strangest installations exist in the field, with end users wondering why the valves do not function correctly (Figure 6.14). 

Figure 18.4 Fabrication and operation of a hybrid organic—inorganic nanovalve based on grafting of valve functionality to preformed nanoporous silica, (a) Grafting of ICTES to the surface of the mesoporous silica powders (b) linkage of a dialkylammonium pseudorotaxane to the surface of the silica through reaction with ICTES (c) loading of the pore volume with molecules (d) closing of the nanovalve by complexation of the dialkylammonium pseudorotaxane with a crown ether and (e) release of the pore volume contents by disruption of the crown ether-ammonium complex.

The simplest valve function is on-off service. Examples of this valve type are gate and ball valves, shown in Figure 8.2. A ball valve is used for tight shutoff. One application is a drain valve on a tank, where it is required to have the... 

Control of leakage rate Metering-valve function... 

Reactants are pumped from storage, then heated and injected into a mixing chamber (black flow lines). Sample is added to the mixing chamber, the mixture is injected into the flow cell, and the formazan production is monitored every 15 s for 3.5 min. The mixture is flushed, the system is rinsed, and the cycle begins again. The hatched regions are maintained at surface seawater temperatures. The four solenoid valves function most of the time in normally open (NO) or normally closed (NC) positions. A Technicon Autoanalyzer pump and a Bausch and Lomb Spectronic 88 spectrophotometer were used. 

There is also an adjustable check valve functioning as a gas release valve at the... 

Echocardiography Angiography Intravascular ultrasound Angioscopy Chamber size Wall motion Valve function Valve structure Pericardium Coronary anatomy... 

Normal mitral valve function requires intact leaflet structure, preserved subvalvular apparatus (i.e., chordae tendinae and papillary muscles), and a nondi-lated mitral annulus. Disruption of any one of these elements can lead to regurgitation of blood into the left atrium under the high pressure of left ventricular systole. 

In HPLC, the injection of a precise volume of sample onto the head of the column must be made as fast as possible in order to cause the minimum disturbance to the dynamic regime of the mobile phase whose flow must be stable from column to detector. This is done by a special high pressure valve, either manual or motorized, possessing several flow paths, which is situated just prior to the column (Figure 3.4). This must be a component of precision able to resist pressures greater than 30 000 kPa. The valve functions in two positions ... 

A great number of valving principles exists on the pressure driven laminar flow platform, summarized in a review by Oh and Ahn [38]. Active as well as passive solutions have been presented. However, no standards have emerged so far, so the choice and implementation of valves remains a difficulty on this platform. A possible approach is to transfer the valving functionality off-chip [113], thus decreasing the complexity and cost of the disposable. 

Due to its softness hydrogel elements are extremely particle permissive. This feature is important especially for valves. If a particle is present inside the valve seat during the closing process then the swelling hydrogel encloses it without any disturbance of the valve function. 

Given the flow through valve and pipe from equation (10.34), we will wish to find the throat pressure, p,. But the non-integer exponentiation in the nozzle-valve function, means that this will require the iterative solution of a nonlinear, implicit equation. Fortunately, however, fm may be approximated to excellent accuracy by the function, /wx. where ... 

Figure A4.3 shows /fugse and /nv against valve pressure ratio, pi p, when the friction coefficient is Cfgh = 1.25, typical of a globe valve. The FUGSE function predicts flows significantly smaller than the nozzle-valve function as the valve pressure ratio falls below about 0.9. The FUGSE function does not predict choked flow until Pi p has fallen to about O.IS, approximately a third of the valve pressure ratio.

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